EBOLA

December 6th, 2014

EBOLA: 

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Prologue:  

The most dangerous outbreak of an emerging infectious disease since the appearance of HIV seems to have begun on December 6, 2013, in the village of Meliandou, in Guinea, in West Africa, with the death of a two-year-old boy who was suffering from diarrhea and a fever. We now know that he was infected with Ebola virus. After Ebola infected the boy, it went from him to his mother, who died, to his three-year-old sister, who died, and to their grandmother, who died, and then it left the village and began moving through the human population of Guinea, Liberia, and Sierra Leone. Ebola virus is one of a group of zoonotic viruses that can cause severe disease in humans. The virus is known as a “zoonotic” virus because it’s transmitted to humans from animals. With pressures from a growing global population, climate change, deforestation, urbanization and uneven economic growth, zoonotic diseases are only likely to increase. The current 2014 epidemic is caused by the Zaire strain of Ebola virus, which has a mortality of 50 to 90%. Ebola virus is of great public health importance because of its ability to spread to carers and healthcare workers, the often high case fatality rate (CFR), difficulties in its rapid recognition, and the lack of effective specific treatment. Ebola first appeared in 1976 in a village near the Ebola River in the Democratic Republic of Congo (former Zaire). Forty years ago, Ebola was just the name of a river. It was a small waterway of no particularly sinister character that flowed through northern Zaire, not far from the village hospital where the first known outbreak of a new viral disease had been centered. That river gave its name to the new virus, and now “Ebola” is a global byword for ugly death, misery, and fear of contagion. The always frightening and often contradictory messages – and rumors – prompt patients to avoid going to the hospital due to fear of isolation and lack of effective treatments. It becomes impossible to identify the cases, confirm diagnosis, protect and monitor contacts. Violent protests – with loss of life, involving sometimes the medical staff – have been reported in some outbreaks. The disease threatens humanity by preying on humanity. Without seeing a single Ebola case, I am writing on Ebola as I felt that it is the most important topic that concerns the world as we move from 2014 into 2015.  

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Ebola the virus that scares even scientists: 

The figure above shows a researcher working with the Ebola virus while wearing a BSL-4 positive pressure suit to avoid infection. Everything entering or leaving the level 4 laboratory, even the air, is strictly controlled. When a level 4 agent is in the chambers, the air inside is kept at a slightly lower pressure, so a leak causes air to be sucked in rather than blown out. Any changes in pressure, for instance resulting from a pinprick in a rubber glove, cause an alarm to sound. A Russian scientist at a former Soviet biological weapons laboratory in Siberia has died in 2004 after accidentally sticking herself with a needle laced with ebola, the deadly virus for which there is no vaccine or treatment.  

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Abbreviations and synonyms:

EVD = Ebola virus disease = Ebola hemorrhagic fever (EHF) = Ebola  

EBVO = Ebola virus

ZEBOV = Zaire ebola virus  

SEBOV = Sudan ebola virus

TEBOV = Tai Forest ebola virus

REBOV = Reston ebola virus

BEBOV = Bundibugyo ebola virus    

R0 = Ro =RO = R ‘naught’ = Basic reproduction number

GP = Glycoprotein present on the surface of ebola virus

PPE = Personal protective equipment = biohazard suit

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In this article, Ebola means EVD caused by ZEBOV unless specified otherwise.

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On September 18th 2014, the United Nations Security Council held its first-ever emergency meeting on a health crisis. A Liberian man named Jackson Naimah spoke to the Council via video link from Liberia. Jackson works for Médecins Sans Frontières (MSF), and is a team leader in one of MSF’s Ebola treatment centers in Monrovia. He told the Council that he had lost a niece and a cousin to the virus – both of them nurses infected at work. He said that, as he was speaking to us, sick people were outside the gates of the MSF clinic, begging to be let in and treated. MSF had to turn them away, because they had no more beds. Jackson said, “I feel that the future of my country is hanging in the balance. If the international community does not stand up, we will be wiped out.”

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We all are familiar with the statistics of what Ebola has done to Liberia, Guinea, and Sierra Leone. More than 10,000 people infected. More than 5,000 people killed, nearly 250 of them health professionals. More than 4,000 children orphaned. Governments of affected countries were initially in denial over the occurrence of the disease. Subsequently, they relinquished responsibility for the care of infected patients to overworked international non-governmental organisations and issued incoherent directives, such as the closure of markets and borders. The Ebola outbreak has now become so serious that health infrastructure is beginning to collapse and hospitals are closing. Without effective medical care patients are dying not only of Ebola but of malaria, diarrhoea, and other conditions. As the Ebola epidemic in West Africa has spiraled out of control, affecting thousands of Liberians, Sierra Leonians, and Guineans, and threatening thousands more, the world’s reaction has been glacially, lethally slow. Only in the past few weeks have heads of state begun to take serious notice. There is no Ebola Vaccine because “the virus previously affected only poor African nations”, WHO chief Dr Margaret Chan says. She criticized drugs companies for turning their backs on markets that cannot pay.

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Introduction to Ebola:

Ebola typically strikes like the worst and most humiliating flu you could imagine. People get the sweats, along with body aches and pains. Then they start vomiting and having uncontrollable diarrhea. These symptoms can appear anywhere between 2 and 21 days after exposure to the virus. Sometimes, they go into shock. Sometimes, they bleed. In fatal cases, death comes fairly quickly — within a few days or a couple of weeks of getting sick. Survivors return to a normal life after a months-long recovery that can include periods of hair loss, sensory changes, weakness, fatigue, headaches, eye and liver inflammation.

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Ebola, previously known as Ebola hemorrhagic fever, is a rare and deadly disease caused by infection with one of the Ebola virus strains. Ebola can cause disease in humans and nonhuman primates (monkeys, gorillas, and chimpanzees). Ebola is caused by infection with a virus of the family Filoviridae, genus Ebolavirus. There are five identified Ebola virus species, four of which are known to cause disease in humans: Ebola virus (Zaire ebolavirus); Sudan virus (Sudan ebolavirus); Taï Forest virus (Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus); and Bundibugyo virus (Bundibugyo ebolavirus). The fifth, Reston virus (Reston ebolavirus), has caused disease in nonhuman primates, but not in humans. Ebola viruses are found in several African countries. Ebola was first discovered in 1976 near the Ebola River in what is now the Democratic Republic of the Congo. Since then, outbreaks have appeared sporadically in Africa. The natural reservoir host of Ebola virus remains unknown. However, on the basis of evidence and the nature of similar viruses, researchers believe that the virus is animal-borne and that bats are the most likely reservoir. Four of the five virus strains occur in an animal host native to Africa. Ebola hemorrhagic fever (EHF) is one of the most severe viral infections of humans. In outbreaks in central Africa caused by the Zaire species of ebolavirus (ZEBOV), the mortality rate among identified cases has reached 80–90%, while fatalities in epidemics caused by the Sudan species have been in the range of 50–60% (Bwaka et al., 1999; Sanchez et al., 2004). The natural reservoir of these agents has not been identified; humans are only accidental or “dead-end” hosts (Mahanty & Bray, 2004).  Ebola virus causes an acute infection. The infection lasts for about two weeks and then it is over. If the patient is lucky, he or she survives, but unfortunately, in many cases, the patients die. But unlike other viruses, including HIV, Ebola virus does not persist in the infected patient. In this aspect it behaves more like the influenza virus. You get ill and a couple of days later it is over—one way or another.

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What is a virus?

Viruses are particles of nucleic acids, either RNA or DNA, which are surrounded by proteins and sometimes additionally by lipid membranes. With few exemptions, viruses are very small, about 100 times smaller than bacteria. Most importantly, viruses have a parasitic life style and must infect living cells to reproduce. They hijack cellular machineries to amplify their genomes and produce their own proteins and membranes. Virus is alive yet dead, simple yet complex, mindless yet prophetic, seemingly able to anticipate our every move. For scientists who study the evolution and behavior of viruses, the Ebola pathogen is performing true to its vast, ancient and staggeringly diverse kind. By all evidence, researchers say, viruses have been parasitizing living cells since the first cells arose on earth nearly four billion years ago. Some researchers go so far as to suggest that viruses predate their hosts. That they essentially invented cells as a reliable and renewable resource they could then exploit for the sake of making new viral particles. Researchers are deeply impressed by the depth and breadth of the viral universe, or virome. Viruses have managed to infiltrate the cells of every life form known to science. They infect animals, plants, bacteria, slime mold, even larger viruses. As so-called obligate parasites entirely dependent on host cells to replicate their tiny genomes and fabricate their protein packages newborn viruses, or virions, must find their way to fresh hosts or they will quickly fall apart, especially when exposed to sun, air or salt. Viruses are masters at making their way from host to host and cell to cell, using every possible channel. Viruses are also notable for what they lack. They have no ribosomes, the cellular components that fabricate the proteins that do all the work of keeping cells alive. Instead, viruses carry instructions for co-opting the ribosomes of their host, and repurposing them to the job of churning out capsid and other viral proteins. Other host components are enlisted to help copy the instructions for building new viruses, in the form of DNA or RNA, and to install those concise nucleic texts in the newly constructed capsids. Viruses also work tirelessly to evade the immune system that seeks to destroy them. One of the deadliest features of the Ebola virus is its capacity to cripple the body’s first line of defense against a new pathogen, by blocking the release of interferon. That gives the virus a big advantage to grow and spread. Yet the real lethality of Ebola stems from a case of mistaken location, a zoonotic jump from wild animal to human being. The normal host for Ebola virus is the fruit bat, in which the virus replicates at a moderate pace without killing or noticeably sickening the bat. A perfect parasite is able to replicate and not kill its host. The Ebola virus is the perfect parasite for a bat.  

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The virus needs to replicate inside an infected cell. Like many other viruses, Ebola virus brings its own genome replication machinery into the cell. If we understand how this machinery works, we can identify targets for antiviral compounds that block viral replication. This approach has been used successfully for other viruses, such as herpes viruses and HIV.  Ebola virus infects specific cells of the immune system that are needed to fight the virus at an early stage of infection. In these cells, Ebola virus blocks antiviral pathways and reprograms the cells in a way that they are not able to respond to the infection effectively. On top of this, the infected cells are used as vessels to transport the virus to almost all organs of the body, where it infects additional cells. This leads to a so-called systemic infection with the devastating consequences for which Ebola virus infections are notorious. Therefore, our goal is to identify antiviral pathways that can be activated in Ebola virus–infected cells, which would lead to the destruction of the infected cells before the virus can spread further. For example, researchers have tested an antiviral drug that selectively induces a suicide program in virus-infected cells. They showed that it kills Ebola virus–infected cells without harming uninfected cells. If the infected cells are eliminated, the virus cannot spread through the body anymore.  

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The viral haemorrhagic fevers (VHFs) are caused by four types of ribonucleic acid (RNA) virus:

Although agents that cause viral hemorrhagic fever syndrome constitute a geographically diverse group of viruses, all of those identified to date are RNA viruses with a lipid envelope, all are considered zoonoses, all damage the microvasculature (resulting in increased vascular permeability), and all are members of one of the following 4 families:

•Filoviruses cause Ebola and Marburg.

•Arenaviruses cause Lassa fever, Argentine haemorrhagic fever (HF), Bolivian HF, Brazilian HF and Venezuelan HF.

•Bunyaviruses cause Korean HF (Hantavirus), Rift Valley fever (RVF) and Crimean-Congo HF (CCHF).

•Flaviviruses cause yellow fever and dengue fever.

They are all infectious and lead to a potentially fatal disease with fever, malaise, vomiting, mucosal and gastrointestinal bleeding, oedema, and hypotension. Many VHF viruses are virulent, and some are highly infectious (e.g., filoviruses and arenaviruses) with person-to-person transmission from direct contact with infected blood and bodily secretions. Effective therapies and prophylaxis are extremely limited for VHF; therefore, early detection and strict adherence to infection control measures are essential. Ebola virus is one of at least 30 known viruses capable of causing viral hemorrhagic fever syndrome.

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A New Virus Emerges:

In the summer of 1976, Ngoy Mushola, a doctor from Bumba, Zaire, traveled to Yambuku, a town on the shores of the Ebola river.  There, at a local hospital, Mushola recorded the first clinical description of a new disease that was killing almost all of the patients who contracted it. “The illness is characterized with a high temperature of about 39°C, hematemesis [the vomiting of blood], diarrhea with blood, abdominal pain, prostration with “heavy” articulations, and rapid evolution death after a mean of three days,” he wrote in his daily log. The illness, which was later named Ebola hemorrhagic fever after the nearby river, was successfully contained in Zaire over the course of a few months, but not before 318 people contracted the virus. Nearly 90 percent of the victims died within a few days of becoming infected. Hundreds of miles away, in Maridi and Nzara, two cities in the southern tip of Sudan, doctors were witnessing an outbreak, describing patients with high fevers, aches, nausea, bleeding, delirium, and what they termed a “mask-like” or “ghost-like” face. Two hundred and eighty-four were infected and over half died.  One of the main risk-factors associated with Ebola virus in the Sudan outbreak was caring for the sick. The disease was spread within hospitals, and many medical care personnel were infected. In several of the Ebola hemorrhagic fever outbreaks that have followed, health care workers have been at risk, and there have been many documented cases of doctors and nurses contracting Ebola virus from the patients they were tending.  Scientists and laboratory personnel working with the live virus are also at risk, and a few months after the Sudan outbreak, a scientist working with the virus in England became infected after he accidentally stuck himself with an infected needle.

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Virulent and Rare:

The virus is intriguing because it acts so quickly. It kills people in two weeks or less.  As deadly as Ebola virus is, it has never sustained a large outbreak, probably due to its speed of action and how powerfully sick it makes people. Even as case-fatality can approach 90 percent, infected patients become bed-ridden while they are most infectious, and infection is spread only through direct contact with bodily fluids. Thus, patients are easily quarantined and outbreaks contained. Humans are the unlikely target. Humans are not the natural reservoir for Ebola virus, but merely incidental or accidental hosts.  Ebola and Lassa are both non-human viruses. They are persistent in animal populations in the wild, and remain in this animal “reservoir” population because they are not deadly enough to kill the infected animals—an evolutionary advantage for a virus to remain endemic in its host species population.

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Deadly features of Ebola:

•Its kill rate: In this particular outbreak of 2014, a running tabulation suggests that 54 percent of the infected die, though adjusted numbers suggest that the rate is much higher.

•Its exponential growth: At this point, the number of people infected is doubling approximately every three weeks.

•The gruesomeness with which it kills: by hijacking cells and migrating throughout the body to affect all organs, causing victims to bleed profusely.

•The ease with which it is transmitted: through contact with bodily fluids, including sweat, tears, saliva, blood, urine, vomitus, semen, etc., including objects that have come in contact with bodily fluids (such as bed sheets, clothing, and needles) and corpses.

•The threat of mutation: Prominent figures have expressed serious concerns that this disease will go airborne, and there are many other mechanisms through which mutation might make it much more transmissible.

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Ebola BSL 4 pathogen:

Because of its high mortality rate, EBOV is listed as a select agent, World Health Organization Risk Group 4 Pathogen (requiring Biosafety Level 4-equivalent containment), a U.S. National Institutes of Health/National Institute of Allergy and Infectious Diseases Category A Priority Pathogen, U.S. CDC Centers for Disease Control and Prevention Category A Bioterrorism Agent, and listed as a Biological Agent for Export Control by the Australia Group. Viruses are ranked on a biosafety level (BSL) scale from 1 – 4, with 4 being the most severe. Ebola is a BSL4 pathogen, for which there are no approved therapeutics or vaccines. The virus is transmitted from one individual to another through the exchange of bodily fluids and enters the body through exposed cuts or mucous membranes, such as an individual’s mouth or nose.

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Case definition and contact tracing:

Ebola virus disease (EVD; also Ebola hemorrhagic fever, or EHF), or simply Ebola, is a disease of humans and other primates caused by ebola viruses. Signs and symptoms typically start between two days and three weeks after contracting the virus as a fever, sore throat, muscle pain, and headaches. Then, vomiting, diarrhea and rash usually follow, along with decreased function of the liver and kidneys. At this time some people begin to bleed both internally and externally. Death rates can vary widely, with death occurring in about 50% of cases. This is often due to low blood pressure from fluid loss, and typically follows six to sixteen days after symptoms appear. Surveillance is also a problem. The case definition that was adopted was accurate in the epidemic setting, but it would be much less so in sporadic infections or at the beginning of an epidemic. The finding of copious amounts of Ebola virus antigen in skin opened the way to confirm cases by taking simple skin biopsies, which could be placed in formalin and analyzed later by immunohistochemistry. This obviates the need for cold chain or special precautions while processing or shipping infectious material. One could argue that Ebola diagnostics should be placed at many sites in the potentially endemic areas, but this may be unrealistic given the small number of expected cases and the economics.

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Case definition of Ebola Virus Disease (EVD):

Name Definition
Index case Very first case (probable or confirmed, see below) found to be the origin of the outbreak
Alert case Any person with sudden onset of high fever or sudden death or bleeding or bloody diarrhea or blood in urine
Suspect case (person under investigation) Any person, dead or alive, who present (or presented before the death):
(i) fever (>38.5°C or 101.5 °F) with additional symptoms (severe headache, muscle pain, vomiting, diarrhea, abdominal pain, or unexplained hemorrhage) and (ii) epidemiologic risk factors within the past 21 days before the onset of symptoms (close contact with body fluids of a suspect or probable case of EVD, or direct handling of bush animals from disease-endemic areas)
Probable case Person with symptoms compatible with EVD, as evaluated by a clinician, or a dead person with an epidemiological link with a confirmed case
Contacts Person without suggestive symptom of the disease, but who has been in contact with a suspect or probable case of EVD (living in the same house, provided care during the illness, participated in the burial rites etc.). It should be important to assess the risk level.
If laboratory samples are obtained at an appropriate time during the illness, the previous notification categories should be reclassified as “laboratory-confirmed” cases and “not a case”
Confirmed case Case with positive laboratory response for either PCR or viral isolation or Ebola virus antigen or Ebola antibody
“Not a case” Person with no Ebola-specific detectable antibody or antigen

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Contacts of dead or sick animals:

Any person having been exposure to a sick or dead animal in at least one of the following ways:

- has had direct physical contact with the animal

- has had direct contact with the animal’s blood or body fluids

- has carved up the animal

- has eaten raw bush-meat

Provided that this exposure has taken place less than 21 days before the identification as a contact by surveillance teams

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Laboratory contacts:

Any person having been exposed to biological material in a laboratory in at least one of the following ways:

- has had direct contact with specimens collected from suspected Ebola patients

- has had direct contact with specimens collected from suspected Ebola animal cases

Provided that this exposure has taken place less than 21 days before the identification as a contact by surveillance teams

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The contact person should be followed for 21 days after exposure. If the contact person is asymptomatic for 21 days after exposure, he is released from follow-up.

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Contact tracing:

Contact tracing is considered important to contain an outbreak. It involves finding everyone who had close contact with infected individuals and watching for signs of illness for 21 days. If any of these contacts comes down with the disease, they should be isolated, tested and treated. Then the process is repeated by tracing the contacts’ contacts. Social mobilization and culturally appropriate health education efforts are critical to successful case identification and tracking of contacts.

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Why contact tracing so important for ebola:


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The table below shows risk associated with types of contact:

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Epidemiology, ecology and outbreak of ebola:   

Epidemiology of ebola:

The first cases of filovirus haemorrhagic fever were reported in 1967 in Germany and the former Yugoslavia, and the causative agent was identified as Marburg virus (named after the German city where it was first seen in researchers who caught it from imported non-human primates). Similar cases of haemorrhagic fever were described in 1976 from outbreaks in two neighbouring locations: first in southern Sudan and subsequently in northern Zaire, now Democratic Republic of the Congo (DRC). An unknown causative agent was isolated from patients in both outbreaks and named Ebola virus after a small river in northwestern DRC. These two epidemics were caused by two distinct species of Ebola virus, Sudan Ebola virus and Zaire Ebola virus, a fact not recognised until years later. The third African Ebola virus species, Côte d’Ivoire Ebola virus was discovered in 1994. The virus was isolated from an infected ethnologist who had worked in the Tai Forest reserve in Côte d’Ivoire and had done a necropsy on a chimpanzee. The animal came from a troop that had lost several members to an illness later identified as Ebola haemorrhagic fever. The latest discovery is Bundibugyo Ebola virus, the fourth African species of human-pathogenic Ebola virus found in equatorial Africa (approximate distribution 10° north and south of the equator). An additional Ebola virus species, Reston Ebola virus, is found in the Philippines. It was first described in 1989 and isolated from Cynomolgus monkeys (Macaca fascicularis) housed at a quarantine facility in Reston, VA, USA. These monkeys were imported from the Philippines; an unusually high mortality was noted in infected animals during quarantine, but simian haemorrhagic fever virus co-circulated in the animals. Subsequently, Reston Ebola virus has been found in the Philippines on several occasions with surprising reports documenting infections in pigs.

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Epidemiologic studies (including a specific search in the Kikwit epidemic) have failed to yield evidence for an important role of airborne particles in human disease. This lack of epidemiologic evidence is surprising and seems to conflict with the viruses’ classification as biosafety level 4 pathogens (which is based in large part on aerosol infectivity) and with formal laboratory assessments showing a high degree of aerosol infectivity for monkeys. Sick humans apparently do not usually generate sufficient amounts of infectious aerosols to pose a significant hazard to those around them. Although numerous die-offs have been reported among chimpanzees and gorillas (some even threatening the viability of these endangered species), these animals (like humans) appear to be sentinels for virus activity. Speculation about the true reservoirs has centered on bats, and preliminary evidence indicates that bats may indeed be the reservoirs of filoviruses. This evidence includes the detection of antibodies and reverse-transcriptase polymerase chain reaction (RT-PCR) products in bats, the epidemiologic findings in subterranean gold mines in Durba (DRC) where Marburg transmission has occurred, and reported associations of human antibody production with the handling of bats. Recent isolation of Marburg virus from Egyptian fruit bats (Rousettus aegyptiacus) captured in Uganda in proximity to cases of human disease further supports bats as reservoirs, but the exact biologic relation and the natural cycle remain to be elucidated.

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Epidemiologic Investigations:

Health authorities have to gather data on possible transmission chains from hospital records and through interviews with patients in whom EBOV infection was suspected and their contacts, affected families, inhabitants of villages in which deaths occurred, attendants of funerals, public health authorities, and hospital staff members.

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Ecology of ebola:

Ebola haemorrhagic fever is thought to be a classic zoonosis with persistence of the Ebola virus in a reservoir species generally found in endemic areas. Apes, man, and perhaps other mammalian species that are susceptible to Ebola virus infection are regarded as end hosts and not as reservoir species. Although much effort has been made to identify the natural reservoirs with every large outbreak of Ebola haemorrhagic fever, neither potential hosts nor arthropod vectors have been identified.  Rodents and bats have long been thought to be potential reservoir species. This idea was supported by experimental studies in African plants and animals that resulted in productive infection of African fruit and insectivorous bats with Zaire Ebola virus, but a firm link could not be established. The first evidence for the presence of Zaire Ebola virus in naturally infected fruit bats was documented by detection of viral RNA and antibodies in three tree-roosting species: Hypsignathus monstrosus, Epomops franqueti, and Myonycteris torquata. However, despite efforts, Zaire Ebola virus has not been successfully isolated from naturally infected animals. The identification and successful isolation of Marburg virus from the cave-dwelling fruit bat Rousettus aegyptiacus further lends support to the idea of bats as a reservoir species for filoviruses. This finding is reassuring since several of the Marburg virus outbreaks have been associated with caves or mines that are usually heavily infested by bats. Data for potential reservoirs for any of the other four Ebola virus species do not exist. Infections with Ebola virus are rare in equatorial Africa, although probably under-reported. Transmission from the reservoir species to man or other end hosts might therefore be an infrequent event, given the restricted distribution of or restricted contact with the reservoir species. However, bats are frequently encountered in equatorial Africa and hunted for food in many places. Therefore, Ebola virus might persist as an asymptomatic or subclinical infection in the reservoir species, with little or no transmission, and might be sporadically activated through an appropriate stimulus. The stimulus might be stress, co-infection, change in food sources, and pregnancy, as shown experimentally in vivo and in vitro. This hypothesis would explain the sporadic nature and periodicity of outbreaks of Ebola haemorrhagic fever in Africa.

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Seasonal variation in mortality in chimpanzees of the Tai forest, Ivory Coast, and prevalence of specific antibodies against Zaire ebolavirus virus in febrile patients from East Africa suggests an influence of the climate in the occurrences of Ebola epidemics. Pinzon et al. found a close relationship between the onset of epidemics and particularly dry conditions at the end of the rainy season, leading to a change in the behavior of fruit-eating mammals, particularly sensitive to weather changes, resulting in the increase of virus circulation or human contamination. The seasons punctuate migration of bats, which could explain the emergence of epidemics.

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Mapping the zoonotic niche of Ebola virus disease in Africa: a 2014 study:

Ebola virus disease (EVD) is a complex zoonosis that is highly virulent in humans. The largest recorded outbreak of EVD is ongoing in West Africa, outside of its previously reported and predicted niche. Authors assembled location data on all recorded zoonotic transmission to humans and Ebola virus infection in bats and primates (1976-2014). Using species distribution models, these occurrence data were paired with environmental covariates to predict a zoonotic transmission niche covering countries across Central and West Africa. Vegetation, elevation, temperature, evapotranspiration, and suspected reservoir bat distributions define this relationship. At-risk areas are inhabited by 22 million people; however, the rarity of human outbreaks emphasizes the very low probability of transmission to humans. Increasing population sizes and international connectivity by air since the first detection of EVD in 1976 suggest that the dynamics of human-to-human secondary transmission in contemporary outbreaks will be very different to those of the past.

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Ebola Outbreak 2014:

Epidemics usually begin with a single case acquired from an unknown reservoir in nature (bats are suspected) and spread mainly through close contact with sick persons or their body fluids, either at home or in the hospital.  Since 1976, there have only been about 20 known Ebola outbreaks. Until last year, the total impact of these outbreaks included 2,357 cases and 1,548 deaths, according to the Centers for Disease Control and Prevention. They all occurred in isolated or remote areas of Africa, and Ebola never had a chance to go very far. And that’s what makes the 2014 outbreak so remarkable: the virus has spread to six countries in Africa plus America, and has already infected more than 13,000 people. It has killed nearly 5,000 people. That is more than six times the sum total of all previous outbreaks combined.

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A complex epidemic of Zaire ebolavirus (EBOV) has been affecting West Africa since approximately December 2013, with the first cases likely occurring in southern Guinea. The causative Ebola strain is closely related to a strain associated with past EBOV outbreaks in Central Africa and could have been circulating in West Africa for about a decade. However, the current epidemic was not identified until March 2014, which facilitated several transmission chains to progress essentially unchecked in the region and to cross porous borders with neighboring Sierra Leone and Liberia and seed a limited outbreak in Nigeria via commercial airplane on 20 July 2014. The World Health Organization declared the Ebola epidemic in West Africa a Public Health Emergency of International Concern on 8 August 2014, with exponential dynamics characterizing the growth in the number of new cases in some areas. Economic and sociocultural factors together with the delay in identifying the outbreak in urban settings have hindered a timely and effective implementation of control efforts in the region.

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The Situation:

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The 2014 Ebola epidemic is centered in the area where Liberia, Sierra Leone and Guinea meet and has infected almost 14,000 victims since December 2013, killing about 5,000. More will die, given a fatality rate of 71 percent in this outbreak. The U.S. Centers for Disease Control and Prevention estimates actual cases are 2.5 times higher and are roughly doubling every month. The epidemic spread to Nigeria and Senegal, which successfully contained it. It reached Mali in late October. Early on, the disease was transmitted by victims who avoided hospitals because of stigma and fear, as well as by unsafe burial practices. As cases increased, efforts to control the epidemic were hampered by a shortage of trained workers at a time when humanitarian groups were dealing with many crises elsewhere. The U.S. responded by sending hundreds of military personnel to Liberia, which in October 2014 began to see a reduction in cases. Ebola jumps to humans through contact with secretions from animals such as chimpanzees, gorillas and bats. It spreads among humans the same way, with medical workers and family members the most at risk. A separate outbreak reported in late August has killed scores of people in the Democratic Republic of Congo. In the first known instance of Ebola transmission outside Africa, medical workers in the U.S. and Spain were infected after caring for people who had contracted Ebola in Africa. Ebola patients infected in Africa have been treated in a number of other European countries.

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Ebola response roadmap – Situation Report- 3rd December 2014:  WHO:

A total of 17,145 confirmed, probable, and suspected cases of Ebola virus disease (EVD) have been reported in five affected countries (Guinea, Liberia, Mali, Sierra Leone, and the United States of America) and three previously affected countries (Nigeria, Senegal and Spain) up to the end of 30 November. There have been 6070 reported deaths. Cases and deaths continue to be under-reported in this outbreak. 

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Some countries have encountered difficulties in their efforts to control the epidemic. In some areas, people have become suspicious of both the government and hospitals, some of which have been attacked by angry protesters who believe either that the disease is a hoax or that the hospitals are responsible for the disease. Many of the areas seriously affected by the outbreak are areas of extreme poverty with limited access to the soap and running water needed to help control the spread of disease.  Other factors include reliance on traditional medicine and cultural practices that involve physical contact with the deceased, especially death customs such as washing and kissing the body of the deceased. Some hospitals lack basic supplies and are understaffed, increasing the chance of staff catching the virus themselves. In August, the WHO reported that ten percent of the dead have been health care workers. By the end of August, the WHO reported that the loss of so many health workers was making it difficult for them to provide sufficient numbers of foreign medical staff. In September 2014, the WHO estimated that the countries’ capacity for treating EVD patients was insufficient by the equivalent of 2,122 beds. By the end of October many of the hospitals in the affected area had become dysfunctional or had been closed, leading some health experts to state that the inability to treat other medical needs may be causing “an additional death toll [that is] likely to exceed that of the outbreak itself”. By September 2014, Médecins Sans Frontières/Doctors Without Borders (MSF), the largest NGO working in the affected countries, had grown increasingly critical of the international response. Speaking on 3 September, the president of MSF spoke out concerning the lack of assistance from the United Nations member countries saying, “Six months into the worst Ebola epidemic in history, the world is losing the battle to contain it.” A United Nations spokesperson stated, “They could stop the Ebola outbreak in West Africa in 6 to 9 months, but only if a ‘massive’ global response is implemented.” The Director-General of the WHO, Margaret Chan, called the outbreak “the largest, most complex and most severe we’ve ever seen” and said that it is “racing ahead of control efforts”. In a 26 September statement, the WHO said, “The Ebola epidemic ravaging parts of West Africa is the most severe acute public health emergency seen in modern times.”

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Ebola tip of the iceberg:

For every four cases of Ebola we know of, there might be six that we don’t:

While official estimates suggest there are already more than 13,000 cases of Ebola this year, the real number is likely much, much higher. The Centers for Disease Control and Prevention estimate that the actual number of Ebola cases is roughly 2.5 times higher than the reported figures — so for every four Ebola cases we know of, there could be six that we don’t. The CDC isn’t alone in this. “There is widespread under-reporting of new cases,” warns the World Health Organization. The WHO has continually said that even its current dire numbers don’t reflect the full reality. The estimated 13,000-plus Ebola cases in West Africa could just be the tip of the iceberg.

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Could Ebola become endemic worldwide?

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Global health agencies were too slow in responding to the Ebola crisis:

Ebola is a very preventable disease. We’ve had over 20 previous outbreaks and we managed to contain all of them. It could take months for a full response to get off the ground. But this time, the international response just wasn’t there. There was no mobilization. The World Health Organization didn’t call a public health emergency until August — five months after the first international spread [in March]. It took three months for health officials to identify Ebola as the cause of the epidemic, another five months to declare a public health emergency, and two more months to mount a humanitarian response. In reality, a full response could take several more months still to get off the ground. Part of the reason for the slow response can be attributed to budget cuts at the WHO that have left the agency understaffed and under-resourced. The WHO also now sees itself as a “technical agency,” providing analysis and data, and not as a first responder. But, as an editorial in the journal Nature pointed out: “If the WHO is not the first responder to an emergency such as this, then who is?” The International Health Regulations governing disease responses are also flawed and broken, leaving us unprepared for outbreaks. So this Ebola epidemic has served as a reminder of just how slow and poorly coordinated our global responses to outbreaks are, and this is a problem because any infectious diseases expert will tell you that the best way to stop an outbreak is to contain it early.

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Health is not free from politics, either. Sadly, the world only seemed to wake up to Ebola after two American missionaries got infected in Liberia. One of them, Dr. Kent Brantly, testified before the Senate in the US to make that point: “This unprecedented outbreak began nine months ago but received very little attention from the international community until the events of mid-July when my friend and colleague, Nancy Writebol, and I became infected.” He added: “The response, however, is still unacceptably out-of-step with the size and scope of the problem now before us.” “Ebola could establish itself as an endemic infection because of a highly inadequate and late global response.” The awakening came too late. Preeminent disease researchers, in an article in the New England Journal of Medicine, wrote, “Ebola has reached the point where it could establish itself as an endemic infection because of a highly inadequate and late global response.” Still, the global health community is now moving aggressively. The director of the World Health Organization called this Ebola epidemic “the greatest peacetime challenge” the world has ever faced. President Barack Obama called the epidemic “not just a threat to regional security… [but] a potential threat to global security.” For this reason, the United States has sent more than 3,000 troops to fight Ebola and has now funded the largest international response in the history of the CDC. In October 2014, the Obama administration appointed Ron Klain it’s first-ever “Ebola Czar” to coordinate the response. In other desperate and unprecedented measures, the United Nations Security Council characterized the virus a threat to international peace and security, holding its second-ever disease-focused meeting and setting up a special UN mission to deal with the epidemic. The Security Council unanimously passed a resolution asking countries around the world to urgently send medical workers and supplies to stop the epidemic. If these measures fail, the world may be faced with something it has never seen before: endemic Ebola.

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Potential for large outbreaks of Ebola virus disease: a 2014 study:
Outbreaks of Ebola virus can cause substantial morbidity and mortality in affected regions. The largest outbreak of Ebola to date is currently underway with a total of 15,935 confirmed, probable, and suspected cases of Ebola virus disease (EVD) reported in six affected countries till 23 November 2014. To develop a better understanding of Ebola transmission dynamics, authors revisited data from the first known Ebola outbreak, which occurred in 1976 in Zaire (now Democratic Republic of Congo). By fitting a mathematical model to time series stratified by disease onset, outcome and source of infection, they were able to estimate several epidemiological quantities that have previously proved challenging to measure, including the contribution of hospital and community infection to transmission. They found evidence that transmission decreased considerably before the closure of the hospital, suggesting that the decline of the outbreak was most likely the result of changes in host behaviour. Their analysis suggests that the person-to-person reproduction number was 1.34 (95% CI: 0.92–2.11) in the early part of the outbreak. This has profound implications: it suggests that a large outbreak (involving thousands of cases) could have happened even without changing any epidemiological conditions. Authors estimated the probability of such a large outbreak (>1000 cases) to be around 3%. This means that given the same initial conditions, Ebola outbreaks would have been occasionally been large, just by chance. Moreover, a relatively high person-to-person transmission component (R0pp ≈ 1) implied that the 1976 epidemic would have been difficult to control via hospital-based infection control measures alone. If the reduction in community transmission had been smaller, or infection had been seeded into a number of different communities, the outbreak could have continued for some time. The results also suggest that changes in behaviour caused a significant reduction in both hospital-to-community and within-community transmission. Although Yambuku Mission hospital closed on the 30th September, they found that the reduction in transmission occurred well before this point, most likely from susceptible hosts having less contact with infected patients, and making fewer routine outpatient visits to the hospital (Breman et al., 1978). As well as contributing to transmission, infections from syringes also appeared to have a higher case fatality ratio (CFR) than person-to-person infections. This could have been the result of a larger viral inoculum during contact with a contaminated syringe.

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Is India prepared to keep Ebola out?

World Health Organisation’s (WHO) India office says it is holding regular meetings with the technical staff at the Union health ministry for developing “appropriate response measures”. It is also guiding the ministry on how to prevent and control the infection “at health facilities, train rapid response teams for laboratory testing, surveillance and emergency contingency planning”. Screening for the virus at the country’s 18 international airports has been stepped up. Scanners that can detect high body temperatures have been placed at the immigration counters.  A mandatory health card is distributed to all passengers who have either travelled to the four Ebola-affected countries, Liberia, Guinea, Sierra Leone and Nigeria (now declared Ebola-free), or have transited through these countries during the past 21 days. Travelers are questioned about their contact, if any, in the last 21 days – the incubation period for the virus – with any Ebola patient and whether they worked or visited high-risk areas like hospitals. All flights carrying suspected cases are disinfected before the next batch of passengers is allowed to board. To date, around 22,000 passengers have been screened at airports across India. Of these, 55 were found to be high-risk (those with fever), seven were medium-risk (those with contact history) and 21,737 were low-risk (those who did not have symptoms or history of contact) passengers.  The health ministry says the suspected and high-risk cases have all tested negative. Over 1,000 passengers, mostly from Maharashtra, Kerala, Tamil Nadu, Gujarat, West Bengal and Delhi, have also been tracked by the Integrated Disease Surveillance Program (IDSP). High-risk passengers are taken in an ambulance to the designated quarantine facility through a dedicated route without entering the immigration area or mixing with other passengers. Medium-risk passengers have to share their contact details and are tracked actively for at least 21 days by IDSP. Low-risk passengers are provided another health card and advised to contact a helpline if any symptom appears. The immigration staff deputed for Ebola detection has been provided with protective gear. Like at IGI, at the Chhatrapati Shivaji International Airport in Mumbai, a team of trained doctors appointed by the Airport Health Organisation is screening passengers at counters in the pre-immigration arrival area. “Doctors have been instructed to keep a look out for passengers suffering from flu,” says an airport health official. The airport does not have a laboratory, so blood samples of any suspected Ebola case are sent to the National Institute of Virology in Pune for testing. “The test result is ready in 24, at most 48, hours,” says a scientist at the Pune institute. “The virus shows in the blood once the symptoms appear,” he adds. The only other designated laboratory equipped to test for Ebola is the National Centre for Disease Control in Delhi. Now the Indian Council for Medical Research has shortlisted another 10 laboratories to test the virus. At the government’s 24-hour Ebola emergency helplines (011-23061469, 23063205 and 23061302), set up at the health ministry in Delhi, doctors from central government hospitals are on duty round the clock. “We have been getting calls from people wanting to discuss their travel history and risks attached,” says a doctor on duty.  Private hospitals too have been calling for details about Ebola symptoms and precautions to be taken. The control room has received about 800 calls since its inception on August 9. The standing instruction is to immediately direct suspected cases to RML Hospital.

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India quarantines man recovering from Ebola:

India has quarantined a man who was cured of Ebola in Liberia but continued to show traces of the virus in samples of his semen after arriving in the country. The Indian man carried with him documents from Liberia that stated he had been cured. It is not an Ebola case, he is an Ebola-treated patient who is negative in blood but whose body fluid is positive. He has no symptoms. Tests of his semen detected traces of the virus. He will be kept in quarantine until the virus is no longer present in his body. The Indian government has now asked those travelling to India from Ebola-affected countries to carry a certificate stating that there is no evidence of the deadly virus in their body fluids, after this person cured of the disease was found to be carrying the virus in his semen. Peter Piot, a former WHO official who was one of the discoverers of the virus, has in the past expressed concerns about the disease spreading to India. There are nearly 45,000 Indian nationals living in West Africa. Many experts say densely populated India is not adequately prepared to handle any spread of the highly infectious haemorrhagic fever among its 1.2 billion people. Government health services are overburdened and many people in rural areas struggle to get access to even basic health services. Hygiene standards are low, especially in smaller towns and villages, and defecating and urinating in the open are common. 

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Social and cultural aspects of ebola:

Socio-cultural factors:

Socio-cultural factors have not only contributed significantly to Ebola spread, but have also complicated the implementation of control interventions. Specifically, cultural practices involving touching the body of the deceased naturally (and greatly) contribute to the dissemination of the Ebola virus. In particular, the potential for transmission to neighboring and distant areas by exposed funeral attendants could facilitate the development of major epidemics. Moreover, the lack of prior experience or knowledge of the disease can lead communities to deny its existence and to associate illness with witchcraft or conspiracy theories presumably created by governments to gain control of populations or attract resources from the international community. For instance, during the ongoing epidemic in West Africa, a group of individuals looted equipment and potentially contaminated materials in an isolation facility in a quarantined neighborhood. Finally, the stigma carried by Ebola survivors and family members of Ebola victims could exacerbate disease spread. In particular, uninformed families tend to hide relatives and friends infected with Ebola to avoid being shunned by their own communities, which enhances transmission rates. The problem is compounded by the high case fatality ratio of EVD whereby misinformed communities tend to associate case isolation with a death sentence.

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Ebola is spread through close physical contact with infected people. This is a problem for many in the West African countries currently affected by the outbreak, as practices around religion and death involve close physical contact. Hugging is a normal part of religious worship in Liberia and Sierra Leone, and across the region the ritual preparation of bodies for burial involves washing, touching and kissing. Those with the highest status in society are often charged with washing and preparing the body. For a woman this can include braiding the hair, and for a man shaving the head. If a person has died from Ebola, their body will have a very high viral load. Bleeding is a usual symptom of the disease prior to death. Those who handle the body and come into contact with the blood or other body fluids are at greatest risk of catching the disease. MSF has been trying to make people aware of how their treatment of dead relatives might pose a risk to themselves. It is a very difficult message to get across. All previous outbreaks were much smaller and occurred in places where Ebola was already known – in Uganda and the DR Congo for example. In those places the education message about avoiding contact has had years to enter the collective consciousness. In West Africa, there simply has not been the time for the necessary cultural shift.

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In the case of Guinea, while the medical teams knew exactly what had to be done to help the population, the implementation of the response plan was hit by poor collaboration with communities. The teams were beaten up and NGOs couldn’t get to the villages to implement the protocols. The transmission of the Ebola virus is not understood as a biological phenomenon in rural parts of the country where traditional beliefs — in particular sorcery — have the upper hand over science. The low literacy level in Guinea — around 25 per cent — and the inadequacy of information channels further hinder the fight against the epidemic. At one point text messages spread a rumour that a Guinean researcher based in Senegal had developed a cure for Ebola based on hot chocolate, milk, sugar and onions. This was enough for these products to run out in various shops around the country, including in Conakry, the capital. We have reached a situation in which people don’t want to hear what they’re being told. In such a difficult situation, it is difficult to find a balance between the fears and resistance of local people and the need to bring the epidemic under control. For example, they have recommended that medical staff stop using the term ‘isolation centers’ to refer to the places where people infected with Ebola are gathered, and instead to use the more reassuring term ‘treatment centers’. At one point, the treatment centers became synonymous with death chambers. People refused to go there, saying that, once you entered, you wouldn’t come out again alive — a reference to the high mortality among victims of Ebola. A study published recently in the New England Journal of Medicine estimates that overall 71 per cent of people who get Ebola do not survive it — and that figure only drops to 64 per cent among those who are hospitalised. In these societies, in which death is accompanied by a set of traditional rituals including the preparation of the corpse and the invocation of the spirits before burial, they don’t understand when we explain that they mustn’t touch the bodies of Ebola victims. From the point of view of their traditions, the corpse must be interrogated to discover the cause of death: whether the person died a natural death or died of ‘sorcery’. It is therefore necessary to touch the body. Yet given the virulence of the Ebola virus, the medical advice is to avoid touching the bodies of people who have died of the disease. We have to find a solution that enabled us to save what is essential: human lives. We have to find a balance, which was to allow the populations to at least see the body and to throw objects into the body bag before the burial. That, at least, would calm their feelings and enabled us to avoid serial contamination of the population. That’s how the principle of secure burials was accepted. 

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Poverty and illiteracy spread Ebola:

Ebola can be stopped. But it takes resources, and a functioning health-care system. The three countries hardest hit by the Ebola epidemic — Guinea, Sierra Leone, and Liberia — all have very weak health systems and little money to spend on health care. That has constrained their ability to stop the epidemic. In most of West Africa, health spending amounts to less than $100 per person per year (in the United States, it’s about $8,000). Guinea, Sierra Leone, and Liberia have some of the worst maternal and child mortality rates on the planet — an indicator of a failing health system. Experts point out that scarce resources make it extremely difficult to contain the Ebola epidemic: “If you’re in a hospital in Sierra Leone or Guinea, it might not be unusual to say, ‘I need gloves to examine this patient,’ and have someone tell you, ‘We don’t have gloves in the hospital today,’ or ‘We’re out of clean needles,’ — all the sorts of things you need to protect against Ebola,” says Daniel Bausch, associate professor at the Tulane University School of Public Health and Tropical Medicine, who is working with the WHO on the outbreak. Bausch would walk into the hospital in the morning and find patients on the floor in pools of vomit, blood, and stool. They had fallen out of their beds during the night, and they were delirious. “What should happen is that a nursing staff or sanitation officer would come and decontaminate the area,” he said. “But when you don’t have that support, obviously it gets more dangerous.” Along with poverty and a health system too weak to combat the virus, illiteracy has contributed to the problem. Guinea, Liberia, and Sierra Leone have some of the lowest literacy rates in the world. Poor literacy has made it much harder for aid workers to mount a public-health information campaign and explain to people how they can stop the spread of Ebola. It also helped to fuel a rumor mill about supposed cures. For example, one persistent myth has been that hot water and salt can stop Ebola. 

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Stigmatization of Some Populations:

Several populations and countries are being stigmatized because of the presence of Ebola within their borders. For former residents of Guinea, Liberia and Sierra Leone now living in the U.S., the fears of stigmatization are very real. Some groups and politicians are advocating that anyone from these countries, sick or not, should not be allowed to come into the U.S. This won’t work. These politicians are also saying that travel into these countries should be severely restricted, which means that aid workers, the U.S. military and medical personnel helping these citizens, cannot enter any of these countries.

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Survivors of Ebola face second ‘disease’ the stigma:

The doctor has beaten the odds and survived Ebola, but he still has one more problem: The stigma carried by the deadly disease. Even though he is completely healthy, people are afraid to come near him or to have anything to do with him. For example, the man was supposed to give an interview on Guinean radio to describe his triumphant tale. But the station would not allow him into the studio. “We’d prefer he speak by phone from downstairs,” the station’s director told a representative of Doctors Without Borders, while the survivor waited outside in a car. “I can’t take the risk of letting him enter our studio.”  For the lucky survivors, the stink of stigma lingers long after the virus has been purged from their bodies. “Thank God, I am cured. But now I have a new disease: the stigmatization that I am a victim of,” said the Guinean doctor, who spoke to The Associated Press but refused to give his name for fear of further problems the publicity would cause him and his family. “This disease (the stigma) is worse than the fever.” Several other people who survived the disease refused to tell their stories when contacted by the AP, either directly or through Doctors Without Borders. Sam Taylor, the Doctors Without Borders spokesman who had taken the doctor to the radio station, confirmed that the man had been infected and survived. The doctor believes he caught Ebola while caring for a friend and colleague who died in Conakry, Guinea’s capital. At the time, he said, he did not know that his friend had Ebola. Shortly after his friend’s death, the doctor got a headache and came down with an intractable fever. And then the vomiting and diarrhea began. “I should have died,” the doctor said, but he responded to care, which includes intensive hydration, and unlike most other Ebola patients, he lived. Surviving Ebola is a matter of staying alive long enough to have the chance to develop enough antibodies to fight off the virus. That’s because it’s typically the symptoms of Ebola — severe fever, hemorrhaging, dehydration, respiratory problems — that kills a patient. Even though he has been cleared of Ebola, the doctor says that people avoid him. “Now, everywhere in my neighborhood, all the looks bore into me like I’m the plague,” he said. People leave places when he shows up. No one will shake his hand or eat with him. His own brothers are accusing him of putting their family in danger.

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Ebola Deaths Hype:

The Ebola virus is extremely rare. Among the leading causes of death in Africa, it only accounts for a tiny fraction. People are much more likely to die from AIDS, respiratory infections, or diarrhea, as you can see below.

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Since 1976, Ebola has infected fewer than 5,000 people and killed fewer than 3,000. That’s in Africa, where over 1 billion people live. By contrast, poor, “boring” measles still kills 122,000 people every year and killed over 2 million a year in 1980, before widespread vaccination campaigns. According to the WHO, in 2012, malaria caused an estimated 627,000 deaths, mostly among African children. Also according to the WHO, since the beginning of the AIDS epidemic (which dates back almost as far as the discovery of the Ebola virus), HIV has infected over 75 million and killed 36 million, with approximately 35 million currently living with the infection. None of this means that we shouldn’t take Ebola seriously or that much larger outbreaks couldn’t happen. Nor does noting this difference minimize the deaths of people infected with the disease. We should note from these observations and others, however, that Ebola is unlikely to reach such numbers because it is simply not infectious enough and Ebola outbreaks tend to “burn themselves out” because, unlike HIV or measles (which are also transmissible human-to-human), Ebola virus disease is so rapidly fatal. The public fear of ebola, the latest outbreak of which has killed almost 6,500 people mostly in West Africa, far outweighs concern about other more deadly diseases, such as rabies which has killed 65,000 people in the last year, or emerging dangers like Middle East Respiratory Syndrome (MERS). MERS is a disease in camels and when passed to humans spread quickly between them through the air, while ebola, which originated in bats, requires physical contact to move. Flu-like in nature, MERS has killed more than 190 people since it surfaced in Saudi Arabia two years ago.

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The majority of Ebola deaths may not be from Ebola in West Africa:

Of this epidemic, the World Bank said Ebola may deal a “potentially catastrophic blow” to the West African countries reeling with the virus. Businesses are shutting down, people aren’t working, and kids aren’t going to school. The epidemic has also led to widespread food insecurity. “The fertile fields of Lofa County, once Liberia’s breadbasket, are now fallow. In that county alone, nearly 170 farmers and their family members have died from Ebola,” the WHO director warned. “In some areas, hunger has become an even greater concern than the virus.” People are going to suffer and die more from other diseases as the already scarce health resources in the region go to Ebola. Speaking at the United Nations, Dr. Joanne Liu, international president of Médecins Sans Frontières, said, “Mounting numbers are dying of other diseases, like malaria, because health systems have collapsed.” Jimmy Whitworth, the head of population health at Britain’s Wellcome Trust, told the Independent in an interview, “People aren’t going to hospitals or clinics because they’re frightened, there aren’t any medical or nursing staff available.” “West Africa will see much more suffering and many more deaths during childbirth and from malaria, tuberculosis, HIV-AIDS, enteric and respiratory illnesses, diabetes, cancer, cardiovascular disease, and mental health during and after the Ebola epidemic,” wrote disease researchers Jeremy Farrar, of the Wellcome Trust, and Peter Piot, of the London School of Hygiene and Tropical Medicine in an article in the New England Journal of Medicine. So this virus has wreaked incalculable damage on not only the bodies of those infected, but on others who are not getting health care they need, and the health systems and economies of West Africa. Dr. Ezie Patrick, with the World Medical Association who is based in Abuja, Nigeria, focused on the simple and disquieting fact that Ebola has also taken the lives of health workers in places where the ratio of doctors per population is abysmally low. “Sadly Ebola is claiming the lives of the few doctors who have decided to work in these challenging health systems thereby worsening the dearth and also increasing the brain drain leading to far fewer doctors in the region.” The disaster could last longer than the epidemic itself. Before the Ebola outbreak, West African nations were seeing promising signs of economic growth. Sierra Leone, for example had the second highest real GDP growth rate in the world. Liberia was 11th in 2013. Now, there’s worry that Ebola will slam the brakes on that development. “A prolonged outbreak could undercut the growth that these countries were finally starting to experience, taking away the resources that would be necessary for improving the health and education systems,” says Jeremy Youde,  a professor of political science at the University of Minnesota Duluth. “These countries are generally not starting from a great position as it is, so they don’t have much of a cushion to absorb long-term economic losses. If the international economy turns away from West Africa and brands it as diseased, that could be very problematic.”   

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Why is containing Ebola proving difficult?

In West Africa, the man-made elements of conflict, confusion and culture have all combined to create a perfect-storm for Ebola. A growing population, decades of civil war, widespread government corruption, dysfunctional health system, a growing distrust in Western medicine and worsening conditions in West Africa contribute to a “perfect storm,” The scientist who first identified Ebola in 1976 gives direct and simple advice on how to contain this latest outbreak: “Soap, gloves, isolating patients, not reusing needles and quarantining the contacts of those who are ill – in theory it should be very easy to contain Ebola,” Dr Peter Piot told the BBC. In practice, this is a much tougher proposition. The main outbreak has emerged in war ravaged West Africa, where much of the health care infrastructure has been totally destroyed.  Poverty has combined with fear, ignorance and superstition, particularly in remote communities, where distrust of government is understandably high, and belief in witchcraft and sorcery is interwoven into everyday life. Testing for Ebola often requires multiple blood tests – which is difficult to conduct in areas where strong cultural beliefs prohibit collection of a “life force”.  In Liberia, some communities believe the outbreak is a hoax, and that health care workers have been sent to kill them. In one town, health care workers spraying chlorine – a cheap and effective counter to the spread of the disease – were attacked. In Guinea, Medicines Sans Frontiers (MSF) doctors and medics were attacked by villagers who believed the clinical team had brought Ebola to their country. Governmental response has been heavy handed. Liberia’s president threatened to jail anyone sheltering or hiding suspected Ebola cases. An un-coordinated rush by the international community to assist can also complicate efforts, says African governance expert Kim Yi Dionne, especially when it appears that no one is in charge. Already involved in the Ebola response are the local ministries of health for Liberia, Guinea and Sierra Leone, the World Health Organisation, MSF, UNICEF and many other agencies.

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Etiology: The Ebola Virus:

Virologists have been using the names Marburg virus and Ebola virus for the type viruses of the genera Marburgvirus and Ebolavirus, respectively, for decades and have not accepted the novel names for these agents (Lake Victoria marburgvirus and Zaire ebolavirus) suggested in the 8th ICTV Report.

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Taxonomy of ebola virus:

Group: Group V [(-)ssRNA]

Order: Mononegavirales

Family: Filoviridae

Genus: Ebolavirus

Species: Zaire ebolavirus

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The family Filoviridae resides in the order Mononegavirales and contains the largest genome within the order. This family contains 2 genera: Ebolavirus (containing 5 species) and the antigenically distinct Marburgvirus (containing a single species). EVD in humans is caused by four of five viruses of the genus Ebolavirus. The four are Bundibugyo virus (BEBOV), Sudan virus (SEBOV), Taï Forest virus (TEBOV) and the Zaire Ebola virus (ZEBOV). ZEBOV is the most dangerous of the known EVD-causing viruses, and is responsible for the largest number of outbreaks. The fifth virus, Reston virus (REBOV), is not thought to cause disease in humans, but has caused disease in other primates. All five viruses are closely related to marburgviruses. In patients who have Ebola virus infection, exposure to the virus may be either primary (involving presence in an Ebolavirus -endemic area) or secondary (involving human-to-human or primate-to-human transmission). Physical findings depend on the stage of disease at the time of presentation.

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Is Ebola an RNA virus? And why is it considered a filovirus? What does that mean?

Yes, Ebola is an RNA virus. It belongs to the family of filoviruses. The family name was derived from the Latin word filum, which alludes to the thread-like appearance of the virions when viewed under an electron microscope. The family Filoviridae comprises two antigenically and genetically distinct genera: Marburgvirus and Ebolavirus. Ebola virus particles are rod-shaped and are surprisingly simply organized. The small viral RNA genome, which consists of only 19 thousand nucleotides—human genomes consist of billions of these nucleotides—is tightly associated with only seven proteins and encased in a membrane. One of the viral proteins sticks out of the membrane and can bind to receptors on the surface of cells. Binding to these receptors helps the virus enter the cell. Inside the cells, Ebola virus replicates itself. Then the new viral particles leave the cells and are ready to infect fresh cells. At some point, the infected cells get exhausted because they have to provide all the material needed to form the virus—and they die. However, Ebola virus–infected cells survive for a pretty long time, making it easy for the virus to spread throughout the body of the infected host.

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Phylogenetic tree of filoviruses:

Filoviridae, of which Ebola virus is a member, is a family of viruses that contain single, linear, negative-sense ssRNA genomes. Filoviruses have been divided into two genera: Ebola-like viruses with species Zaire, Sudan, Reston, Cote d’Ivoire and Bundibugyo; and Marburg-like viruses with the single species Marburg. All of these are responsible for hemorrhagic fevers in primates that are characterized by often fatal bleeding and coagulation abnormalities.

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Ebola is a filovirus, and filoviruses appear to have been around in some form for millions of years. The figure above shows phylogenetic tree comparing ebolaviruses and marburgviruses. Numbers indicate percent confidence of branches. Marburgvirus and Ebolavirus are seen to be two different genera. The genus Ebolavirus includes five distinct species. Note that the Yambuku and Kikwit Zaire viruses are virtually identical even though the epidemics for which they were responsible are separated by two decades and hundreds of kilometers. Virtually every virus sequenced from each of those two epidemics is identical over the part of the genome examined. This pattern is typical of that seen with single introductions followed by human-to-human passage via needle or close contact in an African hospital. In the Marburgvirus branch of the tree, there is one major clade with a slightly divergent group characterized by the Ravn 1987 Kenya isolate. All the viruses from the major Angola 2005 outbreak are represented by a single virus because the sequences in this human-to-human epidemic are virtually identical. However, in the outbreak occurring in the Democratic Republic of the Congo (DRC) in 1999 and resulting from multiple independent infections after cave entry, two viruses with slightly different phylogenies are represented within the major group, and there is even another virus within the Ravn subgroup. These sequences were selected from hundreds determined at the U.S. Centers for Disease Control and Prevention and elsewhere.

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Ebola virus genome:

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Ebolaviruses contain single-stranded, non-infectious RNA genomes. Ebolavirus genomes are approximately 19 kilobase pairs long and contain seven genes in the order 3′-UTR-NP-VP35-VP40-GP-VP30-VP24-L-5′-UTR. The genomes of the five different ebolaviruses differ in sequence and the number and location of gene overlaps. As all filoviruses, ebolavirions are filamentous particles that may appear in the shape of a shepherd’s crook, of a “U” or of a “6,” and they may be coiled, toroid or branched. In general, ebolavirions are 80 nanometers (nm) in width and may be as long as 14,000 nm (average 800 to 1000 nm). Their life cycle begins with a virion attaching to specific cell-surface receptors, followed by fusion of the virion envelope with cellular membranes and the concomitant release of the virus nucleocapsid into the cytosol. Ebolavirus’ structural glycoprotein (known as GP) is responsible for the virus’ ability to bind to and infect targeted cells. The viral RNA polymerase, encoded by the L gene, partially uncoats the nucleocapsid and transcribes the genes into positive-strand mRNAs, which are then translated into structural and nonstructural proteins. The most abundant protein produced is the nucleoprotein, whose concentration in the host cell determines when L switches from gene transcription to genome replication. Replication of the viral genome results in full-length, positive-strand antigenomes that are, in turn, transcribed into genome copies of negative-strand virus progeny. Newly synthesized structural proteins and genomes self-assemble and accumulate near the inside of the cell membrane. Virions bud off from the cell, gaining their envelopes from the cellular membrane from which they bud from. The mature progeny particles then infect other cells to repeat the cycle. The genetics of the Ebola virus are difficult to study because of EBOV’s virulent characteristics.

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Figure above shows a protein map of Ebola virus RNA. 

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Ebola is a lipid enveloped, filamentous, negative-sense virus with an RNA genome. The virus is transmitted from one individual to another through exchange of bodily fluids and enters through exposed cuts or mucous membranes (mouth, nose, etc.).

Lipid enveloped:

Lipid enveloped viruses contain a lipid bilayer coat (outer membrane of a cell) that protects their genome and helps them enter (infect) cells. The lipid bilayer of Ebola is composed of the same lipids as human cells and scientists believe this lipid coat may be extracted from lipid rafts of human cells as new virions “bud” or leave cells after intracellular expansion of the virus. Contained within the lipid bilayer of Ebola are virus proteins that help the virus infect new cells and contribute to its replication. All together, the lipid bilayer performs three functions, 1) to cloak the virus from the immune system because it closely resembles normal host cells, 2) to facilitate binding of virus to cells and entry in lipid-to-lipid interactions, and 3) to facilitate viral replication.

Negative-sense RNA:

Mammalian genetic code is DNA to RNA to protein. There are multiple forms of RNA synthesized by mammalian cells, and it is the messenger form of RNA, abbreviated as mRNA, that is translated into protein. Unlike mammals, some viruses (such as Ebola) use RNA rather than DNA as their genetic code. RNA viruses are further classified according to the “sense” or polarity of their RNA.  Positive-sense viral RNA is similar to mammalian mRNA and as a result can be immediately translated by the host cell after infection into viral protein. Negative-sense viral RNA is the mirror image of mRNA; consequently it must be converted to positive-sense RNA by an enzyme called RNA polymerase before translation into protein. As such purified RNA of a negative-sense virus is not infectious by itself and needs to be transcribed into positive-sense RNA to make viral protein that can be assembled into new, infectious virus particles. The Ebola genome encodes seven proteins named nucleoprotein, VP24, VP30, VP35, L protein, transmembrane glycoprotein and the matrix protein VP40.

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Inside each Ebola particle is a tube made of coiled proteins, which runs the length of the particle, like an inner sleeve. Within the inner sleeve of an Ebola particle, invisible even to a powerful microscope, is a strand of RNA, the molecule that contains the virus’s genetic code, or genome. The code is contained in nucleotide bases, or letters, of the RNA. These letters, ordered in their proper sequence, make up the complete set of instructions that enables the virus to make copies of itself. A sample of the Ebola now raging in West Africa has, by recent count, 18,959 letters of code in its genome; this is a small genome, by the measure of living things. Viruses like Ebola, which use RNA for their genetic code, are prone to making errors in the code as they multiply; these are called mutations. Right now, the virus’s code is changing. As Ebola enters a deepening relationship with the human species, the question of how it is mutating has significance for every person on earth.

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The genome consists of seven genes in the order 3′ leader, nucleoprotein, virion protein (VP) 35, VP40, glycoprotein, VP30, VP24, RNA-dependent RNA polymerase (L)—5′ trailer. With the exception of the glycoprotein gene, all genes are monocistronic, encoding for one structural protein. The inner ribonucleoprotein complex of virion particles consists of the RNA genome encapsulated by the nucleoprotein, which associates with VP35, VP30, and RNA-dependent RNA polymerase to the functional transcriptase—replicase complex. The proteins of the ribonucleoprotein complex have additional functions such as the role of VP35, which is an interferon antagonist. VP40 serves as the matrix protein and mediates particle formation. VP24, another structural protein associated with the membrane, interferes with interferon signaling. The glycoprotein is the only transmembrane surface protein of the virus and forms trimeric spikes consisting of glycoprotein 1 and glycoprotein 2—two disulphide-linked furin-cleavage fragments. An important distinction of Ebola virus from other Mononegavirales is the production of a soluble glycoprotein, which is the primary product of the GP gene, and gets secreted to large quantities from infected cells.

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Ebola actually encodes two forms of its glycoprotein gene. The small, non-structural, dimeric soluble form (sGP) is transcribed directly from the viral mRNA and its function remains mostly unknown. This protein is not found in virus particles, but is instead secreted from infected cells into the blood. A second glycoprotein results from transcriptional editing of the glycoprotein origin of replication and encodes a trimeric, membrane-bound form. This envelope GP spike is expressed at the cell surface, and is incorporated into the virion to drive viral attachment and membrane fusion. It has also been shown as the crucial factor for Ebola virus pathogenicity. GP is actually post-translationally cleaved by the proprotein convertase furin to yield disulphide-linked GP1 and GP2 subunits. GP1 allows for attachment to host cells, while GP2 mediates fusion of viral and host membranes. This protein assembles as a trimer of heterodimers on the viral envelope, and ultimately undergoes an irreversible conformation change to merge the two membranes. The product of the third gene, VP40, is located beneath the viral envelope where it helps to maintain structural integrity. It has also been associated with late endosomes and likely mediates filovirus budding due to its ability to induce its own release from cells in the absence of all other viral proteins. The second matrix protein, VP24, has been shown to suppress interferon production. However, interferon interference may not be its only function. Other experiments have shown that this protein, along with VP35 and NP are sufficient to form nucleocapsid structures. Lastly, VP24 is necessary for the correct assembly of a functional nucleocapsid, as a lack of VP24 leads to reduced transcription/translation of VP30. The remaining structural proteins form the nucleocapsid, and are thus intimately associated with the viral genome. These are the nucleoprotein NP, the polymerase cofactor VP35, the viral-specific transcription activator VP30 and the viral RNA polymerase L. These nucleocapsid proteins have a dual function in the viral replication cycle: they are involved as structural components, but also catalyze replication and transcription of the genome. While NP, VP35 and L are sufficient for replication, transcription initiation will not proceed without VP30.

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There’s also evidence that the glycoprotein (GP) is what actually kills individual cells. Inserting the gene alone into cells that normally line blood vessels is enough to cause their deaths. Glycoprotein appears to kill cells by blocking their ability to put new proteins on their surface. This causes the cells to lose contact with their neighbors and die. (It also has the side effect of limiting cells’ ability to inform the immune system that they are infected.) Further studies suggest that this effect is level-dependent; moderate amounts of glycoprotein don’t cause cells much difficulty. It’s only the high levels that accumulate later in infections that can kill them. This ensures that high levels of virus are made before their host dies.

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Viral Replication:

Viruses are unique pathogens in that they use host cell machinery to make their viral proteins and assemble new virus particles, or virions. In other words, they carry their genetic blueprint with them but have the cell they infect do all production and assembly of new virions. Conceptually, they hijack cellular factories in order to replicate. In order for Ebola to infect and replicate it must be able to accomplish two things: it must enter a host cell and it must utilize host cell machinery to produce new virions that can then go on to infect the next individual. This is termed “productive infection.” In the absence of those two things Ebola infection does not spread and would be considered “abortive infection,” meaning the process ends because replication cannot occur.

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Filovirus Transcription:

During transcription, the RNA genome is transcribed into seven monocistronic mRNAs whose length is determined by highly conserved start and stop signals. These start signals are predicted to form stable stem-loop structures. Just as in other negative sense RNA viruses, the transcription process begins with the binding of the polymerase complex to a single binding site located within the leader region of the genome. The complex then slides along the RNA template and sequentially transcribes the individual genes in their 3’ to 5’ order. However, the polymerase is released from the template following mRNA formation, so reinitiation at downstream genes is attenuated. Thus, the first gene, NP, is transcribed at the highest levels, whereas the last gene, L, is transcribed at the lowest. VP30 is assumed to be a transcription activation factor that is essential for the viral life cycle. While the mechanism is not completely understood, it is suggested that this protein is involved in initiation because VP30-dependent transcription is regulated by RNA of the first transcription start signal. The first 23 nucleotides of this NP mRNA are involved in stem-loop structure formation which might interfere with the progression of transcription by physically hampering polymerase movement. However, the N-terminus of VP30 contains a Zn+2 binding Cys-His motif and is rich in basic amino acids, allowing it to directly interact with RNA. Therefore, the protein could either resolve or cover this secondary structure and allow transcription to proceed. Further research has also shown that VP30 is important in transcription reinitiation, and may bind stem-loops formed by the promoter of each Ebola virus gene. Interestingly, VP24 has also been shown to inhibit transcription and replication of the Ebola virus genome. While the exact mechanism has not yet been elucidated, it is possible that VP24 binds to NP and hampers the function of VP35, VP30 or L. This interference could be important in converting the viral genome from a transcription or replication competent form to one that is ready for virion assembly and egress.

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Disruption of Cell Adhesion:

Expression of Ebola GP in cultured cells causes a disruption in cell adhesion that results in a loss of cell-cell contacts, as well as a loss of attachment to the culture substrate. The effects of GP are caused by the mucin domain, a highly glycosylated region of GP1 composed of roughly 150 amino acids and containing numerous N- and O- linked glycosylation sites. While this loss of endothelial cell attachment is key for the characteristic hemorrhaging, only recently has a mechanism for the disturbance of cell adhesion been proposed. For years, staining by flow cytometry has associated Ebola infection with a reduction in membrane levels of β1 integrin, a receptor that mediates attachment with the extracellular matrix, as well as major histocompatibility complex 1 (MHC1), a molecule important in immune system recognition. While these effects were previously assumed to result from removal of surface proteins, Francica et al. propose that GP-mediated loss of surface protein recognition occurs via steric shielding of surface epitopes. Observations that this down regulation is relieved by enzymatic removal of carbohydrate modification suggest that the steric occlusion is mediated by N- and O-linked modification of GP. In fact, the O-linked glycosylation of the mucin domain may promote an extended conformation that allows this domain to serve as a 150 residue long flexible rod that can mask domains in the immediate vicinity. Inherent in this mechanism is the fact that GP must localize in close proximity to the affected proteins, possibly explaining the variety of cell receptors regulated by this viral protein. This mechanism also helps the virus in immune system avoidance. The ability of GP to mask MHC1 may be a strategy for avoiding CD8 T cell-mediated killing of Ebola infected cells.

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Ebola virus mutation:

Mutations are a way of life for an RNA virus and mutations come and go every time a genome replicates – it is likely that every single genome copy of an RNA virus has a mutation. The key is to determine whether these changes affect any of the biological properties of the virus, such as transmission, stability, or virulence. Recent advances in genomic technologies have been applied to the analysis of blood samples from those infected in the 2014 outbreak. A massively parallel viral sequencing of genetic material collected from 78 patients with confirmed Ebola virus disease, representing more than 70% of cases diagnosed in Sierra Leone from late May to mid-June, 2014 was carried out. This work provided near–real-time insights into the transmission dynamics and genetic evolution, shedding light on the origins of the virus causing the 2014 outbreak in West Africa, and whether the 2014 outbreak is still being fed by new contacts with its natural reservoir (no such evidence was found). Genomic surveillance elucidates Ebola virus origin and transmission during the 2014 outbreak and concludes that the current outbreak probably resulted from the spread of the virus from central Africa in the past decade. As is typical of RNA-coded viruses, the Ebola virus was found to mutate rapidly, both within a person during the progression of disease and in the reservoir among the local human population. The observed mutation rate of 2.0 x 10-3 substitutions per site per year is as fast as that of seasonal influenza. This is likely to represent rapid adaptation to human hosts as the virus is repeatedly passed from human to human (as opposed to usually being passed between fruit bats and only occasionally crossing over into humans), and may pose challenges for the development of a vaccine to the virus. The genetic study by Gire and his colleagues (five of whom were dead of Ebola by the time their study appeared) found 341 mutations as of late August, some of which are significant enough to change the virus’s functional identity. The higher the case count in West Africa goes, the more chances for further mutations, and therefore the greater possibility that the virus might adapt somehow to become more transmissible-perhaps by becoming less pathogenic, sickening or killing its victims more slowly and thereby leaving them more time to infect others. That’s why, the Gire group wrote, we need to stop this thing everywhere as soon as possible. Future spillovers of Ebola are bound to occur, but those freshly emerged strains of the virus, direct from the reservoir host, won’t contain any adaptive mutations that the West Africa strain is acquiring now. We need to terminate Ebola 2014 before the virus learns too much about us.

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Ebola 2014 is mutating as fast as Seasonal Flu: a 2014 study:

The current Ebola 2014 virus is mutating at a similar rate to seasonal flu (Influenza A).  This means the current Ebola outbreak has a very high intrinsic rate of viral mutation.  The bottom line is that the Ebola virus is changing rapidly, and in the intermediate to long term (3 months to 24 months), Ebola has the potential to evolve.  Authors cannot predict exactly what the Ebola virus will look like in 24 months.  There is an inherent stochastic randomness to viral evolution which makes predictions on future viral strains difficult, if not impossible.  One basic tenet they can rely on is this: Viruses tend to maximize their infectivity (basic reproduction number) within their biological constraints (Nowak, 2006). These evolutionary constraints can be extremely complex, and can include trade-offs between virulence and infectivity, conditions of superinfection, host population dynamics, and even outbreak control measures.

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Ebola Mutation Rate:

Analysis of the available research suggests that the Ebola 2014 virus is currently mutating at a rate 200% to 300% higher than historically observed (Gire, 2014).  Furthermore, the Ebola-2014 virus’s mutation rate of 2.0 x 10³ subs/site/year is nearly identical to Influenza A’s mutation rate of 1.8 x 10³ subs/site/year (Jenkins, 2002).  This means Ebola 2014 is mutating as fast as seasonal flu.

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Many recent Ebola viral mutations have been synonymous mutations, some have been in intergenic regions, while others are non-synonymous substitutions in protein-coding regions. All have unknown impact at the present time. Such questions should be the subject of future scientific research.  Until the Ebola outbreak is brought under control, the Ebola-2014 virus will continue to seed and adapt in its growing pool of West African human hosts. We need to consider that as the weeks and months go on, the rapidly-changing Ebola-2014 virus will undergo repeated export from the West African region to countries around the world. As new Ebola cases grow in West Africa and elsewhere, we are effectively conducting ‘serial passage’ experiments of Ebola-2014 through human hosts. The repeated passage of Ebola-2014 through humans is exerting selection pressure on the Ebola-2014 virus to adapt to our species (instead of fruit bats).  The introduction of Ebola-2014 into a large pool of West African human hosts (coupled with the complex dynamics of evolutionary selection pressure) may allow the Ebola-2014 virus to become more transmissible as the months go on, particularly in the absence of effective control interventions. 

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Authors chose to compare Ebola-2014 to Influenza A (Seasonal Flu) because Influenza is one of the fastest-mutating viruses (Jenkins, 2002).  Unlike chickenpox (VZV), which people usually only contract once per lifetime, Influenza can infect a single individual many times repeatedly over the years.  One of the reasons Influenza is able to re-infect humans each year is because the Influenza’s high mutation rate allows the virus to generate ‘escape mutants’.  Escape mutants are Influenza viruses which are no longer recognized by human immune systems.  Each winter presents us with a new mutated strain of the Influenza virus. Rapid mutation is beneficial to Influenza genetic fitness (in regards to antigenic regions), because it allows a ‘new’ Influenza virus to circulate year after year. The benefit of a high mutation rate in Ebola 2014 is different — the genetic changes in Ebola-2014 allow for rapid exploration of the entire fitness landscape in a brand new host — humans. We need to be aware that the Ebola-2014 virus is undergoing rapid adaptation. The high mutation rate we see in Ebola-2014 reflects its ability to rapidly explore the fitness landscape. The ability of Ebola to undergo rapid genome substitutions and SNPs, coupled with genetic recombination, will allow ‘survival of the fittest’ in Ebola-2014 genetic variants (on both the intra-host and inter-host levels). New Ebola sub-clades are created with each passing month (there are already four sub-clades as of August 2014). New Ebola genetic variants are created with each new infection, though most are selected against. Rapid adaptation emerges from the high intrinsic Ebola-2014 mutation rate, coupled with the virus’s ability to undergo RNA recombination during superinfection.

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Figure above shows acquisition of genetic variation of ebola-2014 virus over time. Fifty mutational events (short dashes) and 29 new viral lineages (long dashes) were observed.

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The diagram above suggests that as the Ebola-infected host pool grows, so does the number of unique Ebola viral lineages. This implies that Ebola acquires genetic diversity as it infects more people, particularly if the virus undergoes recombination during superinfection.  The growing number of new Ebola viral lineages will undergo natural selection for some ‘optimum’ balance of virulence, infectivity, tissue tropism, immune suppression, and other parameters which maximize the reproductive fitness of the Ebola virus in humans.  What that final virus might eventually look like 2 years from now is anyone’s guess.  But the explosion of genetic variation suggests that the Ebola virus will become more difficult to contain as time goes on, which is why early action is important. The idea that the Ebola-2014 Virus jumped species, but is now somehow ‘static’ or ‘frozen in time’ is a mistake. The Ebola-2014 virus is undergoing a period of rapid adaptation in human hosts, as evidenced by the Ebola RNA sequences deposited in Genbank, and other studies.  Hopefully, interventions (like contact tracing) will be able to stop Ebola-2014 before the virus optimizes its genotype.

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As more people become infected, a significant mutation arises that allows for a longer asymptomatic but infectious period, increasing the Ro. Globally, cases continue to double every 16 days, contact tracing infrastructure outside the West becomes saturated, and hospitals are overrun. By early-to-mid 2015, the global pools of Ebola-infected patients are in the millions, mainly centered in West Africa and Southeast Asia with multiple strains of varying virulence. A sudden change in the outbreak epidemiology caused by a recombinant Ebola strain causes confusion about how to respond. Efforts at developing treatments/vaccines become logistically complex and ineffective. The implication of the Ebola 2014 mutation rate is this:  A single Ebola mutation doesn’t necessarily mean the virus will become ‘airborne’, or that the virus has altered tissue tropism, or that the virus spreads more easily.   But a high intrinsic rate of Ebola mutation means that such changes may become possible in the future.  If the number of people infected grows into the hundreds of thousands, or even low millions, then the probability of a significant ‘constellation’ of accumulated Ebola mutations with phenotypic impact becomes more likely.  The problem is that accumulated Ebola mutations will scale with the size of the population infected.  Conversely, in a small population, such Ebola mutations are not likely to have a significant impact.  It’s a bit like the virus is buying lottery tickets… The more lottery tickets the Ebola virus ‘buys’, the more chances it has to ‘win’.

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Scientists use Mutations to track Ebola 2014 Origins:

In a new paper in Science, researchers reveal that they have sequenced the genomes of Ebola from 78 patients in Sierra Leone who contracted the disease in May and June. Those sequences revealed some 300 mutations specific to this outbreak. The new analysis could help determine if the virus’ behavior has changed — and provide information for future diagnostic tests and treatments. Among their findings, the researchers discovered that the current viral strains come from a related strain that left Central Africa within the past ten years. And the research confirms that the virus likely spread into Sierra Leone when women became infected after attending the funeral of a traditional healer who had been treating Guinean Ebola patients. 

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An expert scientist from the National Institute of Allergy and Infectious Disease (NIAID) has publicly warned that the Ebola strain currently in circulation appears to be far more virulent and infectious than previous strains. Dr. Peter Jahrling has been on the ground in the Liberian capital of Monrovia, studying the disease with a team of researchers, which is also helping to care for and treat patients. He says the viral loads that his team is witnessing exceed what has been observed during previous outbreaks, suggesting that, this time, the disease is far more deadly. Echoing the warnings given by others, Dr. Jahrling believes that this strain of Ebola is not only more deadly than other strains but also mutating at an alarming rate. More of the virus is infecting patients, and it appears to be advancing and spreading more rapidly than usual. “We are using tests now that weren’t [used] in the past, but there seems to be a belief that the virus load is higher in these patients [today] than what we have seen before,” stated Dr. Jahrling to Vox. “If true, that’s a very different bug.” 

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Filoviruses are ancient and integrated into mammalian genomes: a 2010 study:

Integrated elements of filoviruses could indicate a coevolutionary history with a mammalian reservoir, but integration of nonretroviral RNA viruses is thought to be nonexistent or rare for mammalian viruses (such as filoviruses) that lack reverse transcriptase and replication inside the nucleus. Here, authors provide direct evidence of integrated filovirus-like elements in mammalian genomes by sequencing across host-virus gene boundaries and carrying out phylogenetic analyses. Further they test for an association between candidate reservoir status and the integration of filoviral elements and assess the previous age estimate for filoviruses of less than 10,000 years. In 19 of the tested vertebrate species, authors discovered as many as 80 high-confidence examples of genomic DNA sequences that appear to be derived, as long ago as 40 million years, from ancestral members of 4 currently circulating virus families with single strand RNA genomes. Surprisingly, almost all of the sequences are related to only two families in the Order Mononegavirales: the Bornaviruses and the Filoviruses, which cause lethal neurological disease and hemorrhagic fevers, respectively. Phylogenetic and sequencing evidence from gene boundaries was consistent with integration of filoviruses in mammalian genomes. Authors detected integrated filovirus-like elements in the genomes of bats, rodents, shrews, tenrecs and marsupials. Moreover, some filovirus-like elements were transcribed and the detected mammalian elements were homologous to a fragment of the filovirus genome whose expression is known to interfere with the assembly of Ebolavirus. The phylogenetic evidence strongly indicated that the direction of transfer was from virus to mammal. Eutherians other than bats, rodents, and insectivores (i.e., the candidate reservoir taxa for filoviruses) were significantly underrepresented in the taxa with detected integrated filovirus-like elements. The existence of orthologous filovirus-like elements shared among mammalian genera whose divergence dates have been estimated suggests that filoviruses are at least tens of millions of years old. Author’s findings indicate that filovirus infections have been recorded as paleoviral elements in the genomes of small mammals despite extranuclear replication and a requirement for cooption of reverse transcriptase. Author’s results show that the mammal-filovirus association is ancient and has resulted in candidates for functional gene products (RNA or protein).

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Ancient ebola virus: a 2014 study:

A new study is helping to rewrite Ebola’s family history. It shows that Ebola and Marburg are each members of ancient evolutionary lines, and that these two viruses last shared a common ancestor sometime prior to 16-23 million years ago. The research shows that filoviruses — a family to which Ebola and its similarly lethal relative, Marburg, belong — are at least 16-23 million years old. According to the PeerJ article, knowing more about Ebola and Marburg’s comparative evolution could “affect design of vaccines and programs that identify emerging pathogens.” The research does not address the age of the modern-day Ebolavirus. Instead, it shows that Ebola and Marburg are each members of ancient evolutionary lines, and that these two viruses last shared a common ancestor sometime prior to 16-23 million years ago. The new study builds on the study depicted in previous paragraph, which used viral fossil genes to estimate that the entire family of filoviruses was more than 10 million years old. However, those studies used fossil genes only distantly related to Ebola and Marburg, which prevented the researchers from drawing conclusions about the age of these two viral lines. The current PeerJ publication fills this viral “fossil gap,” enabling the scientists to explore Ebola’s historical relationship with Marburg. 

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The Filoviridae Journey:

 After transmission to a new host, the virus enters a cell through a mechanism that has yet to be determined. Once inside the host cell’s cytoplasm, the filovirus uncoats itself and releases transcriptase (polymerase), which is contained in the virion. Transcriptase transcribes the viral -ssRNA into the complimentary +ssRNA. This positive, single stranded RNA will then be used as the template for the new viral genomes. Soon after the infection, the cell develops cytoplasmic inclusion bodies that contain the highly structured viral nucleocapsid (the nucleocapsid contains the genome and can sometimes have other proteins in it as well). After the nucleocapsid has been formed, the new virus will self-assemble and bud from the cell membrane stealing some of the membrane for its envelope. Not very much is known about the pathogenesis of filoviruses. But we do know that Ebola attacks cells important to the function of lymphatic tissues. It can be found in fibroblastic reticular cells (FRC) among the loose connective tissue under the skin and in the FRC conduit (FRCC) in lymph nodes. This allows the virus to rapidly enter the blood and leads to disruption of lymphocyte homing at high endothelial venules (HEV). Ebola virus seems to be most active in infecting fibroblasts of any type (especially fibroblastic reticular cells). The next most frequent cell types are mononuclear phagocytes with dendritic cells more affected than monocytes or macrophages. Endothelial cells become infected after the connective tissue surrounding them is fully involved. Then, almost as a final insult, epithelial cells of any type are infected.  In general, epithelial cells become infected only if they contact other cells that amplify the virus such as fibroblastic reticular cells (FRC) and mononuclear cells. This would be true for skin appendages like hair follicles and sweat glands because they are heavily vascularized and have a lot of FRC networks associated with them. Liver cells and adrenal gland epithelial cells have fibroblastic reticulum as their main connective tissue and both have resident mononuclear cell phagocytes hanging on FRC cells near the blood/epithelial cell interface.

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Route of infection:

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The figure below shows modes of viral entry:

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Ebola virus seems to enter the host through mucosal surfaces, breaks, and abrasions in the skin, or by parenteral introduction. Most human infections in outbreaks seem to occur by direct contact with infected patients or cadavers. Infectious virus particles or viral RNA have been detected in semen, genital secretions, and in skin of infected patients; they have also been isolated from skin, body fluids, and nasal secretions of experimentally infected non-human primates.

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Laboratory exposure through needle stick and blood has been reported.  Reuse of contaminated needles played an important part in the 1976 outbreaks of Ebola virus in Sudan and Zaire. Butchering of a chimpanzee for food was linked to outbreaks of Zaire Ebola virus in Gabon, and contact exposure was the probable route of transmission. Although proper cooking of foods should inactivate infectious Ebola virus, ingestion of contaminated food cannot wholly be ruled out as a possible route of exposure in natural infections. Notably, handling and consumption of freshly killed bats was associated with an outbreak of Zaire Ebola virus in DRC. Organ infectivity titers in non-human primates infected with Ebola virus are frequently in the range of 107 to 108 pfu/g; thus, exposure through the oral route could invariably be associated with very high infectious doses. In fact, Zaire Ebola virus is highly lethal when given orally to rhesus macaques. The role of aerosol transmission in outbreaks is unknown, but is thought to be rare. In human beings, the route of infection seems to affect the disease course and outcome. The mean incubation period for cases of Zaire Ebola virus infection known to be due to injection is 6·3 days, versus 9·5 days for contact exposures. Moreover, the case-fatality rate in the 1976 outbreak of Zaire Ebola virus was 100% (85 of 85) in cases associated with injection compared with about 80% (119 of 149) in cases of known contact exposure. For non-human primates infected with Zaire Ebola virus, the disease course seems to progress faster in animals exposed by intramuscular or intraperitoneal injection than in animals exposed by aerosol droplets.

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Virus entry: Macropinocytosis (a type of endocytosis):

As the first step of the viral life cycle, entry into the host cell is a popular drug target as infection could be stopped before replication disrupts cell function. However, the entry mechanism of Ebola virus is poorly understood. Endocytosis offers an efficient way for viruses to cross the significant physical barrier imposed by the plasma membrane and to traverse the underlying cortical matrix. Viruses have also evolved to target distinct endocytic pathways that are capable of delivering the capsid into the cell cytoplasm at sites suitable to initiate replication and to avoid destructive compartments like the lysosome. Understanding the pathway of virus entry and deciphering the mechanism regulating it is important for understanding viral pathogenesis as virus entry into host cell is the first critical step in pathogenesis of infection. While there is ample evidence that ZEBOV enters cells through endocytosis in a pH-dependent manner, the specific endocytic and trafficking pathways have not been clearly defined. Many enveloped viruses, Ebola virus included, rely upon endocytosis to infect cells. Several distinct endocytic mechanisms exist in mammalian cells, and can be distinguished by the type of cargo they carry as well as the proteins involved in their regulation. However, all mechanisms ultimately transport virions through successive endocytic vesicles until a compartment with adequate conditions, low pH in the case of Ebola, is reached. Upon membrane fusion, the capsid moves into the cell cytoplasm at a site where replication proceeds optimally. Recently experiments have been performed with wild-type Ebola virus Zaire that demonstrates that cellular entry involves uptake by a macropinocytosis-like mechanism. Macropinocytosis is one of the path that has already been shown to be important for the uptake of vaccinia virus. This mechanism is associated with outward extensions of the plasma membrane formed by actin polymerization. These so called membrane ruffles can fold back upon themselves and form a macropinosome upon fusion of the distal loop ends. The involvement of macropinocytosis was tested through the use of EIPA (5-(N-ethyl-N-isopropyl amiloride), a potent and specific inhibitor of Na+/H+ exchanger activity important for macropinosome formation. They discovered a dose-dependent inhibition of gfpZEBOV infection as well as severe inhibition of ZEBO-VLP entry in the presence of this amiloride. Further experiments determined that Ebola virions colocalize with internalized dextran, a complex polysaccharide taken in by macropinocytosis, and requires the activity of p53-activated kinase 1, another hallmark of this entry pathway. Lastly, it was noted that gfpZEBO-VLPs were associated with Arp2 and vasodilator-stimulated phosphoprotein (VASP), two actin-associated proteins that promote actin assembly. This also points towards macropinocytosis, since actin is required for the formation of plasma membrane ruffles as well as vesicle trafficking. All of these findings points towards a macropinocytosis-like pathway as the primary internalization method of Ebola. Authors also indicate a role of actin in viral entry and suggest that the virus can actively promote localized actin remodeling through its interaction with Arp2 and VASP. The mechanism by which the virus causes macropinocytosis is not understood, but most likely involves the interaction of GP with cell surface receptors. The receptor tyrosine kinase Ax1 and integrin βI have been implicated as viral receptors, with evidence that several other receptor tyrosine kinases and integrins can trigger macropinocytosis.

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Virus entry needs two host proteins: NPC1 and TIM-1:

There are two candidates for host cell entry proteins. The first is a cholesterol transporter protein, the host-encoded Niemann–Pick C1 (NPC1), which appears to be essential for entry of Ebola virions into the host cell and for its ultimate replication. In one study, mice with one copy of the NPC1 gene removed showed an 80 percent survival rate fifteen days after exposure to mouse-adapted Ebola virus, while only 10 percent of unmodified mice survived this long. In another study, small molecules were shown to inhibit Ebola virus infection by preventing viral envelope glycoprotein (GP) from binding to NPC1. Hence, NPC1 was shown to be critical to entry of this filovirus, because it mediates infection by binding directly to viral GP. When cells from Niemann Pick Type C patients lacking this transporter were exposed to Ebola virus in the laboratory, the cells survived and appeared impervious to the virus, further indicating that Ebola relies on NPC1 to enter cells; mutations in the NPC1 gene in humans were conjectured as a possible mode to make some individuals resistant to this deadly viral disease. The same studies described similar results regarding NPC1′s role in virus entry for Marburg virus, a related filovirus.  A further study has also presented evidence that NPC1 is critical receptor mediating Ebola infection via its direct binding to the viral GP, and that it is the second “lysosomal” domain of NPC1 that mediates this binding.

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People whose cells lack or don’t have properly functioning NPC1 protein get NPC disease. There are several research groups looking for compounds that can block the protein on the Ebola virus from coming into contact with NPC1 protein. These drugs ultimately could be used as a means to prevent people from getting infected or for making an infection less severe. Parents of children with NPC disease are supporting research into the Ebola-NPC connection. Researchers want to know if Ebola survivors also have mutations on one copy of their NPC gene. And by studying cells from parents who are NPC carriers, they hope to better understand how changes on the NPC gene might lower the risk of dying from Ebola virus. There are an estimated 500 cases of NPC disease diagnosed world-wide, mostly in children. Researchers in the Ebola field say there is still a lot to learn. In mice, at least, they believe that the NPC1 gene plays an essential role in Ebola infection, but how that finding translates into humans remains under study. They also contend that there are a number of different genes and other factors, from the amount of virus to someone’s underlying health, that likely play a role in Ebola survival as well.

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The second candidate is TIM-1 (aka HAVCR1). T-cell Ig and mucin domain 1 (TIM-1) binds to the receptor binding domain of the Zaire Ebola virus (EBOV) glycoprotein, and ectopic TIM-1 expression in poorly permissive cells enhances EBOV infection by 10- to 30-fold. TIM-1 was shown to bind to the receptor binding domain of the EBOV glycoprotein, to increase the receptivity of Vero cells. Silencing its effect with siRNA prevented infection of Vero cells. TIM-1 expression within the human body is broader than previously appreciated, with expression on mucosal epithelia from the trachea, cornea, and conjunctiva—tissues believed to be important during in vivo transmission of filoviruses. Recognition that TIM-1 serves as a receptor for filoviruses on these mucosal epithelial surfaces provides a mechanistic understanding of routes of entry into the human body via inhalation of aerosol particles or hand-to-eye contact. TIM1 is expressed in tissues known to be seriously impacted by EBOV lysis (trachea, cornea, and conjunctiva). A monoclonal antibody against the IgV domain of TIM-1, ARD5, blocked EBOV binding and infection. Together, these studies suggest NPC1 and TIM-1 may be potential therapeutic targets for an Ebola anti-viral drug and as a basis for a rapid field diagnostic assay.

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Replication:

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Being acellular, viruses such as Ebola do not replicate through any type of cell division; rather, they use a combination of host- and virally encoded enzymes, alongside host cell structures, to produce multiple copies of themselves. These then self-assemble into viral macromolecular structures in the host cell. The virus completes a set of steps when infecting each individual cell: The virus begins its attack by attaching to host receptors through the glycoprotein (GP) surface peplomer and is endocytosed into macropinosomes in the host cell. To penetrate the cell, the viral membrane fuses with vesicle membrane, and the nucleocapsid is released into the cytoplasm. Encapsidated, negative-sense genomic ssRNA is used as a template for the synthesis (3′-5′) of polyadenylated, monocistronic mRNAs and, using the host cell’s ribosomes, tRNA molecules, etc., the mRNA is translated into individual viral proteins. These viral proteins are processed, a glycoprotein precursor (GP0) is cleaved to GP1 and GP2, which are then heavily glycosylated using cellular enzymes and substrates. These two molecules assemble, first into heterodimers, and then into trimers to give the surface peplomers. Secreted glycoprotein (sGP) precursor is cleaved to sGP and delta peptide, both of which are released from the cell. As viral protein levels rise, a switch occurs from translation to replication. Using the negative-sense genomic RNA as a template, a complementary +ssRNA is synthesized; this is then used as a template for the synthesis of new genomic (-)ssRNA, which is rapidly encapsidated. The newly formed nucleocapsids and envelope proteins associate at the host cell’s plasma membrane; budding occurs, destroying the cell.

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The figure below shows replication of ebola virus in host cell:

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Budding of ebola virus from infected host cell: 

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Once an Ebola particle enters the bloodstream, it drifts until it sticks to a cell. The particle is pulled inside the cell, where it takes control of the cell’s machinery and causes the cell to start making copies of it. Most viruses use the cells of specific tissues to copy themselves. For example, many cold viruses replicate in the sinuses and the throat. Ebola attacks many of the tissues of the body at once, except for the skeletal muscles and the bones. It has a special affinity for the cells lining the blood vessels, particularly in the liver. After about eighteen hours, the infected cell is releasing thousands of new Ebola particles, which sprout from the cell in threads, until the cell has the appearance of a ball of tangled yarn. The particles detach and are carried through the bloodstream, and begin attaching themselves to more cells, everywhere in the body. The infected cells begin spewing out vast numbers of Ebola particles, which infect more cells, until the virus reaches a crescendo of amplification. The infected cells die, which leads to the destruction of tissues throughout the body. This may account for the extreme pain that Ebola victims experience. Multiple organs fail, and the patient goes into a sudden, steep decline that ends in death. In a fatal case, a droplet of blood the size of the “o” in this text could easily contain a hundred million particles of Ebola virus.

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Target cells and tissues:

Ebola virus has a broad cell tropism, infecting a wide range of cell types. In-situ hybridisation and electron microscopic analyses of tissues from patients with fatal disease or from experimentally infected non-human primates show that monocytes, macrophages, dendritic cells, endothelial cells, fibroblasts, hepatocytes, adrenal cortical cells, and several types of epithelial cells all lend support to replication of these viruses. Temporal studies in non-human primates experimentally infected with Zaire Ebola virus suggest that monocytes, macrophages, and dendritic cells are early and preferred replication sites of these viruses. These cells seem to have pivotal roles in dissemination of the virus as it spreads from the initial infection site via monocytes, macrophages, and dendritic cells to regional lymph nodes, probably through the lymphatic system, and to the liver and spleen through the blood. Monocytes, macrophages, and dendritic cells infected with Ebola virus migrate out of the spleen and lymph nodes to other tissues, thus disseminating the infection.

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Ebola virus pathogenesis:

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Humans infected with ebolaviruses commonly present initially with nonspecific symptoms such as fever, vomiting, and severe diarrhea, with visible hemorrhage occurring in less than half the cases, as in the current outbreak. Owing to poor infrastructure, biosafety concerns associated with processes of patient care and autopsy, and the essential focus on disease containment during outbreaks, there has been little empirical study to elucidate the pathogenesis or pathology of human ebolavirus infection. The closest surrogate disease models are cynomolgus and rhesus macaques, which show clinical signs of viral hemorrhagic fever when infected with most ebolaviruses. Zaire ebolavirus is uniformly lethal in these macaques, and experts have assumed that its pathology and pathophysiology closely resemble those of ebolavirus infections in humans; immunosuppression, increased vascular permeability, and impaired coagulation have been identified as hallmarks of the disease.  Evidence of microscopic hemorrhage is usually found, but the degree of bleeding ranges from undetectable to acutely visible. The recently introduced term “Ebola virus disease” may not convey the seriousness of a viral hemorrhagic fever, a clinical syndrome that should trigger isolation guidelines that ensure appropriate case management and implementation of infection-control measures.   

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The figure below shows how infected monocytes release cytokines that damage endothelial cells:

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Initially during initial stages of infection, the Ebola virus selectively targets dendritic cells, monocytes and macrophages, which spread through the circulatory and lymphatic systems to the liver spleen and lymph nodes. From here the virus can efficiently spread throughout the body. The infected monocytes and macrophages also release massive amounts of cytokines, helping to trigger virus-induced shock by causing damage to the endothelial structures. Infected dendritic cells are prevented from releasing co-stimulatory cytokines necessary for the production of T-cells, preventing sufficient immune response to the infection. The massive release of cytokines and virus particles from monocytes and macrophages impairs the function of endothelial tissue, allowing it to become permeable to water and macromolecules. Virus spreads from the initial infection site (small lesions) to regional lymph nodes, liver, and spleen. Although ebola virus does not infect lymphocytes, their rapid loss by apoptosis is a prominent feature of disease. The direct interaction of lymphocytes with viral proteins cannot be discounted as having a role in their destruction, but the substantial loss of lymphocytes probably results from a combination of factors including infection-mediated impairment of dendritic cells and release of soluble factors from monocytes and macrophages. Soluble factors released from target cells also contribute to the impairment of the vascular system leading to vascular leakage. The systemic virus spread and replication, the general dysregulation of the host immune response, the coagulation abnormalities, the impairment of the vascular system, and hypotension all together finally result in shock and multi-organ failure.

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Although the endothelium is thought to play an important part in the pathogenesis of Ebola virus, studies defining the molecular mechanisms of endothelial impairment are incomplete. Researchers thought that the virus’ glycoprotein is the primary determinant of vascular-cell injury and that Ebola virus infection of endothelial cells induces structural damage, which could contribute to the haemorrhagic diathesis. However, histological analysis of autopsy tissues from several of the early outbreaks did not identify vascular lesions, and no vascular lesions in any subsequent studies have been reported so far. Similarly, no evidence of substantial vascular lesions in non-human primates infected with Ebola virus exists. In one temporal study in cynomolgus macaques, infection of endothelial cells by Zaire Ebola virus was infrequent and was mainly restricted to the terminal stages of disease.

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Together with the macrophage-rich lymphoid tissues, the liver and the adrenal gland seem to be important targets for filoviruses, and this tropism probably has an equally important role in the disease pathogenesis. Various degrees of hepatocellular necrosis have been reported in infected people and non-human primates; however, the hepatocellular lesions are generally not serious enough to explain the cause of death. Importantly, haemorrhagic tendencies could be related to decreased synthesis of coagulation and other plasma proteins because of severe hepatocellular necrosis. Adrenocortical infection and necrosis have also been reported in humans and non-human primates infected with Ebola virus. The adrenal cortex plays an important part in control of blood pressure homoeostasis. Impaired secretion of enzymes that synthesise steroids leads to hypotension and sodium loss with hypovolaemia, which are important elements that have been reported in nearly all cases of Ebola haemorrhagic fever. Impairment of adrenocortical function by Ebola virus infection could therefore have an especially important role in the evolution of shock that typifies late stages of Ebola haemorrhagic fever.

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In addition to sustaining direct damage from viral infection, patients infected with Ebola virus (Zaire) have high circulating levels of proinflammatory cytokines, which presumably contribute to the severity of the illness. In fact, the virus interacts intimately with the cellular cytokine system. It is resistant to the antiviral effects of interferon , although this mediator is amply induced. Viral infection of endothelial cells selectively inhibits the expression of major histocompatibility complex class I molecules and blocks the induction of several genes by the interferons. In addition, glycoprotein expression inhibits V integrin expression, an effect that leads to detachment and subsequent death of endothelial cells in vitro and that correlates with the limited inflammatory response evident in lesions.

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Acute infection is associated with high levels of circulating virus and viral antigen. Clinical improvement takes place when viral titers decrease concomitant with the onset of a virus-specific immune response, as detected by enzyme-linked immunosorbent assay (ELISA) or fluorescent antibody testing. In fatal cases, there is usually little evidence of an antibody response, and there is extensive depletion of spleen and lymph nodes. Ebola Sudan virus amplification by PCR shows a correlation between serum viral RNA concentration and the likelihood of death. Recovery is apparently mediated by the cellular immune response: convalescent-phase plasma has little in vitro virus-neutralizing capacity and is not protective in humans or in passive transfer experiments in monkey and guinea pig models.

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Immune System Evasion:

One of the reasons that Ebola is so deadly is that it has multiple ways of interfering with or avoiding the human immune system. While the virus is busy destroying the human body, the immune system is either still in the process of discovering that there is a problem, or is in such disarray that it would be next to impossible to mobilize a unified effort to fight off the invader. Among the five strains of Ebola virus, the Zaire strain appears to be the most virulent, with a mortality rate of up to 90%. Despite extensive research, the molecular basis for this virulence has not been determined. Fatal Ebola infections are marked by unchecked viral replication combined with an inadequate antiviral response. In order for this to occur, the early antiviral innate immune response must be delayed or inhibited. During infection, monocytes/macrophages in the lymphoid tissues are early and sustained targets of this deadly virus. Since these cells usually elicit the response cascade in the acute phage of inflammation, their early infection helps Ebola evade the immune system while subsequently spreading throughout the host. In addition, infected macrophages release increased amounts of nitric oxide (NO), a gaseous hormone that normally functions in cell communication. However, in high concentrations, NO depresses the mitochondrial membrane potential, causing apoptosis in nearby natural killer cells. So far, most of the processes by which Ebola escapes or hampers immune response involve viral structure proteins.

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Most filovirus proteins are encoded in single reading frames; the surface GP is encoded in 2 frames (open reading frame [ORF] I and ORF II). The ORF I (amino-terminal) of the gene encodes for a small (50-70 kd), soluble, nonstructural secretory glycoprotein (sGP) that is produced in large quantities early in Ebola virus infection. The sGP binds to neutrophil CD16b, a neutrophil-specific Fc g receptor III, and inhibits early neutrophil activation. The sGP also may be responsible for the profound lymphopenia that characterizes Ebola infection. Thus, sGP is believed to play pivotal roles in the ability of Ebola to prevent an early and effective host immune response. One hypothesis is that the lack of sGP production by Marburg virus may explain why this agent is less virulent than African-derived Ebola virus.  Leroy et al reported their observations of 24 close contacts of symptomatic patients actively infected with Ebola. Eleven of the 24 contacts developed evidence of asymptomatic infection associated with viral replication. Viral replication was proven by the author’s ability to amplify positive-stranded Ebola virus RNA from the blood of the asymptomatic contacts.  A detailed study of these infected but asymptomatic individuals revealed that they had an early (4-6 days after infection) and vigorous immunologic response with production of interleukin (IL) and tumor necrosis factor (TNF), resulting in enhanced cell-mediated and humoral-mediated immunity. In patients who eventually died, proinflammatory cytokines were not detected even after 2-3 days of symptomatic infection.  A second, somewhat larger (120-150 kd) GP, transmembrane glycoprotein, is incorporated into the Ebola virion and binds to endothelial cells but not to neutrophils. Ebola virus is known to invade, replicate in, and destroy endothelial cells. Destruction of endothelial surfaces is associated with disseminated intravascular coagulation, and this may contribute to the hemorrhagic manifestations that characterize many, but not all, Ebola infections.

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Interferon blocking:

Interferon is critical to our ability to defend ourselves against viruses. It makes a variety of responses to viral infection possible, including the self-destruction of infected cells and the blockage of supplies necessary for viral reproduction. The VP24 and VP35 structural proteins of EBOV play a key role in blocking interferon. When a cell is infected with EBOV, receptors located in the cell’s cytosol (such as RIG-I and MDA5) or outside of the cytosol (such as Toll-like receptor 3 (TLR3), TLR7, TLR8 and TLR9), recognize infectious molecules associated with the virus. On TLR activation, proteins including interferon regulatory factor 3 and interferon regulatory factor 7 trigger a signaling cascade that leads to the expression of type 1 interferons. The type 1 interferons are then released and bind to the IFNAR1 and IFNAR2 receptors expressed on the surface of a neighboring cell. Once interferon has bound to its receptors on the neighboring cell, the signaling proteins STAT1 and STAT2 are activated and move to the cell’s nucleus. This triggers the expression of interferon-stimulated genes, which code for proteins with antiviral properties. EBOV’s V24 protein blocks the production of these antiviral proteins by preventing the STAT1 signaling protein in the neighboring cell from entering the nucleus. The VP35 protein directly inhibits the production of interferon-beta. By inhibiting these immune responses, EBOV may quickly spread throughout the body. The Ebola virus VP35 protein inhibits the activation of IRF-3, a critical transcription factor for the induction of early antiviral immunity resulting in high level of virulence of Ebola Virus. 

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Tetherin blocked:

The virus disables a cellular protein called tetherin that normally can block the spread of virus from cell to cell. Tetherin represents a new class of cellular factors that possess a very different means of inhibiting viral replication. Tetherin is the first example of a protein that affects the virus replication cycle after the virus is fully made and prevents the virus from being able to go off and infect the next cell.  When a cell is infected with a virus like Ebola, which is deadly to 90 percent of people infected, the cell is pirated by the virus and turned into a production factory that makes massive quantities on new virions. These virions are then released from that cell to infect other cells and promote the spreading infection.  Tetherin is one of the immune system’s responses to a viral infection. If working properly, tetherin stops the infected cell from releasing the newly made virus, thus shutting down spread to other cells. A study shows that the Ebola virus has developed a way to disable tetherin, thus blocking the body’s response and allowing the virus to spread. Binding of a protein produced by Ebola to tetherin apparently inactivates this cellular factor. Understanding how the Ebola protein blocks the activity of tetherin may facilitate the design of therapeutics to inhibit this interaction, allowing the cell’s natural defense systems to slow down viral replication and give the animal or person a chance to mount an effective antiviral response and recover. Previous research had found that tetherin plays a role in the immune system’s response to HIV-1, a retrovirus, and that tetherin is also disabled by HIV.

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Cytokine storm:

Ebola loves not having to deal with the fully functional immune system, because now it can replicate and wreak havoc without interference. This suppression of the innate antiviral immune system then facilitates a cytokine storm. A cytokine storm is basically too many cytokines (a class which interferons belong to), the result of which is a rapid and potentially deadly immune over-response. The production of cytokines is a normal response when the immune system encounters an ordinary invader, and their role is to tell your immune cells to go to some location and do their respective immune cell jobs, and also to produce more cytokines. A healthy or at least in-balance body regulates how many cytokines the immune cells create, so they’re kept in check. And keeping cytokines in check means keeping the body’s immune responses in check. In a cytokine storm, however, the body never gets the message to stop making cytokines. This results in a positive feedback loop in which the body is telling itself to make more and more cytokines without anything ever telling them to stop. The body’s inflammatory immune responses go into hyper-drive, with the results including a skyrocketing fever (potentially deadly in itself) and the rapid build-up of fluids and dead immune cells (pus). Take the shedding of this fluid coupled with a catastrophic decline in the body’s blood clotting ability and the result is Ebola’s infamous blood spewing from orifices, which, in fairness, is really more of an oozing if it occurs at all.

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The normal job of the immune system is to eliminate infections. But when it’s activated at extreme levels or it’s out of control, it becomes damaging to the host. The most extreme immune attack is the “cytokine storm.” Although many viruses, like bird flu and SARS, can trigger this shock and awe assault, Ebola is probably the best at it. And at the end of an Ebola infection, it’s the cytokine storm that kills you. In essence, a cytokine storm is an SOS signal that causes the immune system to launch its entire arsenal of weapons all at once. This last-ditch, kamikaze attack hurts the virus. But it leaves behind tons of collateral damage. Blood vessels take the brunt of it. The cytokine storm makes the blood vessel walls more permeable. So the arteries, veins and capillaries start to leak blood and plasma. The storm also triggers a big release of nitric oxide, which thins out the blood and damages vessels further. All these factors combine together to reduce blood pressure to dangerous levels. So you don’t die of blood loss, but from something similar to severe septic shock. 

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Results from several studies show an important role for reactive oxygen and nitrogen species in pathogenesis of Ebola haemorrhagic fever. Increased concentrations of nitric oxide in blood were reported in non-human primates experimentally infected with Zaire Ebola virus and were noted in patients infected with Zaire Ebola virus and Sudan Ebola virus. Increased blood concentrations of nitric oxide in patients were associated with mortality.  Abnormal production of nitric oxide has been associated with several pathological disorders including apoptosis of bystander lymphocytes, tissue damage, and loss of vascular integrity, which might contribute to virus-induced shock. Nitric oxide is an important mediator of hypotension, and hypotension is a prominent finding in most of the viral haemorrhagic fevers including those caused by Ebola virus.

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Decoy Strategy:

Ebola also employs a second dastardly trick, another cheat. It releases large amounts of secreted glycoprotein – sGP – into the bloodstreams of its victims. A decoy, sGP looks like the glycoprotein on the exterior of the virus, GP, which should be the immune system’s chief target. By tricking the immune system into seeing it, not GP as the invader, sGP undermines the system’s ability to react effectively to stem the infection.

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What Ebola does to the human body at a molecular level is far more disturbing:

Once patients contract Ebola, the virus begins to mow down their immune system, killing off the body’s T-lymphocyte cells, the same ones affected by the AIDS virus. However, Ebola is far more aggressive than AIDS and begins tearing through several types of immune cells far more quickly. The virus produces several proteins, one of which blocks immune cells from signaling antibodies to attack. Once the patient’s first line of defense against pathogens is dismantled, the virus can begin replicating. The first symptoms of Ebola are a sudden increase in body temperature, accompanied by strong headaches, joint and muscle pain. Decreased appetite and sore throat are also early indicators of the disease. One of the first tissues the virus settles in is collagen. Collagen keeps the body’s organs in place, like organic glue. Ebola eats away at collagen, causing all kinds of problems. The patient’s upper layer of skin ends up floating on a layer of liquefied tissue, resulting in tiny white blisters and red spots on the surface that can tear off with just a small amount of pressure. Rips in the skin can appear and spontaneous bleeding can occur from several orifices, including the eyes, nose and mouth. At the same time, immune cells called macrophages trigger coagulation, which forms small blood clots throughout the bloodstream, according to a study published in Cell Host & Microbe. Blood vessels all over the body begin to burst and leak, reducing the blood supply to the body’s vital organs. This circulatory failure deprives the organs of oxygen and causes them to shut down. The process is most severe in the liver. All the while, a patient suffering from Ebola will have severe diarrhea and fits of vomiting, both of which will become increasingly filled with blood. The terminal phase of the infection occurs when the immune system, completely thrown out-of-whack, begins attacking a patient’s own body. Large blood blisters appear on the skin and the patient’s eyes become red. Blood pours from the body. Shock sets in as one organ after another fails. 

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Lymphocyte apoptosis in ebola:

Lymphocytes do not support filoviral replication, perhaps because they lack receptors for these viruses. Nevertheless, lymphocyte apoptosis is a characteristic feature of filovirus infections and can be observed in both blood and tissues of infected patients and animals. The apoptotic lymphocytes are not infected and are engulfed by surrounding macrophages. Filovirus-induced lymphocyte apoptosis is also observed in EBOV-infected human PBMCs. The apoptosis of non-infected lymphocytes is not unique to filoviruses. It has been reported in a number of viral infections, including lymphocyte choriomeningitis virus, human immunodeficiency virus, human herpesvirus 6 and Vaccinia virus infections. Although protection from apoptosis of infected cells is a strategy for survival for a number of viruses, induced periods of transient or chronic lymphocytopenia brought about by bystander apoptosis is thought to contribute to the generalized immunosuppression that accompanies some viral infections. The best known example of bystander lymphocyte apoptosis in viral infections is in CD4 T cells during HIV infection. In the case of filovirus infection, not only are CD4 T cells depleted, but CD8 T cells and NK cells as well, suggesting that some generalized mechanisms may contribute to lymphocyte apoptosis in filovirus disease. Using a mouse model of EBOV infection, Bradfute et al. suggested that both intrinsic and extrinsic apoptotic pathways may contribute to lymphocyte depletion. If this is also the case for the disease in humans and non-human primates, then it is likely that multiple mechanisms contribute to the generalized lymphocyte depletion. The loss of lymphocytes has been postulated to contribute to the failure to generate fully protective adaptive immune responses in these species. In fact, extensive lymphocyte apoptosis has been shown to proceed the generation of adaptive responses in humans with fatal disease, making this hypothesis all the more plausible. EBOV-infected cells may secrete TRAIL and increased levels of soluble Fas have been detected in the sera of some EBOV-infected non-human primates. Moreover, increased expression levels of TRAIL and Fas mRNA have been observed in peripheral blood mononuclear cells of infected non-human primates. These could trigger conventional extrinsic pathways of apoptosis in susceptible cells, including T cells. It is also possible that dysregulated DCs and macrophages could contribute in other ways to lymphocyte apoptosis. Infected DCs and macrophages fail to produce regulated cytokine responses, and they are also impaired in their ability to upregulate co-stimulatory molecules, such as CD40 and the B7 family member CD86, consistent with their inability to efficiently prime T cells. Alternatively, T cell apoptosis may result in part from the dysregulated cytokine responses during filovirus infections.

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Impairment of coagulation:

Defects in blood coagulation and fibrinolysis during Ebola virus infections are manifested as petechiae, ecchymoses, mucosal haemorrhages, congestion, and uncontrolled bleeding at venepuncture sites. However, massive loss of blood is infrequent and, when present, is mainly limited to the gastrointestinal tract. Even in these cases, the amount of blood that is lost is not substantial enough to cause death. Thrombocytopenia, consumption of clotting factors, and increased concentrations of fibrin degradation products are other indicators of the coagulopathy that characterises Ebola virus infections. Results from clinical laboratory data strongly suggest that the coagulation abnormalities that occur during human Ebola haemorrhagic fever are generally consistent with disseminated intravascular coagulation. Furthermore, results from many studies have shown histological and biochemical evidence of disseminated intravascular coagulation during Ebola virus infection in several non-human primate species. The mechanism responsible for triggering the coagulation disorders that typify Ebola haemorrhagic fever are not wholly understood. Results from several studies strongly suggest that expression or release of tissue factor from monocytes and macrophages infected with Ebola virus are key factors that induce the development of coagulation irregularities reported in Ebola haemorrhagic fever. However, coagulopathy noted during Ebola haemorrhagic fever could be caused by several factors, especially during the later stages of disease. For example, rapid reductions in plasma concentrations of the natural anticoagulant protein C were recorded during the course of Zaire Ebola virus infection of cynomolgus monkeys. Together, the data so far suggest that an impaired and ineffective host response leads to high concentrations of virus and proinflammatory mediators in the late stages of disease, which is important in the pathogenesis of haemorrhage and shock. The prevailing hypothesis at this time is that infection and activation of antigen-presenting cells is fundamental to the development of Ebola haemorrhagic fever. The release of proinflammatory cytokines, chemokines, and other mediators from antigen presenting cells, and perhaps other cells, causes impairment of the vascular and coagulation systems leading to multiorgan failure and a syndrome that in some ways resembles septic shock.

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Global Suppression of the Host Antiviral Response by Ebola- and Marburgviruses: a 2006 study:

In both primate and human models, most of the major organs, including the liver, lymph nodes, and spleen, show high titers of virus, and immunohistochemical analysis has shown that endothelial and mononuclear cells become heavily infected and play central roles in disease progression. Early and sustained infection in monocytes also plays a central role in the occurrence of viral hemorrhagic fever through the expression of proinflammatory and antiviral cytokines, including alpha interferon (IFN-α), interleukin-1 (IL-1), IL-6, IL-8, IL-12, and TNF family members (e.g., TNF-α and TRAIL), and coagulation factors (e.g., tissue factor [TF]), leading to activation of the extrinsic coagulation pathway and ultimately to endothelial cell destruction and permeability. Defective adaptive immune responses, including impaired humoral responses and apoptosis of B and T cells, have been observed in fatal cases of EBOV infection. Interestingly, it has been reported that type I IFN (IFN-α-2b) treatment has little effect on disease progression or pathology in EBOV-infected cynomolgus macaques. Thus, it has been concluded that the progression and ultimate outcome of human clinical filovirus infections are dependent on early antiviral events in EBOV infection that are predicated on the establishment of well-regulated antiviral and immune responses.

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Filaments are loaded with VP40 and may act as needles that prick neighboring cells and inject the toxic material:

As recently as a decade ago, it wasn’t possible to view live cells under microscopes. Scientists pored over fixed dead ones to puzzle out clues about their behavior. But a new technique called fluorescence dynamics allows researchers to track cells as they grow by tagging them with bright inks. Three people won the Nobel Prize in chemistry this year for their development of super-resolved fluorescence microscopy. Still, it isn’t easy to trace the progress of the infinitesimally small viral particles. Digman and her colleagues created three-dimensional models and now compress hours of raw data to track VP40. There’s no risk from the isolated protein in the cell culture rooms; it needs the disease genome and six other proteins to fully form infectious Ebola. Usually, cells can absorb viruses and other harmful substances and neutralize them with acidic lipids. Not so with Ebola. Digman and the others have discovered that VP40 multiplies unimpeded inside the cell until finally the infected body’s membrane bulges out under the accumulated weight, budding into the needle-like filaments. They’ve learned that the protein hijacks the cell’s motor to form the protrusions. They’ve seen detached filaments floating outside cells. Now they just need to see them pricking other cells. A fluorescent green limb pokes outward from a cell wall under a high-powered microscope. The filament is loaded with VP40, an essential protein in the Ebola virus. The microscope is capturing it budding out in real time. It’s followed by another and another. Those green protrusions may be the means by which the deadly virus races from cell to cell in humans, killing up to 60 percent of those infected. Their hypothesis is that the filaments may act as needles that prick neighboring cells and inject the toxic material, a process that quickly goes viral. If that proves true, it could be key to the development of effective inhibitor treatments.  

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Protective immune response against ebola:

The components of the immune system that may protect against Ebola virus infection have not been defined. Antibody titers against Ebola virus GPs are readily detectable in patients who recover from Ebola virus infection; however, anecdotal reports have indicated that serum from recovered patients did not consistently protect against infection or exhibit neutralization of virus replication in cell culture. Furthermore, passive transfer of antibodies in animal models only delays the onset of symptoms and does not alter overall survival. More recently, the neutralization of virus replication by selected monoclonal antibodies isolated from the bone marrow of recovered patients was demonstrated in vitro, and monoclonal antibodies that recognize specific epitopes of Ebola virus GP have been shown to confer immune protection in a murine model of Ebola virus infection and in guinea pigs. However, it is relatively easy to protect against infection in the mouse model, and protection of guinea pigs required a high dose of antibody administered very close to the time of virus challenge. Taken together, these results suggest that antibodies alone do not provide protective immunity in a natural context and that cellular immunity is likely to play a significant role in virus clearance. Whether hyperimmune serum from surviving vaccinated animals or certain infrequently occurring antibodies are capable of attenuating infection remains unknown, but such antibodies could potentially contribute to therapy if they can be identified and optimized.

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A comparison of immune parameters in survivors and nonsurvivors of infection has provided clues into the constituents of an effective immune response. Baize et al. characterized the immune responses of patients in two large Ebola virus outbreaks in Gabon in 1996. There was no significant difference in viral antigen load between survivors and nonsurvivors, but immune responses varied, suggesting that survival is dependent on the initial or innate immune response to infection. Survivors exhibited more significant IgM responses, clearance of viral antigen, and sustained T-cell cytokine responses, as indicated by high levels of T-cell-related mRNA in the peripheral blood. In contrast, antibodies specific for the virus were nearly undetectable in fatal cases, and while gamma interferon (IFN-γ) was detected early after infection, T-cell cytokine RNA levels were more indicative of a failure to develop adaptive immunity in the days preceding death.

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During infection, there is evidence that both host and viral proteins contribute to the pathogenesis of Ebola virus. Increases in the levels of inflammatory cytokines IFN-γ, IFN-α, interleukin-2 (IL-2), IL-10, and tumor necrosis factor alpha were associated with fatality from Ebola hemorrhagic fever. Moreover, in vitro experiments demonstrated that tumor necrosis factor released from filovirus-infected monocytes and macrophages increased the permeability of cultured human endothelial cell monolayers. However, other reports have observed an association between elevated levels of IFN-γ mRNA and protection from infection, and a protective effect of IFN-α and -γ is suggested by the fact that the virus has evolved at least one protein, VP35, that acts as an IFN-α/β antagonist. Whether the effects of cytokines are protective or damaging may depend not only on the cytokine profile but also may represent a delicate balance influenced by the route and titer of incoming virus as well as factors specific to the individual host immune response.

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Natural killer (NK) cells confer protection against ebola virus infection:

Natural killer (NK) cells serve as a crucial first line of defense against tumors and a diverse range of pathogens. Recognition of infection by NK cells is accomplished by the activation of receptors on the NK cell surface, which initiate NK cell effector functions. Many of the receptors and ligands involved in NK cell antimicrobial activity have been identified, and we are beginning to appreciate how they function during infection. In addition, NK cells are activated by cytokines (e.g. interleukin 12 and type I interferons), which are products of activated macrophages and dendritic cells. In response to these activating stimuli, NK cells secrete cytokines and chemokines and lyse target cells. Recent studies have focused on the mechanisms by which NK cells recognize and respond to viruses, parasites and bacteria, and on the unique role of NK cells in innate immunity to infection. NK cells are key components of the innate immune system, rapidly responding to invading microbes by exocytosis of perforin and granzymes, which mediate the destruction of infected cells. Additionally, NK cell secretion of cytokines such as IFN-γ, IFN-α/β, and TNF-α serve a dual purpose in that they initiate the immediate activation of antimicrobial pathways in infected cells, followed by modulation of adaptive responses to the pathogen. The induction of cytokines and chemokines by viral infections is also known to trigger NK cell activity. Specifically, virus-induced IFN-α/β enhances NK cell–mediated cytotoxicity. Alternately, the induction of IL-12 by some viral infections is responsible for the production of high levels of IFN-γ by NK cells, as well as the induction of NK cytotoxic activity. NK cells appear to play a critical role in the immune response to Epstein-Barr virus, murine cytomegalovirus (MCMV), and herpes simplex virus-1. The clinical importance of NK cells to antiviral immunity is documented by the fact that recurrent herpesvirus infections have been observed in a NK-deficient patient. NK cell activity is closely regulated by a myriad of activating and inhibiting cell surface receptors, and consequently, viruses have evolved multiple mechanisms to evade or modulate these receptors. Such mechanisms include the up-regulation of HLA-C and HLA-E molecules on the surface of virus-infected cells, expression of viral MHC homologues to trigger NK inhibitory receptors, and/or the release of cytokine homologues with inhibitory activities. In contrast, virus-infected cells often down-regulate MHC class I on their surface, which enhances NK cell–mediated lysis due to removal of the inhibitory signals delivered by the MHC. The innate immune system provides early surveillance and control of viral infections. A study shows that the innate immune response, specifically NK cells, can mediate rapid and complete protection against lethal Ebola virus infection. These observations represent a key advance in understanding the requirements for protective immunity against Ebola virus infection. The identification of NK cells as critical mediators of early protection against Ebola virus infection are an important step forward in the identification of prophylactic and therapeutic interventions against filovirus and other incapacitating acute viral infections. Although the exact application of these findings to therapeutics in treating Ebola virus–infected primates and humans is unclear at this time, therapeutic agents that bolster the innate immune response, including activation of NK cells, should be the target of future studies.

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Virulence of ebola:

The reproductive success of a pathogen is dependent upon its ability to replicate itself and to infect new hosts by transfer of its propagules. Rapid replication can increase a pathogens chance of transference, but this requires a greater toll on the hosts system and is likely to lead to an increased chance of host mortality. Due to this, there is believed to be a natural correspondence between a pathogens growth rate and virulence. The relationship between these two factors is explained by the trade-off hypothesis of virulence evolution. This theory largely replaced the commonly accepted idea that a parasite or pathogen should evolve towards avirulence, but it not fully accepted. The avirulence theory assumed that a parasite low virulence would maximize a pathogen’s overall lifetime reproductive success by increasing the time of infection to nearly infinite limits. The reasoning behind this avirulence theory has been explained thusly: The parasite makes a profession out of living at its neighbours’ expenses and all its industry consists of exploiting it with economy, without putting its life in danger. It is like a poor person who needs help to survive, but who nevertheless does not kill its chicken in order to have the eggs. The frequent down trend in virulence from the time a pathogen is introduced to a novel population was offered as evidence for this theory. The trade-off theory developed when evolutionary ecologists began to question the avirulence theory. It proposes that there is a link between ease of transmission and virulence. According to this theory, virulence is an outgrowth of a rapid replication rate in the pathogen, which strains host resources and reduces host fitness (resulting in host mortality). The Trade-off theory links the variables of virulence, transmission and host recovery in a relationship. A high transmission rate will typically go along with a high virulence and low recovery rate. The reproductive success of a pathogen comes from successfully balancing these variables to maximize Ro. High Virulence will allow for high reproduction and transmission, but only up to a point. Natural selection should favor strains that are able to maximize this trade-off. Eventually, virulence can reach a level where the increased transmission is no longer balanced out by the risk of dying along with a host before being able to jump to a new one. This is especially true in isolated host populations or other conditions that limit horizontal transmission, which could possibly explain the low virulence and chronic nature of some infections.

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Virulence is typically defined as morbidity and mortality of the host organism as a result of parasite or pathogen activity. Measurements of a pathogen’s virulence are traditionally given in terms of parasite induced death rate (PIHD). This definition is suitable for a general discussion of a disease as it includes all deleterious effects on the host. A more specific and narrow definition is required in order to examine selective pressures on the evolution of virulence in a disease, however. The generalized definition, according to Ebert and Bull in their work on virulence evolution, fails to differentiate between virulence’s effects on host and pathogen fitness, and therefore fail to give an accurate assessment of selective pressure on the pathogen’s evolution. For this reason it is important to consider specific aspects of the host/pathogen system (such as means of transference, rate of pathogen growth, etc) before drawing conclusions about the selective pressures for increased or reduced virulence in the pathogen. In the case of the Ebola virus and Ebola Hemorrhagic Fever virulence can be discussed in terms of host death. Unlike with some pathogens, death of the host does not immediately end transmission of the virus. Some studies indicate that the corpse can remain infectious for several days after death. Several epidemics have been traced to contact between the index case and the contaminated remains of a chimpanzee (Ivory Coast 1994, Gabon 1996, Gabon 1996-97) and contaminated monkey meat may have played a role in the index case of the initial 1976 Zaire outbreak (Ebola Haemorrhagic Fever in Zaire 1978). Ebert and Bull define three general stages of evolution in a pathogen transferring to a novel host and the selective pressures involved in each. The first phase includes the initial interactions between a pathogen and the novel host. In some cases this infection is not capable of horizontal transfer between hosts in the novel population. Other situations involve short chains of secondary infection from the index infection. Infections in this phase are likely exposed to great selective pressures, as they are in an entirely new environment, one for which their genes may or may not be particularly suitable. Genes that may not have had a measureable fitness effect in the pathogens normal host environment can suddenly exert great selective pressure. Because of this there is frequently a great range of virulence expressed by different pathogens during this phase. The second phase occurs during the period when a pathogen has established a foothold within the novel population. It follows the epidemic infection model and increases rapidly within the population, because of this rapid growth it is possible for a pathogen to evolve rapidly in this phase. Selective pressure on the host can also be extreme in this phase. The second phase also applies when a mutation in a parasite that has already obtained equilibrium within a host population is significant enough that it gains a selective advantage over other strains and spreads rapidly. Ebert and Bull’s third phase is reached when a pathogen has become firmly established within a host population. Pathogens in this phase are well adapted to the host, but will still experiences selective pressures due to host demographic and environmental changes. The Ebola virus, in human hosts, remains largely within the first phase, although it could be argued that it briefly enters the second phase on a local level during some outbreaks. It causes short lived epidemics when it does infect a human population, but fails to survive long term and become an endemic pathogen. During this initial stage the virus can be exposed to great selective pressure as it is in an unusual host. Evolutionary dynamics within an epidemic scenario, as proposed by Bolker et al, favor pathogens with a high growth and transference rates, and the high virulence that is associated with them, due to the large number of susceptible hosts in the novel population. This differs from a pathogen in later stages, which has reached dynamic equilibrium with the host. These situations tend to select for moderate virulence and longer duration of infection. (Bolker et al). A possible explanation for the extreme virulence in Ebola outbreaks may simply be reporting bias. Many of the early and milder symptoms of Ebola Hemorrhagic Fever are quite similar to those of other diseases endemic to the region, such as malaria, and measles. Some outbreaks are actually mistaken for cases of other diseases until post-infection laboratory tests detect particles of an Ebola strain. A 1994 outbreak in gold mining camps in Gabon (52 cases, 60% mortality) was believed to be a yellow fever epidemic until almost a year after the last case. It is possible that less virulent strains of the virus are simply mistaken for other common infections, treated as such, and never reported. Ebola virus antibodies were detected in sera from 18% of adults in the 1979 Nzara outbreak who were not infected. This is evidence that “It is likely that sporadic infection is more common than can be appreciated from these dramatic outbreaks, which probably represent the extreme of the interaction between man and the virus.” (Baron et al). This fits in with the inherent virulence variance in phase one pathogens suggested by Ebert and Bull above. Other factors that can affect the evolution of virulence in a pathogen are host population density and ease of transmission. These factors are frequently interrelated, as both directly influence the number of susceptible hosts a pathogen is able to infect during its lifespan. A high density of susceptible hosts (such as when a pathogen is emerging in a novel host population) is likely to greatly increase a pathogens reproductive success, and select for pathogens that can replicate quickly and take advantage of the abundant hosts. Likewise, easy transition from one host to the next also selects for pathogens that are able to rapidly replicate and “seize the day”, as it were. Both of these conditions, which favor pathogens with high growth rates, also favor high virulence in accordance with the Trade-off hypothesis (Ebert & Bull 2008).

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The abovementioned concepts and principles fit in with epidemiological data from outbreaks of Ebola Hemorrhagic Fever. Initial outbreaks of Ebola Hemorrhagic Fever took place within areas with a relatively high concentration of susceptible hosts. The 1976 outbreak centered on the Yambuku Mission Hospital is a good example. This hospital served as the primary medical facility for a local population of around 60,000 as well as travelers. This facility was relatively small, having 17 staff members and holding 120 beds in its crowded wards. It also processed some 6000-12000 outpatients on a monthly basis. Combine this with the five improperly sterilized syringes used to administer injections (the primary dosage method at this facility) and a severe lack of barrier nursing procedures. This would appear to be an optimal situation for the transmission of pathogens that spread through contaminated body fluids. According to the Trade-off Hypothesis and the selective conditions outlined above, pathogen strains that have high reproduction rates (and hence high virulence) would be at a distinct selective advantage. Cases cared for out of the hospital setting would also tend to favor quickly reproducing and more virulent pathogens. Horizontal transfer by physical contact is directly affected by the concentration of virus particles in a contaminated fluid; hence a virus with a higher reproduction rate would be able to successfully exploit a given number of transfer opportunities. This setting lacks the direct viral inoculation by contaminated needle present in the hospital setting, which would perhaps result in less effective transmission. This would also favor more strongly virulent pathogens, which reproduce quickly and successfully exploit transmission opportunities (Ebola Haemorrhagic Fever in Zaire 1978). The conditions present during the 1976 Sudan outbreak were largely similar. Transmission occurred mainly to family members providing nursing care (without barrier nursing techniques) and through contaminated medical equipment and direct contact in a hospital setting. These conditions would also seem to favor more virulent pathogens. Other examples of particularly high virulence outbreaks (in terms of host mortality) also occur under conditions with large amounts of close contact between potential hosts, likely resulting in high transmission. Examples of these situations are found in the 1994 and 1996-97 Gabon outbreaks, which took place at a mining camp and (initially) a remote forest camp respectively. Both of these outbreaks featured transmission of numerous secondary infections through close contact with infected individuals.

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According to the Trade-off hypothesis, high transmission rates are linked to high levels of virulence. By reducing rate of transmission it may be possible to artificially select for less virulent strains. In the hospital and home care setting, hosts suffering from highly virulent strains with high symptom manifestation (high virulence) are likely to transmit the virus to other hosts, favoring virulent strains. Application of sanitation and barrier nursing practices can reduce transmission of the virulent strains present under these conditions. This could potential favor any less virulent strains, i.e. ones that do not manifest severe symptoms that require hospitalization and are unlikely to be fatal, present in the environment. This could gradually reduce overall virulence over the course of the outbreak. Even if less virulent strains are not present, prevention of transmission is likely to slow and eventually stop the outbreak as the number of remaining susceptible hosts is reduced through various means (Ewald 2004).

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The Ebola Virus and Ebola Hemorrhagic Fever present an interesting case for evolution of virulence in a pathogen. The periodic outbreaks of the disease offer examples of how selective pressures imposed on a pathogen follow the predictions of the Trade-off hypothesis linking virulence (and attendant host mortality) with rate of transmission. This hypothesis and the conclusions it suggests fit with data observed in outbreaks of virulent Ebola Hemorrhagic Fever. Conditions of dense susceptible host population and rapid and effective transmission seem to demonstrate high incidences of virulence indicating that there may be selective pressure for virulent strains under these conditions. Evidence of strains showing low virulence is suggested by the Ebola virus’ presence in a natural reservoir species and by the formation of antibodies by healthy individuals not linked to current epidemics. Due to this (presumed) variation amongst strains and the relationship between transmission and virulence proposed by the Trade-off hypothesis, reduction of transmission of the virus in hospital and homecare settings may lead to a reduction in strain virulence in prolonged outbreaks.

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Relationship between the inhibition of antiviral responses and viral fitness:

Viral fitness is a measurement of the ability of a virus to achieve the highest rates of replication and production of progeny virions in a given host. One strategy to increase viral fitness is to control the response of the host cell to infection by affecting cellular gene expression to maximize expression of viral proteins and production of new virus and to minimize the activation of an antiviral state that would increase viral clearance by apoptosis or immune cell killing. In particular, for RNA viruses with relatively small genomes encoding few viral proteins, such as EBOV and influenza virus, control of host cell gene expression is critical for viral fitness. The ability of EBOV and MARV to evade the cellular antiviral response and suppress the immune response during clinical infections demonstrates the profound ability of these viruses to alter host cell gene expression programs. For example, one of the principal components of the innate immune and antiviral responses is the type I IFN response. As a key parameter of viral fitness, IFN antagonists are encoded in many viral genomes, including those of influenza virus, vaccinia virus, and EBOV. Genomics analysis demonstrated that not only IFN induction but also IFN signaling was impaired in ZEBOV- and MARV-infected cells. This significant suppression of the IFN response leads to increased immune evasion, replication, and virulence of ebola virus.

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Case fatality ratio (CFR) as a measure of virulence of ebola:  

A case fatality rate (CFR) – is a relatively simple measurement. It’s the number of people who die from an illness divided by the number of people diagnosed with it. The case fatality ratio (CFR) is calculated as the proportion of deaths among the total number of EVD cases, thereby informing the virulence of the infectious pathogen. EVD can be fatal, but it is important to note that the CFR being ‘almost 100%’ for EVD in general does not rest on any empirical arguments. For the well documented outbreaks of Ebola (excluding only isolated cases who are likely to have acquired infection from animal contact), the expected value of CFR has always been below 90%, with the range from 41% to 89%. The so-called Zaire strain is considered to be slightly more fatal than the Sudan strain. While the CFR for the Sudan strain ranges from 41% to 65%, the CFR for the Zaire strain ranges from 61% to 89%. Considering that the corresponding quartile for the Zaire strain, as determined by the distribution of outbreak-specific estimates, ranges from 73.3% to 84.3%, the CFR of the ongoing 2014 epidemic among cases with definitive recorded clinical outcomes for Guinea, Liberia and Sierra Leone has been consistently estimated at 70.8% (95% CI: 68.6 to 72.8), which is in good agreement with estimates from prior outbreaks. Nevertheless, it must be noted that earlier studies have not addressed ascertainment bias. It is important to follow up the reasons why the estimated 53% (as of 31 August 2014 which involved an underestimation bias due to time delay from illness onset to death) in real-time has been much lower than the published estimate of 70.8% among a portion of cases. Given the potential presence of asymptomatic cases, addressing ascertainment error may be the key to appropriately capture the disease burden for the entire population. The current outbreak has a CFR of about 54% – though it’s subject to change as the outbreak goes on. This figure of 54%, however, is an average taken from several countries. The fatality rate varies from one country to another – in Guinea it’s about 73%, whereas in Liberia its 55%, and in Sierra Leone it’s 41%. Why the variation?  The main factors are the level of preparedness and the availability and quality of medical care. Another factor – when it comes to the varying CFR from one outbreak to the next – may be the different strains of the disease. Of the five known ebola strains, the “Zaire” and “Sudan” strains have been responsible for most deaths. The Zaire strain’s average fatality rate is 79% and the Sudan strain’s is 54% – research on the current outbreak, in Guinea, suggests that it is caused by the Zaire strain. The CFR doesn’t tell you how contagious a disease is. Ebola, transmitted through contact with bodily fluids, is much less contagious than airborne diseases such as influenza or measles. What it can do is indicate how serious the disease is, for those patients infected with it. But as we’ve seen, this varies.

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Overestimation of CFR of ebola:

Is it really true that the fatality rate of ebolavirus is ‘up to 90 percent’?

According to the WHO page on Ebola haemorrhagic fever, Zaïre, Sudan and Bundibugyo species have been associated with large Ebola haemorrhagic fever (EHF) outbreaks in Africa with high case fatality ratio (25–90%) while Côte d’Ivoire and Reston have not. Reston species can infect humans but no serious illness or death in humans has been reported to date.

Till 2011, there have been roughly 1850 recorded cases with over 1200 deaths since ebolavirus was discovered, an average fatality rate of 65%.

But have there been only 1850 human infections till 2011?

The answer is clearly no. The results of several serological surveys have shown that many individuals have antibodies against Zaire ebolavirus – purportedly the most lethal. The results of one study revealed antibodies in 10% of individuals in non epidemic regions of Africa. A similar seroprevalence rate (9.5%) was reported in villages near Kikwit, DRC where an outbreak occurred in 1995. In addition, a 13.2% seroprevalence was detected in the Aka Pygmy population of Central African Republic. No Ebola hemorrhagic fever cases were reported in these areas. A more recent study examined sera from 4,349 individuals in 220 villages in Gabon. Antibodies against Zaire ebolavirus were detected in 15.3% of those tested, with the highest levels in forested regions. The authors believe that the seropositive individuals had mild or asymptomatic ebolavirus infection: The high frequency of ‘immune’ individuals with no disease or outbreak history raises questions as to the real pathogenicity of ZEBOV for humans in ‘natural’ conditions. These findings indicate that the fatality rates of Zaire ebolavirus that are quoted widely are likely to be vast overestimates. Why the infection is more lethal during outbreak conditions is not known. One possibility is related to the size of the viral inoculum received. During outbreaks the virus is spread by contact with the blood, secretions, organs or other body fluids of infected individuals, which contain very large quantities of virus. In contrast, infections in nature – by contact with contaminated fruit, for example – may involve far less virus.  

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The virulence of Ebola virus in man is variable and is dependent on the species or strain; a similar variability seems to recapitulate well in non-human primates. Within the genus Ebola virus, infections with the Zaire Ebola virus species have the highest case-fatality rates (60—90%) followed by those for the Sudan Ebola virus species (40—60%). On the basis of one outbreak, case-fatality rates for Bundibugyo strain infections are estimated to be only 25%. The only reported person infected with Côte d’Ivoire Ebola virus became ill but survived.  By comparison, case-fatality rates for Marburg virus infection in Africa are 70—85% but were much lower in the outbreak in Europe in 1967, with a case-fatality rate of only 22%. This low rate has led to speculation that proper intensive care with supportive therapy would increase the survival rate of infected patients. This hypothesis is hard to test because of austere field conditions and ethical dilemmas about not providing care to some patients. Reston Ebola virus is deemed non-pathogenic for man, but laboratory tests have documented the occurrence of infection.

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Genetic factors of ebola virus responsible ebola virulence:

Ebola virus (EBOV) is the etiological agent of human and primate infections with a high mortality rate; epidemic outbreaks and sporadic cases of this infection are periodically recorded mainly in the Central African region. In spite of increasing evidence points toward bats as natural reservoir of EBOV, the mystery of how it emerges remains unsolved. One of the hypotheses is that avirulent strains of this virus circulate in the populations of natural hosts and change their virulence under certain conditions (Leroy et al., 2004, 2005; Peterson et al., 2004; Pinzon et al., 2004). Indirect evidence for this hypothesis is the presence of anti-EBOV antibodies in individuals having no severe fever. For example, antibodies to EBOV have been detected in populations of Liberia (Knobloch et al., 1982), Cameroon (Bergmann, 1981), Republic of Central Africa (Georges et al., 1989), North Rhodesia, and Republic of Congo (Van der Groen, 1984). This suggests a possible circulation of nonpathogenic EBOV strains in these regions. Examination of serum samples in Zaire in 1972 demonstrated that some EBOV subtypes had circulated there 4 years before the first large-scale outbreak was recorded (Ivanov et al., 1986; Van der Groen, 1984). Similar results were obtained when assaying human blood samples in Ethiopia in 1961–1962 (Tignor et al., 1993). These data suggest a rather wide distribution of EBOV strains nonpathogenic for humans, which cause a subclinical disease. Therefore, genetic factors of ebola virus determine the virulence and range of their variation are of paramount interest for understanding the biology of this pathogen. 

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Elucidating variations in the nucleotide sequence of Ebola virus associated with increasing pathogenicity: a 2014 study: Ebolaviruses causes a severe and often fatal hemorrhagic fever in humans, with some species such as Ebola virus having case fatality rates approaching 90%. Currently the worst Ebola virus outbreak since the disease was discovered is occurring in West Africa. Although thought to be a zoonotic infection, a concern is that with increasing numbers of humans being infected, Ebola virus variants could be selected which are better adapted for human-to-human transmission. To investigate whether genetic changes in Ebola virus become established in response to adaptation in a different host, a guinea pig model of infection was used. In this experimental system, guinea pigs were infected with Ebola virus (EBOV), which initially did not cause disease. To simulate transmission to uninfected individuals, the virus was serially passaged five times in naive animals. As the virus was passaged, virulence increased and clinical effects were observed in the guinea pig. An RNAseq and consensus mapping approach was then used to evaluate potential nucleotide changes in the Ebola virus genome at each passage. Upon passage in the guinea pig model, EBOV become more virulent, RNA editing and also coding changes in key proteins become established. The data suggest that the initial evolutionary trajectory of EBOV in a new host can lead to a gain in virulence. Given the circumstances of the sustained transmission of EBOV in the current outbreak in West Africa, increases in virulence may be associated with prolonged and uncontrolled epidemics of EBOV. 

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Natural protection against ebola:

Two other features that may play into the outcome of the life or death struggle between humans and Ebola are age and genetic predisposition. A recently published study which tracked case outcomes in Sierra Leone during the current West African outbreak showed a higher survival rate for patients under the age of 21 compared to those over the age of 45. Earlier, a study done based on blood samples from people who had been infected during a 2000 outbreak of Ebola Sudan in Uganda found that certain people were more likely to have milder disease and survive. Another recently published paper looking at the spectrum of disease in mice also suggests genetics play a role in survival.  Geisbert is one of the discoverers of an Ebola species known as Ebola Reston, unique among the five types of the viruses because it does not originate in Africa and so far it has not been seen to sicken people. Reston viruses come from the Philippines; on six occasions research monkeys imported from that country have triggered animal outbreaks. It has also been found in pigs, though the animals do not show signs of infection. Ebola Reston is lethal in primates. Research done after animal outbreaks shows that several people have developed antibodies (or “seroconverted”) to Ebola Reston, but did not become noticeably ill.

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Asymptomatic infection:

Evidence suggests that many Ebola infections are asymptomatic, a factor overlooked by recent outbreak summaries and projections.  Particularly, results from one post-Ebola outbreak serosurvey showed that 71% of seropositive individuals did not have the disease; another study reported that 46% of asymptomatic close contacts of patients with Ebola were seropositive. The latter study also found minute concentrations of Ebola virus in these individuals’ blood, suggesting that their antibodies could not be explained by their exposure to dead virus, but that rather they had truly been infected by live virus. Could silent Ebola infections be contagious? Given that Ebola typically spreads through contact with bodily fluids of very sick individuals, who have exceedingly high viral counts, it is very unlikely that silent (asymptomatic) cases can spread the virus with the low levels found in their blood. Although asymptomatic infections are unlikely to be infectious, they might confer protective immunity and thus have important epidemiological consequences. The spread of Ebola in West Africa reveals two truths: The disease is swift, and it is devastating. Amid the chaos of deadly outbreak, researchers say another truth may exist: The disease might be quietly inoculating a significant portion of the population who are exposed to the virus but never succumb to it or show symptoms of being infected. If those individuals have acquired immunity to Ebola, the strategies for the intervention and treatment of the disease need to be reconsidered. If infection without disease protects people from future Ebola infections and illness, the epidemic should decline sooner than currently predicted and affect a smaller number of people.

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But the question remains, are these asymptomatically infected people immune to future Ebola infection? Since survivors of full-blown Ebola disease seem to become immune to re-infection, we hope that the answer is yes. Immunization of any kind — via vaccine or natural infection — makes people resistant and thereby slows transmission. If silent Ebola infections actually protect against future re-infection, then Ebola is acting as its own vaccine, leaving a large wake of uninfectable people in its path. Importantly, this wake is likely to include healthcare workers who frequently contact patients and are at considerable risk for future exposure. If so, Ebola is simultaneously killing some individuals while protecting others within the population subgroup at highest priority for interventions, such as future vaccines. Widespread acquired immunity would therefore have three important implications. First, outbreak forecasts that do not consider this phenomenon will overestimate the future extent of the outbreak. Second, naturally acquired immunity will amplify the effects of disease control measures, including vaccination. Third, if we can reliably detect immune individuals, then they can safely take on risky health care tasks and thereby prevent spread to non-immune caregivers. If these people are protected from future infections, this would open up new opportunities for controlling the disease. The asymptomatic individuals can help slow the spread of Ebola in two important ways: They can be recruited to work as caregivers in high-risk communities; and their natural immunity may make them prime candidates for donating blood for transfusions. If we can take advantage of natural immunity within the affected communities, we may be able impact the course of the epidemic even before a vaccine becomes available.   

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A surprisingly high proportion of the Gabonese population could have immunity against Ebola. Antibodies to the virus were found in 15.3% of rural communities, whereas these people had never had haemorrhagic fever or other specific symptoms of the disease (such as severe diarrhoea or vomiting). IRD researchers and their partners recently discovered this large number of healthy carriers among Gabonese people, even in areas where there has never been an Ebola outbreak. The scientists consider that these people have somehow come into contact with the virus, probably present in fruit contaminated by saliva from Chiroptera (fruit bats).  

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Human asymptomatic Ebola infection and strong inflammatory response: a 2000 study:

Ebola virus is one of the most virulent pathogens, killing a very high proportion of patients within 5-7 days. Two outbreaks of fulminating haemorrhagic fever occurred in northern Gabon in 1996, with a 70% case-fatality rate. During both outbreaks authors identified some individuals in direct contact with sick patients who never developed symptoms. Authors aimed to determine whether these individuals were indeed infected with Ebola virus, and how they maintained asymptomatic status. 11 of 24 asymptomatic individuals developed both IgM and IgG responses to Ebola antigens, indicating viral infection. Western-blot analysis showed that IgG responses were directed to nucleoprotein and viral protein of 40 kDa. The glycoprotein and viral protein of 24 kDa genes showed no nucleotide differences between symptomatic and asymptomatic individuals. Asymptomatic individuals had a strong inflammatory response characterised by high circulating concentrations of cytokines and chemokines. This study showed that asymptomatic, replicative Ebola infection can and does occur in human beings. The lack of genetic differences between symptomatic and asymptomatic individuals suggests that asymptomatic Ebola infection did not result from viral mutations. Elucidation of the factors related to the genesis of the strong inflammatory response occurring early during the infectious process in these asymptomatic individuals could increase our understanding of the disease.

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Ebola virus: Genes ‘play significant role in survival’: A 2014 study:

Researchers have found that natural immunity may exist to Ebola, after discovering that some animals get over the disease quickly, without major symptoms. Ebola may not be a deadly disease for everyone, after scientists discovered that some people are likely to be naturally immune to the virus.  A study in mice showed that genetic variations govern how ill victims will get after contracting the disease.  Some completely resist the disease, while others suffer only a moderate illness. However many still succumb to bleeding, organ failure and shock. The research was conducted in a highly secure, state-of-the-art bio lab in Montana, US.  Researchers found that all mice lost weight in the first few days after infection. However, nearly one in five of the mice not only survived, but also fully regained their lost weight within two weeks. After a fortnight they had no evidence of the disease and their livers looked normal. One in nine of the mice were partially resistant and less than half of these died.  However susceptible mice had greater than 50 per cent mortality. The authors believe that those who have survived during the recent outbreak in West Africa may have had natural immunity.  “Our data suggests that genetic factors play a significant role in disease outcome,” said co-author Dr Michael Katze, of Washington University’s Department of Microbiology.  “We hope that medical researchers will be able to rapidly apply these findings to candidate therapeutics and vaccines.”  Prof Andrew Easton, Professor of Virology, University of Warwick, said: “This paper demonstrates that the genes of the host play a role in determining the outcome of Ebola infection in terms of the severity of the disease, at least in mice.  Prof Jonathan Ball, Professor of Molecular Virology, University of Nottingham, added: “We know that host genetics influences infection outcome for a range of viruses, like HIV and norovirus. We’ve also suspected that genetics plays a role in susceptibility to Ebola virus infection. “It’s a reminder of how infectious diseases shape the evolution of a host; and the human host is no different to any other.” Angela Rasmussen, from the Katze Laboratory at the University of Washington, said the different ways in which the mice were affected mirrored the variety of symptoms seen in humans in the 2014 outbreak. Recent Ebola survivors could have had immunity to this virus or a related virus which may have saved them, for example. This would have meant the disease reacting in a particular way to a host’s genes, which is seen with many other viruses. Andrew Easton, professor of virology at the University of Warwick, said the study provided valuable information, but the data could not be directly applied to humans because they have a much larger variety of genetic combinations than mice.

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When a person becomes infected with Ebola, the virus depletes the body’s immune cells, which defend against infection. In particular, the Ebola virus depletes immune cells called CD4 and CD8 T lymphocytes, which are crucial to the function of the immune system.  But if a person’s immune system can stand up to this initial attack — meaning their immune cells are not as depleted in the first stages of infection — then studies suggest they are more likely to survive the disease. But if the body is not able to fend off this attack, then the immune system becomes less able to regulate itself. This means the immune system is more likely to run out of control and release a “storm” of inflammatory molecules, which cause tiny blood vessels to burst, leading in turn to a drop in blood pressure, multi-organ failure and eventually death. Another marker linked with people’s ability to survive Ebola is a gene called human leukocyte antigen-B, which makes a protein that is important in the immune system. A 2007 study found that people with certain versions of this gene, called B07 and B14, were more likely to survive Ebola, while people with other versions, called B67 and B15, were more likely to die. Finally, some people may be resistant to Ebola infection entirely, if they have a mutation in a gene called NPC1. Studies show that, when researchers take cells from people with the NPC1 mutation and try to infect them with Ebola in a laboratory dish, these cells are resistant to the virus. In European populations, about 1 in 300 to 1 in 400 people have this mutation. But in some populations, this mutation is more common: in Nova Scotia, between 10 and 26 percent of people have this mutation. But the frequency of this mutation in African populations is not known.   

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Natural reservoir of ebola and animal to human transmission:

Reservoir Host:

A reservoir host is one that carries the virus, is asymptomatic (displaying no symptoms of infectious virus), and that transmits the disease to humans or to other animals. The Ebola virus likely originated in African fruit bats. The virus is known as a “zoonotic” virus because it’s transmitted to humans from animals. Humans can also transfer the virus to each other. Other animals known to transmit the virus include:

•chimpanzees

•forest antelopes

•gorillas

•monkeys

•porcupines

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The natural reservoir for Ebola has yet to be confirmed; however, bats are considered to be the most likely candidate species. Three types of fruit bats (Hypsignathus monstrosus, Epomops franqueti and Myonycteris torquata) were found to possibly carry the virus without getting sick. As of 2013, whether other animals are involved in its spread is not known. Plants, arthropods and birds have also been considered possible viral reservoirs. Bats were known to roost in the cotton factory in which the first cases of the 1976 and 1979 outbreaks were observed, and they have also been implicated in Marburg virus infections in 1975 and 1980. Of 24 plant and 19 vertebrate species experimentally inoculated with EBOV, only bats became infected. The bats displayed no clinical signs of disease, which is considered evidence that these bats are a reservoir species of EBOV. In a 2002–2003 survey of 1,030 animals including 679 bats from Gabon and the Republic of the Congo, 13 fruit bats were found to contain EBOV RNA. Antibodies against Zaire and Reston viruses have been found in fruit bats in Bangladesh, suggesting that these bats are also potential hosts of the virus and that the filoviruses are present in Asia. Between 1976 and 1998, in 30,000 mammals, birds, reptiles, amphibians and arthropods sampled from regions of EBOV outbreaks, no Ebola virus was detected apart from some genetic traces found in six rodents (belonging to the species Mus setulosus and Praomys) and one shrew (Sylvisorex ollula) collected from the Central African Republic. However, further research efforts have not confirmed rodents as a reservoir. Traces of EBOV were detected in the carcasses of gorillas and chimpanzees during outbreaks in 2001 and 2003, which later became the source of human infections. However, the high rates of death in these species resulting from EBOV infection make it unlikely that these species represent a natural reservoir for the virus. More than 100 viruses have been identified in bats, and that number too is rising.

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A group of 17 European and African tropical disease researchers, ecologists and anthropologists spent three weeks talking to people and capturing bats and other animals near the village of Meliandoua in remote eastern Guinea, where the present epidemic appeared in December 2013. They have concluded that the disease was spread by colonies of migratory fruit bats. If you’re a virus and your primary goal in life is to reproduce and survive, you don’t necessarily want to kill your host really quickly, so bats and viruses have achieved a nice equilibrium. Bats live with Ebola by having certain components of their immune system constantly switched on, so they are prepared before the virus enters their system. What we need to do now is learn how bats tolerate high levels of activation of the immune system, constantly, without any detrimental effects. In contrast, the immune system of humans is only activated after contact with the virus. Initially the virus shuts down the early response which then leads to a deadly overreaction.

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Ebola cycle:

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No bats culling to control ebola:

Bats are the primary pollinators of many tropical plants, and they disperse the seeds from fruit they eat. In Africa and Asia, that makes fruit bats responsible for about 50 percent of the tropical rainforest there. You can get sick to death from eating the bats, and the loss of the fruit bat population could hurt other aspects of the environment on which residents depend for their survival. Bats are critical to the health of people and the planet. Best known are the chemical-free pest control and pollination services they perform. Some bats, especially when nursing, can consume more than their body weight in bugs during a single night. If bats are confirmed as the reservoir of the disease, forest communities could try to destroy their vast colonies. That would be an ecological disaster because bats pollinate plants and devour insects. And bat hunts would also only increase human contact with potentially infected animals. It’s tempting to look to culling as the answer to deal with bats as the natural hosts of Ebola. This suggestion was made during the spillover of Hendra virus from bats to horses in Australia. But it is not the answer; bats are an extremely successful group of mammals, making up 20% of all mammalian diversity. They are critical to ecosystems, with roles in insect control and pollination.

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Unlocking the bat immune system:

Studying how bats control viral replication may unlock alternative mechanisms for tackling Ebola as well as other new and emerging infectious diseases. Increasing antimicrobial resistance of viruses, bacteria and fungi, for instance, is becoming a global concern and we need to think creatively to find solutions. Bats and viruses have achieved an equilibrium that allows them to co-exist. Clues from studies of bat genomes have revealed differences in genes associated with the very early immune response that could help bats respond to infections. These genes appear to be evolving at a faster rate in bats compared with other species, providing evidence that they are likely co-evolving with the viruses that bats carry. Functional differences in the immune system may also play a role. Unlike humans and mice, which activate their immune systems only in response to an infection, bats appear to have certain components of their immune system constantly switched on. This may allow bats to control viral replication much more efficiently compared with other species. Clues are starting to emerge following gene analysis, which suggests bats’ capacity to evade Ebola could be linked with their other stand-out ability – the power of flight. Flying requires the bat metabolism to run at a very high rate, causing stress and potential cell damage, and experts think bats may have developed a mechanism to limit this damage by having parts of their immune system permanently switched on. Researchers found an unexpected concentration of genes for repairing DNA damage, hinting at a link between flying and immunity. This raises the interesting possibility that flight-induced adaptations have had inadvertent effects on bat immune function. If we can redirect the immune responses of other species to behave in a similar manner to that of bats, the high death rate associated with diseases such as Ebola could be a thing of the past. Rather than persecuting bats, we need to unravel the secrets of the success of this group of mammals. Understanding how bats control viral replication would not only assist in developing future therapeutics but may also help predict transmission events from bats into human and animal populations.

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Experimental inoculation of plants and animals with Ebola virus: 1996 study:
Thirty-three varieties of 24 species of plants and 19 species of vertebrates and invertebrates were experimentally inoculated with Ebola Zaire virus. Fruit and insectivorous bats supported replication and circulation of high titers of virus without necessarily becoming ill; deaths occurred only among bats that had not adapted to the diet fed in the laboratory.

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Bushmeat:

In Africa, wild animals including fruit bats are hunted for food and are referred to as bushmeat. In equatorial Africa, human consumption of bushmeat has been linked to animal-to-human transmission of diseases, including Ebola. Although it is not entirely clear how Ebola initially spreads from animals to humans, the spread is believed to involve direct contact with an infected wild animal or fruit bat. Scientists at the World Health Organisation believe that fruit bats from the Pteropodidae family are the natural hosts of the ebola virus. The disease infects humans through close contact with infected animals, including chimpanzees, fruit bats and forest antelope. It then spreads between humans by direct contact with infected blood, bodily fluids or organs, or indirectly through contact with contaminated environments. Even funerals of Ebola victims can be a risk, if mourners have direct contact with the body of the deceased.

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Natural history of ebola viruses:

The emergence, less than 50 years ago, of Ebola virus remains an enigma. It is possible that sporadic cases or limited outbreaks occurred in the past and were unreported due to lack of epidemiological surveillance or appropriate diagnosis. Scattered and minor manifestations of EVD suggest that Ebola viruses circulate in a pathogen complex showing no (or few) contacts with human populations. Destruction of forests and human impact on broader areas could explain the increased frequency and severity of outbreaks. However, we cannot exclude a recent emergence of the virus that would spread rapidly in a susceptible population. According to Polonsky et al., increasing frequency of epidemics may result from the combination of: improvement of monitoring and diagnostic capacities, increase of contact among humans and the natural reservoirs of the virus, and growth of the viral load and prevalence of the virus in reservoirs. Several epidemiological investigations in Central and East Africa have shown circulation of Ebola virus in the human population at a significant rate, but that does not always entail the emergence of an epidemic. The natural reservoir of the virus is not known with certainty. Extensive investigations made in small mammals, even sensitive to the Ebola viruses, were negative during the various epidemics in Central Africa. Subsequent investigations continued outside epidemics. Although viral RNA and specific antibodies have been identified in small mammals, no potential natural host has been acknowledged until 2005. However, initially dismissed due to many negative samples, fruit bats were found with specific viral DNA and antibodies. These animals seem resistant to Filoviridae pathogenicity. The search for potential vectors, especially among arthropods, has always proved negative, including bedbugs (Cimex hemipterus) captured in the beds of infected persons. Deadly outbreaks of Ebola virus have been observed in non-human primates with high mortality. In addition to the contamination of the Swiss primatologist in Ivory Coast, the index case of several outbreaks have been more or less directly associated with hunting or consumption of bush meat, i.e. monkeys, antelopes, bats. Natural infection of bats and sharing their narrow ecological niche with many species of non-human primates are strong arguments in favor of their role as a natural reservoir of the virus. Some species, including Eidolon helvum, Hypsignathus monstrosus, Myonycteris torquata and Epomops franqueti, migrate long distances (>2,500 km), which could explain the multiple remote epidemic clusters.

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Ebola in Wild animals:

Ebola has a high mortality among primates. Frequent outbreaks of Ebola may have resulted in the deaths of 5,000 gorillas. Outbreaks of Ebola may have been responsible for an 88 percent decline in tracking indices of observed chimpanzee populations in 420 square kilometer Lossi Sanctuary between 2002 and 2003. Transmission among chimpanzees through meat consumption constitutes a significant risk factor, whereas contact between the animals, such as touching dead bodies and grooming, is not. Recovered carcasses from gorillas contain multiple Ebola virus strains, which suggest multiple introductions of the virus. Bodies decompose quickly and carcasses are not infectious after 3 to 4 days. Contact between gorilla groups is rare, suggesting transmission among gorilla groups is unlikely, and that outbreaks result from transmission between viral reservoir and animal populations.

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Ebola in Domestic animals:

In 2012 it was demonstrated that the virus can travel without contact from pigs to nonhuman primates, although the same study failed to achieve transmission in that manner between primates. Dogs may become infected with EBOV but not develop symptoms. Dogs in some parts of Africa scavenge for food, and they sometimes eat EBOV-infected animals and also the corpses of humans. A 2005 survey of dogs during an EBOV outbreak found that although they remain asymptomatic, about 32 percent of dogs closest to an outbreak showed a seroprevalence for EBOV versus 9 percent of those farther away. The authors concluded that there were “potential implications for preventing and controlling human outbreaks.”

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Transmission from dogs to human:

Public health officials are concerned about the role of dogs in Ebola virus transmission because there is scientific evidence that another mammal, the bat, is a reservoir for the disease. Based upon a research study in 2005 we know that feral dogs in African villages where there have been large scale epidemics seroconvert to Ebola. Seroconversion means the dogs have been exposed to virus and have produced antibodies specific for Ebola virus. Seroconversion does not imply production of infectious virus that can be transmitted to people or other animals. In other words, this study indicates that Ebola virus breached the dog’s mucosal barrier, was recognized by the canine immune system as being foreign and the body responded by producing anti-Ebola antibodies. In this study, dogs were described as being asymptomatic, and there was no evidence that virus was transmitted between dogs or from dogs to any other host. In summary, there is currently no evidence that exposed dogs become productively infected and shed Ebola virus. As on today, we do not know if the dog’s intracellular machinery can support viral replication, packaging and formation of infectious viral particles, nor do we know how the dog might shed virus for transmission to another host if it is asymptomatic. Extensive research is necessary to answer this question. The American Veterinary Medical Association (AVMA) is currently working on recommendations for handling, testing and treatment of companion animals associated with human cases, and that information will be forthcoming.

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Human to human transmission and spread of ebola:

Human-to-human transmission leads to outbreaks, which are often started by a single introduction from the wildlife reservoir or another end host and involve virus variants with little genetic diversity, as in the current outbreak in West Africa. Some recorded outbreaks, on the other hand, have stemmed from multiple introductions, which have resulted in greater genetic viral diversity among the subsequent distinct chains of human-to-human transmission. Within a given species, however, virus variants have been shown to have low genetic diversity, often less than a few percent, as illustrated by the new variant isolated from patients in Guinea. Such limited diversity generally leads to neutralizing cross-reactivity within the species. Biologic characterization of various Zaire ebolaviruses, their case fatality rates, and their virulence in animal models have so far failed to provide convincing evidence of obvious differences in pathogenicity. Thus, it should be assumed that the new West African variant is not more virulent than previous Zaire ebolaviruses; a case fatality rate of about 70%, if confirmed, might even indicate lower virulence. The finding that the Guinea variant resides at a more basal position within the clade than previously known Zaire ebolaviruses  argues against an introduction from Central Africa and instead supports the likelihood of distinct evolution in West Africa. These findings reinforce the hypothesis that ebolaviruses have a broader geographic distribution than previously thought.

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Mode of Transmission:

In an outbreak, it is hypothesized that the first patient becomes infected as a result of contact with an infected animal.  Person-to-person transmission occurs via close personal contact with an infected individual or their body fluids during the late stages of infection or after death. Nosocomial infections can occur through contact with infected body fluids for example due to the reuse of unsterilized syringes, needles, or other medical equipment contaminated with these fluids.  Humans may be infected by handling sick or dead non-human primates and are also at risk when handling the bodies of deceased humans in preparation for funerals. In laboratory settings, non-human primates exposed to aerosolized ebolavirus from pigs have become infected, however, airborne transmission has not been demonstrated between non-human primates. Viral shedding has been observed in nasopharyngeal secretions and rectal swabs of pigs following experimental inoculation.

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Communicability:

 Communicable as long as blood, body fluids or organs, contain the virus. Ebolavirus has been isolated from semen 61 to 82 days after the onset of illness, and transmission through semen has occurred 7 weeks after clinical recovery

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What are body fluids?

Basically any kind of fluid that comes from the body is body fluid. Body fluids include blood, saliva, mucus, vomit, feces, sweat, tears, breast milk, urine, and semen.

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People in West Africa are avoiding hugs and handshakes because the virus can be spread through the sweat on someone’s hand. The uninfected person would have to have a break in the skin of their hand that would allow entry of the virus, CNN’s Dr. Sanjay Gupta says. But “we all have minor breaks in our skin. And there is a possibility that some of the virus can be transmitted that way.” Health care providers — or family and friends — caring for Ebola patients are often at the highest risk of getting sick because they are most likely to come in contact with the body fluids of sick patients, according to the CDC. People with Ebola suffer from extreme vomiting, diarrhea and high fevers, which causes sweating. In the later stages, they may start bleeding from their eyes, mouth or other orifices.

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What does “direct contact” mean?

Direct contact means that body fluids (blood, saliva, sweat, mucus, vomit, urine, or feces) from an infected person (alive or dead) have touched someone’s eyes, nose, or mouth or an open cut, wound, or abrasion. Ebola is transmitted through contact with body fluids (blood, saliva, semen, vomit, urine, or feces) in much the same way HIV or hepatitis B. Ebola is transmitted from infected human only during symptomatic phase and not in incubation period, and transmission is maximum in advanced stage of disease when patient is gravely ill as his body fluids would contain maximum number of viruses at that time.  Although transmission through aerosol has been demonstrated in the laboratory between pigs and primates, it has never been conclusively demonstrated to happen from human to human and the evidence is fairly compelling that it does not. The virus persists on surfaces for days, and only 1-10 virus particles are needed to initiate infection.

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Human transmission of Ebola viruses:

The contamination of index cases is probably due to contact with an infected animal. Human transmission happens only through close contact with an ill or convalescent person, although at this stage the risk of infection is very small. Studies conducted during the various epidemics have shown that less than one fifth of the people living with a confirmed or probable primary patient have developed the disease. All secondary cases were recorded among people with close contact with the patient and exposed to infected biological fluids. Conversely, people who had no contact with the patient were not sick. Such close contact with the patient throughout care occurs mainly during the illness or burial preparation, including washing the body and funeral ritual that can be long and intimate. The risk greatly increases due to the delay in diagnosis and appropriate management. Ebola viruses have been detected in most patient secretions. They are present in the blood, saliva, feces, breast milk, tears and genital secretions. They have not been isolated from vomit, sputum, sweat or urine. However, the number of tested samples was low. The virus persists in breast milk, genital secretions and eyes during convalescence and up to 13 weeks after recovery. Finally, the risk of transmission from fomites (towels, clothes and sheets from the patient), especially during convalescence, is low and basic protection measures are likely to be sufficient. Nosocomial transmission is behind many hospital outbreaks. Injection materials reused without precaution or inadequately sterilized have been repeatedly denounced and remain a major cause of epidemic spread. This also applies to traditional healers whose practices are often septic. 

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Entry points;

Entry points for the virus include the nose, mouth, eyes, open wounds, cuts and abrasions. Contact with objects contaminated by the virus, particularly needles and syringes, may also transmit the infection. The virus is able to survive on objects for a few hours in a dried state and can survive for a few days within body fluids. The Ebola virus may be able to persist for up to 7 weeks in the semen of survivors after they recovered, which could lead to infections via sexual intercourse.  Ebola may also occur in the breast milk of women after recovery, and it is not known when it is safe to breastfeed again. Otherwise, people who have recovered are not infectious.

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Dead bodies transmitting ebola:

Dead bodies remain infectious; thus, people handling human remains in practices such as traditional burial rituals or more modern processes such as embalming are at risk. Nearly two thirds of the cases of Ebola infections in Guinea during the 2014 outbreak are believed to have been contracted via unprotected (or unsuitably protected) contact with infected corpses during certain Guinean burial rituals.

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Viral transmission through the air has not been reported to occur during EVD outbreaks. Transmission among rhesus monkeys via breathable 0.8–1.2 μm aerosolized droplets has been demonstrated in the laboratory. The apparent lack of airborne transmission among humans may be due to levels of the virus in the lungs that are insufficient to cause new infections. Spread of EBOV by water or food, other than bushmeat, has also not been observed. No spread by mosquitoes or other insects has been reported. The centre explained that Ebola is not spread through the air, water, or food and a person infected with Ebola can’t spread the disease until symptoms appear. The time from exposure to when signs or symptoms of the disease appear, known as the incubation period, is two to 21 days, but the average time is eight to 10 days. Ebola is spread through direct contact, through broken skin or through eyes, nose, or mouth, via blood and body fluids of a person who is sick with Ebola, or objects, such as needles, that have been contaminated with the blood or body fluids of a person sick with Ebola.

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How does Ebola spread?

When infection occurs in humans, the virus can be spread in several ways to others. Ebola is spread through direct contact (through broken skin or mucous membranes in, for example, the eyes, nose, or mouth) with

•blood or body fluids (including but not limited to urine, saliva, sweat, feces, vomit, breast milk, and semen) of a person who is sick with Ebola

•objects (like needles and syringes) that have been contaminated with the virus

•Ebola is not spread through the air or by water, or in general, by food. However, in Africa, Ebola may be spread as a result of handling bushmeat (wild animals hunted for food) and contact with infected bats.

•Only a few species of mammals (for example, humans, monkeys, and apes) have shown the ability to become infected with and spread Ebola virus. There is no evidence that mosquitoes or other insects can transmit Ebola virus.

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According to a new Ebola situation assessment issued by the World Health Organization, saliva and tears may also carry some risk. However, the studies implicating these additional bodily fluids were extremely limited in sample size and the science is inconclusive, W.H.O. said. “In studies of saliva, the virus was found most frequently in patients at a severe stage of illness. The whole live virus has never been isolated from sweat.” CDC Director Dr. Tomas Frieden notes that only a person showing symptoms can spread the disease. While the Ebola virus is believed to be able to survive for some days in liquid outside an infected organism, Doctors Without Borders says, agents such as chlorine, heat, direct sunlight, soaps and detergents can kill it.

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According to the World Health Organization, Ebola spreads through “human-to-human transmission via direct contact (through broken skin or mucous membranes) with blood, secretions, organs or other bodily fluids of infected people.” This means that the most common way Ebola is spread is direct contact with vomit, blood or fecal matter of an infected patient. Individuals who have such contact are at high risk. The Centers for Disease Control and Prevention says “being within approximately 3 feet of an (Ebola) patient or within the patient’s room or care area for a prolonged period of time,” is also potential cause for concern. But the organization noted the risk is low. There is also potential risk of transmission through contaminated surfaces and objects, however the World Health Organization notes the danger is, again, low, and most studies from previous Ebola outbreaks show that “all cases were infected by direct close contact with symptomatic patients.” Finally, experts note that individuals are not infectious — meaning they cannot spread the virus — until they are showing symptoms, which takes between 2 and 21 days. Symptoms start with a fever, followed by vomiting and diarrhea. So to be at a high risk of contracting Ebola, you need to come into contact with the blood, feces or vomit of someone who is showing symptoms. The number of people who find themselves in this situation are relatively small. There is potential for it to spread other ways — such as being in close range with someone who has the disease or touching an object contaminated by an infected person — but the risk is low, because “as an enveloped virus, it has a low tendency to stay viable outside the body,” said Thomas Fekete, a professor of infectious diseases at the Temple University School of Medicine. “And because it is not aerosolized it isn’t especially easy to catch through the respiratory tract.”

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Touching or kissing the corpses of Ebola victims at funerals is helping to spread the deadly virus. Traditional cultural and religious beliefs in parts of Africa help spread the virus. There are very strong traditional beliefs and traditional funeral rites which require that the whole family touch the dead body and they have a meal in the presence of the dead body. Part of what’s fueling the deadly outbreak is funeral rites that involve touching or kissing the bodies of the deceased; dead bodies can still host the Ebola virus and spread the disease to the living.

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Ebola transmission through fomites:

If an infected person contaminates an environmental surface with body fluids, it might be possible to acquire infection by touching these surfaces and transferring virus to mucous membranes. This type of transmission is more likely to occur in health care settings where ill patients are shedding large amounts of virus particles. However, transmission of the virus from inanimate objects has rarely been observed in previous outbreaks.

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Fomite:

A fomite is any object or substance capable of carrying infectious micro-organisms and hence transferring them from one individual to another. Skin cells, hair, clothing, and bedding are common hospital sources of contamination. Fomites are associated particularly with hospital-acquired infections (HAI), as they are possible routes to pass pathogens between patients. Stethoscopes and neckties are two such fomites associated with health care providers. Basic hospital equipment, such as IV drip tubes, catheters, and life support equipment can also be carriers, when the pathogens form biofilms on the surfaces. Careful sterilization of such objects prevents cross-infection. Researchers have discovered that smooth (non-porous) surfaces like door knobs transmit bacteria and viruses better than porous materials like paper money because porous, especially fibrous, materials absorb and trap the contagion, making it harder to contract through simple touch.

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Fragility of virus:

One reason Ebola is not as contagious as some viruses is that the virus is relatively fragile. That’s in contrast to, say, smallpox, a virus that can remain infectious for long periods even when outside of a host. But Ebola virus left alone, outside a host, on a surface, will begin to disintegrate rather quickly. Ebola is an ‘enveloped’ virus, which means it is surrounded by a lipid membrane.  That membrane protects it from its surroundings, but even more importantly is essential to its ability to fuse with and enter living cells.  And it’s pretty poor protection, as it is vulnerable to light, heat, dryness, and almost any detergent or alcohol you care to name.  The virus in saliva on a counter top will be inactive in minutes. How long will it remain infectious? Hard to say, exactly, though there have been scientific studies on just that question. In one laboratory experiment, scientists couldn’t recover Ebola virus that had contaminated a surface kept at room temperature. In another study, Ebola virus kept at cold temperature was recovered from plastic and glass surfaces after more than three weeks.

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Susceptibility to Disinfectants:

Ebolavirus is susceptible to 3% acetic acid, 1% glutaraldehyde, alcohol-based products, and dilutions (1:10-1:100 for ≥10 minutes) of 5.25% household bleach (sodium hypochlorite) and calcium hypochlorite (bleach powder).  The WHO recommendations for cleaning up spills of blood or body fluids suggest flooding the area with a 1:10 dilutions of 5.25% household bleach for 10 minutes for surfaces that can tolerate stronger bleach solutions (e.g., cement, metal) For surfaces that may corrode or discolour, they recommend careful cleaning to remove visible stains followed by contact with a 1:100 dilution of 5.25% household bleach for more than 10 minutes.

Physical inactivation:

 Ebola are moderately thermolabile and can be inactivated by heating for 30 minutes to 60 minutes at 60°C, boiling for 5 minutes, or gamma irradiation (1.2 x10^6 rads to 1.27 x10^6 rads) combined with 1% glutaraldehyde.  Ebolavirus has also been determined to be moderately sensitive to UVC radiation.

Survival outside host:

 Filoviruses have been reported capable to survive for weeks in blood and can also survive on contaminated surfaces, particularly at low temperatures (4°C).  One study could not recover any Ebolavirus from experimentally contaminated surfaces (plastic, metal or glass) at room temperature.   In another study, Ebolavirus dried onto glass, polymeric silicone rubber, or painted aluminum alloy is able to survive in the dark for several hours under ambient conditions (between 20°C and 25°C and 30–40% relative humidity) (amount of virus reduced to 37% after 15.4 hours), but is less stable than some other viral hemorrhagic fevers (Lassa).  When dried in tissue culture media onto glass and stored at 4 °C, Zaire ebolavirus survived for over 50 days. This information is based on experimental findings only and not based on observations in nature. This information is intended to be used to support local risk assessments in a laboratory setting.

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Assessment of the Risk of Ebola Virus Transmission from Bodily Fluids and Fomites in isolation ward: a 2007 study:

Although Ebola virus (EBOV) is transmitted by unprotected physical contact with infected persons, few data exist on which specific bodily fluids are infected or on the risk of fomite transmission. Therefore, authors tested various clinical specimens from 26 laboratory-confirmed cases of Ebola hemorrhagic fever, as well as environmental specimens collected from an isolation ward, for the presence of EBOV. Virus was detected by culture and/or reverse-transcription polymerase chain reaction in 16 of 54 clinical specimens (including saliva, stool, semen, breast milk, tears, nasal blood, and a skin swab) and in 2 of 33 environmental specimens. Authors conclude that EBOV is shed in a wide variety of bodily fluids during the acute period of illness but that the risk of transmission from fomites in an isolation ward and from convalescent patients is low when currently recommended infection control guidelines for the viral hemorrhagic fevers are followed.

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The table above shows virus culture and reverse-transcription polymerase chain reaction (RT-PCR) results from 54 clinical samples collected from 26 patients with laboratory-confirmed Ebola hemorrhagic fever. The skin, the sputum, the urine, the sweat and the vomitus showed no virus in this study.

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The table above shows virus culture and reverse-transcription polymerase chain reaction (RT-PCR) results from 33 environmental samples. All most all fomites (environmental surfaces) except hand gloves and IV insertion site showed no virus in this study.

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These results suggest that environmental contamination and fomites are not frequent modes of transmission, at least in an isolation ward. However, the infectious dose of EBOV is thought to be low, and neither cell culture nor the RT-PCR assay used for EBOV in this study has not been extensively validated for use in environmental detection. Hence, the sensitivity and specificity are unknown. It is possible that EBOV was present in the environment below the threshold of detection or that environmental surfaces in the isolation ward were, at times, initially contaminated by EBOV but then decontaminated through the daily cleaning routine. However, many of the inanimate objects tested, such as bed frames and bedside chairs, would not routinely be specifically decontaminated with bleach solutions under existing guidelines unless they happened to be visibly contaminated, suggesting that environmental contamination did not occur. Taken together with empirical epidemiological observations during outbreaks, the results suggest that current recommendations for the decontamination of filoviruses in isolation wards are effective. The risk from environmental contamination and fomites might vary in the household or other settings where decontamination would be less frequent and thorough, especially if linens or other household materials were to become visibly soiled by blood. Taken together, the results support the conventional assumptions and field observations that most EBOV transmission comes from direct contact with blood or bodily fluids of an infected patient during the acute phase of illness. The risk of casual contacts with the skin, such as shaking hands, is likely to be low. Environmental contamination and fomites do not appear to pose a significant risk when currently recommended infection control guidelines for the viral hemorrhagic fevers are followed.

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The absence of EBOV infection in multiple tested urine specimens suggests that the virus may not be efficiently filtered in the kidney. Consequently, exposure to urine appears to be of low risk during both acute illness and convalescence. The absence of EBOV in the urine, low prevalence on the skin, and rapid clearance from the saliva in surviving patients provides some reassurance that the risk of secondary transmission from casual contacts, fomites, or the sharing of toilet facilities in the home after discharge from the hospital is minimal. This conclusion is supported by previous empirical observations.

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Another study on fomites:

The table below shows Ebola virus detection by reverse-transcription polymerase chain reaction (RT-PCR) in body fluids collected from EVD patients during an outbreak in Gulu, Uganda and the maximum described persistence after symptom onset described in the literature:

Body Fluid Acute phase of illness
number detected/number tested (percent)
Convalescent phase of illness
number detected/number tested (percent)
Last day detected after symptom onset described in the literature
Skin 1/8 (13%) 0/4 (0%) 6
Saliva 8/12 (67%) 0/4 (0%) 8
Urine 0/7 (0%) 0/4 (0%) 23
Stool / Feces 2/4 (50%) n/d 29
Breast milk 1/1 (100%) 1/1 (100%) 15
Semen n/d 1/2 (50%) 101
Vaginal fluid n/d n/d 33

n/d = not done on specimens from the EVD outbreak in Gulu, Uganda

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Ebola can survive on surfaces for almost Two Months: Tests reveal certain strains survive for weeks when stored at low temperatures:
For their 2010 paper, ‘The survival of filoviruses in liquids, on solid substrates and in a dynamic aerosol’, Sophie Smither and her colleagues tested two particular filoviruses on a variety of surfaces. These were the Lake Victoria marburgvirus (Marv), and ZEBOV. Each was placed into guinea pig tissue samples and tested for their ability to survive in different liquids, and on different surfaces at different temperatures, over a 50-day period. When stored at 4° (39°F), by day 26, viruses from three of the samples were successfully extracted; Zebov on the glass sample, and Marv on both glass and plastic. By day 50, the only sample from which the virus could be recovered was the Zebov from tissue on glass. ‘This study has demonstrated that filoviruses are able to survive and remain infectious, for extended periods when suspended within liquid and dried onto surfaces,’ explained the researchers. ‘Data from this study extend the knowledge on the survival of filoviruses under different conditions and provide a basis with which to inform risk assessments and manage exposure.’ The researchers do stress that these tests were carried out in a controlled lab environment, and not in the real world, but published their findings to highlight the survival rates.

•Research claims certain strains of Ebola can remain on surfaces for 50 days

•It survived the longest on glass surfaces stored at 4° (39°F)

•Center for Disease Control and Prevention claims Ebola typically lives on a ‘dry’ surface for hours – including doorknobs and tables

•But when stored in moist conditions such in mucus, this is extended

•Survival time depends on the surface, and the room temperature

•Virus can be killed using household bleach and people must come into direct contact with the sample to risk infection.

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How long can Ebola live on a surface?

In one study by the Centers for Disease Control and Prevention, the Ebola virus lived on a surface in a perfectly controlled environment for up to six days. The virus can live on surfaces for a few hours at most. Ebola is a vicious virus inside the body, but it dies very quickly on surfaces. It’s not a hardy virus. It’s a very wimpy virus. Ebola is easily destroyed outside of the body, experts say. UV light, heat and exposure to oxygen all deactivate the virus over time. CDC Director Dr. Thomas Frieden said that while it’s theoretically possible for someone to catch Ebola by touching a surface that an infected patient sneezed on, for example, past outbreaks have shown that direct contact with a patient’s bodily fluids is the way the virus is spread.

What kills the virus?

Health care workers in West Africa rely on bleach. But the CDC says any hospital disinfectant will work on a nonporous surface. Any EPA-approved disinfectant — Chlorox, Lysol, etc. — will work on a nonporous surface. A dishwasher or washing machine will also kill it.

Would any bodily fluids ebola patient flushed contaminate the water system?

The virus wouldn’t survive long in water. The virus depends heavily on its host — either a human or animal — to stay active. Sanitary sewers and waste water treatment system will kill the virus.

How long does the Ebola virus live on contaminated surfaces, such as bed sheets, door knobs, etc.?

It’s different in every set of circumstances. The Ebola virus eventually dries out in the air and dies. It’s not like anthrax, which forms a hard capsule around itself and can survive for months or a year. Ebola is a virus that is meant to live inside blood or fluid in your cells. It’s not meant to live in the open air, so it dies. A sheet that has wet blood in it is more dangerous than one with dried blood, because by then it would have dried out. There’s not one answer, but it is considered to be fairly safe after about 24 hours, certainly in environments that are cleaned regularly like hospitals.

Can I get Ebola from public transportation? As in, if a passenger coughed into their hand and then held onto the pole, and then another passenger held onto that pole and inadvertently wiped their eye?

 It is extremely unlikely for the Ebola virus to spread through public transit for several reasons. Not all viruses build up to infectious doses in all bodily fluids. Usually, Ebola does not at first make victims cough or sneeze, although someone who also had the flu could, in theory, spray vomitus or blood. Once Ebola invades the lungs, the body will cough to clear them. But passengers that deathly ill are not likely to be on public transit. According to the recent W.H.O. statement, high levels of Ebola virus in saliva are rare except in the sickest victims, and whole virus has never been found in sweat. The fluids known to build up high viral loads are blood, feces and vomit.

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Mother to baby transmission:

The finding of EBOV in breast milk raises the possibility of direct mother-to-child transmission. In fact, breastfed children of the mothers whose milk was later tested died of laboratory-confirmed EHF during early stages of the outbreak. The isolation of virus from breast milk in one case even after clearance from the blood suggests that transmission may occur even during convalescence. It is possible that the mammary gland, like the gonads and chambers of the eye, is an immunologically protected site in which clearance of virus is delayed. It seems prudent to advise breastfeeding mothers who survive EHF to avoid breastfeeding for at least some weeks after recovery and to provide them with alternative means of feeding their infants.

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Recommendations for Breastfeeding/Infant Feeding in the Context of Ebola:

Key Points

•When safe alternatives to breastfeeding and infant care exist, mothers with probable or confirmed Ebola virus disease should not have close contact with their infants (including breastfeeding).

•In resource-limited settings, non-breastfed infants are at increased risk of death from starvation and other infectious diseases. These risks must be carefully weighed against the risk of Ebola virus disease.

In most situations, breastfeeding is the best choice for feeding an infant, particularly in resource-limited settings. However, for lactating women with probable or confirmed Ebola virus disease, decisions about how to feed their infant must be made on a case-by-case basis by weighing the risk of transmitting the virus to their baby through breastfeeding with the risks of stopping breastfeeding. Mothers infected with Ebola virus may be critically ill and unable to breastfeed. When mothers infected with Ebola virus are able to breastfeed, decisions about whether or not to breastfeed may depend on the age of the infant, the availability and feasibility of safe nutrition and infant care, and overall sanitary conditions. These risks must be balanced against the likely high risk of Ebola virus transmission through breastfeeding, the act of suckling, and close contact with their ill mother. Although Ebola virus has been detected in breast milk, it is not known whether Ebola virus can be transmitted from mothers to their infants through breastfeeding. However, given what is known about transmission of Ebola virus, regardless of breastfeeding status, infants whose mothers are infected with Ebola virus are already at high risk of acquiring Ebola virus infection through close contact with the mother, and are at high risk of death overall. Therefore, when safe replacements to breastfeeding and infant care exist, mothers with probable or confirmed Ebola virus infection should not have close contact with their infants (including breastfeeding).  In resource-limited settings; however, because non-breastfed infants are at increased risk of death from starvation and other infectious diseases, such as diarrheal and respiratory diseases, these risks must be carefully weighed against the risk of Ebola virus infection. There is not enough evidence to provide guidance on when it is safe to resume breastfeeding after a mother’s recovery, unless her breast milk can be shown to be Ebola virus-free by laboratory testing. In the one case in which breast milk was tested, Ebola virus was identified in the breast milk of a lactating woman 7 and 15 days after disease onset.

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Sexual transmission:

In one study the isolation of EBOV from semen 40 days after the onset of illness underscores the risk of sexual transmission of the filoviruses during convalescence. In another study Zaire EBOV has been detected in the semen of convalescent patients by virus isolation (82 days) and RT-PCR (91 days) after disease onset. Marburg virus has also been isolated from the semen and linked conclusively to sexual transmission 13 weeks into convalescence. Abstinence from sex or the use of condoms during sex, as well as avoidance of breastfeeding and contact with the mucous membranes of the eye for at least 3 months after recovery, are still recommended to avoid possible exposure to EBOV in the aforementioned immunologically protected sites.

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Transmission to health care workers:

Health-care workers treating those who are infected are at greatest risk of getting infected themselves. The risk increases when these workers do not have appropriate protective clothing such as masks, gowns, gloves and eye protection; do not wear it properly; or handle contaminated clothing incorrectly. This risk is particularly common in parts of Africa where health systems function poorly and where the disease mostly occurs. Hospital-acquired transmission has also occurred in some African countries resulting from the reuse of needles. Some health-care centers caring for people with the disease do not have running water. In the United States the spread to two medial workers treating an infected patient prompted criticism of inadequate training and procedures.

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Why are health care workers most at risk?

Ebola is spread by direct contact with bodily fluids of someone who has the disease. These fluids include blood, vomit and secretions. Health care workers are at higher risk for Ebola infection because they often treat patients who have reached the stage of the infection with the most symptoms, including vomiting, diarrhea and bleeding. This means there is much more potential for exposure. Health care workers also perform procedures that bring a higher risk of contact with bodily fluids, such as kidney dialysis and respiratory intubation.

Is there something “special” about Ebola that makes it more infectious than other diseases?

Although Ebola is not very contagious — that is, it is not easily spread from person to person by causal contact — the virus has a low “infectious dose,” meaning direct contact with even a small amount of virus could cause infection. Just one viral particle could cause an Ebola infection. A minuscule amount of body fluid may contain more than a sufficient amount of Ebola to get an infection.

Why is it that the two nurses got sick, but the family members that ebola patient Duncan was staying with didn’t?

People with Ebola get progressively more infectious as their disease worsens. Although Duncan’s family lived with him when he first showed symptoms, health care workers took care of the patient when the potential for exposure to his blood and other bodily fluids was much higher.

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Why high death toll of health care workers?

Ebola virus can be transmitted by direct contact with blood, body fluids, or skin of EVD patients or persons who have died of EVD. As of October 23, 2014, 450 healthcare personnel are known to have become infected with Ebola, of whom 244 died. One disturbing feature of the current epidemic is that so many health workers have lost their lives while caring for the sick or trying to spread public-health messages about Ebola. This is partly because Ebola is transmitted through bodily fluids, and no one has more contact with the bodily fluids of an Ebola patient than his or her doctor and nurse. The first reason for high death toll is that health workers haven’t had access to the supplies they need. Since the disease is transmitted through direct exposure to bodily fluids, they are advised to wear face masks, goggles, gowns and gloves while caring for patients. But doctors and nurses in the developing-country context don’t always have that protective gear. Or if they do, they want to use their scarce supplies when absolutely necessary, which brings us to another reason for the alarming loss of health workers: many doctors caring for Ebola patients in West Africa had no idea they were seeing Ebola patients. The disease had never appeared in this part of Africa, and it’s difficult to diagnose, sometimes masquerading as malaria or the flu until symptoms worsen. So doctors and nurses weren’t always protecting themselves as they would from a deadly virus. A third reason for the outsized health-worker death toll is that the total number of people infected with the virus this year is so much greater. In 1976, the death toll was 280 and there were 318 reported cases. In this 2014 outbreak, that denominator is thirty times larger. Finally, the scale of this outbreak requires medical personnel that just weren’t at the ready in West Africa. Sierra Leone has 2.2 doctors for every 100,000 people. The OECD average is 320 per 100,000 population.

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What is transmission by droplet contact?

Some diseases can be transferred by infected droplets contacting surfaces of the eye, nose, or mouth. This is referred to as droplet contact transmission. Droplets containing microorganisms can be generated when an infected person coughs, sneezes, or talks. Droplets can also be generated during certain medical procedures, such as bronchoscopy. Droplets are too large to be airborne for long periods of time, and quickly settle out of air. Droplet transmission can be reduced with the use of personal protective barriers, such as face masks and goggles. Measles and SARS are examples of diseases capable of droplet contact transmission.

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What is airborne transmission?

Airborne transmission refers to situations where droplet nuclei (residue from evaporated droplets) or dust particles containing microorganisms can remain suspended in air for long periods of time. These organisms must be capable of surviving for long periods of time outside the body and must be resistant to drying. Airborne transmission allows organisms to enter the upper and lower respiratory tracts. Fortunately, only a limited number of diseases are capable of airborne transmission.

Diseases capable of airborne transmission include:

Tuberculosis

Chickenpox

Measles

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Air transmission of ebola:

There are two distinct ways a virus can travel in the air. In what’s known as droplet infection, the virus can travel inside droplets of fluid released into the air when, for example, a person coughs. The droplets travel only a few feet and soon fall to the ground. The other way a virus can go into the air is through what is called airborne transmission. In this mode, the virus is carried aloft in tiny droplets that dry out, leaving dust motes, which can float long distances, can remain infective for hours or days, and can be inhaled into the lungs. Particles of measles virus can do this, and have been observed to travel half the length of an enclosed football stadium. Ebola may well be able to infect people through droplets, but there’s no evidence that it infects people by drying out or getting into the lungs on dust particles. Unlike the bacteria that cause tuberculosis or the virus that caused smallpox, the Ebola virus is not airborne. With airborne viruses, infectious particles can remain in the air even after a person leaves the room, the air is still considered infectious. Any droplets of fluid from cough or sneeze that could contain Ebola can travel only about 3 feet before they fall to the ground, because of gravity and therefore not considered airborne. In 1989, a virus known today as Reston, which is a filovirus related to Ebola, erupted in a building full of monkeys in Reston, Virginia, and travelled from cage to cage. One possible way, never proved, is that the virus particles hitched rides in mist driven into the air by high-pressure spray hoses used to clean the cages, and then circulated in the building’s air system. A rule of thumb among Ebola experts is that, if you are not wearing biohazard gear, you should stand at least six feet away from an Ebola patient, as a precaution against flying droplets.

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The question often asked is whether Ebola could evolve to spread through the air in dried particles, entering the body along a pathway into the lungs. In order to become fully airborne, Ebola virus particles would need to be able to survive in a dehydrated state on tiny dust motes that remain suspended in the air and then be able to penetrate cells in the lining of the lungs. Ebola is very unlikely to develop these abilities. That would be like saying that a virus that has evolved to have a certain life style, spreading through direct contact, can evolve all of a sudden to have a totally different life style, spreading in dried form through the air. However, there are many ways by which Ebola could become more contagious even without becoming airborne. For example, it could become less virulent in humans, causing a milder disease and killing maybe twenty per cent of its victims instead of fifty per cent. This could leave more of them sick rather than dead, and perhaps sick for longer. That might be good for Ebola, since the host would live longer and could start even more chains of infection. In the lab in Liberia, Lisa Hensley and her colleagues had noticed something eerie in some of the blood samples they were testing. In those samples, Ebola particles were growing to a concentration much greater than had been seen in samples of human blood from previous outbreaks. Some blood samples seemed to be supercharged with Ebola. This, too, would benefit the virus, by enhancing its odds of reaching the next victim. Higher the number of viruses in body fluids, greater is chance of transmission.

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There is considerable misunderstanding concerning the potential for aerosol transmission of filoviruses. The data on formal aerosol experiments leave no doubt that Ebola and Marburg viruses are stable and infectious in small-particle aerosols, and experience of transmission between experimental animals in the laboratory supports this. Indeed, during the 1989–1990 epizootic of the Reston subtype of Ebola, there was circumstantial evidence of airborne spread of the virus, and supporting observations included suggestive epidemiology in patterns of spread within rooms and between rooms in the quarantine facility, high concentrations of virus in nasal and oropharyngeal secretions, and ultrastructural visualization of abundant virus particles in alveoli. However, this is far from saying that Ebola viruses are transmitted in the clinical setting by small-particle aerosols generated from an index patient. Indeed patients without any direct exposure to a known EHF case were carefully sought but uncommonly found. The conclusion is that if this mode of spread occurred, it was very minor.  What then were the major routes of transmission? Nonhuman primate studies found conjunctival and oral routes of infection to be possible. It seems likely that the increased risk from late-stage patients reflects increased virus excretion as the disease progresses, similar to that seen in monkey models. Thus, mucous-membrane exposure, pharyngeal contamination during swallowing, inoculation via small skin breaks, or even infection from swallowed infectious material may all contribute to virus transmission.

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WHO insisted that Ebola is not an airborne pathogen, meaning one you can catch by inhaling an infectious dose from “a suspended cloud of small dried droplets. In contrast with viruses like measles and chickenpox, this type of transmission has not been seen in Ebola studies over several decades. Theoretically, wet and bigger droplets from a heavily infected individual, who has respiratory symptoms caused by other conditions or who vomits violently, could transmit the virus—over a short distance—to another nearby person,” the WHO said. But it said it has not seen any studies that demonstrate this type of transmission—whereas solid studies from previous outbreaks show that all cases resulted from “direct close contact with symptomatic patients.”

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WHO statements:

On 6 October 2014, the World Health Organization (WHO) released a situation assessment reiterating what scientists know thus far about how Ebola is transmitted. The WHO noted that no evidence to date supports the belief that Ebola is airborne and did not indicate in any fashion that rumors suggesting otherwise had any merit:

1. Ebola virus disease is not an airborne infection. Airborne spread among humans implies inhalation of an infectious dose of virus from a suspended cloud of small dried droplets.

2. This mode of transmission has not been observed during extensive studies of the Ebola virus over several decades.

3. Common sense and observation tell us that spread of the virus via coughing or sneezing is rare, if it happens at all. Epidemiological data emerging from the outbreak are not consistent with the pattern of spread seen with airborne viruses, like those that cause measles and chickenpox, or the airborne bacterium that causes tuberculosis.

4. Theoretically, wet and bigger droplets from a heavily infected individual, who has respiratory symptoms caused by other conditions or who vomits violently, could transmit the virus — over a short distance — to another nearby person.

5. This could happen when virus-laden heavy droplets are directly propelled, by coughing or sneezing (which does not mean airborne transmission) onto the mucus membranes or skin with cuts or abrasions of another person.

 WHO is not aware of any studies that actually document this mode of transmission. On the contrary, good quality studies from previous Ebola outbreaks show that all cases were infected by direct close contact with symptomatic patients. According to the WHO, no known leaps of a similar nature have occurred with viruses that affect humans:

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Could ebola mutate becomes airborne?

You can now get Ebola only through direct contact with bodily fluids. If certain mutations occurred, it would mean that just breathing would put one at risk of contracting Ebola. Infections could spread quickly to every part of the globe, as the H1N1 influenza virus did in 2009, after its birth in Mexico. But viruses like Ebola are notoriously sloppy in replicating; meaning the virus entering one person may be genetically different from the virus entering the next. The current Ebola virus’s hyper-evolution is unprecedented; there has been more human-to-human transmission in the past four months than most likely occurred in the last 500 to 1,000 years. When viruses enter a cell, they make copies of their genetic information to assemble new virus particles. Viruses such as Ebola virus, which have genetic information in the form of RNA (not DNA as in other organisms), are notoriously bad at copying their genome. The viral enzyme that copies the RNA makes many errors, perhaps as many as one or two each time the viral genome is reproduced. There is no question that RNA viruses are the masters of mutation. This fact is in part why we need a new influenza virus vaccine every few years. The more hosts infected by a virus, the more mutations will arise. Not all of these mutations will find their way into infectious virus particles because they cause lethal defects. The virus was only discovered to infect humans in 1976, but it surely infected humans long before that. Furthermore, the virus has been replicating, probably for millions of years, in an animal reservoir, possibly bats. There has been ample opportunity for the virus to undergo mutation. If certain mutations occurred, it would mean that just breathing would put one at risk of contracting Ebola. Infections could spread quickly to every part of the globe, as the H1N1 influenza virus did in 2009, after its birth in Mexico. The key phrase here is ‘certain mutations’. We simply don’t know how many mutations, in which viral genes, would be necessary to enable airborne transmission of Ebola virus, or if such mutations would even be compatible with the ability of the virus to propagate. What allows a virus to be transmitted through the air has until recently been unknown. We can’t simply compare viruses that do transmit via aerosols (e.g. influenza virus) with viruses that do not (e.g. HIV-1) because they are too different to allow meaningful conclusions. One approach to this conundrum would be to take a virus that does not transmit among mammals by aerosols – such as avian influenza H5N1 virus – and endow it with that property. This experiment was done by Fouchier and Kawaoka several years ago, and revealed that multiple amino acid changes are required to allow airborne transmission of H5N1 virus among ferrets. These experiments were met with a storm of protest from individuals who thought they were too dangerous. The other important message from the Fouchier-Kawaoka ferret experiments is that the H5N1 virus that could transmit through the air had lost its ability to kill. The message is clear: gain of function (airborne transmission) is accompanied by loss of function (virulence). When it comes to viruses, it is always difficult to predict what they can or cannot do. It is instructive, however, to see what viruses have done in the past, and use that information to guide our thinking. Therefore we can ask: has any human virus ever changed its mode of transmission? The answer is no. We have been studying viruses for over 100 years, and we’ve never seen a human virus change the way it is transmitted. HIV-1 has infected millions of humans since the early 1900s. It is still transmitted among humans by introduction of the virus into the body by sex, contaminated needles, or during childbirth. Hepatitis C virus has infected millions of humans since its discovery in the 1980s. It is still transmitted among humans by introduction of the virus into the body by contaminated needles, blood, and during birth. There is no reason to believe that Ebola virus is any different from any of the viruses that infect humans and have not changed the way that they are spread. Every time a new person gets Ebola, the virus gets another chance to develop new capabilities. Ebola is an RNA virus, which means every time it copies itself; it makes one or two mutations. Experts say the chances are relatively small that Ebola will make that jump from contact transmission to airborne transmission.  I am fully aware that we can never rule out what a virus might or might not do. But the likelihood that Ebola virus will go airborne is so remote that we should not use it to frighten people. We need to focus on stopping the epidemic, which in itself is a huge job. Ebola virus infection can also be transmitted if an infected person coughs or vomits at close range. In this case large droplets landing on the mucous membranes can initiate infection. Although these droplets are traveling through the air, this mode of transmission is considered a form of contact transmission, not airborne transmission.

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Are we sure Ebola isn’t airborne?  A 2012 study:

In a porcine transmission experiment animals were infected by dripping virus into the nose, eyes and mouth, and placed in a room with cynomolgous macaques. The pigs were allowed to roam the floor, while the macaques were housed in cages. All of the macaques became infected. They did find aerosolized Ebola in air samples, and some of the macaques did come down with symptoms of Ebola. So, it looked like pigs could spread Ebola through the air, which is something that had already been suggested by the epidemiology of the 2008 pig Ebola outbreak. It’s always nice when experimental data matches up with that observed during a real-life occurrence of the virus.

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Ebola Believed to be Potentially Airborne, Researchers Report:

Healthcare workers play a very important role in the successful containment of outbreaks of infectious diseases like Ebola. The correct type and level of personal protective equipment (PPE) ensures that healthcare workers remain healthy throughout an outbreak—and with the current rapidly expanding Ebola outbreak in West Africa, it’s imperative to favor more conservative measures. The report goes on to note that any action which can be taken to “reduce risk” of Ebola exposure should not wait until a “scientific certainty” develops. The minimum level of protection in high-risk settings should be a respirator with an assigned protection factor greater than 10. A powered air-purifying respirator (PAPR) with a hood or helmet offers many advantages over an N95 filtering facepiece or similar respirator, being more protective, comfortable, and cost-effective in the long run. The working theory about Ebola transmission from the CDC and the agency’s director Thomas Frieden, is incorrect and “outmoded” according to the report. Virus-laden bodily fluids may be aerosolized and inhaled while a person is in proximity to an infectious person and that a wide range of particle sizes can be inhaled and deposited throughout the respiratory tract. Background information detailing why these experts believes the CDC and WHO are functioning under an outdated mode of thought when it comes to how infectious diseases are transmitted via aerosols is also included in the new report. Medical and infection control professionals have relied for years on a paradigm for aerosol transmission of infectious diseases based on very outmoded research and an overly simplistic interpretation of the data. In the 1940s and 50s, William F. Wells and other ‘aerobiologists’ employed now significantly out-of-date sampling methods (e.g., settling plates) and very blunt analytic approaches (e.g., cell culturing) to understand the movement of bacterial aerosols in healthcare and other settings. Their work, though groundbreaking at the time, provides a very incomplete picture, the report said. According to researchers, early aerobiologists were unable to measure small particles near an infected person and therefore made an assumption that such particles existed on far from the source and airborne transmission could have happened around 3-feet or so from the source.

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Lethal experimental infections of rhesus monkeys by aerosolized Ebola virus: 1995 study:

The potential of aerogenic infection by Ebola virus was established by using a head-only exposure aerosol system. Virus-containing droplets of 0.8-1.2 microns were generated and administered into the respiratory tract of rhesus monkeys via inhalation. Inhalation of viral doses as low as 400 plaque-forming units of virus caused a rapidly fatal disease in 4-5 days. The illness was clinically identical to that reported for parenteral virus inoculation, except for the occurrence of subcutaneous and venipuncture site bleeding and serosanguineous nasal discharge. Immunocytochemistry revealed cell-associated Ebola virus antigens present in airway epithelium, alveolar pneumocytes, and macrophages in the lung and pulmonary lymph nodes; extracellular antigen was present on mucosal surfaces of the nose, oropharynx and airways. Aggregates of characteristic filamentous virus were present within type I pneumocytes, macrophages, and air spaces of the lung by electron microscopy. Demonstration of fatal aerosol transmission of this virus in monkeys reinforces the importance of taking appropriate precautions to prevent its potential aerosol transmission to humans.

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Infectivity, transmissibility and mortality:

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The basic reproduction number, R0:

The most important epidemiological quantity to estimate for an infectious disease is typically the basic reproductive ratio, R0, defined as the expected number of secondary cases produced per primary case early in the epidemic. When R0 is greater than 1, the expectation is that a new epidemic will eventually infect a significant percentage of the population if it is not stopped by interventions or chance extinction; conversely, when R0 is less than 1, chance events may lead to a large number of cases, but these are always expected to be much less numerous than the total population size. The basic reproduction number, R0, is interpreted as the average number of secondary cases caused by a typical infected individual throughout its entire course of infection in a completely susceptible population and in the absence of control interventions. In the context of a partially susceptible population owing to prior exposure or vaccination, the (effective) reproduction number, R, quantifies the potential for infectious disease transmission. If R <1, transmission chains are not self-sustaining and are unable to generate a major epidemic. By contrast, an epidemic is likely to occur whenever R >1. When measured over time t, the effective reproduction number Rt, can be helpful to quantify the time-dependent transmission potential and evaluate the effect of control interventions in almost ‘real time’. In summary, R0 is regarded as a summary measure of the transmissibility of infectious diseases, playing a key role in determining the required control effort (for example, intensity of quarantine and isolation strategies). R0 could also be useful for guiding the numbers of antivirals and vaccines that would be needed to achieve control whenever these are available.  

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R0 estimates for prior Ebola outbreaks in Central Africa:

R0 has been estimated for prior EVD outbreaks in Central Africa using mathematical modeling and epidemiological data for two Ebola outbreaks, namely the 1995 outbreak in Democratic Republic of Congo and the 2000 Uganda outbreak, respectively. Unlike the ongoing epidemic in West Africa, past outbreaks in Central Africa have been confined to relatively rural and isolated areas without spreading to urban sectors which facilitated the effective implementation of control interventions. Using a homogenous mixing SEIR (Susceptible-Exposed-Infectious-Removed) model that accounted for a gradual decay in the transmission rate at the start of interventions, Chowell et al. estimated R0 at 1.83 for Congo and 1.34 for Uganda. Using the same epidemic model but employing a Bayesian estimation method, Lekone and Finkenstadt  estimated slightly lower values at 1.33 to 1.35 for the outbreak in Uganda. Legrand et al. employed a different modeling approach: while allowing for homogeneous mixing, the study took into account three different transmission settings, that is, transmissions in community, hospital settings and during funerals. R0 was estimated at 2.7 for Congo, 1995 and 2.7 for Uganda, 2000, but estimates showed substantial uncertainty. Transmission from burials alone accounted for 1.8 secondary transmissions in Congo while community transmission in Uganda accounted for 2.6 secondary transmissions. Variability in R0 estimates across studies can be attributed to differences in model structure and underlying assumptions.

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An assessment of R0 based on the growth rate of the 2014 Ebola epidemic in West Africa:

Assuming that the mean generation time is 12 days (with standard deviation 5.2 days) based on contact tracing data from an outbreak in Uganda 2000, R0 for Liberia is estimated at 1.96 (95% CI: 1.92, 2.01). For Sierra Leone, R0 is 3.07 (95% CI: 2.85, 3.32) and 1.30 (95% CI: 1.26, 1.33) for the early and late phases, respectively.

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Comparing R0 with other infectious diseases:

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Fortunately, it is harder to contract Ebola:

Ebola, SARS and chicken pox take roughly the same amount of time to pass from one sick person to the next group of people, called a “generation.” If Ebola were as easy to catch as chicken pox, thousands of people would have been sickened by the fourth generation. 

Four generations of Ebola:

Infected 15 people, killed 11 people. A carrier can infect up to 2 people every 9 to 15 days.

Four generations of SARS:

Infected 15 people, killed 2 people. A carrier can infect up to 3 people every 8 to 9 days.

Four generations of Chicken pox:

Infected 5,220 people, killed 0 people. A carrier can infect up to 17 people every 14 to 16 days.

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The average reproductive ratio is a measure of how easily a disease travels from person to person. A rate of 5 means each sick person passes the disease to an average of five other people. When the number is below 1, the epidemic dies out. The average serial interval is the length of time between the first patient showing symptoms and a secondary case showing symptoms. The longer the better, because that allows time to find and isolate people who have been exposed before they spread the virus.

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Infectivity:

The virus is extremely infectious. Experiments suggest that if one particle of Ebola enters a person’s bloodstream it can cause a fatal infection. This may explain why many of the medical workers who came down with Ebola couldn’t remember making any mistakes that might have exposed them. One common route of entry is thought to be the wet membrane on the inner surface of the eyelid, which a person might touch with a contaminated fingertip. The virus is believed to be transmitted, in particular, through contact with sweat and blood, which contain high concentrations of Ebola particles. People with Ebola sweat profusely, and in some instances they have internal hemorrhages, along with effusions of vomit and diarrhea containing blood.

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Ebola spreads slower but it is deadly:

It means it is not easily transmitted from one infected person to another although case fatality rate is high. Compared to other infectious diseases, Ebola spreads slowly and to relatively few people. But it is extremely deadly: The World Health Organization said 70 percent of cases in this year’s outbreak are fatal.

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The figure below shows that even though case fatality rates of HIV (untreated) and tuberculosis (untreated) are similar to Ebola, HIV and tuberculosis are far more contagious than Ebola.

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Since we have effective treatment of HIV and TB, CFR of treated HIV and TB would be far lower than untreated cases.

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Where and How Much? 

The speed and degree to which Ebola manages to overcome an individual depends on a couple of factors, scientists who study the virus say. If you are unlucky enough to be infected with Ebola, the amount (or dose) of virus to which you are exposed and the route by which the virus makes its way into your body could mean the difference between whether you live or die. In the world of Ebola, less is better but even a very little is bad. Scientists have differing views on the sometimes cited claim that a single virion – just one virus – is sufficient to trigger infection. While that may, or may not be the true figure for the minimum infectious dose for humans, it is likely that infection can occur from contact with small amounts of virus. Nevertheless, a low-dose exposure may prove less lethal if it allows the immune system to get into gear before the viruses have a chance to disable too many of the early responders. How you get infected likely also plays a role in how sick you become. An exposure that delivers the virus into the blood stream ­– for example a needle-stick injury, dreaded in the filovirus research world ­– is more damaging than when viruses are introduced via the mucus membranes surrounding the eyes, nose and in the mouth. Onset of symptoms is quickest with direct-to-blood exposures; they typically account for the short end of the incubation period range, two to 21 days. Most infections become apparent within eight to 10 days of exposure.  If you get a direct injection with a lot of virus particles, I don’t think anything’s going to save you, because you’re just overwhelmed. In the 1976 Ebola epidemic that brought the disease to the attention of the world, 85 people were known to have been infected through the reuse of contaminated syringes. All 85 died, along with nearly 200 others in and around Yambuku, in the former Zaire (now the Democratic Republic of Congo).

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The Ebola virus is highly infectious but not very transmissible. That may sound to a lay person’s ear like a contradiction. What this means is that very little virus – in animal experiments, as few as 10 virus particles (virions) – can potentially lead to a fatal infection. That’s the “infectious” part of the equation. But it’s not easy for that virus to be transmitted. Ebola is much less contagious than measles or influenza. It’s not an airborne virus. It’s transmitted through bodily fluids. The overwhelming majority of people who have been infected with Ebola are people who have directly cared for a person who is actively sick with the disease or have handled the body of someone who have died from it. Experts call it “a caregivers disease,” and note that children don’t typically get it even though they are running around touching many objects and surfaces. They don’t care for sick people as a rule. Ebola is terrifying but not as easy to catch as people think. The cases have had direct, intimate interactions with sick people or bodies: taking care of someone at home, treating a patient without protection, or preparing the body of an Ebola victim for burial.  We’re talking about very sick people with vomit and stool on their skin and clothes in a house without running water or a toilet, not someone with a runny nose on a public bus.  Bodies are dangerous because the virus inside is protected for a few days, and the cleaning and preparation for burial of a body requires very close interaction with it. And we see relatively few kids with Ebola, when any parent knows that kids run around touching everything and never washing their hands.  If it was on surfaces or as contagious as something like measles then we’d see a lot more sick kids. 

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The figure below shows that ebola patient becomes more contagious as disease worsens and dead body is maximally contagious as recently dead bears maximum virus in body fluids:

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Note:

Please avoid confusion between infectiousness and contagiousness even though they are used synonymously. Infectiousness (infectivity) is a measure of the ability of a microorganism to establish itself in the host and refers to the individual dose or numbers of the microorganisms required to infect susceptible host. Infectiousness is quantified by infectious dose; lesser the number of organisms required to cause infection, greater is infectiousness (infectivity). Contagiousness means ease of transmission from one person to another by any means.    

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Risk factors for ebola:

For most people, the risk of getting Ebola is low. The risk increases if you:

•Travel to Africa. You’re at increased risk if you visit or work in areas where Ebola virus outbreaks have occurred.

•Conduct animal research. People are more likely to contract the Ebola virus if they conduct animal research with monkeys imported from Africa or the Philippines.

•Provide medical or personal care. Family members are often infected as they care for sick relatives. Medical personnel also can be infected if they don’t use protective gear, such as surgical masks and gloves.

•Prepare people for burial. The bodies of people who have died of Ebola hemorrhagic fever are still contagious. Helping prepare these bodies for burial can increase your risk of developing the disease.

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Individuals at the highest risk for Ebola infection include the following:

•Anyone who has had direct contact with the blood and body fluids of an individual diagnosed with Ebola

•Anyone who has had close physical contact with an individual diagnosed with Ebola

•Anyone who lived with or visited an Ebola-diagnosed patient while the patient was ill

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The Ebola age divide:

A study found that age is a key factor establishing the fatality rate; for over 45s it is 94% while for those aged up to 21 it is 57%. 

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Who is most at risk?

During an outbreak, those at higher risk of infection are:

* health care workers;

* family members or others in close contact with infected people;

* mourners who have direct contact with the bodies of the deceased as part of burial ceremonies; and

* hunters in the rain forest who come into contact with dead animals found lying in the forest.

More research is needed to understand if some groups, such as immuno-compromised people or those with other underlying health conditions, are more susceptible than others to contracting the virus. Exposure to the virus can be controlled through the use of protective measures in clinics and hospitals, at community gatherings, or at home.

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Definition and assessment of risk exposure:

Risk level Definition
High-risk exposure • Percutaneous injury, e.g. needlestick, or mucous membrane exposure to body fluids of an EVD patient
• Direct care or exposure to body fluids of an EVD patient without appropriate personal protective equipment (PPE)
• Laboratory worker processing body fluids of confirmed EVD patients without appropriate PPE or standard biosafety precautions
• Participation in funeral rites that include direct contact with human remains in the geographic area where an outbreak is occurring without appropriate PPE
Low-risk exposure • Household member or other casual contact with an EVD patient
• Providing patient care or casual contact without high-risk exposure with EVD patients in health care facilities in EVD outbreak affected countries
No known exposure Persons with no known exposure were present in an EVD outbreak affected country in the past 21 days with no low-risk or high-risk exposures
Casual contact is defined as (i) being within approximately 3 feet (1 meter) or within the room or care area for a prolonged period of time (e.g. healthcare personnel, household members) while not wearing recommended personal protective equipment; or (ii) having direct brief contact (e.g., shaking hands) with an EVD case while not wearing recommended personal protective equipment

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Public health workers will use these risk levels along with assessing symptoms to decide how best to monitor for symptoms and what other restrictions may be needed.

Recommended actions for people without Ebola symptoms:

RISK LEVEL PUBLIC HEALTH ACTION
Active Monitoring Travel Restrictions Restricted Public Activities
HIGH risk Yes—direct active Yes Yes
SOME risk Yes—direct active Possible Possible
LOW risk Yes—direct active for some*; active for others No No
NO risk No No No

*Direct active monitoring is recommended for healthcare workers caring for sick Ebola patients while wearing appropriate PPE correctly and for travelers on an airplane who were seated within 3 feet of a person sick with Ebola.

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Clinical manifestation of ebola:

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The following two types of exposure history are recognized:

•Primary exposure: This typically involves travel to or work in an Ebola-endemic area

•Secondary exposure: This refers to human-to-human exposure (e.g., medical caregivers, family caregivers, or persons who prepared deceased patients for burial), primate-to-human exposure (e.g., animal care workers who provide care for primates), or persons who collect or prepare bush meat for human consumption.

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Infectious dose:

Ebola fever has an infectious dose of only 1 to 10 viral particles.

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Incubation period:

2 to 21 days (average 10 days).

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Signs and symptoms typically begin abruptly within 5 to 10 days of infection with Ebola virus.

Early signs and symptoms include:

•Fever

•Severe headache

•Joint and muscle aches

•Chills

•Weakness

Over time, symptoms become increasingly severe and may include:

•Nausea and vomiting

•Diarrhea (may be bloody)

•Red eyes

•Raised rash

•Chest pain and cough

•Stomach pain

•Severe weight loss

•Bleeding, usually from the eyes, and bruising (people near death may bleed from other orifices, such as ears, nose and rectum)

•Internal bleeding

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Physical Examination:

Physical findings depend on the stage of disease at the time of presentation. Early in the disease, patients may present with fever, pharyngitis, and severe constitutional signs and symptoms. A maculopapular rash, more easily seen on white skin than on dark skin, may be present around day 5 of infection and is most evident on the trunk. Bilateral conjunctival injection is also common.  Late in the disease, patients often develop an expressionless facies. At this point, bleeding from intravenous (IV) puncture sites and mucous membranes is common. It is worth noting that in the 1976 Ebola outbreak, bleeding was seen in most cases, whereas in the 1995 Ebola outbreak, bleeding occurred in only half of the patients. Myocarditis and pulmonary edema also are seen in the later stages of the disease. Terminally ill patients often die tachypneic, hypotensive, anuric, and in a coma. 

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The different species of Ebola virus seem to cause somewhat different clinical syndromes, but opportunities for close observation of the diseases under good conditions have been rare. Generally, the abrupt onset of Ebola haemorrhagic fever follows an incubation period of 2—21 days (mean 4—10) and is characterised by fever, chills, malaise, and myalgia. The subsequent signs and symptoms indicate multisystem involvement and include systemic (prostration), gastrointestinal (anorexia, nausea, vomiting, abdominal pain, diarrhoea), respiratory (chest pain, shortness of breath, cough, nasal discharge), vascular (conjunctival injection, postural hypotension, oedema), and neurological (headache, confusion, coma) manifestations. Haemorrhagic manifestations arise during the peak of the illness and include petechiae, ecchymoses, uncontrolled oozing from venepuncture sites, mucosal haemorrhages, and post-mortem evidence of visceral haemorrhagic effusions. A macropapular rash associated with varying severity of erythema and desquamate can often be noted by day 5—7 of the illness; this symptom is a valuable differential diagnostic feature and is usually followed by desquamation in survivors. Abdominal pain is sometimes associated with hyperamylasaemia and true pancreatitis. In later stages, shock, convulsions, severe metabolic disturbances, and, in more than half the cases, diffuse coagulopathy supervene.

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Patients with fatal disease develop clinical signs early during infection and die typically between day 6 and 16 with hypovolaemic shock and multiorgan failure. Haemorrhages can be severe but are only present in fewer than half of patients. In non-fatal cases, patients have fever for several days and improve typically around day 6—11, about the time that the humoral antibody response is noted. Patients with non-fatal or asymptomatic disease mount specific IgM and IgG responses that seem to be associated with a temporary early and strong inflammatory response, including interleukin β, interleukin 6, and tumour necrosis factor α (TNFα). However, whether this is the mechanism for protection from fatal disease remains to be proven. Convalescence is extended and often associated with sequelae such as myelitis, recurrent hepatitis, psychosis, or uveitis. Pregnant women have an increased risk of miscarriage, and clinical findings suggest a high death rate for children of infected mothers. This high death rate could be due to transmission from the infected mother to the child during breastfeeding, either through milk or close contact.

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A typical ebola case:

A “typical” case of EVD begins after an incubation period of about 1 week with the abrupt onset of fever, chills, and a variety of nonspecific signs and symptoms. At the time of presentation, the pulse and blood pressure may be within normal limits. Virus is detectable in the blood at the onset of illness, and persists at high levels in fatal cases. An erythematous, maculopapular rash may be seen during the first week, more commonly in light-skinned individuals. A variety of minor hemorrhagic manifestations, such as petechiae, ecchymoses, and persistent bleeding from needle punctures, are also seen. Laboratory abnormalities include leukopenia and lymphocytopenia, with an increased percentage of neutrophils; thrombocytopenia; and increased serum AST and ALT levels, with AST > ALT. Leukocytosis with a left shift and the appearance of atypical lymphocytes are seen as the disease progresses. Worsening illness is characterized by the development of hypotension, renal insufficiency, and shock, and in many cases by major bleeding from the gastrointestinal tract. Fatally infected patients usually die during the second week of illness, without developing a detectable antibody response. Extensive hemorrhage, hepatocellular necrosis, and a diffuse loss of lymphocytes are the principal findings at autopsy. Survivors undergo a prolonged convalescence, with persistent asthenia, weight loss, and sloughing of skin and hair. Infectious virus may persist for weeks to months in the anterior chamber of the eye or the testes, with the potential for sexual transmission.

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Fever not a surefire sign of infection:

Ebola study finds that in nearly 13% of confirmed and probable cases tracked, there was no fever. Some experts say the assumption that Ebola spreads only when an infected person has fever should be reassessed. For public health workers screening more than 1,000 air travelers who arrive each week in the United States from Ebola-stricken West Africa, one symptom above all others is supposed to signal danger: fever. So long as an individual’s temperature does not exceed 101.5 degrees and there are no visible symptoms of Ebola, health authorities say it should be assumed the person is not infectious. Yet the largest study of the current outbreak found that in nearly 13% of “confirmed and probable” cases in Liberia, Sierra Leone, Guinea and elsewhere, those infected did not have fevers. The study, sponsored by the World Health Organization and published by the New England Journal of Medicine, analyzed data on 3,343 confirmed and 667 probable cases of Ebola. The finding that 87.1% of those infected exhibited fever — but 12.9% did not — illustrates the challenges confronting health authorities as they struggle to contain the epidemic. U.S. health officials have repeatedly emphasized that fever is a reliable sign of infectiousness. As a defense against the spread of the virus to this country, the Obama administration has ordered that passengers arriving from West Africa at five U.S. airports be checked for fever. Dr. Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention, underlined the importance of fever in discussing the case of Thomas E. Duncan, a Liberian who traveled by air to Dallas and was diagnosed with Ebola. He died recently. Referring to those who had close contact with Duncan, Frieden said a week ago: “The only thing we need to ensure is that their temperature is monitored, and if they develop a fever, that they are immediately assessed, isolated and if found to be positive, then appropriately cared for.” Frieden has said that about 150 air passengers per day — or 1,050 per week — enter the U.S. from Liberia, Sierra Leone and Guinea, the countries at the heart of the outbreak. Dr. Anthony Fauci, who is helping to shape the U.S. response to Ebola as director of the National Institute of Allergy and Infectious Diseases, was asked by a CNN interviewer on Oct. 4 whether a person could be “contagious without having a fever.” Fauci replied that “the answer to that is no.” He continued: “You never say 100% but it’s essentially 100%. … In biology nothing is 100%, but that’s quite a reasonable conclusion to make.” Asked in the same interview about screening of air travelers, Fauci said, “Almost invariably, fever is the thing that signals the onset.”

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Duration of Illness in Fatal Cases:

In 25 well-documented fatal cases of Marburg and Ebola HF, the majority of deaths occurred during the second week of illness, with a median survival of 9 days from onset of illness to death. The only patient who died after day 16 suffered a terminal intracerebral hemorrhage while being treated in an intensive care unit. The observation that persons who live through the second week of illness are likely to recover is consistent with a report from the 1995 Ebola Zaire HF outbreak that showed that patients who were still alive on day 14 had a >75% chance of survival.

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Convalescence:

All descriptions of survivors of ebola agree that recovery is prolonged, lasting weeks to months. Sequelae of the acute illness include asthenia, weight loss, headache, dysesthesias, migratory arthralgias, sloughing of skin, loss of scalp hair, and persistent anemia. In a number of instances, acute orchitis or uveitis has developed weeks after the resolution of acute illness, and virus was detected in samples of semen or aqueous humor. During the 1967 Marburg HF outbreak, a convalescent male patient transmitted the virus to his wife, apparently through sexual intercourse.

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Complications:

Ebola hemorrhagic fevers leads to death for a high percentage of people who are affected. As the illness progresses, it can cause:

  • Multiple organ failure
  • Severe bleeding
  • Jaundice
  • Delirium
  • Seizures
  • Coma
  • Shock

For people who survive, recovery is slow. It may take months to regain weight and strength, and the viruses remain in the body for weeks. People may experience:

  • Hair loss
  • Sensory changes
  • Liver inflammation (hepatitis)
  • Weakness
  • Fatigue
  • Headaches
  • Eye symptoms (Iritis, iridocyclitis, choroiditis, blindness)
  • Testicular inflammation

EBOV may be able to persist in the semen of some survivors for up to seven weeks, which could give rise to infections and disease via sexual intercourse.

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How doctors know an Ebola patient is no longer contagious:

The blood, or serologic, tests are typically done to assess if a patient with an infectious disease is still sick. Blood test results of someone recovering from the Ebola virus will indicate a decreased viral load compared to someone with an acute infection. Doctors will also look to see if the patient has developed certain antibodies that indicate the body is fighting off the infection.  In addition to lab work, doctors also rely on less high-tech approaches such as basic physical exams. The standard is if the symptoms have resolved and the patient has clinically improved that means the patient has recovered from the acute infection. There is some indication that a patient may continue to shed the virus even after a doctor determines the acute infection has subsided. Most likely, the rate at which the virus clears the body varies just as much as the incubation period, which is between 2 and 21 days. According to the World Health Organization, in one instance, a lab worker who contracted Ebola on the job and survived was found to have traces of the virus in his semen 61 days after the initial infection. This could theoretically mean a man could infect his partner during sexual intercourse weeks after he’s declared disease-free, although no such cases have been documented.

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Prognosis:

EVD has a high risk of death in those infected which varies between 25 percent and 90 percent of those infected. Death, if it occurs, follows typically six to sixteen days after symptoms appear and is often due to low blood pressure from fluid loss. Early supportive care to prevent dehydration may reduce the risk of death. If an infected person survives, recovery may be quick and complete. Prolonged cases are often complicated by the occurrence of long-term problems, such as inflammation of the testicles, joint pains, muscle pains, skin peeling, or hair loss. Eye symptoms, such as light sensitivity, excess tearing, iritis, iridocyclitis, choroiditis, and blindness have also been described.

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Laboratory findings:

Laboratory variables are less characteristic but the following findings are often associated with Ebola virus disease: early leucopenia (as low as 1000 cells per μL) with lymphopenia and subsequent neutrophilia, left shift with atypical lymphocytes, thrombocytopenia (50 000—100 000 cells per μL), highly raised serum aminotransferase concentrations (aspartate aminotransferase typically exceeding alanine aminotransferase), hyperproteinaemia, and proteinuria. Prothrombin and partial thromboplastin times are extended and fibrin split products are detectable, indicating diffuse intravascular coagulopathy. In a later stage, secondary bacterial infection might lead to raised counts of white blood cells.

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In patients, the diagnosis is carried out by the detection of viral antigens through ELISA, identification of nucleic acid by PCR, specific antibody titer, or virus isolation. Specific IgM and IgG antibodies appear during the second week following the first clinical signs (about 15 to 20 days after the infection). IgM titers persist about two months whereas IgG titers remain several years after the end of the disease. Virus isolation can be achieved by inoculation in mice, guinea pigs or non-human primates in whom the disease is very close to what is observed in humans. The virus grows on kidney cell lines from African green monkey Cercopithecus aethiops. The diagnosis is made by optical microscopy examination of cytopathic effects, visualization of the virions by electron microscopy, identification of specific proteins by ELISA, or RNA detection by PCR. IgG titration allows retrospective diagnosis in convalescents or exposed persons, or epidemiological investigations even years after the epidemic.

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Specific Ebola laboratory diagnostic tests:

The diagnosis of EVD is confirmed by isolating the virus, detecting its RNA or proteins, or detecting antibodies against the virus in a person’s blood. Isolating the virus by cell culture, detecting the viral RNA by polymerase chain reaction (PCR) and detecting proteins by enzyme-linked immunosorbent assay (ELISA) are methods best used in the early stages of the disease and also for detecting the virus in human remains. Detecting antibodies against the virus is most reliable in the later stages of the disease and in those who recover. During an outbreak, isolation of the virus via cell culture methods is often not feasible. In field or mobile hospitals, the most common and sensitive diagnostic methods are real-time PCR and ELISA. In 2014, with new mobile testing facilities deployed in parts of Liberia, test results were obtained 3–5 hours after sample submission. Filovirions, such as EBOV, may be identified by their unique filamentous shapes in cell cultures examined with electron microscopy, but this method cannot distinguish the various filoviruses.

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Viremia:

There is no evidence that persons infected with Ebola or Marburg virus are viremic during the incubation period, but virus has been detected in blood samples on the day of illness onset. Serum levels of viral genomes, as detected by reverse transcription–polymerase chain reaction (RT-PCR), and of viral antigen, as detected by enzyme-linked immunosorbent assay (ELISA), increase during the first week of illness, and in fatal cases remain elevated until death. Studies performed during outbreaks in Gabon and Uganda found that titers of circulating viral genomes were significantly higher in fatal than in nonfatal cases. In patients who survive infection, viremia usually becomes undetectable by the end of the second week of illness. However, infectious virus may persist in certain anatomic sites, such as the testes, breasts or the anterior chamber of the eye.   

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RT-PCR ebola:

Reverse transcription polymerase chain reaction (RT-PCR) is one of many variants of polymerase chain reaction (PCR). This technique is commonly used in molecular biology to detect RNA expression. RT-PCR is often confused with real-time polymerase chain reaction (qPCR) by students and scientists alike. However, they are separate and distinct techniques. While RT-PCR is used to qualitatively detect gene expression through creation of complementary DNA (cDNA) transcripts from RNA, qPCR is used to quantitatively measure the amplification of DNA using fluorescent probes. The laboratory uses antigen capture and reverses transcription-PCR (RT-PCR) to diagnose ebolavirus infection in suspect patients. The RT-PCR and antigen-capture diagnostic assays proved very effective for detecting ebolavirus in patient serum, plasma, and whole blood. In samples collected very early in the course of infection, the RT-PCR assay could detect ebolavirus 24 to 48 h prior to detection by antigen capture.

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Viral Isolation:

About 100 μl of serum samples are used to inoculate Vero E6 cells maintained in 25-cm2 flasks in Dulbecco’s modified Eagle’s medium containing 2 to 5% fetal-calf serum and penicillin–streptomycin. Cells and supernatant were passaged several times. Virus growth in the cells was verified on immunofluorescence with the use of polyclonal mouse anti-EBOV–specific antibodies in the serum of mice challenged with EBOV or on the basis of an increase in viral levels in the cell-culture supernatant over several orders of magnitude, as measured on RT-PCR. 

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Electron Microscopy:

Specimens from patients are prepared for electron microscopy with the use of a conventional negative-staining procedure. In brief, a drop of 1:10 diluted serum was adsorbed to a glow-discharged carbon-coated copper grid and stained with freshly prepared 1% phosphotungstic acid (Agar Scientific). Images are taken at room temperature with the use of a Tecnai Spirit electron microscope (FEI) equipped with a LaB6 filament and operated at an acceleration voltage of 80 kV.

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Antibody Response:

Because immunofluorescence assays have a high positive background rate, the detection of antifilovirus antibodies has been based on ELISA since the 1995 Kikwit outbreak. Experience during several large epidemics has shown that most fatally infected patients fail to develop an antibody response; the detection of virus-specific immunoglobin M (IgM) or G (IgG) in a serum specimen is therefore a favorable prognostic sign. When an IgM response occurs, it is generally detectable during the first week of illness, and peaks during the second week. Virus-specific IgG appears soon after the IgM. Limited reports indicate that IgG can be detected by ELISA in disease survivors for as long as 11 years.

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The diagnosis of EVD is confirmed definitively in a laboratory through several types of tests:

  • by isolating the virus by cell culture,
  • detecting viral RNA by polymerase chain reaction (PCR) 
  • detecting viral antigens by enzyme-linked immunosorbent assay (ELISA),
  • detecting antibodies against the virus in a person’s blood.

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These testing methods take anywhere from 12 hours to four days to show results. These tests are not entirely foolproof, though. One test for Ebola, the indirect fluorescence assay, is known to have a rather low specificity, and therefore a rather high false negative rate. PCR testing has also been known to miss cases of affliction.  In other words, it is possible for an Ebola test to be negative when the person actually does have Ebola. Dr. Brantly’s first Ebola test was negative:  According to Dr. Brantly’s employer, Samaritan’s Purse, a U.S.-based international relief organization that has operated in Liberia for 13 years, Dr. Brantly first felt ill July 23 but tested negative. Despite that negative result, he was placed into isolation – a provident decision. His symptoms soon worsened, and a repeat test showed evidence of the virus.     

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Laboratory tests used in diagnosis include:

Timeline of Infection Diagnostic tests available
Within a few days after symptoms begin
  • Antigen-capture enzyme-linked immunosorbent assay (ELISA) testing
  • IgM ELISA
  • Polymerase chain reaction (PCR)
  • Virus isolation
Later in disease course or after recovery
  • IgM and IgG antibodies
Retrospectively in deceased patients
  • Immunohistochemistry testing
  • PCR
  • Virus isolation

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Laboratory diagnosis for viral haemorrhagic fevers is generally done in national and international reference centers, which should be contacted immediately on suspicion for advice on sampling, sample preparation, and sample transport. Laboratory diagnosis of Ebola virus is achieved in two ways: measurement of host-specific immune responses to infection and detection of viral particles, or particle components in infected individuals. Nowadays, RT-PCR and antigen detection ELISA are the primary assays to diagnose an acute infection. Viral antigen and nucleic acid can be detected in blood from day 3 up to 7—16 days after onset of symptoms. For antibody detection the most generally used assays are direct IgG and IgM ELISAs and IgM capture ELISA. IgM antibodies can appear as early as 2 days post onset of symptoms and disappear between 30 and 168 days after infection. IgG-specific antibodies develop between day 6 and 18 after onset and persist for many years. A IgM or rising IgG titre constitutes a strong presumptive diagnosis. Decreasing IgM, or increasing IgG titers (four-fold), or both, in successive paired serum samples are highly suggestive of a recent infection. All these assays can be done on materials that have been rendered non-infectious. An efficient way to inactivate the virus for antigen and antibody detection is the use of gamma irradiation from a cobalt-60 source or heat inactivation. Similarly, the nucleic acid can be amplified by purification of the virus RNA from materials treated with guanidinium isothiocyanate—a chemical chaotrope that denatures the proteins of the virus and renders the sample non-infectious.

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Fast ebola tests:

Genalyte’s $10 10-minute finger prick test:

Genalyte has spent seven years developing a totally new approach. By placing an array of sensors on one tiny silicon chip, it is able to avoid the many manual (and thus variable and messy) steps involved in sample prep that comprise the bulk of testing time. There’s no chemistry involved. It’s just straightforward watching the compounds and binding is seen directly. So it’s a fundamental new diagnostic technology. Eliminating the sample prep is “revolutionary” – and it should be able to test not just for Ebola, but for all types of infectious disease (including influenza), as well as allergy testing and autoimmune testing.

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Ebola diagnosis in 10 minutes: researchers working on tool to curb global epidemic:

Corgenix researchers say the test they’re developing works like a pregnancy test and can quickly identify whether or not a patient has contracted Ebola using a blood sample in only 15 minutes. However, researchers are “at a standstill” until their certain the tests are 100 percent accurate. 

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Fast, simple diagnostic test specific to 2014 Ebola outbreak by Primerdesign: 

Viruses all have a unique genetic fingerprint the same as we do. Ours is encoded in DNA but the Ebola virus uses RNA (Ribonucleic acid). So the kit is designed to specifically detect the Ebola RNA in a patient blood sample.

Process:

1. Blood sample is taken from patient

2. RNA is extracted with a few simple steps

3. RNA is placed in a tube with our kit ingredients

4. Tube goes in to machine

5. Analysis complete within 90 minutes

Primerdesign is a spinoff company from the University of Southampton specialising in Real-Time PCR technology. Real-Time PCR, also known as ‘qPCR’ is a mature technology based on the same DNA testing technology of ‘CSI’ fame.

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This slip of paper can detect the Ebola virus in less than an hour:

Two teams of researchers at Harvard University’s Wyss Institute for Biologically Inspired Engineering have devised a way to embed synthetic gene networks onto pocket-sized matrices of paper. These slips can be freeze-dried and stored at room temperature for up to a year and rehydrated with water whenever they’re needed. This is noteworthy because these slips of paper can essentially be “programmed” to give visual cues when it detects certain bacteria or viruses. A very timely use case involves a strain-specific Ebola sensor, which produces certain proteins only if it detects the particular Ebola strain. In this instance, the protein stains the paper with a dark purple in less than an hour if one of two Ebola strains are detected. One of the major benefits of this innovation, laid out in a paper titled “Paper-Based Synthetic Gene Networks,” is the extension of synthetic biology beyond laboratories. “We’ve harnessed the genetic machinery of cells and embedded them in the fiber matrix of paper, which can then be freeze dried for storage and transport — we can now take synthetic biology out of the lab and use it anywhere to better understand our health and the environment,” says lead author and Wyss staff scientist Keith Pardee, Ph.D. These paper-based tests are also very cheap. James Collins, an author of the paper and a synthetic biologist at Boston University, estimates that each slip of this detection paper could be designed and produced in about a day and would cost between 4 and 65 cents. There’s still room for improvement, especially when it comes to the ability to detect low concentrations of molecules. “We’re now comfortably in the picomolar range, which is getting close to where you want to be, but I think we’d like to be even lower,” Collins says.

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Development of an Immunofiltration-Based Antigen-Detection Assay for Rapid Diagnosis of Ebola Virus Infection: 

Ebola virus (EBOV) has caused outbreaks of severe viral hemorrhagic fever in regions of Central Africa where medical facilities are ill equipped and diagnostic capabilities are limited. To obtain a reliable test that can be implemented easily under these conditions, monoclonal antibodies to the EBOV matrix protein (VP40), which previously had been found to work in a conventional enzyme-linked immunosorbent assay, were used to develop an immunofiltration assay for the detection of EBOV antigen in chemically inactivated clinical specimens. The assay was evaluated by use of defined virus stocks and specimens from experimentally infected animals. Its field application was tested during an outbreak of Ebola hemorrhagic fever in 2003. Although the original goal was to develop an assay that would detect all EBOV species, only the Zaire and Sudan species were detected in practice. The assay represents a first-generation rapid field test for the detection of EBOV antigen that can be performed in 30 min without electrical power or expensive or sensitive equipment.

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Fast ebola test problems:

Many faster tests use lateral flow strips (think of a pregnancy test) where antibodies bind to an Ebola virus protein. All that’s required is a finger prick of blood on the strip and a tube with a solution that reveals a line if the virus is present. These tests can take as few as 15 minutes, but like home pregnancy tests, they’re not nearly as accurate. In the case of Ebola, false positives could place people without Ebola in contact with other infected patients, while false negatives could release Ebola patients back into the public.

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Biomarkers of Inflammation:

Cytokines and chemokines are a diverse group of proteins that modulate the immune response and have been extensively studied in many different disease processes. Serum samples from this outbreak have been analyzed in the past, and increased levels of IL-10 were reported in patients with fatal outcomes. The acute-phase response refers to a constellation of host responses that occur during infection and other inflammatory processes. These responses are classically triggered by proinflammatory cytokines and lead to increased levels of acute-phase reactants. These markers of inflammation are often used clinically to assist in diagnosis and to track a patient’s response to therapy in many infectious or inflammatory processes. The acute-phase reactants —SAA, C-reactive protein, ferritin, and IgG—are elevated.  Given the role of the endothelium in maintaining vascular integrity and modulation of hemodynamic stability and the vascular leakage seen in EVD, several markers of endothelial function sICAM, sVCAM, and soluble E-selectin need to be measured. The frequent presence of hemorrhagic manifestations in EVD patients warrants an examination of the measureable factors that control coagulation and fibrinolysis.  PAI-1, fibrinogen, tissue plasminogen activator, D-dimer, thrombomodulin, and TF need to be measured in patient samples.   

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Diagnosis of EVD:

When EVD is suspected in a person, his or her travel and work history, along with an exposure to wildlife, are important factors to consider for possible further medical examination. Most patients acutely ill as a result of infection with Ebola or Marburg virus have high concentrations of virus in blood. Antigen-detection ELISA is a sensitive, robust diagnostic modality. Virus isolation and reverse-transcription PCR are also effective and provide additional sensitivity needed in some cases. Recovering patients develop IgM and IgG antibodies that are readily detected by ELISA. The indirect fluorescent antibody test with paired sera is an effective diagnostic tool in most acute cases but is extremely misleading in population-based serologic surveys for Ebola virus activity. RT-PCR is extremely useful in detecting the need for quarantine or geographic spread. Skin biopsies are an extremely useful adjunct in postmortem diagnosis of infection with Ebola virus (and, to a lesser extent, Marburg virus) because of the presence of large amounts of viral antigen, the relatively low risk posed by sample collection, and the lack of cold-chain requirements for formalin-fixed tissues.

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Findings at autopsy:

Pathologic changes in fatal cases of filoviral HF are known from a few autopsies performed during the 1967 Marburg HF outbreak and in single cases and epidemics in Africa; they have been summarized by Zaki and Goldsmith. In both Marburg and Ebola HF, the principal gross abnormality is the presence of multiple foci of hemorrhage. The most characteristic histopathologic finding is extensive hepatocellular necrosis, with eosinophilic inclusion bodies corresponding to aggregates of nucleocapsids seen by electron microscopy. The spleen and lymph nodes show a marked decrease in lymphocytes, variously described as follicular “necrosis” or “atrophy,” leaving residual cellular debris. Evidence of acute tubular necrosis, consistent with hypovolemic shock, is seen in the kidneys. Other organs show scattered foci of necrosis, edema, and other nonspecific changes. Few autopsies have been performed on people who have died from Ebola virus disease, because of the high risk posed by the procedures. In fact, a scientific review published in October 2014 identified only 30 human cases where an autopsy or post-mortem biopsies were performed.

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Differential diagnosis of ebola:

When considering the diagnosis of EVD, other, more common diseases should not be overlooked; for example, malaria, typhoid fever, shigellosis, cholera, leptospirosis, plague, rickettsiosis, relapsing fever, meningitis, hepatitis and other viral haemorrhagic fevers.

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The complete differential diagnosis is extensive and requires consideration of many other infectious diseases such as typhoid fever, shigellosis, rickettsial diseases, cholera, sepsis, borreliosis, EHEC enteritis, leptospirosis, scrub typhus, plague, Q fever, candidiasis, histoplasmosis, trypanosomiasis, visceral leishmaniasis, measles and viral hepatitis among others. Non-infectious diseases that may result in symptoms similar to those of EVD include acute promyelocytic leukemia, hemolytic uremic syndrome, snake envenomation, clotting factor deficiencies/platelet disorders, thrombotic thrombocytopenic purpura, hereditary hemorrhagic telangiectasia, Kawasaki disease and warfarin poisoning.

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Treatment of ebola:

Case management is based on isolation of patients and use of strict barrier nursing procedures, such as protective clothing and respirators. These procedures have been sufficient to rapidly interrupt transmission in hospital settings in rural Africa. For members of rural African communities, cadavers are residual risks and should be handled accordingly. Traditional funeral and caretaking methods contribute to the spread of the virus and potentiate outbreaks. Methods to achieve barrier nursing, waste disposal, and other key elements inexpensively and practically in Africa have been devised, and field-tested manuals are available. Important elements for outbreak prevention are provision of sterile equipment for injections, which is remarkably and tragically missing in Africa, and personal protective equipment to doctors, nurses, and caretakers, who are at high risk of contraction of infections in hospitals. As a part of their contingency plans, many developed countries have established proper isolation and intensive care units to deal with imported cases. Whether patients with viral haemorrhagic fever should be transported at later stages of disease is a persistent debate. Nevertheless, any hospital should be safely capable of minimum management of Ebola and other viral haemorrhagic fevers, and should prioritise an initial crucial assessment and an early rapid diagnosis.

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No specific treatment is currently approved. However, survival is improved by early supportive care with rehydration and symptomatic treatment. Treatment is primarily supportive in nature. These measures may include management of pain, nausea, fever and anxiety, as well as rehydration via the oral or by intravenous route. The World Health Organization recommends avoiding the use of aspirin or ibuprofen for pain due to the bleeding risk associated with use of these medications. Blood products such as packed red blood cells, platelets or fresh frozen plasma may also be used. Other regulators of coagulation have also been tried including heparin in an effort to prevent disseminated intravascular coagulation and clotting factors to decrease bleeding. Antimalarial medications and antibiotics are often used before the diagnosis is confirmed, though there is no evidence to suggest such treatment is in any way helpful. Interferon therapies have been tried as a form of treatment for EVD, but were found to be ineffective. If professional care is not possible, guidelines by WHO for care at home have been relatively successful. In such situations, recommendations include using towels soaked in bleach solutions when moving infected people or bodies and applying bleach on stains. It is also recommended that the caregivers wash hands with bleach solutions and cover their mouth and nose with a cloth.

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Supportive Treatment:

The mainstay of treatment for Ebola virus disease involves supportive care while the immune system mobilizes an immune response. The most important aspect of supportive care involves preventing intravascular volume depletion, correcting profound electrolyte abnormalities, and avoiding the complications of shock:

●Patients require careful hemodynamic monitoring, and intravenous fluid repletion requirements may be high (e.g., 5 to 10 liters per day). Ebola virus disease may result in reduced effective arterial blood volume despite extracellular fluid volume overload (i.e., “third spacing”).

●Patients may develop significant electrolyte disturbances (e.g., hyponatremia, hypokalemia, and hypocalcemia) and may require frequent repletion of electrolytes to prevent cardiac arrhythmias.

●Patients may require nutrition support.

●Intensive nursing may be required in order to respond to the patient’s changing clinical situation.

Additional measures may include correction of severe coagulopathy, and symptomatic management of fever, nausea, vomiting, diarrhea, and abdominal pain. If dialysis is required, clinicians should refer to the CDC document on how to safely perform acute hemodialysis in patients with Ebola virus disease.

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Infected patients may also require evaluation and/or treatment of other concomitant infections; for example:

●Patients should be evaluated and treated for concomitant malaria if they are at risk for this disease. 

●Empiric antimicrobial treatment should be considered when patients develop vomiting, diarrhea, and/or other signs of severe gastrointestinal dysfunction and/or signs of sepsis. However, the importance of gastrointestinal bacteria in the clinical course of patients with Ebola virus disease is uncertain.

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Intensive care:

Intensive care is often used in the developed world. This may include maintaining blood volume and electrolytes (salts) balance as well as treating any bacterial infections that may develop. Dialysis may be needed for kidney failure, and extracorporeal membrane oxygenation may be used for lung dysfunction.

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Rationale of experimental treatment of ebola without trial: Europe vs. USA:

A consortium including European universities and medical groups plans to give experimental drugs to West African Ebola patients without assigning some to a placebo group, touching off an intense trans-Atlantic quarrel over what is ethical and effective in treating the virus. Academics and medical groups in the U.K. and France, such as Oxford University, the Wellcome Trust, Doctors Without Borders and Institute Pasteur of France, have decided to give the drugs to sick African patients without randomly assigning other patients to a control group not getting the medicines. They say that in a ghastly epidemic, it is unethical to hold back treatment from anyone. That has put them at odds with senior U.S. officials at the Food and Drug Administration and the National Institutes of Health. Dr. Luciana L. Borio, FDA assistant commissioner for counterterrorism and emerging threats, told public-health officials at the World Health Organization in Geneva this month she was extremely concerned by the plans to give the medicines to patients without better evidence they work and aren’t highly toxic. “This is too urgent an issue for us not to start out with what we know is scientifically best,” said Dr. Borio. “The fastest and most definitive way to get answers about what are the best products is a randomized clinical trial.” U.S. officials recommend a gold-standard study in which all patients get best possible care; one group also would get a drug, and the other group a placebo. In the case of Ebola, standard care includes aggressively replacing fluids in patients since they can vomit and have diarrhea. Without randomly assigning some patients to the placebo group, scientists say, it can’t be known whether the drugs used to treat the epidemic are saving lives or killing people. Dr. Piero Olliaro, an infectious-diseases doctor at Oxford University who also works at a WHO-affiliated group, is among the leaders of the European group proposing to give experimental drugs to all patients. Among the drugs that could be used, according to Dr. Olliaro, would be experimental medicines brincidofovir from Chimerix  Inc. and one called Avigan, or T-705, from  Fujifilm Holdings  Corp’s Toyama Chemical unit. Doctors from some African countries have joined the efforts of the European coalition. The number of cases in the current Ebola outbreak neared 16,000, the World Health Organization said recently.  “What we want to do is not cutting corners. It’s perfectly acceptable,” said Dr. Olliaro. “The problem is where there’s no treatment, people are going to die. Has any American been offered placebo? How would that go down with the American public?” Seven patients were given the experimental drug ZMapp from Mapp Biopharmaceutical, and two died. It isn’t known what effect ZMapp had on the patients’ outcomes. The drug’s limited supply was exhausted in August, and the company and partners are now manufacturing more. Brincidofovir is an experimental anti-viral drug that has worked against Ebola in test-tube cell cultures and now has been used in at least three patients in the U.S. A relatively high dosage in a clinical trial of bone-marrow transplant patients was linked to a high rate of severe diarrhea. Avigan was approved in Japan for influenza, but is still experimental in the U.S. It has shown some anti-Ebola activity in mice and cell cultures, and has been used in some Ebola patients in Europe. Officials at Chimerix and Fujifilm have said they are willing to supply their drugs for use in clinical trials in Africa, but declined to discuss the design of those trials. Fujifilm said it is providing Avigan for use in a clinical trial in Ebola patients in Guinea that is being planned by French and Guinea officials. The European group says plans are in place to start the trials in Africa this year, and some African health officials have publicly said they support the move. European regulators generally require randomized clinical trials before they will approve drugs, as do U.S. regulators. Ideally, in clinical trials, doctors and patients don’t know who is getting the real drug. An independent committee can stop the trial if it discovers the drug is a winner, or dangerous. Dr. Olliaro’s view echoes arguments made in the late 1980s by AIDS activists who wanted access to experimental AIDS drugs. AIDS was then a death sentence, so even an experimental drug was worth trying to some patients. Death rates from Ebola range from 40% to 70% throughout West Africa, Dr. Olliaro said. Dr. Olliaro says a placebo group is unnecessary because in given villages or clinics, doctors will know roughly what the death rate has been there. They can use that rate as a historical control where patients getting a drug are compared with past experience. Historical controls are widely criticized by medical experts because historical results change. A village could improve its medical care, for example. Defenders of the European plan argued in The Lancet that the death rate among Ebola patients is high enough to justify unusual measures. “When conventional care means such a high probability of death, it is problematic to insist on randomizing patients to [placebo] when the intervention arm holds out at least the possibility of benefit,” they wrote. At the NIH’s National Institute for Allergy and Infectious Diseases, Deputy Director for Research H. Clifford Lane is working with the FDA and officials in West Africa to get a randomized, controlled study going of several yet-to-be-determined Ebola drugs. “We want to get the most effective treatments into as many people as quickly as possible, and the only way to do that is a randomized clinical trial,” Dr. Lane said. Without a control group, he said, “you could hurt people.”

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Experimental therapies in brief: 

There are no approved therapies for patients who have developed Ebola or Marburg virus disease. However, several different treatments have been used during the 2014 outbreak in West Africa. Several experimental treatments for Ebola are being developed, which have shown promising results in monkeys when given up to five days after infection. However, they have not been tested in more than a handful of people and none has been licensed. These strategies have included the use of antibody preparations, small RNA particles, and novel antiviral agents. [vide infra]

1. Antibodies preparations:

Two types of antibody preparations have been used:

●A “cocktail” of three monoclonal antibodies directed against the Ebola viral glycoprotein (“ZMapp”) has been administered to several patients. ZMapp was administered to two United States healthcare workers, both of whom survived and recovered. Two other severely ill healthcare workers given ZMapp did not survive, possibly due to the late initiation of therapy. This agent has been found to prevent the death of Ebola-infected macaques, even when initiated after the animals had developed fever, viremia, and abnormalities in white blood cell counts and blood chemistry.

●The use of whole blood or serum from convalescent Ebola virus disease survivors is being used for the treatment of affected patients. The World Health Organization has issued interim guidance for the collection and administration of convalescent whole blood or plasma for treatment of Ebola virus disease during an outbreak.

2. Small RNA particles:

●An RNA interference agent (TKM-Ebola) that suppresses the production of viral proteins. This agent decreases the occurrence of Ebola virus disease when administered to nonhuman primates following filovirus challenge.  Antisense phosphorodiamidate morpholino oligomers that also target viral messenger RNA encoding Ebola virus proteins are being evaluated. Small interfering RNAs and phosphorodiamidate morpholino oligomers have been found to decrease the occurrence of disease when administered to nonhuman primates following filovirus challenge. When small interfering RNA molecules targeting three different viral genes were delivered to macaques 30 to 60 minutes after virus challenge, 60 to 100 percent of animals survived infection, whereas all controls died. In a related approach, antisense oligonucleotides also resulted in the survival of most animals.

3. Antiviral agents:

●A novel antiviral agent, brincidofovir, which is undergoing evaluation as a treatment for cytomegalovirus. This agent has been reported to have in vitro activity against the Ebola virus.

●The synthetic small molecule drug, BCX4430, inhibits viral RNA polymerase function, acting as a non-obligate RNA chain terminator. BCX4430 protected macaques against disease when treatment was begun as late as 48 hours after infection.

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Antivirals:

A number of antiviral medications are being studied.

•Favipiravir, approved in Japan for stockpiling against influenza pandemics, appears to be useful in a mouse model of Ebola. On 4 October 2014, it was reported that a French nun who contracted Ebola while volunteering in Liberia was cured with Favipiravir treatment.

•BCX4430 is a broad-spectrum small molecule antiviral drug developed by BioCryst Pharmaceuticals and undergoing animal testing as a potential human treatment for Ebola by USAMRIID. The drug has been approved to progress to Phase 1 trials, expected late in 2014.

•Brincidofovir is a broad-spectrum antiviral drug. Its maker has been granted FDA approval to proceed with a trial to test its safety and efficacy in Ebola patients. It has been used to treat the first patient diagnosed with Ebola in the USA, after he had recently returned from Liberia.

•Lamivudine, usually used to treat HIV/AIDS, was reported in September 2014 to have been used successfully to treat 13 out of 15 Ebola-infected patients by a doctor in Liberia, as part of a combination therapy also involving intravenous fluids and antibiotics to combat opportunistic bacterial infection of Ebola-compromised internal organs.  Western virologists have however expressed caution about the results, due to the small number of patients treated and confounding factors present. Researchers at the NIH stated that lamivudine had so far failed to demonstrate anti-Ebola activity in preliminary in vitro tests, but that they would continue to test it under different conditions and would progress it to trials if even slight evidence for efficacy is found.

•JK-05 is developed by the Chinese company Sihuan Pharmaceutical along with the Chinese Academy of Military Medical Sciences. It is reportedly being fast tracked through human trials for Ebola treatment after successful tests in mice.

•Lack of available treatment options has spurred research into a number of other possible antivirals targeted against Ebola,including natural products such as scytovirin and griffithsin, as well as synthetic drugs including DZNep, FGI-103, FGI-104, FGI-106, dUY11 and LJ-001, and other newer agents.

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Successful treatment of advanced Ebola virus infection with T-705 (favipiravir) in a small animal model: a 2014 study:

Outbreaks of Ebola hemorrhagic fever in sub-Saharan Africa are associated with case fatality rates of up to 90%. Currently, neither a vaccine nor an effective antiviral treatment is available for use in humans. Here, authors evaluated the efficacy of the pyrazinecarboxamide derivative T-705 (favipiravir) against Zaire Ebola virus (EBOV) in vitro and in vivo. T-705 suppressed replication of Zaire EBOV in cell culture by 4 log units with an IC90 of 110 μM. Mice lacking the type I interferon receptor (IFNAR−/−) were used as in vivo model for Zaire EBOV-induced disease. Initiation of T-705 administration at day 6 post infection induced rapid virus clearance, reduced biochemical parameters of disease severity, and prevented a lethal outcome in 100% of the animals. The findings suggest that T-705 is a candidate for treatment of Ebola hemorrhagic fever.

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Antiviral Drug Therapy of Filovirus Infections: S-Adenosylhomocysteine Hydrolase Inhibitors Inhibit Ebola Virus in vitro and in a Lethal Mouse Model:

Ebola (subtype Zaire) viral replication was inhibited in vitro by a series of nine nucleoside analogue inhibitors of S-adenosylhomocysteine hydrolase, an important target for antiviral drug development. Adult BALB/c mice lethally infected with mouse-adapted Ebola virus die 5–7 days after infection. Treatment initiated on day 0 or 1 resulted in dose-dependent protection, with mortality completely prevented at doses ⩾0.7 mg/kg every 8 h. There was significant protection (90%) when treatment was begun on day 2, at which time, the liver had an average titer of 3 × 105 pfu/g virus and the spleen had 2 × 106 pfu/g. Treatment with 2.2 mg/kg initiated on day 3, when the liver had an average titer of 2 × 107 pfu/g virus and the spleen had 2 × 108 pfu/g, resulted in 40% survival. As reported here, Carbocyclic 3-deazaadenosine is the first compound demonstrated to cure animals from this otherwise lethal Ebola virus infection.  S-adenosylhomocysteine (SAH) hydrolase is a cell-encoded enzyme that is an important intracellular target for antiviral drug development. Inhibitors of the cellular enzyme indirectly inhibit transmethylation reactions by a feedback mechanism. Several transmethylation reactions involved in viral replication are potential targets. Inhibition of SAH hydrolase by a drug effectively shuts down methylation and any steps in viral replication that are dependent upon methylation.

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Protection against filovirus diseases by a novel broad-spectrum nucleoside analogue BCX4430: a 2014 study:

In the journal Nature, scientists — who conducted much of their work in the secretive, high-containment biological laboratory maintained by USAMRIID at Fort Detrick, Maryland — have reported the discovery of a small molecule that rescues rodents and monkeys from various hemorrhagic fevers. Even more, the drug exhibited activity against a wide range of viruses. The molecule, named BCX4430, resembles the famous “A” found in DNA: adenosine. (Recall that DNA is made of Adenosine, Thymidine, Cytidine and Guanosine.) The RNA-based filoviruses also use “A” in their genomes. BCX4430, because it resembles “A”, can be accidentally used by the virus when it is trying to grow inside of our cells. For the virus, this is a fatal mistake. BCX4430 blocks further growth and reproduction. Hold up a minute, you’re probably thinking. Don’t all cells use “A” too? Shouldn’t this drug be expected to hurt not only the virus, but humans as well? That would be a reasonable expectation, but for some reason, BCX4430 appears to only hurt the virus. Human cells appear not to be fooled by BCX4430 and do just fine in its presence. The most compelling experiment the research team ran involved the infection of cynomolgus macaque monkeys with deadly Marburg virus. Macaques were given twice daily doses of BCX4430 for 14 days beginning 1 hour, 24 hours, or 48 hours post-infection. All of the monkeys that did not receive BCX4430 died by day 12. However, every monkey (except for one) that received a dose of BCX4430 survived, even if the initial dose came 48 hours after infection. In total, 17 out of 18 treated monkeys lived. Amazingly, in vitro experiments showed that BCX4430 could potentially work against a wide range of viruses, including SARS, MERS, influenza, dengue, and measles. The Nature paper demonstrated that BCX-4430 given after a viral challenge could stop Ebola and related Marburg infections from taking hold in rodents. Most notably, BCX-4430 given 48 hours after Marburg virus infection confers complete protection to cynmologous monkeys. Biocryst’s BCX-4430 is a much smaller molecule intended for broad spectrum anti-viral use, described by the company as “an RNA dependent-RNA polymerase inhibitor that has demonstrated broad-spectrum.

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Chimerix announces Emergency Investigational New Drug Applications for Brincidofovir  (CMX001) authorized by FDA for Patients With Ebola Virus Disease:

Chimerix’s lead product candidate, brincidofovir, is an oral nucleotide analog that has shown broad-spectrum in vitro antiviral activity against all five families of DNA viruses that affect humans, including viruses in the herpes virus family and adenovirus. Brincidofovir has shown no evidence of kidney or bone marrow toxicity in nearly 900 patients treated to date. Building on the positive Phase 2 results in cytomegalovirus (CMV) prevention, Chimerix initiated the Phase 3 SUPPRESS trial in 2013. If positive, data from SUPPRESS will support Chimerix’s initial regulatory submission for brincidofovir for the prevention of CMV infection in adult hematopoietic cell transplant (HCT) recipients. Chimerix recently initiated AdVise, a Phase 3 trial in adenovirus, which is an often-fatal viral infection with no approved treatment; enrollment is ongoing for the pilot portion of the trial. Chimerix is also working with the Biomedical Advanced Research and Development Authority (BARDA) to develop brincidofovir as a medical countermeasure against smallpox. Brincidofovir has received Fast Track designation from the FDA for CMV, adenovirus, and smallpox.

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Antisense technology:

Advanced antisense therapies for postexposure protection against lethal filovirus infections: a 2010 study:

Currently, no vaccines or therapeutics are licensed to counter Ebola or Marburg viruses, highly pathogenic filoviruses that are causative agents of viral hemorrhagic fever. Here authors show that administration of positively charged phosphorodiamidate morpholino oligomers (PMOplus), delivered by various dosing strategies initiated 30–60 min after infection, protects >60% of rhesus monkeys against lethal Zaire Ebola virus (ZEBOV) and 100% of cynomolgus monkeys against Lake Victoria Marburg virus (MARV) infection. PMOplus may be useful for treating these and other highly pathogenic viruses in humans.  Both small interfering RNAs (siRNAs) and phosphorodiamidate morpholino oligomers (PMOs) targeting EBOV RNA polymerase L protein may prevent disease in nonhuman primates. Sarepta Therapeutics has completed a Phase I clinical trial with its PMO protecting up to 80-100 percent of the nonhuman primates tested.

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TKM-Ebola:

TKM-Ebola is a small interfering RNA compound, currently being tested in a Phase I clinical trial in humans. The drug, being developed by Tekmira Pharmaceuticals of British Columbia, was in the initial phase of human testing, which is on healthy volunteers, when the F.D.A. halted the trial because side effects were observed. In May 2010, a series of studies demonstrating the ability of an RNAi therapeutic utilizing Tekmira’s LNP technology to protect non-human primates from the Ebola virus were published in The Lancet. Tekmira conducted the studies in collaboration with infectious disease researchers from Boston University and the United States Army Medical Research Institute for Infectious Diseases (USAMRIID). These studies were funded in part by the U.S. Department of Defense’s (DoD) Joint Project Manager Transformational Medical Technologies (JPM-TMT) Office. The results of these preclinical studies demonstrated that when siRNA – delivered by Tekmira’s LNP technology – targeted the Ebola virus to treat previously infected non-human primates, the result was 100 percent protection from an otherwise lethal dose of Zaire Ebola virus.

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TKM-Ebola is an intravenously infused RNAi Therapeutic that has been demonstrated to save the lives of monkeys infected with an otherwise fatal dose of Ebola. It is a cocktail of three Small interfering RNAs that target L protein, VP24, and VP35 genes of Zaire Ebola virus (ZEBOV), encapsulated by a specific formulation of Liposomes (also known as stabilized nucleic lipid particles (SNALPs)). Each Ebola viral particle contains a non-infectious RNA genome of roughly 19 kbp that encodes 7 structural proteins. The L protein and VP35 make up the polymerase complex, which transcribes and replicates the EBOV genome. The L protein provides the RNA-dependent RNA polymerase activity of the complex. VP24 and VP35 are involved (although not fully understood) in the inhibition of the host type 1 interferon response.  Clearly, targeting these 3 proteins would most likely be the most effective strategy to treat the disease. In a series of studies, the team from Tekmira were able to show that siRNA targeting these proteins could indeed be an effective therapeutic strategy. In order to deliver the metabolically-sensitive siRNA into the cytoplasm of the infected cells, they use a lipid-based encapsulation and delivery strategy. They incorporated the siRNA cocktail in their patented formulation of liposomes, which (in case of TKM-Ebola) are made up of cholesterol, DMPC, PEG2000-c-DMA and cationic DLinDMA. Using this delivery system, they were able to show significant reduction in the expression of said proteins in in-vitro studies and hence prevent further proliferation of ZEBOV. Early non-primate studies, with this cocktail, showed 100% protection against ZEBOV, in macaques, when treated with 7 doses of drug, post-exposure to the virus. (Interestingly, only 2 out of 3 rhesus monkeys survived when treated with 4 doses, post-exposure to virus). Unfortunately, in the midst of the outbreak, the FDA instituted a Clinical Hold on the TKM-Ebola safety study because a case of dangerously high cytokine elevations was observed at the highest dose planned in this dose-escalating/dose-finding study (0.5mg/kg). The company argues that the pharmacologic corresponding dose to those curing the monkeys is lower than 0.5mg/kg.  Secondly, a side effect that is not tolerable in healthy volunteers (usually ~20-year old male students) could be well tolerated in subjects with a 70-90% likelihood of dying from a disease in a matter of days.

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Passive Immunity in Prevention and Treatment of Infectious Diseases: 

Antibodies have been used for over a century in the prevention and treatment of infectious disease. They are used most commonly for the prevention of measles, hepatitis A, hepatitis B, tetanus, varicella, rabies, and vaccinia. Although their use in the treatment of bacterial infection has largely been supplanted by antibiotics, antibodies remain a critical component of the treatment of diptheria, tetanus, and botulism. High-dose intravenous immunoglobulin can be used to treat certain viral infections in immunocompromised patients (e.g., cytomegalovirus, parvovirus B19, and enterovirus infections). Antibodies may also be of value in toxic shock syndrome, Ebola virus, and refractory staphylococcal infections. Palivizumab, the first monoclonal antibody licensed (in 1998) for an infectious disease, can prevent respiratory syncytial virus infection in high-risk infants. The development and use of additional monoclonal antibodies to key epitopes of microbial pathogens may further define protective humoral responses and lead to new approaches for the prevention and treatment of infectious diseases. Antibodies have been used for a century for the prevention and treatment of infectious diseases. In bacterial disease, antibodies neutralize toxins, facilitate opsonization, and, with complement, promote bacteriolysis; in viral disease, antibodies block viral entry into uninfected cells, promote antibody-directed cell-mediated cytotoxicity by natural killer cells, and neutralize virus alone or with the participation of complement. Prior to the use of antibiotics, antibodies were the only specific agents for the treatment of certain infections. Although this role has largely been supplanted by antibiotics, there still remains a crucial role for antibody in the treatment of certain infectious diseases. Antibodies can be administered as human or animal plasma or serum, as pooled human immunoglobulin for intravenous (IVIG) or intramuscular (IG) use, as high-titer human IVIG or IG from immunized or convalescing donors, and as monoclonal antibodies (MAb). The therapeutic use of MAb is increasing dramatically, but only one (palivizumab for respiratory syncytial virus) has been licensed for prophylaxis of an infectious disease.

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Rodent models of filovirus infection have been developed and used particularly to investigate immune system correlates of protection. Passive transfer of neutralizing Abs protects guinea pigs from Ebola virus and Marburg virus infection. Vaccination with recombinant vaccinia virus expressing Ebola virus glycoprotein (GP) confers partial protection in guinea pigs that is not observed with constructs expressing other Ebola virus proteins. These studies imply an important role for antibody in protection against filovirus challenge. Other studies suggest that cell-mediated immunity is important. DNA vaccination with constructs expressing either GP or nucleocapsid protein (NP) protects mice from lethal challenge with Ebola virus. Protection of guinea pigs by DNA vaccination was correlated with antibody and cell mediated responses to GP. The extent to which the rodent models are representative of human filovirus infection is not known. Considerable viral adaptation may be involved in the model. For instance, Ebola virus must undergo eightfold serial passage through mice to produce a virus lethal for these animals. It is therefore important to carry out studies in nonhuman primates. One detailed study has been carried out to evaluate the efficacy of passively administered antibody in protection against Ebola virus in macaques. The Ab used was an immunoglobulin G (IgG) preparation from a horse that had been hyperimmunized with Ebola virus and had a high neutralizing-Ab titer as assessed in a plaque reduction assay. The antibody did delay the onset of clinical symptoms and viremia, but 11 of 12 infected monkeys eventually died. As noted by the authors of that study, the polyclonal equine IgG has a number of limitations, suggesting that it may be valuable to investigate the protective and therapeutic benefit of human monoclonal IgGs. The limitations include the inherently rather low specific activity achievable by passive administration of a polyclonal Ab compared to a monoclonal Ab and the unfavorable pharmacokinetics and diminished effector function activity of an equine IgG in macaques. Human IgGs are very similar to macaques IgGs and are expected to show good pharmacokinetics and effector function activity in the macaques. However, although the use of potent neutralizing human Abs to filoviruses could potentially answer a number of questions, it is not clear that such Abs are produced in natural infection as opposed to the hyperimmunization method used to generate equine IgG as described above. Neutralizing-Ab titers in serum of patients recovering from Ebola virus infection are typically low. These could reflect low concentrations of potent neutralizing Abs in serum or higher concentrations of weakly neutralizing Abs. The latter are unlikely to be effective against the virus, given the results of the studies with macaques. On the other hand, potent neutralizing Abs would signal potential approaches for vaccine development and might prove useful in prophylactic or therapeutic reagents.

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Treatment of Ebola Hemorrhagic Fever with Blood Transfusions from Convalescent Patients: a1999 study:

Between 6 and 22 June 1995, 8 patients in Kikwit, Democratic Republic of the Congo, who met the case definition used in Kikwit for Ebola (EBO) hemorrhagic fever, were transfused with blood donated by 5 convalescent patients. The donated blood contained IgG EBO antibodies but no EBO antigen. EBO antigens were detected in all the transfusion recipients just before transfusion. The 8 transfused patients had clinical symptoms similar to those of other EBO patients seen during the epidemic. All were seriously ill with severe asthenia, 4 presented with hemorrhagic manifestations, and 2 became comatose as their disease progressed. Only 1 transfused patient (12.5%) died; this number is significantly lower than the overall case fatality rate (80%) for the EBO epidemic in Kikwit and than the rates for other EBO epidemics. The reason for this low fatality rate remains to be explained. The transfused patients did receive better care than those in the initial phase of the epidemic. Plans should be made to prepare for a more thorough evaluation of passive immune therapy during a new EBO outbreak.

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Blood products for ebola:

The WHO has stated that transfusion of whole blood or purified serum from Ebola survivors is the therapy with the greatest potential to be implemented immediately, although there is little information as to its efficacy. September 2014, WHO issued an interim guideline for this therapy. The blood serum from those who have survived an infection is currently being studied to see if it is an effective treatment. During a meeting arranged by WHO, this research was deemed to be a top priority. Seven of eight people with Ebola survived after receiving a transfusion of blood donated by individuals who had previously survived the infection in a 1999 outbreak in the Democratic Republic of the Congo. This treatment, however, was started late in the disease meaning they may have already been recovering on their own and the rest of their care was better than usual. Thus this potential treatment remains controversial. Intravenous antibodies appear to be protective in nonhuman primates who have been exposed to large doses of Ebola. The WHO has approved the use of convalescent serum and whole blood products to treat people with Ebola. Post-exposure management should consider either passive immunotherapy, or administering drugs that block the action of the virus or its replication. Convalescent sera, thought to contain natural specific protective antibodies developed during the disease, have been used exceptionally, with some success. It is noteworthy that these patients had also received better symptomatic treatments than regular patients, and were not representative. However, despite this indisputable bias, several experimental studies have confirmed, particularly in non-human primates, the effectiveness of such approach. Transfusions are probably useful for the treatment or prevention of shock and may provide coagulation factors to stop or to prevent bleeding. However, because of the small number of patients studied and the lack of control subjects, we cannot conclude that the neutralizing antibodies in transfused convalescent blood improve the outcome for EHF patients.  

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Fortunately, there are examples of provocative new findings that may provide therapy for filovirus infections. Simple convalescent serum has generally had low neutralizing capacity in vitro and has not conferred protection on passive transfer. Nevertheless, high-titered hyperimmune horse anti-Ebola serum has been produced and been found protective in baboons challenged with Ebola virus. This product has been confirmed to be efficacious in guinea pigs, but it is not as useful in rhesus monkeys or the mouse model of Ebola virus infection. The production of human monoclonal antibodies against Ebola virus surface protein from mRNA extracted from bone marrow of Kikwit survivors raises the possibility that an improved, standardized, safe, and replenishable source of therapeutic antibodies could be developed.  

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Points against ebola survivor’s blood transfusion to ebola patient:

It seemed obvious to all at first that the active components in blood transfusions from ebola survivors must be anti-ebola antibodies. Such antibodies would neutralize the virus and help the immune system clear it out. And in fact, a 1999 study reported that seven patients who survived the 1995 outbreak in the Democratic Republic of the Congo after receiving transfusions from survivors had anti-ebola antibodies circulating in their blood. One kind of antibody, called IgM, was absent in another patient who received a transfusion and died. This very small study seemed to indicate that transfusions could work against ebola and that antibodies are key to making them work. (You may be wondering why, if the transfusions worked, more patients weren’t treated this way during the 1995 outbreak. One important reason is that that blood cannot be transfused unless the donor and recipient blood types are compatible.  So the treatment is limited by the number of willing survivors and their blood types.) This idea was challenged by a 2007 study done in a nonhuman primate species, rhesus macaques. For this study, researchers drew blood from a rare few monkeys who had survived ebola infection four or five years earlier and a second “boost” infection 30 days earlier. They transferred the blood into other, recently-infected animals, and none of them survived…even those that made a lot of antibody. There are, of course, caveats. Monkeys are not humans, after all. It is possible that they fight the virus differently. And in the discussion of the paper, the researchers admit the experiments that had successfully transferred antibody-mediated immunity in guinea pigs had not worked in rhesus macaques. There are also caveats to the human study though. The main one being that it can’t account for the better treatment transfusion patients received compared to other patients. The seven may have survived simply because they received better care in the clinics. The boost of cells, fluids, proteins and electrolytes that come along with blood transfusions may also have helped. In spite of it all, the World Health Organization is behind blood transfusions and transfer of plasma from ebola survivors.

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ZMapp:

The biotech product, called ZMapp™, is indeed still experimental – it’s not yet approved for human use, and not yet even in phase I clinical trials – it’s far from secret. The three-antibody mixture originated with Mapp Biopharmaceuticals, a small San Diego-based company established in 2003 and led by Larry Zeitlin, Ph.D., a Johns Hopkins-trained reproductive biologist who became an expert in “plantibodies,” antibody therapeutics produced in, and purified from, bioengineered plants. The ZMapp three-antibody cocktail isn’t a vaccine. Instead, it provides an artifical immune response against sugar-tagged proteins on the outside of the Ebolavirus (GP). The tobacco species, Nicotiana bethamiana, is a common plant molecular biology tool. There is a process of agroinfiltration, where a solution of a recombinant agrobacterium is used to insert new genetic material into the plant. This general biotherapeutic approach is called passive immunity. By injecting the patient with ready-made antibodies raised in the laboratory to latch onto specific parts of an infectious agent, their body can mount an immediate immune response. Passive immunity is therefore different from a vaccine that might require weeks for the person to make their own antibodies against the virus. These three antibodies represent a clever strategy against the virus. One of the antibodies binds up a form of Ebolavirus protein that seems to be sent off by the virus as a decoy against the immune response.

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ZMapp is a cocktail of three monoclonal antibodies, which are immune system proteins that can isolate and neutralize an invading pathogen. The antibodies were initially harvested from mice exposed to a protein from Ebola, then genetically engineered to make them more like human antibodies. The resulting antibodies are then manufactured in genetically engineered tobacco plants. To make ZMapp, the genes encoding for the antibodies were extracted from the hybridomas, genetically engineered to replace mouse components with human components, and transfected into tobacco plants. Like intravenous immunoglobulin therapy, ZMapp contains neutralizing antibodies that provide passive immunity to the virus by directly and specifically reacting with it in a “lock and key” fashion.

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A blend of three monoclonal antibodies has completely protected monkeys against a lethal dose of Ebola virus. Unlike other post-infection therapies, the treatment works even at advanced stages of the disease. These include small ‘interfering’ RNAs (known as TKM-Ebola9) and various combinations of antibodies. But these treatments need to be administered within 2 days of exposure to the virus. So although these approaches were highly important and can be used to treat known exposures, the need for treatments that protect at later times after infection was paramount. Further development and improvement of the antibody-based strategies led to a cocktail of monoclonal antibodies that protected 43% of monkeys when given as late as 5 days after Ebola exposure — a time at which the clinical signs of disease are apparent. Another therapy that combines monoclonal antibodies with interferon-α (a protein that stimulates an antiviral response) provides almost complete protection of macaques when given 3 days after exposure, at which point the virus can be detected but clinical signs are only just beginning to be seen in some animals.

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The composite drug is being developed by Leaf Biopharmaceutical (LeafBio, Inc.), a San Diego based arm of Mapp Biopharmaceutical. LeafBio created ZMapp in collaboration with its parent and Defyrus Inc., each of which had developed its own cocktail of antibodies, called MB-003 and ZMab.

MB-003:

MB-003 is a cocktail of three humanized or human–mouse chimeric mAbs: c13C6, h13F6 and c6D8. A study published in September 2012 found that rhesus macaques infected with Ebola virus (EBOV) survived when receiving MB-003 (mixture of 3 chimeric monoclonal antibodies) one hour after infection. When treated 24 or 48 hours after infection, four of six animals survived and had little to no viremia and few, if any, clinical symptoms. MB-003 was created by Mapp Biopharmaceutical, based in San Diego, with years of funding from US government agencies including the National Institute of Allergy and Infectious Disease, Biomedical Advanced Research and Development Authority, and the Defense Threat Reduction Agency.

ZMAb:

ZMAb is a mixture of three mouse mAbs: m1H3, m2G4 and m4G7. A study published in November 2013 found that EBOV-infected macaque monkeys survived after being given a therapy with a combination of three EBOV surface glycoprotein (EBOV-GP)-specific monoclonal antibodies (ZMAb) within 24 hours of infection. The authors concluded that post-exposure treatment and a second lethal exposure after 10 and 13 weeks resulted in a robust immune response. ZMab was created by Defyrus, a Toronto-based biodefense company, funded by the Public Health Agency of Canada. The identification of the optimal components from MB-003 and ZMab was carried out at the Public Health Agency of Canada’s National Microbiology Laboratory in Winnipeg.

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A 2014 paper described how Mapp and its collaborators, including investigators at Public Health Agency of Canada, Kentucky BioProcessing, and the National Institute of Allergy and Infectious Diseases, first chimerized the three antibodies comprising ZMAb, then tested combinations of MB-003 and the chimeric ZMAb antibodies in guinea pigs and then primates to determine the best combination, which turned out to be c13C6 from MB-003 and two chimeric mAbs from ZMAb, c2G4 and c4G7. This is ZMapp. In an experiment also published in the 2014 paper, 21 rhesus macaque primates were infected with the Kikwit Congolese variant of EBOV. Three primates in the control arm were given a non-functional antibody, and the 18 in the treatment arm were divided into three groups of six. All primates in the treatment arm received three doses of ZMapp, spaced 3 days apart. The first treatment group received its first dose on 3rd day after being infected; the second group on the 4th day after being infected, and the third group, on the 5th day after being infected. All three primates in the control group died; all 18 primates in the treatment arm survived. Mapp then went on to show that ZMapp inhibits replication of a Guinean strain of EBOV in cell cultures.   

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The drug was first tested in humans during the 2014 West Africa Ebola virus outbreak, but has not been subjected to a randomized controlled trial to determine whether it works, and whether it is safe enough to allow on the market. As of October 2014, ZMapp had been used to treat 7 individuals infected with the Ebola virus. Although some of them have recovered, the outcome is not considered to be statistically significant. Mapp announced on August 11, 2014, that its supplies of ZMapp had been exhausted. The lack of drugs and unavailability of experimental treatment in the most affected regions of the West African Ebola virus outbreak spurred some controversy. The fact that the drug was first given to Americans and a European and not to Africans, according to the Los Angeles Times, “provoked outrage, feeding into African perceptions of Western insensitivity and arrogance, with a deep sense of mistrust and betrayal still lingering over the exploitation and abuses of the colonial era”. Salim S. Abdool Karim, the director of an AIDS research center in South Africa, placed the issue in the context of the history of exploitation and abuses. Responding to a question on how people may have reacted if ZMapp and other drugs would have been used first on Africans, said, “It would have been the front-page screaming headline: ‘Africans used as guinea pigs for American drug company’s medicine’”.

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Before there is widespread elation that a cure is at hand, health officials tried to inject some sober reality. World Health Organization spokesman Gregory Hartl says that health authorities “cannot start using untested drugs in the middle of an outbreak, for various reasons.” Doctors Without Borders issued a statement saying: “It is important to keep in mind that a large-scale provision of treatments and vaccines that are in very early stages of development has a series of scientific and ethical implications. As doctors, trying an untested drug on patients is a very difficult choice since our first priority is to do no harm, and we would not be sure that the experimental treatment would do more harm than good.” There is normally a long, complicated process before a drug can be given to patients under FDA regulations. But the FDA does have a “compassionate use” regulation that allows experimental drugs to be administered in emergencies such as this one.

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Researchers in Thailand claim to have developed an antibody-based treatment for Ebola using synthesized fragments of the virus. It has not been tested against Ebola itself. Scientists from the WHO and NIH have offered to test the treatment against live Ebola virus, but there is still a great deal of development needed before human trials.

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Ebola Treatment is very expensive: Treatment for Ebola can cost up to $500,000:

Nina Pham, a Dallas nurse who contracted Ebola while caring for the first person in the U.S. to have the virus, is now Ebola-free. Getting a clean bill of health took 13 days in the hospital and an estimated $110,000. Daily hospital care for Ebola can easily reach $8,500 per day, according to Lockton, a global insurance company in Kansas City, Mo.—$6,000 a day in an intensive care unit, plus $2,500 per day for additional costs, such as physician fees and aggressive support therapy. Costs may even be higher than that, says Eric Justin, Lockton’s chief medical officer, if there are other health complications. That was the case with the U.S.’s first Ebola patient, Thomas Eric Duncan, who was also on dialysis. Based on a two-week confinement, Lockton estimates that the minimum expense for an intensive care unit alone at any hospital would reach $100,000. Experimental medication expenses or care in a specialized biocontainment facility could easily push costs to $500,000 or more. That doesn’t account for potential complications like loss of hearing or vision, bringing disability or long-term health care costs into play. So who would pay? For now, standard health insurance policies would respond, although it’s unclear exactly how much care they may pay for, says Logan Payne of Lockton’s international practice. Most health-care policies, for example, wouldn’t cover experimental treatments, but Justin says patients can’t be charged for such drugs as ZMapp, which has been given to several Ebola victims, until after the FDA approves them. Thus, “for an indeterminate period of time when those experimental drugs are used,” there likely won’t be a cost for the medication, he adds.

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Other treatments:

Two selective estrogen receptor modulators usually used to treat infertility and breast cancer (clomiphene and toremifene) have been found to inhibit the progress of Ebola virus in vitro as well as in infected mice. Ninety percent of the mice treated with clomiphene and 50 percent of those treated with toremifene survived the tests. These drugs inhibit of virus-host cell fusion and viral entry. The study authors conclude that given their oral availability and history of human use, these drugs would be candidates for treating Ebola virus infection in remote geographical locations, either on their own or together with other antiviral drugs. A 2014 study found that three ion channel blockers used in the treatment of heart arrhythmias, amiodarone, dronedarone and verapamil, block the entry of Ebola virus into cells in vitro. Other potential anti-ebloa drugs include antifungal terconazole, antidepressant amitriptyline and some anticancer drugs.  

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Inhibition of Lassa virus and Ebola virus infection in host cells treated with the kinase inhibitors genistein and tyrphostin:

Arenaviruses and filoviruses are capable of causing hemorrhagic fever syndrome in humans. Limited therapeutic and/or prophylactic options are available for humans suffering from viral hemorrhagic fever. In this report, authors demonstrate that pre-treatment of host cells with the kinase inhibitors genistein and tyrphostin AG1478 leads to inhibition of infection or transduction in cells infected with Ebola virus, Marburg virus, and Lassa virus. In all, the results demonstrate that a kinase inhibitor cocktail consisting of genistein and tyrphostin AG1478 is a broad-spectrum antiviral that may be used as a therapeutic or prophylactic against arenavirus and filovirus hemorrhagic fever.  

Where does Genistein come from?

While primarily found in soy products, especially fermented soy foods, wherein beneficial microbes cause the biotransformation of the precursor phytocompund genistin into genistein, it is also found in fava beans, kudzu, coffee and red clover, and many other lesser known medicinal plants.

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Resolving cytokine storms with Selenium: 

The highly pathogenic Zaire strain of the Ebola virus may be dependent on the trace mineral selenium (Se), due to the presence in the Ebola genome of several open reading frames (ORFs) containing clusters of up to 17 inframe UGA codons, which potentially encode the rare amino acid selenocysteine (SeC). This raises the possibility that Se deficiency in host populations may actually foster viral replication, possibly triggering outbreaks linked and perhaps even facilitating the emergence of more virulent viral strains. Selenium is a strong antioxidant and anti-inflammatory that can control the cytokine storms provoked from out of control infections. The clinical investigations in sepsis studies indicate that higher doses of selenium are well tolerated as continuous infusions of selenium as sodium selenite (4,000 μg selenium as sodium selenite pentahydrate on the first day, 1,000 μg selenium/day on the nine following days) and had no reported toxicity issues. In view of this new information, Biosyn introduced the 1,000 µg dose vials for such high selenium clinical usage. Revici used a special molecular form of selenium (bivalent-negative selenium) incorporated in a molecule of fatty acid. In this form, he can administer up to 1 gram of selenium per day, which corresponds to 1 million micrograms per day, reportedly with no toxic side effects. In contrast, too much selenite (hexavalent-positive selenium) has toxic effects on animals, so human intake of commercial selenite is limited to a dosage of only 100 to 150 micrograms by mouth. The last 25 years the average daily selenium intake has fallen from 60µg/day to 35µg/day.  The UK government has established a Reference Nutrient Intake (RNI) level of selenium at 75µg/day.  Therefore a nutritional gap now exists between the actual recommended level of daily selenium and what people are actually achieving through their diets. Selenium-deficient lymphocytes are less able to proliferate in response to mitogen, and in macrophages, leukotriene B4 synthesis, which is essential for neutrophil chemotaxis, is impaired by this deficiency. These processes can be improved by selenium supplementation. The humoral system is also affected by selenium deficiency; for example, IgM, IgG and IgA titers are decreased in rats, and IgG and IgM titers are decreased in humans. In endothelial cells from asthmatics, there is a marked selenium deficiency that results in an increase in expression of adhesion molecules, which causes greater adhesion of neutrophils. Selenium is also involved in several key metabolic activities through its selenoprotein enzymes that protect against oxidative damage. Further, selenium deficiency may allow invading viruses to mutate and cause longer-lasting, more severe illness.  Animal research has shown selenium and vitamin E have synergistic effects, enhancing the body’s response to bacterial and parasitic infections.

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Hemorrhagic Infections resolved with Vitamin C:

To date, no viral infection has been demonstrated to be resistant to the proper dosing of vitamin C as classically demonstrated by Klenner. However, not all viruses have been treated with Klenner-sized vitamin C doses, or at least the results have not been published. Ebola viral infection and the other acute viral hemorrhagic fevers appear to be diseases that fall into this category. Because of the seemingly exceptional ability of these viruses to rapidly deplete vitamin C stores, even larger doses of vitamin C would likely be required in order to effectively reverse and eventually cure infections caused by these viruses. Cathcart (1981), who introduced the concept of bowel tolerance to vitamin C hypothesized that Ebola and the other acute viral hemorrhagic fevers may well require 500,000 mg of vitamin C daily to reach bowel tolerance! Whether this estimate is accurate, it seems clear as evidenced by the scurvy-like clinical manifestations of these infections that vitamin C dosing must be vigorous and given in extremely high doses. If the disease seems to be winning, then even more vitamin C should be given until symptoms begin to lessen. Obviously, these are viral diseases that would absolutely require high doses of vitamin C intravenously as the initial therapy. The oral administration should begin simultaneously, but the intravenous route should not be abandoned until the clinical response is complete. Death occurs too quickly with the hemorrhagic fevers to be conservative when dosing the vitamin C. Viral hemorrhagic fevers typically only take hold and reach epidemic proportions in those populations that would already be expected to have low body stores of vitamin C, such as are found in many of the severely malnourished Africans. In such individuals, an infecting hemorrhagic virus will often wipe out any remaining vitamin C stores before the immune systems can get the upper hand and initiate recovery. When the vitamin C stores are rapidly depleted by large infecting doses of an aggressive virus, the immune system gets similarly depleted and compromised. Intravenous vitamin C is a powerful treatment when people are on the edge between life and death from hemorrhagic fevers with the power to bring people back from the brink. Vitamin C (ascorbic acid) is known to perform many critical functions within the body involving detoxification, tissue building, immune enhancement, pain control, and controlling or killing pathogenic organisms. The Ebola virus kills by way of free radicals which can be neutralized by massive doses of sodium ascorbate intravenously.  

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Vitamin D – Perfect Helpmate to Vitamin C:

Vitamin D reduces the risk of dying from a viral infection. Researchers from Winthrop University Hospital in Mineola, New York found that giving supplements of vitamin D to a group of volunteers reduced episodes of infection with colds and flu by 70% over three years. The researchers said that vitamin D stimulates “innate immunity” to viruses and bacteria. Very few have any idea that Vitamin D can be taken in high dosages like Vitamin C can.

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Glutathione:

Glutathione is required in many of the intricate steps needed to carry out an immune response. It is needed for the lymphocytes to multiply in order to develop a strong immune response, and for killer lymphocytes to be able to kill undesirable cells such as cancer cells or virally infected cells. The importance of glutathione cannot be overstated. It has multiple roles as indicated and, indeed, as one examines each system or organ more closely, the necessity for glutathione becomes increasingly evident. Glutathione values decline with age and higher values in older people are seen to correlate with better health, underscoring the importance of this remarkable substance for maintaining a healthy, well-functioning body.”

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Antimalarial drug Chloroquine shows promise against Ebola:

Several research groups have been scouring medicine cabinets for FDA approved drugs that have activity against Ebola viral replication. The most interesting among these is the antiviral activity of chloroquine and related compound hydroxychloroquine both of which are also used in the treatment of systemic lupus erythematosus and rheumatoid arthritis. These antimalarial agents accumulate in the endosomes and prevent their acidification maturation, which are crucial steps in the activation of not only lysosomal enzymes but also innate immune receptors TLR7 and TLR9. Now it turns out the Ebola and Marburg viruses also pass through the endosomes and their acidication is essential for exiting the endosomes and chloroquine and hydroxychloroquine trap the viral particles preventing their escape.  Among monkeys treated with chloroquine 80-90 percent survived challenge with Ebola and Marburg viruses according to one study. Intraperitoneal administration improved the survival to 100%. Since these drugs target host proteins, the virus is unlikely to develop drug resistance.

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Ozone Therapy:

Ebola hijacks your immune system and suppresses it. Once your immune system realizes the virus is there, it launches a cytokine storm, and it is this cytokine storm that leads to massive tissue destruction and capillary leakage. This is what causes the hemorrhaging associated with Ebola. Ozone modulates the cytokine storm.  It’s anti-infective. It improves circulation and blood flow, oxygen delivery, and likely upregulates mitochondrial respiration, thereby generating more energy in your cells. Oxygen is one of the most important things your body needs for tissue healing when you’re riddled with infection. With bacteria, ozone works by puncturing the membrane of the bacteria, causing it to spill its contents and die. It also inactivates viruses, and does so 10 times faster than chlorine. Ozone also has the advantage of stimulating the immune system, and modulating it—either up or down depending on what your system requires. Ozone is only hard on the lungs, but it can be given in other ways. It can be given intravenously. It can be given in the bladder, in the vagina, in the rectum, via injection – anywhere. It’s just [that] it can be tough on the lungs. You don’t want to be breathing it.

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Red Algae extract defends against Ebola:

Mannose-binding lectins are produced in the human body via a DNA sequence, called the MBL2. When our genes are working properly, these lectins flood the bloodstream and scourge disease – including unwanted fungi, bacteria, and even parasites, which utilize glycoprotein shells to protect themselves. They also inhibit virus growth. They do this by breaking apart the surface of the unwanted microbe and breaking them down, allowing the body’s additional immune cells to kill off the virus or toxin and prevent it from replicating. Research over the past five years has found that low levels of mannose-binding lectins increases the risk of respiratory infections, including syncytial virus infections, pneumonia and others. Ebola, as many other viruses do, comes with a glycoprotein shell that must be broken down in order for someone who is in contact with it to remain healthy. Furthermore, the glycoprotein shell of the Ebola virus produces glycoproteins that damage cells, allowing the virus to penetrate and replicate within the cell – but red algae has been shown to keep this from happening. The reason for this mutation/switch-off has yet to be fully understood. Red algae produces mannose-binding lectins plentifully, which allow the plants to protect themselves from invasion by viruses. The most promising form of mannose-binding lectins is a component of the Scytonema varium red algae called Scytovirin. The protein extract was isolated by researchers from the National Cancer Institute at Frederick, Maryland in 2003. It contains 95 amino acids, and was found to bind to HIV-1 viral shells. Another antiviral protein in red algea broke down the glycoprotein shells of HIV and HCV. And yet another anti-viral extract found in a New Zealand red algae species, Griffithsia was beneficial in treating mice with epidemic-potentiated SARS and also HIV-1. It stopped the viruses from replicating. In 2010, Harvard researchers tested a recombinant version of Griffithsin – called rhMBL – against Ebola, and found that it broke down those pesky viral shells while giving mice complete immunity to the virus. Other animals have since been tested with similar results. So, even if you aren’t certain red algae will keep you from contracting Ebola, you can boost your immune system and protect against a number of diseases, from Ebola to SARS, simply by taking a red seaweed supplement. 

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Ebola survivors:  

Surviving Ebola: For those who live through it, what lies ahead?

Medical experts say most people who manage to recover from an acute Ebola infection will likely be able to return to their life and resume normal activities. But unfortunately, Ebola survivors do often develop certain chronic inflammatory conditions that affect the joints and eyes, problems that can follow a survivor through the remainder of their life. Ebola survivors are at risk for arthralgia, a type of joint and bone pain that can feel similar to arthritis. Ebola survivors also frequently report complications with eyes and vision, an inflammatory condition known as uveitis which can cause excess tearing, eye sensitivity, eye inflammation and even blindness. It’s not completely known how long a person can continue to shed the virus once the acute infection has subsided. It’s likely that the recovery from Ebola varies as much as the incubation period of the virus, which can last anywhere between 2 to 21 days. According to the World Health Organization, a lab worker who contracted Ebola on the job was found to have traces of the virus in his semen 61 days after the initial infection. Though it has not been documented, this could theoretically mean a man could infect his partner during sexual intercourse weeks after he seemed to get over the disease. Researchers are still trying to understand what factors help some patients survive Ebola when so many others do not.

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Ebola survivors are involved in the following aspect of life:

1. Donate their blood/plasma for patients suffering from EVD

2. Can become care-taker of patients suffering from EVD

3. May suffer from chronic complications of EVD

4. May face stigmatization by society

5. Have to abstain from sex or practice safe sex with condoms, not breastfed their children and avoid contact with mucous membrane of eyes; all for at least three months from recovery. 

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Ebola Survivors are likely to be immune to ebola virus:

There is strong epidemiological evidence that once an individual has resolved an Ebola virus infection, they are immune to that strain. Studies of blood samples taken from Ebola survivors a few years after they became infected with the virus show that these people have developed antibodies that can neutralize the Ebola virus. This suggests that Ebola survivors are immune to the disease, and will not get infected again. However, no one has tested what really happens if a survivor is exposed to the virus for a second time. It is not clear whether survivors become immune to all strains of the Ebola virus or only the one that infected them, nor is it clear how long this immunity lasts. There has not been a single case of a person who has been infected who has recovered and has been infected again in the same epidemic. There are five known species of the Ebola virus. The current outbreak is caused by Zaire Ebola virus, which is the deadliest type. In previous outbreaks involving this strain, only 10 percent of patients have survived the infection. In the current outbreak, about 47 percent of people infected with the virus have survived, according to the World Health Organization. It is possible that early treatment efforts have played a role in improving survival rates in this outbreak. It is not clear which biological factors may determine a person’s chance of surviving Ebola, but a stronger immune system appears to be one important factor. Also, laboratory evidence suggests that some people with a genetic mutation may be entirely resistant to Ebola infection. The doctors still don’t know if the experimental drug played any role in helping Ebola patients survive, but patients’ better nutrition and stronger immune systems may have helped their recover.

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Ebola Survivors could be the Best Weapon for fighting the Killer Virus:

Train immune ebola survivors to help medics, says UK nurse Will Pooley. Many public health authorities believe Pooley and others who have survived Ebola could have a significant advantage when interacting with those who have the disease. There are no known cases of a survivor becoming reinfected, and in laboratory tests monkeys have stayed immune to Ebola for several years. Pooley knows this. “It doesn’t seem likely that I would contract it again,” he said. Compassionate care might not be the only benefit Pooley could bring to those suffering from Ebola. After recovering, Pooley traveled to the United States to donate blood to an American doctor named Kent Brantly, who was also infected in Sierra Leone. The experimental treatment is called “convalescent serum” and involves giving patient antibodies from an Ebola survivor’s blood. The serum has not been through any clinical trials, but Brantly is now Ebola free. Pooley is one of several people who beat Ebola and are now ready and willing to care for the sick. In Liberia, the WHO has been training Ebola survivors in a mock treatment center so they can be deployed to new and existing Ebola clinics. Whether or not they’re immune, they are uniquely equipped to help people who are sick because of their experiences. 

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Ebola Survivors and Sex: better safe than sorry:    

Doctors Without Borders, which oversees many Ebola clinics in west Africa, is sending home recovered Ebola patients with a stack of condoms, and health workers are urging them to only engage in protected sex for at least three months after recovery. The virus has been found in the semen and vaginal fluids of convalescents for weeks or even months after symptoms of Ebola have abated, setting off concern that the virus could be spread via sexual contact with otherwise healthy individuals. In men, one study found that Ebola continued to persist in semen for 90 days. U.S. health officials are echoing this caution as a small number of patients have been released from American hospitals. To date, however, there has not been a single documented case of Ebola transmission from sexual activity.  Moreover, simply detecting the genetic presence of the virus in recovering patients does not automatically mean that disease transmission could or would take place—especially if the virus is only present in relatively low concentrations. Although a whole, functioning virus is needed to transmit an infection to another person, current testing methods are also so sensitive they also detect nucleic acids from the virus that continue to lurk in bodily fluids during recovery. That may be why one 1999 study in the Democratic Republic of the Congo, which followed 29 people recovering from Ebola and their household contacts (including sex partners) for up to 21 months, found that although four of the five tested convalescents had at least one semen sample with detected Ebola virus inside it, none of their sexual partners developed symptoms of Ebola, even if they had unprotected sex during that period. So why the “safe sex” warning when thousands of patients have survived Ebola and may have gone on to have sex, apparently without infecting their partners? Extreme caution is not an overreaction with this disease. Studies by Bausch and others have also detected live Ebola virus in sexual fluids that can successfully grow in cell culture, suggesting it could also lead to infections in other individuals. It is possible that sexually transmitted Ebola may have flown under the radar because there has been a dearth of data from outbreaks in years past. Also, although extremely unlikely, it is possible that mild Ebola—with very minor symptoms that were not recognized as such—has developed in patients’ sexual partners. Thus, the CDC warns that convalescing patients must either abstain from intercourse and oral sex for three months or use condoms for that entire time. With any infectious disease, when patients have a high viral load in their bodily fluids, it increases the risk they will pass disease to someone else through direct contact with those fluids. With HIV, for example, the risk of passing the disease between partners increases with higher viral load: For every 10-fold increase in viral concentration, one 2012 study suggests there is about a threefold increase in the risk of transmission per sexual act. And with HIV, condoms are a highly effective mode of blocking disease transmission because the virus is primarily spread via contact with sexual fluids or blood.  As with HIV, when Ebola progresses, a patient’s viral loads inch upward and that boosts the chance of disease transmission via contact with bodily fluids. Moreover, a certain degree of natural immunological protection for certain body parts—the central nervous system, eyes and gonads—makes it difficult for virus to exit those bodily parts, which may lead to the virus continuing to be present even after the virus was cleared from the blood, according to Bausch. And if an Ebola patient’s disease proves fatal, his viral load at death is particularly high, which boosts the risk of contracting the disease from interacting with the corpse. Ebola virus manages to thrive in a variety of bodily fluids. It is found in its highest concentrations in blood, vomit and feces. But coming into direct contact with semen, vaginal fluids, saliva or even sweat could still be risky while a patient is symptomatic. (Although it’s not likely patients in the throes of illness would be engaging in sex. And live Ebola virus, according to WHO, has never been isolated in human sweat.) Just how infectious those fluids may be after recovery, however, remains a series of question marks. Studies in this area have been extremely small and continue to be largely inconclusive. Thus far, there are no recorded cases of sexual transmission of Ebola. With more than 16,000 cases currently in west Africa right now, however, public health officials do not want to take any chances. Bruce Ribner, the clinician who led the Emory University Hospital team that treated patients Kent Brantly and Nancy Writebol, said in a recent interview with Scientific American that although studies have shown Ebola patients shed genetic material from the pathogen into their sexual fluids there is scant evidence they are often shedding viable virus that could infect others. Yet even Ribner advised his patients about the recommended CDC guidelines of not having unprotected sex for three months. For now, it’s better safe than sorry.

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Isolation and quarantine:

Isolation and quarantine help protect the public by preventing exposure to people who have or may have a contagious disease.

•Isolation separates sick people with a contagious disease from people who are not sick. In health care, isolation refers to various measures taken to prevent contagious diseases from being spread from a patient to other patients, health care workers, and visitors, or from others to a particular patient.

•Quarantine separates and restricts the movement of people who were exposed to a contagious disease to see if they become sick. This is often used in connection to disease and illness, such as those who may possibly have been exposed to a communicable disease until they either show signs of the disease (when they will be isolated) or are no longer at risk. Quarantine is usually effective in decreasing spread. Governments often quarantine areas where the disease is occurring or individuals who may transmit the disease outside of an initial area. When someone has been exposed to a contagious disease and it is not yet known if they have caught it, they may be quarantined or separated from others who have not been exposed to the disease. For example, they may be asked to remain at home to prevent further potential spread of the illness. They also receive special care and observation for any early signs of the illness.

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Sartwell conducted one of the first systematic studies on the incubation time for human pathogens and found that a broad spectrum of agents had incubation time distributions that could be modeled as lognormal (although alternative distributional forms were not tested). Leclerc et al. examined the incubation time distribution of a variety of plant pathogens and observed that they could be fit (depending on the pathogen and the plant age) by either the gamma, lognormal, or Weibull distributions. All of these three are skewed right. Williams looked at the theoretical incubation time distribution for pathogens conforming to a stochastic in vivo birth-death process and found that they could also be characterized by a skewed distribution. In general none of the often used incubation time distributions have a maximum upper limit. In other words, therefore there is no quarantine time that will provide absolute assurance of no residual risk from contagion. Nishiura pointed out the importance of examining the upper tail of the incubation time distribution when assessing the quarantine period following exposure to smallpox. This was also discussed in the context of the SARS corona virus outbreak. Both of these previous authors noted the importance of the distributional form in assessing the upper tail probability, and the influence that data truncation may have on such estimates. To make use of this approach, an acceptable residual risk needs to be set. To do this, one needs to balance out the costs and benefits of quarantine and risk reduction. For contagious diseases this will require coupling the risk of premature release from quarantine to a disease transmission model such as Legrand et al. Clearly for pathogens that have a high degree of transmissibility and/or a high degree of severity, the quarantine time should be greater than for agents with lower transmissibility and/or severity.

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Ebola, Quarantine of nurses and travel ban:

The governors of a number of states, including New York and New Jersey, recently imposed 21-day quarantines on health care workers returning to the United States from regions of the world where they may have cared for patients with Ebola virus disease. The motivation for this policy is to protect the citizens of their states from contracting this often-fatal illness. Health care professionals treating patients with this illness have learned that transmission arises from contact with bodily fluids of a person who is symptomatic — that is, has a fever, vomiting, diarrhea, and malaise. We have very strong reason to believe that transmission occurs when the viral load in bodily fluids is high, on the order of millions of virions per microliter. This recognition has led to the dictum that an asymptomatic person is not contagious; field experience in West Africa has shown that conclusion to be valid. Therefore, an asymptomatic health care worker returning from treating patients with Ebola, even if he or she were infected, would not be contagious. Furthermore, we now know that fever precedes the contagious stage, allowing workers who are unknowingly infected to identify themselves before they become a threat to their community. This understanding is based on more than clinical observation: the sensitive blood polymerase-chain-reaction (PCR) test for Ebola is often negative on the day when fever or other symptoms begin and only becomes reliably positive 2 to 3 days after symptom onset. This point is supported by the fact that of the nurses caring for Thomas Eric Duncan, the man who died from Ebola virus disease in Texas in October, only those who cared for him at the end of his life, when the number of virions he was shedding was likely to be very high, became infected. Notably, Duncan’s family members who were living in the same household for days as he was at the start of his illness did not become infected. A cynic would say that all these “facts” are derived from observation and that it pays to be 100% safe and to isolate anyone with a remote chance of carrying the virus. What harm can that approach do besides inconveniencing a few health care workers?  Hundreds of years of experience show that to stop an epidemic of this type requires controlling it at its source. We need tens of thousands of additional volunteers to control the epidemic. We are far short of that goal, so the need for workers on the ground is great. These responsible, skilled health care workers who are risking their lives to help others are also helping by stemming the epidemic at its source. If we add barriers making it harder for volunteers to return to their community, it will discourage future volunteers to travel to West Africa to control epidemic and thereby worsen epidemic. However, some experts say that maybe volunteers aren’t that effective anyway, and that their lack of actual experience may make them more likely to catch Ebola. The key to stopping Ebola worldwide is stopping it in Africa. Unfortunately, restricting the movement of people — whether through travel bans or forced quarantines of potentially exposed health workers — while politically expedient in a time of panic isn’t likely to stop Ebola spread. In fact, it could have the opposite of the desire effect. To completely seal off and don’t let planes in or out of the West African countries involved, then you could paradoxically make things much worse in the sense that you can’t get supplies in, you can’t get help in, you can’t get the kinds of things in there that we need to contain the epidemic.  So restricting travel would render useless the two best methods we have for stopping Ebola: tracking the movements and contacts of potential Ebola cases, and getting aid and resources to West Africa to stop Ebola at the source. Plus, evidence and experience suggests flight restrictions didn’t work to stop HIV/AIDS, SARS, and Swine Flu. This is why health officials unanimously agree that a travel ban is a bad idea.

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Why has the quarantine period for someone suspected of being infected with Ebola virus set at 21 days?

The length of the quarantine period is based on the incubation period, the time before symptoms of an infection appear. For Ebola virus, the incubation period is 2-21 days after infection. If ebola contact does not get symptoms (fever) in 21 days, he/she does not have ebola virus disease. Of course there are silent ebola infections where quarantine logic fails but they are not contagious anyway.

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Prevention of ebola in general:

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Standard precautions for all patients:

It is not always possible to identify patients with EVD early in the course of their illness because initial symptoms may be non-specific. For this reason, it is important that health care workers (HCWs) at all levels carefully apply standard precautions on a consistent basis, with all patients – regardless of their diagnosis – in all practices and at all times.

These include:

1.  hand hygiene

2.  use of disposable medical examination gloves before contact with body fluids, mucous membrane, non-intact skin and contaminated items, and

3. gown and eye protection before procedures and patient-care activities likely to involve contact with or projection of blood or body fluids.

In addition, regular application of best practices for injection safety and safe handling and disposal of sharp instruments, safe cleaning and disinfection of the environment and of reusable equipment, and safe laundry and waste management should be a high priority in the health care facility (HCF).

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WHO hand hygiene guidelines for infectious diseases:

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There are three key preventive interventions:

1. The first is meticulous infection control in health care settings. The greatest risk of transmission is not from patients with diagnosed infection but from delayed detection and isolation. Since the early symptoms of EVD — fever, nausea, vomiting, diarrhea, and weakness — are nonspecific and common, patients may expose family caregivers, health care workers, and other patients before the infection is diagnosed.

2. Second, educating and supporting the community to modify long-standing local funeral practices to prevent contact with body fluids of people who have died from EVD, at least temporarily until the outbreak is controlled, will close the second major route of propagation of the virus. This is a culturally sensitive issue that requires culturally appropriate outreach and education.

3. And third, avoiding handling of bush meat (wild animals hunted for sustenance) and contact with bats (which may be the primary reservoir of Ebola virus) can reduce the risk of initial introduction of Ebola virus into humans. Bush meat consumption could be reduced through socioeconomic development that increases access to affordable protein sources. Where bush meat consumption continues, safer slaughter and handling can be encouraged. The potential effect of deforestation and other environmental changes on increasing human–bat contacts needs to be further studied and addressed.

These are straightforward interventions, but Ebola virus is a formidable enemy. If a single case is missed, a single contact becomes ill and isn’t isolated, or a single lapse in infection control or funeral-practice safety occurs, another chain of transmission can start.

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Good outbreak control relies on applying a package of interventions, namely case management, surveillance and contact tracing, a good laboratory service, safe burials and social mobilisation. Community engagement is key to successfully controlling outbreaks. Raising awareness of risk factors for Ebola infection and protective measures that individuals can take is an effective way to reduce human transmission. Risk reduction messaging should focus on several factors:

1. Reducing the risk of wildlife-to-human transmission from contact with infected fruit bats or monkeys/apes and the consumption of their raw meat. Animals should be handled with gloves and other appropriate protective clothing. Animal products (blood and meat) should be thoroughly cooked before consumption.

2. Reducing the risk of human-to-human transmission from direct or close contact with people with Ebola symptoms, particularly with their bodily fluids. Gloves and appropriate personal protective equipment should be worn when taking care of ill patients at home. Regular hand washing is required after visiting patients in hospital, as well as after taking care of patients at home.

3. Outbreak containment measures including prompt and safe burial of the dead, identifying people who may have been in contact with someone infected with Ebola, monitoring the health of contacts for 21 days, the importance of separating the healthy from the sick to prevent further spread, the importance of good hygiene and maintaining a clean environment.

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Infection control:

Recommendations include isolation of hospitalized patients with known or suspected Ebola virus disease; the use of standard, contact, and droplet precautions; and the correct use of appropriate personal protective equipment (PPE). If possible, aerosol-generating procedures should be avoided. However, if they must be performed, patients should be placed in an airborne infection isolation room. The type of PPE used and the careful placement and removal (i.e., donning and doffing) of such equipment are critical to prevent nosocomial transmission of Ebola virus. During the 2014 outbreak in West Africa, several patients have been cared for in the United States. The staff at Emory University used full body suits and powered air purifying respirators (PAPR) to help staff work for extended periods, decrease the physical discomfort of working in multi-component PPE, and avoid difficulties such as fogged face shields. The donning and doffing of PPE was always observed by another staff member. Infection control includes isolation and treatment of patients, contact tracing, and monitoring each contact for 21 days after exposure. It is difficult to isolate and care for patients with EVD, not because the disease is particularly infectious or the virus particularly hardy, but because a single lapse can be devastating. Neither negative air flow nor special respirators are essential; meticulous attention to gown, glove, mask, and eye protection and great care while removing protective equipment are key. Improved hospital infection control throughout the region would prevent a substantial number of EVD and other illnesses. Soap and water or alcohol-based hand sanitizers readily disrupt the envelope of this single-stranded RNA virus, and decontamination with dilute bleach is effective and readily available even in remote settings.

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Preventing Ebola at individual level:

Individuals can take several precautions to protect against Ebola. These steps include:

•avoiding contact with blood and body fluids

•educating themselves on recognizing the disease and preventing it

•practicing careful hand hygiene, including washing hands with soap and water or an alcohol-based hand sanitizer

•refraining from engaging in burial rituals that involve handling the body of a person who died from Ebola

•refraining from handling items a person with Ebola has handled, including clothing, bedding, needles, or medical equipment

Healthcare workers and lab technicians also must practice very careful precautions. This includes isolating people with Ebola and wearing protective gowns, gloves, masks, and eye shields when coming in contact with the infected person or their belongings. Careful protocol and disposal of these protective materials is also vital for infection prevention.  Cleaning crews should use a bleach solution to clean floors and surfaces that may have come in contact with the Ebola virus.

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Is hand hygiene important in ebola?

Hand hygiene is essential and should be performed:

  • before donning gloves and wearing PPE on entry to the isolation room/area;
  • before any clean or aseptic procedures is being performed on a patient;
  • after any exposure risk or actual exposure with a patient’s blood or body fluids;
  • after touching (even potentially) contaminated surfaces, items, or equipment in the patient’s surroundings; and
  • after removal of PPE, upon leaving the isolation area.

It is important to note that neglecting to perform hand hygiene after removing PPE will reduce or negate any benefits of the PPE. Either an alcohol-based hand rub or soap and running water can be used for hand hygiene, applying the correct technique recommended by WHO. It is important to always perform hand hygiene with soap and running water when hands are visibly soiled. Alcohol-based hand rubs should be made available at every point of care (at the entrance and within the isolation rooms and areas); running water, soap, and single use towels should also be always available.

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Preventing ebola in health care setting:

Health-care workers should always take standard precautions when caring for patients, regardless of their presumed diagnosis. These include basic hand hygiene, respiratory hygiene, use of personal protective equipment (to block splashes or other contact with infected materials), safe injection practices and safe burial practices. Health-care workers caring for patients with suspected or confirmed Ebola virus should apply extra infection control measures to prevent contact with the patient’s blood and body fluids and contaminated surfaces or materials such as clothing and bedding. When in close contact (within 1 meter) of patients with EBV, health-care workers should wear face protection (a face shield or a medical mask and goggles), a clean, non-sterile long-sleeved gown, and gloves (sterile gloves for some procedures). Laboratory workers are also at risk. Samples taken from humans and animals for investigation of Ebola infection should be handled by trained staff and processed in suitably equipped laboratories.

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All HCWs (including aides and cleaners) and visitors should be trained/instructed to use personal protective equipment (PPE) and perform hand hygiene. Instructions should be displayed at the entry of the isolation room/area. Personal clothing should not be worn while working in the patient care areas. Scrub or medical suits should be worn.

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Use of the personal protective equipment (PPE):

Experts agreed that it was most important to have PPE that protects the mucosae – mouth, nose and eyes – from contaminated droplets and fluids. Given that hands are known to transmit pathogens to other parts of the body, as well as to other individuals, hand hygiene and gloves are essential, both to protect the health worker and to prevent transmission to others. Face cover, protective foot wear, gowns or coveralls, and head cover were also considered essential to prevent transmission to healthcare workers. Although PPE is the most visible control used to prevent transmission, it is effective only if applied together with other controls including facilities for barrier nursing and work organization, water and sanitation, hand hygiene, and waste management. Benefits derived from PPE depend not only on choice of PPE, but also adherence to protocol on use of the equipment.

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Health worker with protective ebola suit:

Doffing of personal protective equipment (PPE) is more difficult than donning. A buddy system involving a safety officer with a checklist is recommended for both donning and doffing of PPE. Clinicians must be sure that none of their skin is exposed. Doffing is more difficult than donning because the PPE may be contaminated with blood and bodily fluids from the Ebola patient at that point, and even a small exposure can lead to transmission of the disease. There is no room for error when removing PPE.

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Surgical cap:

The cap forms part of a protective hood covering the head and neck. It offers medical workers an added layer of protection, ensuring that they cannot touch any part of their face whilst in the treatment centre.

Goggles:

Goggles, or eye visors, are used to provide cover to the eyes, protecting them from splashes. The goggles are sprayed with an anti-fogging solution before being worn. In the new guidelines, health workers are advised to use a single use disposable full face shield as goggles may not provide complete skin coverage.

Medical mask:

It covers the mouth to protect from sprays of blood or body fluids from patients. When wearing a respirator, the medical worker must tear this outer mask to allow the respirator through.

Respirator:

A respirator such as N95 respirators or powered air purifying respirators is worn to protect the wearer from a patient’s coughs. According to guidelines from the medical charity Medecins Sans Frontieres (MSF), the respirator should be put on second, right after donning the overalls.

Medical Scrubs:

A surgical scrub suit, durable hospital clothing that absorbs liquid and is easily cleaned, is worn as a baselayer underneath the overalls. It is normally tucked into rubber boots to ensure no skin is exposed.

Overalls:

The overalls are placed on top of the scrubs. These suits are similar to hazardous material (hazmat) suits worn in toxic environments. The team member supervising the process should check that the equipment is not damaged.

Double gloves:

A minimum two sets of gloves are required, covering the suit cuff. When putting on the gloves, care must be taken to ensure that no skin is exposed and that they are worn in such a way that any fluid on the sleeve will run off the suit and glove. Medical workers must change gloves between patients, performing thorough hand hygiene before donning a new pair. Heavy duty gloves are used whenever workers need to handle infectious waste.

Apron:

A waterproof apron is placed on top of the overalls as a final layer of protective clothing. A waterproof apron covers the torso to the level of the mid-calf for use if patients have vomiting or diarrhea.

Boots:

Ebola health workers typically wear rubber boots, with the scrubs tucked into the footwear. If boots are unavailable, workers must wear closed, puncture and fluid-resistant shoes.

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The figure below shows health care workers treating ebola patient in Africa wearing PPE:

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A fundamental principle guiding the selection of different types of PPE was the effort to strike a balance between the best possible protection against infection while allowing health workers to provide the best possible care to patients with maximum ease, dexterity, comfort and minimal heat-associated stress.

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Healthcare workers who may be exposed to people with Ebola should follow these steps:

•Wear appropriate PPE.

•Practice proper infection control and sterilization measures.

•Isolate patients with Ebola from other patients.

•Avoid direct contact with the bodies of people who have died from Ebola.

•Notify health officials if you have had direct contact with the blood or body fluids, such as but not limited to, feces, saliva, urine, vomit, and semen of a person who is sick with Ebola. The virus can enter the body through broken skin or unprotected mucous membranes in, for example, the eyes, nose, or mouth.

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Global health security:

In addition to implementing stringent control efforts, we need to accelerate development and deployment of vaccines and antiviral treatment. In addition to acting to stop this outbreak, we should put systems in place to prevent another one. We have three critical advances that will enable further action: increased societal commitment on a global scale; new  technologies that allow us to work better, faster, and cheaper; and successes, ranging from better control of EVD in Africa to the rapid and effective response to H7N9 influenza in China. The current EVD outbreak is a tragic illustration of the importance of improving global health security. The components of this strategy — prevent wherever possible, detect rapidly, and respond effectively — match the framework for stopping the EVD outbreak. EVD is a painful reminder that an outbreak anywhere can be a risk everywhere. The Global Health Security Agenda aims to strengthen public health systems in countries that need it most in order to stop outbreaks before they become emergencies. I believe that stopping outbreaks in a way that leaves behind stronger systems to identify, stop, and prevent future health threats is a moral imperative.

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Prevention of ebola while traveling:

If you travel to or are in an area affected by an Ebola outbreak, make sure to do the following:

•Practice careful hygiene. For example, wash your hands with soap and water or an alcohol-based hand sanitizer and avoid contact with blood and body fluids.

•Do not handle items that may have come in contact with an infected person’s blood or body fluids (such as clothes, bedding, needles, and medical equipment).

•Avoid funeral or burial rituals that require handling the body of someone who has died from Ebola.

•Avoid contact with bats and nonhuman primates or blood, fluids, and raw meat prepared from these animals.

•Avoid hospitals in West Africa where Ebola patients are being treated. The U.S. embassy or consulate is often able to provide advice on facilities.

•After you return, monitor your health for 21 days and seek medical care immediately if you develop symptoms of Ebola.

•Avoid nonessential travel to Liberia, Guinea, and Sierra Leone. 

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Exit screening for Ebola:

Current exit screening of all persons departing affected countries through international airports, seaports and major land crossings is recommended by WHO and can reduce the numbers of people with symptoms from travelling from the countries with high levels of Ebola transmission. While screening upon entry into non-affected countries may provide an opportunity to further increase public awareness about Ebola, such screening also can require significant resources including staff, facilities and systems to care for ill travelers who might be suspected of having Ebola.

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Is there any evidence that screening travelers arriving at international airports is an effective way of identifying those with serious infections?

The data from Canada, which introduced airport screening during the SARS (severe acute respiratory syndrome) epidemic, are not encouraging. A total of 677 494 people arriving in Canada returned completed questionnaires, of whom 2478 answered “yes” to one or more question. A specially trained nurse referred each of these for in-depth questioning and temperature measurement; none of them had SARS. Thermal scanners were installed at six major airports. Of the 467 870 people screened, 95 were referred to a nurse for further assessment. None of them was confirmed to have a raised temperature. The cost of this unsuccessful program was $15millon.  Why was this measure so ineffective, and could it work now? During the SARS epidemic a simple model was used to assess the fraction of cases that could be detected by entrance screening. Assuming that people with symptoms are not allowed to board, entrance screening can only pick up those who develop symptoms while travelling. The longer the incubation period in relation to the flight duration, the lower the chance that this will happen, and the lower the yield from entrance screening. Updating the model using data on Ebola (incubation time 9.1±7.3 days; direct flight from Freetown to London 6.42 hours), researchers estimate that, if everyone with symptoms was denied boarding, about 7 out of 100 people infected with Ebola travelling to the UK would have symptoms on arrival and hence be detectable by entrance screening (95% confidence interval 3 to 13). The other 93% would enter the UK unimpeded. If passengers arriving via Paris or Brussels (journey time about 13 hours) were not screened in transit, entrance screening in the UK could detect up to 13% of infected people (95% CI 7% to 21%). The majority would still enter the UK before developing symptoms. Only if patients are allowed to fly irrespective of symptoms would entrance screening be able to detect a substantial fraction of cases (43% if there is no direct flight, 95% CI 34% to 53%). People who know they are at risk and develop symptoms will want to seek care immediately, as they will fear for their lives. The priority should be to provide information to all those who may be at risk on how and where to seek care. This would be as effective as screening at a fraction of the cost. Adopting the policy of “enhanced screening” gives a false sense of reassurance. This simple calculations show that an entrance screening policy will have no meaningful effect on the risk of importing Ebola into the UK. Better use of the UK’s resources would be to immediately scale-up our presence in West Africa—building new treatment centers at a rate that outstrips the epidemic, thereby averting a looming humanitarian crisis of frightening proportions. In so doing, we would not only help the people of these affected countries but also reduce the risk of importation to the UK.

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These scientific studies show that airport Ebola screenings are largely ineffective:

The Department of Homeland Security imposed new travel restrictions for anyone arriving from Liberia, Sierra Leone and Guinea, requiring those passengers to come through one of five major U.S. airports in Atlanta, Chicago, New Jersey, New York and Virginia. Those travelers now have to submit to temperature checks and questioning. But scientific studies published by the National Institutes of Health have shown that similar protocols were largely ineffective during an outbreak of Swine Flu in 2009. A study of screenings at Australia’s Sydney Airport during the Swine Flu pandemic found that fever was detected in 5,845 passengers during the roughly two-month period covered by the analysis. Only three of those individuals ended up having the virus, which is known in the scientific community as H1N1. Researchers determined that 45 patients who acquired the illness overseas would have “probably passed through the airport” during the roughly two-month period covered in the study. That means the screeners likely missed the vast majority of individuals who arrived at the facility with Swine Flu, despite grabbing thousands of travelers who showed signs of fever. The Department of Homeland Security requires temperature checks of air passengers arriving from Ebola-ravaged nations, but studies have determined that the method is largely ineffective at detecting individuals who are infected. The report said only 0.5 percent of H1N1 cases in New South Wales, Australia, were detected at the airport, whereas 76 percent were identified in emergency rooms and at general-practice medical centers. Ultimately, researchers concluded that airport temperature checks were “ineffective in detecting cases of H1N1 flu.” Similarly, a study of fever screening in Japan during the pandemic determined that “reliance on fever alone is unlikely to be feasible as an entry screening measure.” Indeed, temperature checks didn’t work for Liberian Thomas Eric Duncan, who died from Ebola this month after arriving in Dallas. Duncan did not have a fever when he landed in Texas on Sept. 28, 2014; and he said he had not been in contact with Ebola patients in his native country, although that later proved to be a false statement. The Australian study concluded that officials should consider “more effective interventions, such as contact tracing in the community.” The findings are in line with what federal officials have said: That the best way to prevent Ebola from spreading is to identify everyone whom infected individuals have contacted.

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WHO: Air travel is low-risk for Ebola transmission:

The World Health Organization (WHO) reiterated its position that the risk of transmission of Ebola virus disease during air travel remains low. Unlike infections such as influenza or tuberculosis, Ebola is not airborne. It can only be transmitted by direct contact with the body fluids of a person who is sick with the disease. On the small chance that someone on the plane is sick with Ebola, the likelihood of other passengers and crew having contact with their body fluids is even smaller. Usually when someone is sick with Ebola, they are so unwell that they cannot travel. WHO is therefore advising against travel bans to and from affected countries. 

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Safe burial:

Dead Bodies still contain high levels of the Ebola virus. At least 20% of new infections occur during burials, WHO says. If a person with Ebola disease dies, direct contact with the body should be avoided. There is risk of transmission in the health facility when ebola patient dies because the bodies and body fluids of deceased patients remain contagious for several days after death. Traditional practices regarding patient care and burial rituals often involve high risk conducts, such as washing and preparation of the body for exposure for several days, during which family and friends pay tribute by stroking or hugging the deceased. Safe burial process involves observing rituals differently, such as “dry ablution” Volunteers with full protective clothing are trained to handle and disinfect bodies. Family and community members are at risk if burial practices involve touching and washing the body. Burial should take place as soon as possible after the body is prepared in the health facility.  Health facility staff should prepare the body safely. Be aware of the family’s cultural practices and religious beliefs. Help the family understand why some practices cannot be done because they place the family or others at risk for exposure. Certain burial rituals, which may have included making various direct contacts with a dead body, require reformulation such that they consistently maintain a proper protective barrier between the dead body and the living. Social anthropologists may help find alternatives to traditional rules for burials.

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The grave should be at least 2 meters deep. Explain to the family that viewing the body is not possible. Help them to understand the reason for limiting the burial ceremony to family only. Disinfect the vehicle after transporting the Body.

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Cremation vs. Burial vis-à-vis Ebola:

Even as Liberians fall ill and die of Ebola, many beds in treatment centers are empty because of the government’s order that the bodies of all suspected Ebola victims in the capital be cremated. Cremation violates values and cultural practices in the western African country. The order has so disturbed people that the sick are often kept at home and, if they die, are being secretly buried, increasing the risk of more infections. Burial, especially in a body bag or coffin, is just as effective at ending transmission as cremation. The danger with Ebola is in handling the corpse of a person who died recently. The world has never seen a serious, grave and complex crisis of this nature where people are dying every day with unsafe burial practices. Once it is buried, the danger is largely over, unless someone digs it up quickly. The virus attacks living cells and does not go on reproducing indefinitely. Once a body is buried, bacteria, which are able to digest dead flesh, quickly overwhelm the corpse.   

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Ebola vaccine:

Many Ebola vaccine candidates had been developed in the decade prior to 2014, but as of October 2014, none had yet been approved by the United States Food and Drug Administration (FDA) for clinical use in humans. Several promising vaccine candidates have been shown to protect nonhuman primates (usually macaques) against lethal infection. These include replication-deficient adenovirus vectors, replication-competent vesicular stomatitis (VSV) and human parainfluenza (HPIV-3) vectors, and virus-like particle preparations. Conventional trials to study efficacy by exposure of humans to the pathogen after immunization are obviously not feasible in this case. For such situations, the FDA has established the “animal rule” allowing licensure to be approved on the basis of animal model studies that replicate human disease, combined with evidence of safety and a potentially potent immune response (antibodies in the blood) from humans given the vaccine. At the 8th Vaccine and ISV Conference in Philadelphia on 27−28 October 2014, Novavax Inc. reported the development in a “few weeks” of a glycoprotein (GP) nanoparticle Ebola virus (EBOV GP) vaccine using their proprietary recombinant technology. A recombinant protein is a protein that whose code is carried by recombinant DNA. The vaccine is based on the newly published genetic sequence of the 2014 Guinea Ebola strain that is responsible for the current Ebola disease epidemic in West Africa. In “preclinical models”, a useful immune response was induced, and was found to be enhanced ten to a hundred-fold by the company’s “Matrix-M” immunologic adjuvant. A study of the response of non-human primate to the vaccine had been initiated. Attractive features of such a vaccine could be no need for frozen storage, and the possibility of rapid scaling to manufacture of large dose quantities. The Health Ministry of Russia also claims to have developed a vaccine called Triazoverin, which is said to be effective against both Ebola and Marburg filoviruses, and might be available for clinical trials in West Africa as soon as the start of 2015. Phase I clinical trials involve the administration of the vaccine to healthy human subjects to evaluate the immune response, identify any side effects and determine the appropriate dosage.

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Two experimental vaccines against Ebola are currently being tested to see whether they are safe to use in people, and health officials have said that millions of doses could be available by the end of next year.

But how do the vaccines work?

Both vaccines essentially consist of a harmless virus that has been “spiked” with a protein from the Ebola virus. If a person is given the vaccine, the body thinks it’s being infected with this rather innocuous virus, [and] part of the virus happens to be the Ebola protein. This prompts an immune response, and the body develops antibodies against the Ebola protein. Ideally, if a vaccinated person were later exposed to the real Ebola virus, these antibodies would be ready to fight off the infection before it could take hold.

1. First vaccine, which began safety testing this summer, is being developed by the National Institute of Allergy and Infectious Diseases (NIAID) and GlaxoSmithKline. It consists of a type of cold virus called an adenovirus that affects chimpanzees and has genetic material from two strains of Ebola: Zaire Ebola (which is causing the current outbreak in West Africa) and Sudan Ebola, according to NIAID. The engineered adenovirus can’t replicate in the human body. It’s used to deliver the Ebola gene to a person’s cells, which, in turn, produce a single Ebola protein. If the vaccine works as it should, this protein will cause an immune response. But in any case, it cannot cause Ebola virus disease, according to the NIAID. In September 2014, two Phase I clinical trials began for the vaccine cAd3-EBO Z, which is based on an attenuated version of a chimpanzee adenovirus (cAd3) that has been genetically altered so that it is unable to replicate in humans. For the trial designated VRC 20, 20 volunteers were recruited by the NIAID in Bethesda, Maryland, while three dose-specific groups of 20 volunteers each were recruited for trial EBL01 by University of Oxford, U.K.

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The first test of an Ebola vaccine in people shows it’s safe and appears to be working as designed. A look at the first 20 people injected with the vaccine, which has been shown to protect monkeys from Ebola, shows no dangerous side effects. And it seems to be producing an immune response that would be expected to protect them from infection. This response is very comparable to the level of the response that actually protected the animals. There’s no ethical way to vaccinate people and then expose them to Ebola on purpose, of course, so the trial is designed to see if the vaccine is safe and if the immune system responds in a way that would be expected to protect them. It did, the NIAID researchers report in the New England Journal of Medicine. They especially looked at immune cells called CD8 T-cells. From previous studies in non-human primates it is known that CD8 T-cells played a crucial role in protecting animals that had been vaccinated with this NIAID/GSK vaccine and then exposed to otherwise lethal amounts of Ebola virus.  The size and quality of the CD8 T-cell response researchers saw in this trial are similar to that observed in non-human primates vaccinated with the candidate vaccine. The real test will come if and when the vaccine is used to protect doctors, nurses and other health care workers who treat actual Ebola patients.

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2. The second vaccine, called VSV-ZEBOV, consists of a virus that mainly infects animals (including rodents, cattle, swine and horses), called the vesicular stomatitis virus (VSV). In the vaccine, one gene of VSV has been replaced with the gene for the outer protein of the Zaire Ebola virus, according to the National Institutes of Health. Safety testing of the VSV-ZEBOV vaccine began recently at the NIH. The study involves 39 healthy adults who will be given either a low dose of the vaccine, a higher dose of the vaccine or a placebo. VSV-ZEBOV was developed by the Public Health Agency of Canada and was licensed to the biopharmaceutical company NewLink Genetics Corp. On 20 October, the Public Health Agency of Canada began air shipment of 800 doses of the VSV-EBOV vaccine to the WHO in Geneva. The WHO has recruited 250 volunteers ready to begin Phase I clinical trials in four locations: Switzerland, Germany, Gabon and Kenya. If the results of this and following trials show that the earlier results in nonhuman primates are replicable in humans, this vaccine could be deployed in areas such as West Africa and would be expected to require only a single dose. Also, its efficacy in protecting nonhuman primates when administered even after viral exposure has occurred may help protect health-care workers after a suspected exposure. The second round of testing is known as Phase 2 trials, which will further test vaccines’ safety, and also look at its effectiveness. If the vaccines are effective, pharmaceutical companies could manufacture several hundred thousand doses in the first half of 2015, and millions of doses by the end of that year, WHO said. The pharmaceutical multinational Merck announced that it will pay $50 million for commercial rights to manufacture and develop the vaccine, invented at the federal government’s National Microbiological Laboratory in Winnipeg. Europe and America have belatedly come to realize that Ebola is not just an African disease. What is odd, however, is that the money goes not to the Canadian publicly owned entity that developed the vaccine but to a small U.S. middleman that appears to have done little.

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Experimental Ebola vaccine protects monkeys for 10 months: a 2014 study:

An experimental Ebola vaccine similar to one being developed by GlaxoSmithKline is effective for at least five weeks in lab monkeys but requires boosting with an additional vaccine to extend its protection to 10 months, according to a study published. The findings offer an early hint of which, if any, of the Ebola vaccines in development will prove effective, and in what form. Johnson & Johnson and NewLink Genetics are also among the firms accelerating their efforts to provide Ebola vaccines and treatments as the worst known outbreak of the virus ravages West Africa, killing more than 6,000 people. The results of the new study suggest, for instance, that a GSK vaccine now being tested on healthy volunteers will protect against Ebola infection in the short term, but may have to be augmented for long-term protection. The study, published in Nature Medicine, is the first to report that a vaccine regimen produced “durable immunity” against Ebola, protecting four out of four monkeys for 10 months. The vaccine uses a chimp adenovirus, closely related to a human version that causes upper respiratory tract infections, into which scientists spliced an Ebola gene. The adenovirus infects cells in a vaccinated animal, causing them to take up the gene and produce Ebola proteins. That primes the immune system to attack the proteins of Ebola viruses when an infection occurs. The vaccine in the study is similar to competing vaccines being developed by GSK, which began human safety trials recently, and by J&J, which aims to start safety trials in early 2015. A third experimental Ebola vaccine uses a different delivery system, a livestock pathogen called vesicular stomatitis virus (VSV). A version developed by the Public Health Agency of Canada and licensed to NewLink Genetics is scheduled to be tested for safety in healthy volunteers this fall. Profectus BioSciences is also developing a VSV vaccine.   

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Nasal spray vaccine has potential for long-lasting protection from Ebola virus: a 2014 study:

A nasal vaccine in development by researchers at The University of Texas at Austin has been shown to provide long-term protection for non-human primates against the deadly Ebola virus. Results from a small pre-clinical study represent the only proof to date that a single dose of a non-injectable vaccine platform for Ebola is long-lasting, which could have significant global implications in controlling future outbreaks. This work is being presented at the 2014 American Association of Pharmaceutical Scientists (AAPS) Annual Meeting and Exposition, the world’s largest pharmaceutical sciences meeting, in San Diego. Maria Croyle, a professor in the College of Pharmacy at The University of Texas at Austin, Kristina Jonsson-Schmunk, a graduate student in pharmacy, and colleagues at the university developed a nasal formulation that improved survival of immunized non-human primates from 67 percent (2 out of 3) to 100 percent (3 out of 3) after challenge with 1,000 plaque forming units of Ebola Zaire 150 days after immunization. This is important since only 50 percent of the primates given the vaccine by the standard route (intramuscular injection) survived challenge. The main advantage of this vaccine platform over the others in clinical testing is the long-lasting protection after a single intranasal dose. This is important since the longevity of other vaccines for Ebola that are currently being evaluated is not fully understood. Moreover, the nasal spray immunization method is more attractive than a needle vaccine given the costs associated with syringe distribution and safety.

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Ebola bioterrorism:

Ebolavirus is classified as a biosafety level 4 agent, as well as a Category A bioterrorism agent by the Centers for Disease Control and Prevention. It has the potential to be weaponized for use in biological warfare, and was investigated by Biopreparat for such use, but might be difficult to prepare as a weapon of mass destruction because the virus becomes ineffective quickly in open air. Fake emails pretending to be Ebola information from the WHO or the Mexican Government have in 2014 been misused to spread computer malware. In the case of a bioterror attack employing Ebola virus, patients with no possible exposure to an Ebola patient would develop the same disease and would be seen in doctors’ offices or hospital emergency rooms. The appearance of multiple patients with a similar, rapidly progressive illness would be especially suggestive of bioterrorism. Any clinician suspecting that such an event is unfolding should report it promptly to local and state health authorities. These high-priority bioterrorism agents are defined by their ability to be easily disseminated or transmitted, their high mortality rates or capacity to generate major public health impacts, their potential for causing mass panic and social disruption, and the requirement for government action to ensure public preparedness. Moreover, there is a paucity of FDA-approved therapeutic options for the bacterial agents and no approved therapeutics for the viral pathogens. The threat of these biological agents is exacerbated by the incessant risk that these agents could become resistant to current therapeutic agents by conventional as well as genetic means. In addition, there is no effective way to address the threats of emerging, engineered, or advanced pathogens in a timely manner, as the current drug discovery and development paradigm takes up to 20 years for introduction of a new, approved drug into the market. Thus, the current de novo drug discovery and development paradigm is ineffective for dealing with biological threat agents.

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Economic impact of ebola:

The economic impact of the Ebola epidemic could reach $32.6 billion by the end of next year if the disease ravaging Guinea, Liberia and Sierra Leone spreads to neighboring countries in West Africa. The World Bank’s assessment said the economic impact of Ebola is already serious in the three countries and could be catastrophic if it becomes a more regional health crisis. However, if the spread of the disease is contained within about the next six months, the economic impact would be limited to about $3.8 billion in the region, the World Bank estimated.  Analysts at Barclays are warning that the continued spread of the deadly Ebola virus beyond the confines of West Africa could have a “significant” impact on the financial markets. If consumers and businesses retrench by reducing flights on airplanes, changing vacation plans, or altering business connections in a globally interdependent world, G.D.P. growth rates will fall farther. The price of cocoa beans spiked more than 10% last month due to fears that Ebola could spread to the Ivory Coast, the world’s largest producer of chocolate’s main ingredient. Ivory Coast shares a border with Guinea and Liberia, two of the three countries (the third being Sierra Leone) that are most affected by the virus. Not only is this West African region ground zero for Ebola, but it’s also home of 70% of the world’s cocoa supply.  Airline stocks are already down about 7% due to fears of a global health crisis. Meanwhile, the World Travel and Tourism Council that represents airlines, hotels, and other travel companies is reporting a 30% plunge in early bookings to Africa, where the disease is deeply entrenched. Nobody has yet to calculate the fallout of the Ebola virus on the health care system. But what’s clear is that the money being poured into the fight against the disease (training, testing, treatment, waste disposal) — not to mention the money lost as hospital beds sit unused in isolation areas — will certainly affect the industry.

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The virus is claiming new victims—African tourism and football:

Safari tents remain zipped, hotel pools are empty, game guides idle among lions and elephants. Tour operators across Africa are reporting the biggest drop in business in living memory. A specialist travel agency, SafariBookings.com, says a survey of 500 operators in September 2014 showed a fall in bookings of between 20% and 70%. Since then the trend has accelerated, especially in Botswana, Kenya, South Africa and Tanzania. Several American and European agents have stopped offering African tours for the time being. The reason is the outbreak of the Ebola virus in West Africa, which has killed more than 6,000 people. The epidemic is taking place far from the big safari destinations in eastern and southern Africa—as far or farther than the homes of many European tourists. There are more air links from West Africa to Europe than to the rest of the continent, whose airlines have in any case largely suspended flights. Moreover Ebola is hardly the biggest killer disease in Africa (AIDS and malaria are bigger). Yet, in the mind of many visitors, all of Africa is a single country. One despairing tour operator calls it an “epidemic of ignorance”. Directly and indirectly, tourism accounts for almost 10% of sub-Saharan Africa’s GDP and pays the salaries of millions of people. The industry is worth about $170 billion a year. In 2013 more than 36 million people visited Africa, a figure that had been growing by 6% per year. Now many safari lodges are closer to extinction than the animals that surround them. Redundant workers might eventually turn to poaching. Fear of Ebola is growing among Africans, too. Morocco said it would not host the African Cup of Nations, the premier football event on the continent, due to start on January 17th 2015. Morocco had sought a year-long postponement, citing the danger of the virus spreading at large gatherings. Miffed, the Confederation of African Football barred Morocco, which has not had a single Ebola case, from the tournament. The three worst-affected countries—Liberia, Sierra Leone and Guinea—have not, or not yet qualified. Organisers are scrambling to find an alternative host. African football may be the next victim of Ebola.  

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Myths of ebola:

Myth: You will not get Ebola if you have a healthy immune system.

Fact: The state of your immune system does not dictate if you can or cannot get infected.  A healthy immune system is definitely very important to prevent diseases, but the Ebola virus has become so virulent that it can infect people with even the most robust immune system. Since the virus interferes with and avoids immune system and also uses person’s immune response to spread, the health of one’s immune system does not stop this virus from infecting a person. Nonetheless, early and effective immune response is most important factor of ebola survival. Therefore people with immunodeficiency due to any cause are unlikely to survive ebola but more studies are required to confirm this hypothesis. There is no study that compares ebola fatality between normal people and HIV infected people.  

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Myth: A patient presenting with symptoms of Ebola and travel to Liberia within the past 21 days can be safely removed from isolation after a negative serum test.

Fact:  An initially negative reverse transcription polymerase chain reaction (RT-PCR) test result for Ebola virus does not rule out Ebola virus infection. If an initial test is negative in a person under investigation for Ebola, repeat testing is indicated in 72 hours. It takes about three days once a person starts showing symptoms for the Ebola virus to accurately show up on tests. In other words, it is possible for an Ebola test to be negative when the person actually does have Ebola. This is critical, as many of those admitting themselves to hospitals with possible Ebola symptoms are doing so the day they start exhibiting them, or possibly the day after at the latest. Unless medical personnel across the world fully understand this, many Ebola patients will be discharged with false negatives, only to spread the disease to their friends and family. 

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Myth: Ebola is not transmissible before a person is symptomatic, so there is no scientific basis for quarantine of contacts.

Fact:  Quarantine is not a strategy to prevent spread of diseases that may be transmissible prior to the onset of symptoms. Quarantine separates and restricts the movement of people who were exposed to a contagious disease to see if they become sick. If they indeed become sick, isolate them, treat them and trace all their contacts. This is especially true of ebola that carries 50 to 70 % mortality with the best available treatment. Contact tracing is most important for ebola as even one missed contact can keep the outbreak going. Also contact tracing finds new cases quickly so that they can be isolated to prevent spread of disease. But there is a downside to overdoing it. Quarantine may have had limited effectiveness when widely used in Canada and Asia in a 2003 SARS outbreak. With several hundred thousand individuals placed in quarantine and relatively few of them later developing SARS, local public health officials later acknowledged that the response was disproportionate to the threat. Thus, the paradox of quarantine and other social distancing measures is that they may be effective in fighting a disease outbreak, but they can be applied too broadly, resulting in a variety of social harms, including economic disruption, personal isolation, and even violence.  There are silent ebola infections where quarantine logic fails but they are not contagious anyway.  Of course the issue is how you define quarantine. The word quarantine comes from the Italian quaranti giorni, meaning ’40 days’. When bubonic plague swept through Europe in the 14th century, the government of Venice required ships to anchor away from the city for 40 days before they could unload passengers or cargo. The authorities thought 40 days would be enough time for any disease to be identified and either treated or pass through its normal course. All ships under quarantine had to fly a yellow flag.

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Myth: Travel bans would keep Ebola from spreading.

Fact: In the past, some nations have banned flights from other countries in hopes of blocking the entry of viruses, including SARS and H1N1 (swine flu). None of the bans were effective, and the viruses spread regardless of government measures took to keep them out. The key to stopping Ebola worldwide is stopping it in Africa. Unfortunately, restricting the movement of people through travel bans isn’t likely to stop Ebola spread. In fact, it could have the opposite of the desire effect. To completely seal off and don’t let planes in or out of the West African countries involved, then you could paradoxically make things much worse in the sense that you can’t get supplies in, you can’t get help in, you can’t get the kinds of things in there that we need to contain the epidemic. For aid workers, it is already difficult to go to affected countries. Stigma makes it even harder for those who want to help. Without human resources, we cannot run our operations; and if we cannot run our operations, we cannot stop Ebola. Travel ban might actually make things worse, because it could encourage people to lie about their travel to West Africa. And without that crucial information, people infected with Ebola could slip into other countries without the health authorities being able to track and monitor them for symptoms and it is even harder to track them systematically.   

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Myth: Ebola is a highly contagious disease.

Fact: Compared with other diseases such as tuberculosis, smallpox, measles, chicken pox, influenza, SARS and polio, Ebola is not particularly contagious. Infection requires a lot of contact with the virus, such as coming in contact with bodily fluids (blood, vomit, saliva, feces, urine, sweat, etc.) Ebola is not easily spread; for example, it does not spread by casual contact — no household contacts of the first Ebola patient in the U.S. Liberian Thomas Eric Duncan contracted the disease. It is only when the patient is critically ill with a high viral load in body fluids that he becomes contagious as ebola is spread via contact with blood and other bodily fluids. That is why nurse caring for Duncan got infected. This is the rationale for the high degree of precaution, including monitored donning and doffing of personal protective equipment (PPE), when caring for such a patient. There is no evidence for airborne transmission of Ebola. While some experts have suggested that Ebola could mutate to become airborne, scientific consensus is that this would be extremely unlikely. Also, ebola is a fragile virus outside host and killed easily by common household disinfectants. 

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Myth: A patient presenting with fever and travel to West Africa within the past 21 days is Ebola.

Fact:  In travelers from sub-Saharan Africa, diseases with short incubation periods, such as malaria and typhoid fever, also present with fever and must be considered in the differential diagnosis of Ebola. Malaria is much more common than Ebola. However, a positive malaria test does not rule out Ebola, as malaria is extremely prevalent in this population and the diseases could coexist.

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Myth:  Cardiopulmonary resuscitation is indicated for Ebola patients in cardiac arrest.

Fact: Prevailing expert opinion is that if a patient has loss of cardiac output due to multisystem organ failure from septic shock in the setting of Ebola, resuscitative efforts would be futile and also extremely risky for the clinicians performing the procedures. Some Ebola centers have requested that patients sign a do-not-resuscitate (DNR) order. Self-sacrifice by health care professionals that results in no offsetting clinical benefits for the patient is not required by the professional virtue of self-sacrifice. However, health workers might apply the argument even to people who show no signs of Ebola but might have come in contact with an Ebola patient.  The efficacy of other invasive procedures such as intubation and dialysis are still being debated, with anecdotal reports arising in the Western world of good outcomes after their application. 

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Myth: Silent ebola infection means ebola survivor.

Fact: Silent ebola infection means person infected with ebola virus but did not develop ebola virus disease and therefore person is asymptomatic and non-contagious. Ebola survivor is a person who suffered ebola virus disease with all symptoms & signs, and was contagious during illness but managed to survive by eliminating ebola infection. Ebola survivor may harbor ebola virus in eye, gonads and breast for few months even after eliminating virus in blood.

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My novel theory of deadliness of infectious diseases:

Deadliness of any infectious disease = infectivity X transmissibility X mortality X susceptible population

In other words, the deadliness of any infectious disease is directly proportional to infectivity (infectiousness), transmissibility (contagiousness), mortality (case fatality rate with treatment) and magnitude of susceptible population. Infectivity means infectious dose in number of organism required for infecting host (N) and transmissibility is basic reproduction number (R0). Lesser the number of organisms (N) required for infection, greater is infectivity.

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Let us compare Deadly Index of Influenza A and Ebola:

Influenza A (common flu) has CFR of 0.05 %

It has R0 = 3

Infectious dose of approximately 790 organisms via the nasopharyngeal route

Deadly Index = 0.00018987 X susceptible population

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Zaire Ebola of 2014 has calculated CFR 54 % (WHO estimated 70 %)

It has R0 = 2

Infectious dose of 10 organisms by contact transmission

Deadly Index = 10.8 X susceptible population

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If susceptible population for influenza A and Ebola is same, Ebola is 57,000 times (10.8/0.00018987) deadlier than influenza A. The only variable in our hand is susceptible population. So to reduce mortality, we have to reduce susceptible population by reducing transmission (isolation, sanitation, barrier nursing, and use of PPE) including quarantine all contacts, and vaccinating the world. Today we have no vaccine, so reducing transmission is the only option. Quarantine of all ebola contact for 21 days is mandatory. Airport exit screening in Ebola infected West African nations along with airport entry screening at all international airports worldwide is mandatory. In order to stop the epidemic, the rate of transmission would have to be cut in half. In order to reduce Ebola deadliness to make it equivalent to influenza deadliness, the ebola transmission rate ought to be reduced by 1/57,000 times of the present rate which is impossible. Of course, giving better treatment would also reduce Ebola deadliness but today we have no effective treatment and experimental ebola therapies like ZMapp, BCX4430 and TKM-Ebola are very expensive and beyond reach of ordinary citizen of third world.  

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The moral of the story: 

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1. Ebola virus disease (EVD) or simply Ebola, previously known as Ebola hemorrhagic fever (EHF) is an acute, rare and severe infection caused by one of the ebola virus strains being transmitted from animal to human and subsequently human to human. Unlike HIV, ebola virus does not persist in infected person, either you die or survive without virus.

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2. Migratory fruit bats are natural reservoir of ebola viruses. Bats carry silent ebola infections and transmit ebola to other animals and humans. Bats supported replication and circulation of high titers of virus without becoming ill. A perfect parasite is able to replicate and not kill its host which is an evolutionary advantage to remain endemic in its host species population. The ebola virus is the perfect parasite for a bat. Humans, apes and other mammals are incidental/accidental hosts. Human infection is a case of mistaken location, a zoonotic jump from wild animal to human being and human lethality in not in favor of survival of ebola virus species.

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3. Phylogenetic and sequencing evidence suggests that ebola viruses are ancient (at least 23 million years old) and ebola virus-like elements are integrated into genome of bats, rodents, shrews, tenrecs and marsupials. No wonder bats are natural reservoir of ebola virus.  

4. Mutations are a way of life for an RNA virus. Scientists have found the origins of the current Ebola 2014 outbreak by tracking its mutations and the current viral strains come from a related strain that left Central Africa within the past ten years. The Ebola-2014 virus’s mutation rate of 2.0 x 10³ subs/site/year is nearly identical to Influenza A’s mutation rate of 1.8 x 10³ subs/site/year. This means Ebola-2014 is mutating as fast as seasonal flu. The Influenza’s high mutation rate allows the virus to generate ‘escape mutants’ which are no longer recognized by human immune systems and therefore we need influenza vaccine every year to immunize us against mutant virus. The high mutation rate of Ebola-2014 may confer survival fitness and more adaptability to human host at both the intra-host and inter-host levels. Ebola acquires genetic diversity as it infects more people. The growing number of new ebola viral lineages will undergo natural selection for some ‘optimum’ balance of virulence, infectivity, tissue tropism, immune suppression, and other parameters which maximize the reproductive fitness of the ebola virus in humans. Longer the 2014 ebola outbreak lasts, greater the reproductive fitness of ebola and lesser the efficacy of treatment/vaccine. Ebola strain currently in circulation appears to be far more virulent and contagious than previous strains. Viral loads observed in 2014 outbreak exceed what has been observed during previous outbreaks. More of the virus is infecting patients, and it appears to be advancing and spreading more rapidly than usual. With increasing numbers of humans being infected, Ebola virus variants (due to mutations) could be selected which are better adapted for human-to-human transmission. The repeated passage of Ebola-2014 through humans is exerting selection pressure on the Ebola-2014 virus to adapt to our species (instead of fruit bats) which may allow the Ebola-2014 virus to become more transmissible and less virulent as the months go on to make ebola endemic, particularly in the absence of effective control interventions.

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 5. Ebola outbreak of 2014 is more than six times the sum total of all previous outbreaks combined. One disturbing feature of the current epidemic is that so many health workers have lost their lives while caring for the sick or trying to spread public-health messages about Ebola. Ebola epidemic of 2014 is unlikely to reach the numbers of HIV pandemic because Ebola outbreaks tend to “burn themselves out” as Ebola virus disease is rapidly fatal. 

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6. The reported cases of ebola in 2014 outbreak are tip of the iceberg. There is widespread under-reporting of new cases in Africa and actual cases are 2.5 times higher and are roughly doubling every month. There are numerous reports of symptomatic persons evading diagnosis and treatment, of laboratory diagnoses that have not been included in national databases, and of persons with suspected Ebola virus disease who were buried without a diagnosis having been made.  

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7. Ebola epidemic 2014 has served as a reminder of just how slow and poorly coordinated the responses to outbreaks are. It took three months for health officials to identify Ebola as the cause of the epidemic, another five months to declare a public health emergency, and two more months to mount a humanitarian response. And the best way to stop an outbreak is to contain it early. Ebola has reached the point where it could establish itself as an endemic infection because of a highly inadequate and late response. 

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8. Ebola is a disease of poverty, weak health care system, nonexistent hospital infection control, poor personal hygiene, illiteracy, fear, ignorance, superstition, and cultural practice of touching dead body. Guinea, Sierra Leone, and Liberia have all these to account for 2014 ebola outbreak but even densely populated India has all these factors. I am afraid if Ebola spreads in India, it would be killing million people.    

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9. Ebola epidemic of 2014 in West Africa caused collapse of health care system, economic slowdown and widespread food insecurity in affected countries. Ebola has also taken the lives of health care workers in places where the ratio of doctors & nurses per population is abysmally low. All these caused even more deaths due to malaria, tuberculosis, HIV, diarrhea and chest infections.

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10. The key to stopping Ebola worldwide is stopping it in Africa. Tracking the movements and contacts of potential Ebola cases, and getting aid & resources to West Africa to stop Ebola at the source are the best methods of stopping ebola in Africa.

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11. 2014 Ebola outbreak must be stopped in a way that leaves behind stronger systems to prevent, identify and stop future Ebola outbreaks.  

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12. Ebola is transmitted from infected human only during symptomatic phase and not in incubation period, and transmission is maximum in advanced stage of disease when patient is gravely ill as his body fluids would contain maximum number of viruses at that time. The viral load isn’t static. It increases as the disease progresses. That is why a person who is infected but without symptoms (incubation period) will not spread the virus initially as there is very little virus present in the blood, and it is not yet present in other bodily fluids. Ebola get progressively more contagious as the disease worsens. Ebola transmission occurs when the viral load in bodily fluids is high, on the order of millions of virions per microliter. Dying patient has highest number of virus in body fluid and so dead body has maximum number of virus in body fluids and thereby highly contagious. At least 20% of new infections occur during burials. Therefore safe burial practice of ebola victims is of paramount importance.

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13. Ebola is spread through direct contact, through broken skin or through eyes, nose, or mouth; via blood and body fluids of a person who is sick with Ebola, or objects, such as needles, that have been contaminated with the blood or body fluids of a person sick with Ebola. Direct contact through broken skin or mucous membranes is the key. Soap, gloves, isolating patients, not reusing needles/syringes and quarantining the contacts of those who are ill should be very easy to contain Ebola but in practice, this is a much tougher proposition in developing countries.

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14. Researchers have concluded that airport temperature checks are ineffective in detecting cases of infectious diseases including influenza or ebola. Also the risk of transmission of Ebola during air travel remains low as Ebola is not airborne unlike infections such as influenza or tuberculosis.

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15. Ebola virus infection can be transmitted if an infected person coughs, sneezes or vomits at close range. In this case large wet droplets landing on the mucous membranes of susceptible host can initiate infection. Although these droplets are traveling through the air, this mode of transmission is considered a form of contact transmission (droplet contact transmission), not airborne transmission. Any droplets of fluid from cough or sneeze that could contain ebola can travel only about 3 feet before they fall to the ground because of gravity as there droplets are large, wet and heavy; and therefore not considered airborne. Airborne transmission means small light dried airborne particles containing ebola viruses that remain suspended in air for several hours even after ebola patient has left the room and that travel hundreds of meter by wind and can transmit infection to another human. Ebola is an ‘enveloped’ virus and its lipid membrane is vulnerable to light, heat and dryness. Such virus is highly unlikely to survive airborne. No human virus has ever changed its mode of transmission. Ebola virus is RNA virus that constantly mutate while replicating but jump from contact transmission to airborne transmission is highly improbable though not impossible. However any action which can be taken to “reduce risk” of Ebola exposure should not wait until a “scientific certainty” develops especially for health care workers. Today there is no scientific certainty that ebola is airborne or not, and therefore better safe than sorry. All ebola healthcare workers right from doctors, nurses and laboratory technicians must wear personal protective equipment (PPE) equipped to protect against airborne transmission while treating ebola patients in hospital. If you are not wearing PPE, then you should stand at least six feet away from an Ebola patient, as a precaution against flying wet droplets.     

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16. Even though infectiousness is synonymous with contagiousness, I would like to differentiate between infectiousness (infectivity) and contagiousness. Infectiousness (infectivity) is a measure of the ability of a microorganism to establish itself in the host and refers to the individual dose or numbers of the microorganisms required to infect susceptible host. Contagiousness means ease of transmission from one person to another by any means. The ebola virus is extremely infectious (infective). Experiments suggest that even if one particle of Ebola enters a person’s bloodstream it can cause a fatal infection (e.g. accidental needle prick). Even 3 ebola particles can transmit infection by direct contact (e.g. splash of vomitus). This may explain why many of the medical workers who came down with Ebola couldn’t remember making any mistakes that might have exposed them. But it is harder to contract Ebola. One ebola patient can infect up to 2 people every 9 to 15 days while one chicken pox patient can infect up to 17 people every 14 to 16 days. One cannot overlook the fact that lesser the number of microorganisms required for acquiring infection, greater the ease of transmission. Despite this fact, ebola spreads slowly means had infectious dose been thousands of viruses, ebola would not be contagious at all. Even though ebola spreads slowly and to relatively few people, it kills more than other diseases. The World Health Organization said 70 percent of cases in 2014 outbreak are fatal. Virulence is a measure of the disease producing ability of microorganisms. Higher the virulence of microorganism, greater the morbidity and mortality of susceptible host. Faster the replication rate of pathogenic microorganism, greater the depletion of host resources and lesser the host fitness, resulting in higher virulence and higher host mortality. However, mere higher replication rate cannot be correlated with severity of disease as equally important is significance of target organ. Ebola virus specifically targets immune cells, endothelial cells and hepatocytes. Ebola has high mortality not only because of faster replication rates but also because of targeting vital systems of body. In a nutshell, ebola is highly virulent, highly infectious (infective) but averagely contagious disease.  Compared with other diseases such as tuberculosis, smallpox, measles, chicken pox, influenza, SARS and polio, Ebola is not particularly contagious.    

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17. Although high transmission rate will typically go along with a high virulence (high reproduction/replication rate) because rapid replication can increase a pathogens chance of transference as higher the number of viruses in body fluids, greater is chance of transmission; ebola is not highly transmissible despite highly virulent and despite highly infectious; because it is not airborne, because it is a fragile virus outside host and because it is transmitted through body fluids of a severely ill patient late in the disease. The severely ill patients late in disease carry maximum viruses in body fluids but they are bedridden and therefore confine viruses to a place where they lie. In order to reduce virulence of ebola to reduce mortality, ebola transmission rate must be further reduced by isolation, sanitation and barrier nursing of ebola patient because reduced transmission would result in selection of lower virulent ebola strains over higher virulent ebola strains. Lower virulent strain would cause a milder disease and killing maybe twenty per cent of its victims instead of seventy per cent. This could leave more of them sick rather than dead, and perhaps sick for longer. That might be good for Ebola, since the host would live longer and could start even more chains of infection. Even if less virulent strains are not present, prevention of transmission is likely to slow and eventually stop the outbreak as the number of remaining susceptible hosts is reduced through various means. In order to stop the epidemic, the rate of transmission would have to be cut in half. This would be equivalent to vaccinating 50% of the susceptible population.

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18. We the humans are in Catch-22 situation. Higher the Ebola mortality, more human lives are lost but outbreak burns itself out. Lesser the human mortality, virus would become endemic and persist at low level all the time.

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19. The overwhelming majority of people who have been infected with Ebola are people who have directly cared for a person who is actively sick with the disease or have handled the body of someone who have died from it. Ebola is a caregiver’s disease and children don’t typically get it even though they are running around touching many objects and surfaces because they are not taking care of sick people as a rule. Studies conducted during the various epidemics have shown that less than one fifth of the people living with a confirmed or probable primary patient have developed the disease. All secondary cases were recorded among people with close contact with the patient and exposed to infected biological fluids. The World Health Organization says 588 health care workers have been infected with Ebola and 337 have died of it. Conversely, people who had no contact with the patient were not sick.

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20. Contact is a person who was/is in direct contact with ebola patient alive or dead, direct contact with sick or dead animal suffering from ebola and direct contact with specimens collected from suspected Ebola patients/animals; provided that this exposure has taken place less than 21 days before the identification as a contact by surveillance teams. Direct contact means physical contact of skin or mucous membrane (eye, mouth, and nose) of anybody with infected (alive/dead) person’s body (skin/mucous membrane) and/or body fluids (blood, saliva, mucus, tears, genital secretions, breast milk, vomitus, urine, sweat or feces) either directly and/or indirectly through fomites.  Contact tracing is most important for ebola as even one missed contact can keep the outbreak going. Also contact tracing finds new cases quickly so that they can be isolated to prevent spread of disease. Contacts are watched for signs of illness for 21 days. If any of these contacts comes down with the disease, they should be isolated, tested and treated. Then the process is repeated by tracing the contacts’ contacts. The best way to prevent Ebola from spreading is to identify everyone whom infected individual has contacted either when alive or after death in the course of funeral/burial rituals. Liberian Thomas Eric Duncan died from Ebola after arriving in Dallas. Duncan said he had not been in contact with Ebola patients in his native country, although that later proved to be a false statement. Since people habitually lie, how on earth can you identify a contact anyway?  

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21. Quarantine is restricting movement of contacts for the incubation period of the contagious disease to see if they become sick. If they indeed become sick, isolate them, treat them and trace all their contacts. If not then set them free. Quarantine is not a strategy to prevent spread of diseases that may be transmissible prior to the onset of symptoms. Ebola is not transmissible in incubation period but we still do need to quarantine ebola contacts in incubation period. There are silent ebola infections where quarantine logic fails but they are not contagious anyway. Isolation refers to separating those who are having contagious disease from those who are not to prevent spread of disease. Theoretically there is no quarantine time that will provide absolute assurance of no residual risk from contagion. Practically one needs to balance out costs and benefits of quarantine and risk reduction. The paradox of quarantine and other social distancing measures is that they may be effective in fighting a disease outbreak, but they can be applied too broadly, resulting in a variety of social harms, including economic disruption, personal isolation, and even violence. 

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22. A study on 3,343 confirmed and 667 probable cases of Ebola in 2014 ebola outbreak found that 87.1% of those infected exhibited fever but 12.9% did not. So fever is not a guaranteed symptom of ebola infection. However, fever precedes the contagious stage, allowing contacts to identify themselves as infected before they become a threat to the community. This is so because the sensitive blood polymerase-chain-reaction (PCR) test for Ebola is often negative on the day when fever or other symptoms begin and only becomes reliably positive 2 to 3 days after symptom onset.  Do not confuse Ebola patient without fever (afebrile Ebola) with asymptomatic Ebola (silent Ebola). Ebola patient without fever is suffering from ebola virus disease and he/she may have symptoms (vomiting, diarrhea, headache etc) except fever. Asymptomatic Ebola is not suffering from ebola virus disease, has no symptoms what so ever, but only infected with ebola virus for some time. Ebola virus disease occurs due to infection with ebola virus; but infection with ebola virus does not necessarily mean Ebola virus disease. Disease will produce some symptoms but infection without disease is silent.  

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23. The RT-PCR and antigen-capture ELISA are very effective for detecting ebola virus in patient’s serum, plasma, and whole blood during acute phase of Ebola. In samples collected very early in the course of infection, the RT-PCR assay could detect ebola virus 24 to 48 h prior to detection by antigen capture. Detection of significant IgM antibody response during the first week of illness suggests ebola survival as fatal cases do not develop antibody response.   

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24. The accuracy of diagnostic test for ebola is of paramount importance. False positives could place people without Ebola in contact with other infected patients, while false negatives could release Ebola patients back into the public. Ebola should never be diagnosed or ruled out by a single laboratory test.

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25. Timing of diagnostic test for Ebola is of paramount importance. It takes about three days once a person starts showing symptoms for the Ebola virus to accurately show up on tests. In other words, it is possible for an Ebola test to be negative when the person actually does have Ebola. This is critical, as many of those admitting themselves to hospitals with possible Ebola symptoms are doing so the day they start exhibiting them, or possibly the day after at the latest. Unless medical personnel across the world fully understand this, many Ebola patients will be discharged with false negatives, only to spread the disease to their friends and family.  

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26. Survival in ebola virus disease is dependent on species of ebola virus (Sudan vs. Zaire), quantum of viral load, route of infection (parenteral vs. direct contact), age, genetic predisposition, mutation in a gene called NPC1, level of preparedness & availability & quality of medical care, and immune response (protective vs. suppressed). Out of all survival factors, an early and effective immune response (innate and acquired) is the most important. Ebola is so deadly because it has multiple ways of interfering with or avoiding the human immune system. Ebola not only invades and evades immune system but also uses immune cells as a vehicle for dissemination throughout human body.  Survivors exhibited more significant IgM responses, clearance of viral antigen, and sustained T-cell cytokine responses, as indicated by high levels of T-cell-related mRNA in the peripheral blood. A detailed study of infected but asymptomatic individuals revealed that they had an early (4-6 days after infection) and vigorous immunologic response with production of interleukin (IL) and tumor necrosis factor (TNF), resulting in enhanced cell-mediated and humoral immunity. A study showed that the innate immune response, specifically natural killer (NK) cells, can mediate rapid and complete protection against lethal Ebola virus infection. In contrast, antibodies specific for the virus were nearly undetectable in fatal cases, and while gamma interferon (IFN-γ) was detected early after infection, T-cell cytokine RNA levels were more indicative of a failure to develop adaptive immunity in the days preceding death. Genomics analysis demonstrated that not only IFN induction but also IFN signaling was impaired in ZEBOV-infected cells as ebola viruses alter host cell gene expression programs. This significant suppression of the IFN response leads to increased immune evasion, replication, and virulence of ebola virus.

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27. The best experimental therapy for ebola virus disease include the use of whole blood, serum or plasma from convalescent Ebola virus disease survivors, a cocktail of three monoclonal antibodies directed against the Ebola viral glycoprotein (ZMapp), a novel broad-spectrum nucleoside analogue BCX4430 which inhibit RNA polymerase and three small interfering RNAs (siRNAs) that target L protein, VP24, and VP35 genes of Ebola virus (TKM-Ebola). I don’t want to comment on ethical aspects of experimental therapy and use of drugs without randomized double blind controlled trials in predominantly fatal illnesses. I am a practicing doctor and if my patient has 70 % chance of death despite best available treatment, I would use experimental therapy with the knowledge and the consent of the patient and his/her family. Provision of supportive care, particularly fluid and electrolyte management and treatment of bacterial superinfections can significantly improve survival.  

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28. Mammary gland (breast), gonads (testes &ovaries) and chambers of the eye are immunologically protected site in which clearance of ebola virus is delayed in ebola survivors and therefore ebola survivors must avoid breast feeding, unprotected sex and contact with the mucous membranes of the eye for 3 months following recovery from ebola. Inadvertent rubbing of eyes by hand is common and therefore ebola survivor must make conscious efforts to prevent hands touching eyes. Although studies have shown Ebola patients shed genetic material from the virus into their sexual fluids, there is scant evidence that they are often shedding viable virus that could infect others. Nonetheless, extreme caution is not an overreaction with the deadly disease.  

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29. We need Ebola Vaccine for pre-exposure and post-exposure prophylaxis of health care workers, household contacts and susceptible population for following reasons:

a) High ebola mortality

b) Very few viral particles can transmit infection

c) Direct contact transmission

d) Lack of effective treatment

e) Very expensive available treatment

f) Prevent endemic ebola

The only reason we don’t have ebola vaccine today is because ebola in past affected poor African nations and it was not cost-effective for big pharmaceutical corporations to spend money on ebola vaccine development. Now ebola has entered United States and we see sea-change in the thinking of pharmaceutical industry and sea-change in the political will of the West.

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30.  The most important point overlooked by the world in recent 2014 ebola outbreak is asymptomatic (silent) ebola infections.  Results from one post-ebola outbreak study showed that 71% of seropositive individuals did not have the disease; another study reported that 46% of asymptomatic close contacts of patients with Ebola were seropositive. The latter study also found minute concentrations of Ebola virus in these individuals’ blood, suggesting that their antibodies could not be explained by their exposure to dead virus, but that rather they had truly been infected by live virus. A study found that asymptomatic Ebola infection did not result from viral mutations. Asymptomatic cases are likely to have a little bit of virus for a little bit of time and then fight it off. Rough approximations tell us that as many as 50 percent of infections are silent. So for every case of severe Ebola, there may be another person who is infected without ever knowing it. That means case fatality rate (CFR) of ebola is overestimated as plenty of silent infections are not taken into account. Ebola typically spreads through contact with bodily fluids of very sick individuals, who have exceedingly high viral counts; therefore it is very unlikely that silent (asymptomatic) cases can spread the virus with the low levels found in their blood for some time.  Although asymptomatic infections are unlikely to be contagious, they might confer protective immunity and thus have important epidemiological consequences. Epidemics are fueled by susceptible people. The more there are, the bigger an epidemic can become. Immunization of any kind — via vaccine or natural infection — makes people resistant and thereby slows transmission. The asymptomatic individuals can also help slow the spread of Ebola by being recruited to work as caregivers in high-risk communities. Also if infection without disease protects people from future Ebola infections and illness, the epidemic should decline sooner than currently predicted and affect a smaller number of people. Also naturally acquired immunity will amplify the effects of disease control measures, including vaccination. I want researchers to conduct studies to find out commonality between silently infected people and people who survived ebola virus disease.   

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31. According to my theory of deadliness of infectious diseases, Ebola is 57,000 times deadlier than influenza (common flu). The only variable in our hand is susceptible population. So to reduce mortality, we have to reduce susceptible population by reducing transmission (isolation, sanitation, barrier nursing, and use of PPE) including quarantine all contacts, and vaccinating the world. Of course, giving better treatment would also reduce Ebola deadliness but today we have no effective treatment and experimental ebola therapies like ZMapp, BCX4430 and TKM-Ebola are very expensive and beyond reach of ordinary citizen of third world.

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Dr. Rajiv Desai. MD.

December 6, 2014 

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Postscript:   

Ebola is not transmitted by the air. Fear and ignorance are transmitted by the air. It is the duty of media to tell truth rather than spread fear. I would like to emphasize that isolation, sanitation and barrier nursing  of Ebola patients would definitely prevent Ebola spread substantially. I strongly recommend quarantine of all Ebola contacts for 21 days till effective Ebola Vaccine is available. Intravenous fluid administration to correct dehydration and maintenance of circulatory blood volume would significantly reduce mortality. I have already proved that intravenous normal saline in adequate doses at appropriate time saves life in severe Dengue patients and the same logic can be deduced for Ebola. Ebola is my last article of 2014. I wish Merry Christmas and hope that the year 2015 shall bring peace, prosperity, security and justice throughout the world. 

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SELF MONITORING (MEASUREMENT) OF BLOOD GLUCOSE (SMBG):

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Prologue:

Way back in 1991, on a Sunday afternoon, a young Parsi lady from Mumbai who was holidaying in a nearby village came to me with sudden breathlessness at my nursing home at Vapi, 160 km north of Mumbai. Clinical examination was normal except severe breathlessness. I suspected diabetic ketoacidosis and asked about history of diabetes. Patient and her relatives flatly denied any history of diabetes and told me that she was investigated in Mumbai for weakness recently and there is no diabetes. In those days, glucometer was not available in India. We used to blood sugar by Folin-Wu method. Being Sunday, laboratory was closed, so I could not do blood and urine sugar. I believed the story of relatives, ignored my gut feeling of diabetes, did ECG and X-ray chest which were normal, gave some primary care and sent patient back to Mumbai in their car. She got admitted in Mumbai same night and they repeated the same story of not having diabetes. However, blood tests in Mumbai revealed diabetic ketoacidosis and she died at Mumbai. Till today I have a guilty feeling of missing diabetes diagnosis. If I had glucometer available, I could have clinched diagnosis, could have given insulin and saved her life. I hope her relatives forgive me. Diabetes was originally identified by the presence of glucose in the urine. Indian physicians around 3500 years ago identified diabetes and classified it as madhumeha or honey urine noting that the urine would attract ants. In the 18th and 19th centuries the sweet taste of urine was used for diagnosis before chemical methods became available to detect sugars in the urine. Tests to measure glucose in the blood were developed over 100 years ago, and hyperglycemia subsequently became the sole criterion recommended for the diagnosis of diabetes. Self-monitoring of blood glucose (SMBG) was described as one of the most important advancements in diabetes management since the invention of insulin in 1920. Since approximately 1980, a primary goal of the management of type 1 and type 2 diabetes mellitus has been achieving closer-to-normal levels of glucose in the blood for as much of the time as possible, guided by SMBG several times a day. The benefits include a reduction in the occurrence rate and severity of long-term complications from hyperglycemia as well as a reduction in the short-term, potentially life-threatening complications of hypoglycemia. Unlike some other diseases that rely primarily on professional medical treatment, diabetes treatment requires active participation by the person who has it. Monitoring your blood glucose level on a regular basis and analyzing the results is believed by many to be a crucial part of the treatment equation. Worldwide, the glucose monitoring devices market is expected to be more than $16 billion by the end of this year. World Diabetes Day is celebrated every year on November 14 and this article will promote awareness about diabetes via SMBG.    

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Abbreviations and synonyms:

DM = diabetes mellitus = diabetes (and not diabetes insipidus)

T1DM = type 1 DM

T2DM = type 2 DM

BG = blood glucose

FPG = fasting plasma glucose (venous)

PPG = post-prandial plasma glucose (venous, 2 hours after meal)

FBS = fasting blood sugar (venous)

PPBS = post prandial blood sugar (venous, 2 hours after meal)

Pre-prandial = before meal

Post-prandial = after meal (usually 2 hour)

Fasting = no calorie intake for 8 hours

Random = anytime other than fasting (test taken from a non-fasting subject)

Glycated Hemoglobin = Hemoglobin A1c = HbA1c = Hb1c = HbA1c = A1c = A1C

SMBG = self monitoring (measurement) of blood glucose = capillary whole blood/plasma glucose

SMUG = self monitoring (measurement) of urine glucose

CGM = continuous glucose monitoring

Hyperglycemia = high blood glucose

Hypoglycemia = low blood glucose

When you ask FBS/PPBS from lab, they usually do FPG/PPG.  

ADA = American Diabetes Association

IDF = International Diabetes Federation

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Terminology of Blood samples:

Blood is pumped around the body by the heart. The major vessels that take blood away from the heart are called arteries. The major vessels that take blood back to the heart are called veins. Between the two networks are many tiny blood vessels called capillaries. The composition of the blood in the three types of vessel varies slightly. When a blood sample is taken by the doctor or nurse, it is taken from a vein and called a venous sample. At the laboratory, the blood may be analysed as it is, in which case it is a ‘whole blood’ measurement. Often the clear liquid part of the blood may be separated from the red blood cells. This yields either serum or plasma (depending on whether or not the blood sample in the tube is treated with a special reagent called an anticoagulant).  A serum or plasma measurement of glucose will give a result which is 10 – 15 % higher than a whole blood measurement. When a home blood glucose test is performed, blood is usually taken from a finger-prick sample which gives capillary whole blood glucose. Now there is a move towards all glucometers giving plasma-calibrated results so that readings made at home and at the laboratory can be more easily compared.  

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Sugar vs. glucose:

Sugar is the generalized name for sweet, short-chain, soluble carbohydrates, many of which are used in food. They are carbohydrates, composed of carbon, hydrogen, and oxygen. Simple sugars are called monosaccharides and include glucose (also known as dextrose), fructose and galactose. The table or granulated sugar most customarily used as food is sucrose, a disaccharide. (In the body, sucrose hydrolyses into fructose and glucose.) Other disaccharides include maltose and lactose. In the physiological context, the term sugar is a misnomer because it refers to glucose, yet other sugars besides glucose are always present. Food contains several different types [e.g., fructose (largely from fruits/table sugar/industrial sweeteners), galactose (milk and dairy products), as well as several food additives such as sorbitol, xylose, maltose, etc.]. But because these other sugars are largely inert with regard to the metabolic control system (i.e., that controlled by insulin secretion), and since glucose is the dominant controlling signal for metabolic regulation, the term has gained currency, and is used by medical staff and lay folk alike. In this article, sugar means glucose. 

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Units of glucose measurement in blood/plasma:

A blood glucose measurement will provide the concentration of glucose that is in your bloodstream; the result is given as the amount of glucose per unit volume (of whole blood/plasma/serum). The measurement unit used for indicating the concentration of blood or plasma glucose can either have a weight dimension (mg/dl) or a molarity (mmol/l).  In some countries, they use millimoles to measure the amount, and take a ‘unit volume’ of blood to be one liter. ‘Millimoles per liter’ is written mmol/l. In the US, and some other countries, milligrams are used to measure the amount and a deciliter is taken as ‘unit volume’. ‘Milligrams per deciliter’ is written mg/dl. Deciliter means 100 ml. Since the molecular weight of glucose C6H12Ois 180, for the measurement of glucose, the difference between the two scales is a factor of 18, so that 1 mmol/L of glucose is equivalent to 18 mg/dL. To convert from mmol/l to mg/dl, simply multiply the figure by a factor of 18.

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Introduction to SMBG:

An important goal in the treatment of diabetes is to achieve and maintain blood glucose levels as close to normal as possible. That is why it is essential to train patients in how to effectively self-manage their diabetes, not only to improve their treatment but also to improve their quality of life. The development in the late 1970s of methods to self-monitor blood glucose levels was an indispensable prerequisite for this. Only through regular self-monitoring of blood glucose levels (SMBG) it has become possible to coordinate drug therapy as well as food intake and exercise so that a good metabolic control can be achieved. Furthermore, it has become easier to identify asymptomatic hypo- and hyperglycemias and blood glucose fluctuations.

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Blood glucose monitoring is a way of testing the concentration of glucose in the blood (glycemia). Particularly important in the care of diabetes mellitus, a blood glucose test is performed by piercing the skin (typically, on the finger) to draw blood, then applying the blood to a chemically active disposable ‘test-strip’. Different manufacturers use different technology, but most systems measure an electrical characteristic, and use this to determine the glucose level in the blood. The test is usually referred to as capillary blood glucose. Blood glucose monitoring reveals individual patterns of blood glucose changes, and helps in the planning of meals, activities, and at what time of day to take medications. Also, testing allows for quick response to high blood sugar (hyperglycemia) or low blood sugar (hypoglycemia). This might include diet adjustments, exercise, and insulin (as instructed by the health care provider).

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Self-monitoring of blood glucose (SMBG) has been accepted as an important instrument that empowers people with diabetes to achieve and maintain therapeutic goals. Nevertheless, it is underprescribed and underused by patients. On the other hand, determination of HbA1c is accepted as the gold standard for assessing glycemic control, but its limitations are not sufficiently appreciated. Patients with normal or near-normal HbA1c levels may still display postprandial hyperglycemia, putting them at risk for long-term adverse outcomes. In addition, frequent unrecognized hypoglycemia may lead to falsely low HbA1c levels, and HbA1c does not allow any estimate of glycemic variability. Determination of immediate blood glucose control is best assessed by SMBG because this provides timely information of hyperglycemia and hypoglycemia. Thus, SMBG is a prerequisite for implementing strategies to optimally treat, as well as to avoid, out-of-range glucose values. Healthcare professionals must be capable of making evidence-based clinical decisions in regard to the use of SMBG and balance issues, such as patient abilities, costs, and clinical outcomes. As a base of diabetes treatment, blood glucose monitoring contributes to clinically determining the level of carbohydrate metabolism, formulating therapeutic measures, evaluating effects, and realizing optimal blood glucose control. Intensive blood glucose monitoring and strict blood glucose control significantly eliminate or postpone occurrence or development of chronic diabetic complications. It is important to monitor accurate blood glucose concentrations which may obviously fluctuate from time to time due to various factors such as daily activity, mental status, diet component, environmental change. Blood glucose monitoring is also a necessary method adopted by many food nutrition experts to investigate the carbohydrate-induced glycemic reaction in addition to its clinic applications to diabetes patients.

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Blood glucose basics:

Glucose is the most important carbohydrate fuel in the body. In the fed state, the majority of circulating glucose comes from the diet; in the fasting state, gluconeogenesis and glycogenolysis maintain glucose concentrations. Very little glucose is found in the diet as glucose; most is found in more complex carbohydrates that are broken down to monosaccharides though the digestive process. About half of the total carbohydrates in the diet are in the form of polysaccharides and the remainder as simpler sugars. About two-thirds of the sugar in the diet is sucrose, which is a disaccharide of glucose and fructose. Glucose is classified as a monosaccharide because it cannot be broken down further by hydrolysis. It is further classified as a hexose because of its six-carbon skeleton and as an aldose, because of the presence of an aldehyde group on carbon 1. The aldehyde group condenses with a hydroxyl group so that glucose exists as a hemiacetal ring structure. This ring structure explains many of the reactions of glucose. Ordinarily the concentration of glucose in the blood is maintained at a relatively stable concentration from 80 to 120 mg/dl. The strong reducing properties of glucose made it relatively easy to measure and thus the clinical estimation of circulating glucose was one of the earliest tests available to the clinician. The recent introduction of microglucose oxidase technology has now made it possible for the patient to measure his or her own blood glucose concentration and undoubtedly makes the estimation of blood glucose the most widely used test of blood chemistry.

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Natural blood glucose regulation:

Glucose is a simple sugar which is a permanent and immediate primary source of energy to all of the cells in our body. Glucose C6H12O6  is a carbohydrate whose most important function is to act as a source of energy for the human body, by being the essential precursor in the synthesis of ATP (adenosine triphosphate). The energy stored in ATP can then be used to drive processes requiring energy, including biosynthesis, and locomotion or transportation of molecules across cell membranes. According to cellular requirements, glucose can also be used in the creation of proteins, glycogen, and lipids. The blood glucose concentration is very tightly regulated. Human body has two hormones released by pancreas that have opposite effects: insulin and glucagon. Insulin is produced by beta cells of the pancreas while glucagon is produced by alpha cells. The release of insulin is triggered when high levels of glucose are found in the bloodstream, and glucagon is released with low levels of glucose in the blood.

This blood glucose regulation process can be explained in the following steps:

1. After the glucose has been absorbed from the food eaten, it gets released in the bloodstream. High blood glucose levels triggers the pancreas to produce insulin. Insulin enables the muscle cells to take glucose as their source of energy and to form a type of molecule called glycogen that works as secondary energy storage in the case of low levels of glucose. In the liver cells, insulin instigates the conversion of glucose into glycogen and fat. In the fat cells of the adipose tissue, insulin also promotes the conversion of glucose into more fat and the uptake of glucose.

2. The pancreas will continue to release insulin and liver and fat cells continue to use glucose till the drop of concentration of glucose is below a threshold; in that case, glucagon will be released instead of insulin.

3. When glucagon reaches the liver cells, it initiates the conversion of glycogen into glucose, and fat into fatty acids, which many body cells can use as energy after the glucagon enables them to. The cells will continue to burn fat from the adipose tissue as an energy source, and follow with the protein of the muscles, until the levels of glucose increase again by the digestion of food, and that terminates the cycle.

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Homeostasis of glucose:

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Essentially blood glucose levels determine the time of secretion of these hormones. The glucose in blood is obtained from the food that you eat. This glucose gets absorbed by intestines and distributed to all of the cells in body through bloodstream and breaks it down for energy. Body tries to maintain a constant supply of glucose for your cells by maintaining a constant blood glucose concentration. The concentration of glucose in blood, expressed in mg/dl, is defined by the term glycemia.

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Glucose metabolism in normal person:

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The blood sugar concentration or blood glucose level is the amount of glucose (sugar) present in the blood of a human or animal. The body naturally tightly regulates blood glucose levels as a part of metabolic homeostasis. With some exceptions, glucose is the primary source of energy for the body’s cells, and blood lipids (in the form of fats and oils) are primarily a compact energy store. Glucose is transported from the intestines or liver to body cells via the bloodstream, and is made available for cell absorption via the hormone insulin, produced by the body primarily in the pancreas. Glucose levels are usually lowest in the morning, before the first meal of the day (termed “the fasting level”), and rise after meals for an hour or two by a few millimoles. Blood sugar levels outside the normal range may be an indicator of a medical condition. A persistently high level is referred to as hyperglycemia; low levels are referred to as hypoglycemia. Diabetes mellitus is characterized by persistent hyperglycemia from any of several causes, and is the most prominent disease related to failure of blood sugar regulation. Intake of alcohol causes an initial surge in blood sugar, and later tends to cause levels to fall. Also, certain drugs can increase or decrease glucose levels.

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The figure below shows fluctuation of blood sugar (red) and the sugar-lowering hormone insulin (blue) in humans during the course of a day with three meals. One of the effects of a sugar-rich vs. a starch-rich meal is highlighted.

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Normal values in humans:

Normal value ranges may vary slightly among different laboratories. Many factors affect a person’s blood sugar level. A body’s homeostatic mechanism, when operating normally, restores the blood sugar level to a narrow range of about 4.4 to 6.1 mmol/L (79.2 to 110 mg/dL) (as measured by a fasting blood glucose test). The normal blood glucose level (tested while fasting) for non-diabetics, should be between 70 and 100 milligrams per deciliter (mg/dL). The mean normal blood glucose level in humans is about 5.5 mM (5.5 mmol/L or 100 mg/dL; however, this level fluctuates throughout the day. Blood sugar levels for those without diabetes and who are not fasting should be below 125 mg/dL. Despite widely variable intervals between meals or the occasional consumption of meals with a substantial carbohydrate load, human blood glucose levels tend to remain within the normal range. However, shortly after eating, the blood glucose level may rise, in non-diabetics, temporarily up to 7.8 mmol/L (140 mg/dL) or slightly more. The actual amount of glucose in the blood and body fluids is very small. In a healthy adult male of 75 kg with a blood volume of 5 liters, a blood glucose level of 5.5 mmol/L (100 mg/dL) amounts to 5 grams, slightly less than two typical American restaurant sugar packets for coffee or tea. Part of the reason why this amount is so small is that, to maintain an influx of glucose into cells, enzymes modify glucose by adding phosphate or other groups to it.

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Diabetes Mellitus:

Diabetes mellitus (DM) refers to a group of common metabolic disorders that share the phenotype of hyperglycemia. Several distinct types of DM are caused by a complex interaction of genetics and environmental factors. Depending on the etiology of the DM, factors contributing to hyperglycemia include reduced insulin secretion, decreased glucose utilization, and increased glucose production. The metabolic dysregulation associated with DM causes secondary pathophysiologic changes in multiple organ systems that impose a tremendous burden on the individual with diabetes and on the health care system.

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Diagnosis of DM:

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Classification of DM:

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The figure above shows spectrum of glucose homeostasis and diabetes mellitus (DM). The spectrum from normal glucose tolerance to diabetes in type 1 DM, type 2 DM, other specific types of diabetes (type 3 DM), and gestational DM (type 4 DM) is shown from left to right. In most types of DM, the individual traverses from normal glucose tolerance to impaired glucose tolerance to overt diabetes (these should be viewed not as abrupt categories but as a spectrum). Arrows indicate that changes in glucose tolerance may be bidirectional in some types of diabetes. For example, individuals with type 2 DM may return to the impaired glucose tolerance category with weight loss; in gestational DM, diabetes may revert to impaired glucose tolerance or even normal glucose tolerance after delivery. The fasting plasma glucose (FPG), the 2-h plasma glucose (PG) after a glucose challenge, and the A1c for the different categories of glucose tolerance are shown at the lower part of the figure. These values do not apply to the diagnosis of gestational DM. The World Health Organization uses an FPG of 110–125 mg/dL for the prediabetes category. Some types of DM may or may not require insulin for survival. *Some use the term “increased risk for diabetes” (ADA) or “intermediate hyperglycemia” (WHO) rather than “prediabetes.”

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DM is classified on the basis of the pathogenic process that leads to hyperglycemia, as opposed to earlier criteria such as age of onset or type of therapy. The two broad categories of DM are designated type 1 (T1DM) and type 2 (T2DM). Both types of diabetes are preceded by a phase of abnormal glucose homeostasis as the pathogenic processes progress. Type 1 DM is the result of complete or near-total insulin deficiency.

Glucose metabolism in T1DM:

 

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Type 2 DM is a heterogeneous group of disorders characterized by variable degrees of insulin resistance, impaired insulin secretion, and increased glucose production. Distinct genetic and metabolic defects in insulin action and/or secretion give rise to the common phenotype of hyperglycemia in type 2 DM and have important potential therapeutic implications now that pharmacologic agents are available to target specific metabolic derangements. Type 2 DM is preceded by a period of abnormal glucose homeostasis classified as impaired fasting glucose (IFG) or impaired glucose tolerance (IGT).

Glucose metabolism in T2DM:

 

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Two features of the current classification of DM diverge from previous classifications. First, the terms insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM) are obsolete. Since many individuals with type 2 DM eventually require insulin treatment for control of glycemia, the use of the term NIDDM generated considerable confusion. A second difference is that age is not a criterion in the classification system. Although type 1 DM most commonly develops before the age of 30, an autoimmune beta cell destructive process can develop at any age. It is estimated that between 5 and 10% of individuals who develop DM after age 30 years have type 1 DM. Although type 2 DM more typically develops with increasing age, it is now being diagnosed more frequently in children and young adults, particularly in obese adolescents.

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Comparison of variation of plasma glucose between non-diabetic and diabetic individuals:

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Other Types of DM (type 3 DM):

Other etiologies for DM include specific genetic defects in insulin secretion or action, metabolic abnormalities that impair insulin secretion, mitochondrial abnormalities, and a host of conditions that impair glucose tolerance . Maturity-onset diabetes of the young (MODY) is a subtype of DM characterized by autosomal dominant inheritance, early onset of hyperglycemia (usually <25 years), and impairment in insulin secretion. Mutations in the insulin receptor cause a group of rare disorders characterized by severe insulin resistance. DM can result from pancreatic exocrine disease when the majority of pancreatic islets are destroyed. Cystic fibrosis-related DM is an important consideration in this patient population. Hormones that antagonize insulin action can also lead to DM. Thus, DM is often a feature of endocrinopathies such as acromegaly and Cushing’s disease. Viral infections have been implicated in pancreatic islet destruction but are an extremely rare cause of DM. A form of acute onset of type 1 diabetes, termed fulminant diabetes, has been noted in Japan and may be related to viral infection of islets.

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Gestational Diabetes Mellitus (GDM) (type 4 DM):

Glucose intolerance developing during pregnancy is classified as gestational diabetes. Insulin resistance is related to the metabolic changes of late pregnancy, and the increased insulin requirements may lead to IGT or diabetes. GDM occurs in 7% (range 2–10%) of pregnancies in the United States; most women revert to normal glucose tolerance postpartum but have a substantial risk (35–60%) of developing DM in the next 10–20 years. The International Diabetes and Pregnancy Study Groups now recommend that diabetes diagnosed at the initial prenatal visit should be classified as “overt” diabetes rather than gestational diabetes.

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Note:

This article is written on SMBG and not DM and therefore detailed discussion on DM is inappropriate.

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Hyperglycemia vs. DM:

For diagnosis of DM, persistent hyperglycemia is must but occasionally you may have transient hyperglycemia without DM. Stress hyperglycemia is a medical term referring to transient elevation of the blood glucose due to the stress of illness. Transient hyperglycemia occurs as a part of stress response in acute illnesses and is brought about by elevated levels of counter regulatory hormones. It usually resolves spontaneously. Stress hyperglycemia is especially common in patients with hypertonic dehydration and those with elevated catecholamine levels (e.g., after emergency department treatment of acute asthma with epinephrine). Steroid diabetes is a specific and prolonged form of stress hyperglycemia. In some people, stress hyperglycemia may indicate a reduced insulin secretory capacity or a reduced sensitivity, and is sometimes the first clue to incipient diabetes. Because of this, it is occasionally appropriate to perform diabetes screening tests after recovery from an illness in which significant stress hyperglycemia occurred.  Even fear of needles or pain during blood collection may provoke transient hyperglycemia. Blood glucose is also amplified by drugs or intravenous glucose. 

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Why do diabetics develop complications?

Chronic elevation of blood glucose level leads to damage of blood vessels (angiopathy). The endothelial cells lining the blood vessels take in more glucose than normal, since they do not depend on insulin. They then form more surface glycoproteins than normal, and cause the basement membrane to grow thicker and weaker. In diabetes, the resulting problems are grouped under “microvascular disease” (due to damage to small blood vessels) and “macrovascular disease” (due to damage to the arteries). The risk of chronic complications increases as a function of the duration and degree of hyperglycemia; they usually do not become apparent until the second decade of hyperglycemia. Since type 2 DM often has a long asymptomatic period of hyperglycemia, many individuals with type 2 DM have complications at the time of diagnosis. The microvascular complications of both type 1 and type 2 DM result from chronic hyperglycemia. Large, randomized clinical trials of individuals with type 1 or type 2 DM have conclusively demonstrated that a reduction in chronic hyperglycemia prevents or delays retinopathy, neuropathy, and nephropathy. Other incompletely defined factors may modulate the development of complications. For example, despite long-standing DM, some individuals never develop nephropathy or retinopathy. The fact that 40% of diabetics who carefully control their blood sugar nevertheless develop neuropathy, and that some of those with good blood sugar control still develop nephropathy, requires explanation. Many of these patients have glycemic control that is indistinguishable from those who develop microvascular complications, suggesting that there is a genetic susceptibility for developing particular complications. The familial clustering of the degree and type of diabetic complications indicates that genetics may also play a role in causing complications such as diabetic retinopathy and nephropathy. Non-diabetic offspring of type 2 diabetics have been found to have increased arterial stiffness and neuropathy despite normal blood glucose levels, and elevated enzyme levels associated with diabetic renal disease have been found in non-diabetic first-degree relatives of diabetics. Evidence implicating a causative role for chronic hyperglycemia in the development of macrovascular complications is less conclusive. However, coronary heart disease events and mortality rate are two to four times greater in patients with type 2 DM. These events correlate with fasting and postprandial plasma glucose levels as well as with the A1c. Other factors (dyslipidemia and hypertension) also play important roles in macrovascular complications.

Mechanisms of Complications:

Although chronic hyperglycemia is an important etiologic factor leading to complications of DM, the mechanism(s) by which it leads to such diverse cellular and organ dysfunction is unknown. At least four prominent theories, which are not mutually exclusive, have been proposed to explain how hyperglycemia might lead to the chronic complications of DM. An emerging hypothesis is that hyperglycemia leads to epigenetic changes in the affected cells. One theory is that increased intracellular glucose leads to the formation of advanced glycosylation end products (AGEs), which bind to a cell surface receptor, via the nonenzymatic glycosylation of intra- and extracellular proteins. Nonenzymatic glycosylation results from the interaction of glucose with amino groups on proteins. AGEs have been shown to cross-link proteins (e.g., collagen, extracellular matrix proteins), accelerate atherosclerosis, promote glomerular dysfunction, reduce nitric oxide synthesis, induce endothelial dysfunction, and alter extracellular matrix composition and structure. The serum level of AGEs correlates with the level of glycemia, and these products accumulate as the glomerular filtration rate (GFR) declines. A second theory is based on the observation that hyperglycemia increases glucose metabolism via the sorbitol pathway. Intracellular glucose is predominantly metabolized by phosphorylation and subsequent glycolysis, but when increased, some glucose is converted to sorbitol by the enzyme aldose reductase. Increased sorbitol concentration alters redox potential, increases cellular osmolality, generates reactive oxygen species, and likely leads to other types of cellular dysfunction. However, testing of this theory in humans, using aldose reductase inhibitors, has not demonstrated significant beneficial effects on clinical endpoints of retinopathy, neuropathy, or nephropathy. A third theory proposes that hyperglycemia increases the formation of diacylglycerol leading to activation of protein kinase C (PKC). Among other actions, PKC alters the transcription of genes for fibronectin, type IV collagen, contractile proteins, and extracellular matrix proteins in endothelial cells and neurons. Inhibitors of PKC are being studied in clinical trials. A fourth theory proposes that hyperglycemia increases the flux through the hexosamine pathway, which generates fructose-6-phosphate, a substrate for O-linked glycosylation and proteoglycan production. The hexosamine pathway may alter function by glycosylation of proteins such as endothelial nitric oxide synthase or by changes in gene expression of transforming growth factor  (TGF-) or plasminogen activator inhibitor-1 (PAI-1). Growth factors appear to play an important role in some DM-related complications, and their production is increased by most of these proposed pathways. Vascular endothelial growth factor A (VEGF-A) is increased locally in diabetic proliferative retinopathy and decreases after laser photocoagulation. TGF- is increased in diabetic nephropathy and stimulates basement membrane production of collagen and fibronectin by mesangial cells. Other growth factors, such as platelet-derived growth factor, epidermal growth factor, insulin-like growth factor I, growth hormone, basic fibroblast growth factor, and even insulin, have been suggested to play a role in DM-related complications. A possible unifying mechanism is that hyperglycemia leads to increased production of reactive oxygen species or superoxide in the mitochondria; these compounds may activate all four of the pathways described above. Although hyperglycemia serves as the initial trigger for complications of diabetes, it is still unknown whether the same pathophysiologic processes are operative in all complications or whether some pathways predominate in certain organs.

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Blood glucose tests:

  1. fasting blood sugar (i.e., glucose) test (FBS)—it means fasting plasma glucose (FPG)
  2. two-hr postprandial blood sugar test (2-h PPBS)—it means postprandial plasma glucose (PPG)
  3. oral glucose tolerance test (OGTT)
  4. intravenous glucose tolerance test (IVGTT)
  5. glycated hemoglobin (HbA1C)
  6. self-monitoring of blood glucose (SMBG) level via patient testing
  7. Random blood sugar (RBS)
  8. Average blood glucose (eAG = estimated average glucose) may be estimated by measuring HbA1c

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What are the Target Ranges?

Blood glucose targets are individualized based on:

  • duration of diabetes
  • age/life expectancy
  • comorbid conditions
  • known CVD or advanced microvascular complications
  • hypoglycemia unawareness
  • individual patient considerations.

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Blood glucose profile:

No matter how mild your diabetes may be, it is very unlikely that any physician can tell you how to normalize your blood sugars throughout the day without knowing what your blood glucose values are around the clock. Don’t believe anyone who tells you otherwise. The only way to know what your around the clock levels are is to monitor them yourself. A table of blood sugar levels, with associated events (meals, exercise, and so on), measured at least 4 times daily over a number of days, is the key element in what is called a blood glucose profile. This profile gives you and your physician or diabetes educator a glimpse of how your medication, lifestyle, and diet converge, and how they affect your blood sugars. Without this information, it is impossible to come up with a treatment plan that will normalize blood sugars. If your treatment includes insulin injections before each meal, your diabetes is probably severe enough to render it impossible for your body to automatically correct small deviations from a target blood glucose range. To achieve blood sugar normalization, it therefore may be necessary for you to record blood glucose profiles every day for the rest of your life, so that you can fine tune any out of range values. If you are not treated with insulin, or if you have a very mild form of insulin treated diabetes, it may only be necessary to prepare blood glucose profiles when needed for readjustment of your diet or medication. Typically, this might be for one to two weeks prior to every routine follow up visit to your physician, and for a few weeks while your treatment plan is being fine tuned for the first time. After all, your physician or diabetes educator cannot tell if a new regimen is working properly without seeing your blood glucose profiles. It is wise, however, that you also do a blood glucose profile for 1 day at least every other week, so you will be assured that things are continuing as planned.

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Hypo and hyperglycemia:

Levels which are significantly above or below normal range are problematic and can in some cases be dangerous. A level of <3.8 mmol/L (<70 mg/dL) is usually described as a hypoglycemic attack (low blood sugar). Most diabetics know when they are going to “go hypo” and usually are able to eat some food or drink something sweet to raise levels. A patient who is hyperglycemic (high blood glucose) can also become temporarily hypoglycemic, under certain conditions (e.g. not eating regularly, or after strenuous exercise, followed by fatigue). Intensive efforts to achieve blood sugar levels close to normal have been shown to triple the risk of the most severe form of hypoglycemia, in which the patient requires assistance from by-standers in order to treat the episode. There were annually 48,500 hospitalizations for diabetic hypoglycemia and 13,100 for diabetic hypoglycemia resulting in coma in the period 1989 to 1991 in the U.S., before intensive blood sugar control was as widely recommended as today. One study found that hospital admissions for diabetic hypoglycemia increased by 50% from 1990-1993 to 1997-2000, as strict blood sugar control efforts became more common. Among intensively controlled type 1 diabetics, 55% of episodes of severe hypoglycemia occur during sleep, and 6% of all deaths in diabetics under the age of 40 are from nocturnal hypoglycemia in the so-called ‘dead-in-bed syndrome,’ while National Institute of Health statistics show that 2% to 4% of all deaths in diabetics are from hypoglycemia. In children and adolescents following intensive blood sugar control, 21% of hypoglycemic episodes occurred without explanation. In addition to the deaths caused by diabetic hypoglycemia, periods of severe low blood sugar can also cause permanent brain damage. Interestingly, although diabetic nerve disease is usually associated with hyperglycemia, hypoglycemia as well can initiate or worsen neuropathy in diabetics intensively struggling to reduce their hyperglycemia. Levels greater than 13-15 mmol/L (230–270 mg/dL) are considered high, and should be monitored closely to ensure that they reduce rather than continue to remain high. The patient is advised to seek urgent medical attention as soon as possible if blood sugar levels continue to rise after 2-3 tests. High blood sugar levels are known as hyperglycemia, which is not as easy to detect as hypoglycemia and usually happens over a period of days rather than hours or minutes. If left untreated, this can result in diabetic coma and death. Prolonged and elevated levels of glucose in the blood, which is left unchecked and untreated, will, over time, result in serious diabetic complications in those susceptible and sometimes even death. There is currently no way of testing for susceptibility to complications. Diabetics are therefore recommended to check their blood sugar levels either daily or every few days. There is also diabetes management software available from blood testing manufacturers which can display results and trends over time. Type 1 diabetics normally check more often, due to insulin therapy. A history of blood sugar level results is especially useful for the diabetic to present to their doctor or physician in the monitoring and control of the disease. Failure to maintain a strict regimen of testing can accelerate symptoms of the condition, and it is therefore imperative that any diabetic patient strictly monitor their glucose levels regularly.

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Hypoglycemia is most commonly caused by drugs used to treat diabetes mellitus or by exposure to other drugs, including alcohol. However, a number of other disorders, including critical organ failure, sepsis and inanition, hormone deficiencies, non–beta-cell tumors, insulinoma, and prior gastric surgery, may cause hypoglycemia. Hypoglycemia is most convincingly documented by Whipple’s triad: (1) symptoms consistent with hypoglycemia, (2) a low plasma glucose concentration measured with a precise method, and (3) relief of those symptoms after the plasma glucose level is raised. The lower limit of the fasting plasma glucose concentration is normally approximately 70 mg/dL (3.9 mmol/L), but substantially lower venous glucose levels occur normally, late after a meal. Glucose levels <55 mg/dL (3.0 mmol/L) with symptoms that are relieved promptly after the glucose level is raised document hypoglycemia. Hypoglycemia can cause serious morbidity; if severe and prolonged, it can be fatal. It should be considered in any patient with episodes of confusion, an altered level of consciousness, or a seizure.

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Glycemic control:

Glycemic control is a medical term referring to the typical levels of blood sugar (glucose) in a person with diabetes mellitus. Much evidence suggests that many of the long-term complications of diabetes, especially the microvascular complications, result from many years of hyperglycemia (elevated levels of glucose in the blood). Good glycemic control, in the sense of a “target” for treatment, has become an important goal of diabetes care, although recent research suggests that the complications of diabetes may be caused by genetic factors or, in type 1 diabetics, by the continuing effects of the autoimmune disease which first caused the pancreas to lose its insulin-producing ability. Because blood sugar levels fluctuate throughout the day and glucose records are imperfect indicators of these changes, the percentage of hemoglobin which is glycosylated is used as a proxy measure of long-term glycemic control in research trials and clinical care of people with diabetes. In nondiabetic persons with normal glucose metabolism the glycosylated hemoglobin is usually 4-6% by the most common methods (normal ranges may vary by method). Measurement of glycated hemoglobin is the standard method for assessing long-term glycemic control. When plasma glucose is consistently elevated, there is an increase in nonenzymatic glycation of hemoglobin; this alteration reflects the glycemic history over the previous 2–3 months, since erythrocytes have an average life span of 120 days (glycemic level in the preceding month contributes about 50% to the A1C value). In patients achieving their glycemic goal, the ADA recommends measurement of the A1C at least twice per year. More frequent testing (every 3 months) is warranted when glycemic control is inadequate or when therapy has changed. The degree of glycation of other proteins, such as albumin, can be used as an alternative indicator of glycemic control when the A1C is inaccurate (hemolytic anemia, hemoglobinopathies). The fructosamine assay (measuring glycated albumin) reflects the glycemic status over the prior 2 weeks. Alternative assays of glycemic control should not be routinely used since studies demonstrating that it accurately predicts the complications of DM are lacking. “Perfect glycemic control” would mean that glucose levels were always normal (70–130 mg/dl, or 3.9-7.2 mmol/L) and indistinguishable from a person without diabetes. In reality, because of the imperfections of treatment measures, even “good glycemic control” describes blood glucose levels that average somewhat higher than normal much of the time. In addition, one survey of type 2 diabetics found that they rated the harm to their quality of life from intensive interventions to control their blood sugar to be just as severe as the harm resulting from intermediate levels of diabetic complications. Accepted “target levels” of glucose and glycosylated hemoglobin that are considered good control have been lowered over the last 25 years, because of improvements in the tools of diabetes care, because of increasing evidence of the value of glycemic control in avoiding complications, and by the expectations of both patients and physicians. What is considered “good control” also varies by age and susceptibility of the patient to hypoglycemia. In the 1990s the American Diabetes Association conducted a publicity campaign to persuade patients and physicians to strive for average glucose and hemoglobin A1c values below 200 mg/dl (11 mmol/l) and 8%. Currently many patients and physicians attempt to do better than that. Poor glycemic control refers to persistently elevated blood glucose and glycosylated hemoglobin levels, which may range from 200–500 mg/dl (11-28 mmol/L) and 9-15% or higher over months and years before severe complications occur. Meta-analysis of large studies done on the effects of tight vs. conventional, or more relaxed, glycemic control in type 2 diabetics have failed to demonstrate a difference in all-cause cardiovascular death, non-fatal stroke, or limb amputation, but decreased the risk of nonfatal heart attack by 15%. Additionally, tight glucose control decreased the risk of progression of retinopathy and nephropathy, and decreased the incidence peripheral neuropathy, but increased the risk of hypoglycemia 2.4 times.

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DM prevalence, awareness, morbidity and mortality:

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In 2006, the General Assembly of the United Nations unanimously adopted a resolution (61/225) which recog­nizes that diabetes is a global pandemic posing a serious threat to global health, acknowledging it to be a chronic, debilitating, and costly disease associated with major complications. Diabetes reduces the quality of life, can generate multi-system morbidities and premature death, and consequently increases healthcare costs. Currently, in many countries, people with diabetes have a significantly decreased life expectancy.

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The figure below shows rising worldwide DM prevalence:

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In our modern world, diabetes prevalence is on the rise. In 2010, statistics showed that over 25 million people in the United States, including children, have diabetes mellitus. Of that population, seven million people who have diabetes are undiagnosed. In addition, diabetes prevalence increases with age. Between 2005 and 2008, statistics showed 26.9% of people with type 1 or type 2 diabetes mellitus were over the age of 65 years, while 17.4% comprised those between 20 and 64 years of age. At this rate, the number of people diagnosed with diabetes in the world is expected to increase by 114% from the year 2000 to 2030. As a result, effective diabetes management will continue to be an important consideration for patients and is key to reducing the risk of complications such as heart disease, blindness, renal disease, and unnecessary amputations.

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WHO on diabetes 2013:

Key facts:

1. 347 million people worldwide have diabetes.

2. In 2004, an estimated 3.4 million people died from consequences of high fasting blood sugar.

3. More than 80% of diabetes deaths occur in low- and middle-income countries.

4. WHO projects that diabetes will be the 7th leading cause of death in 2030.

5. Healthy diet, regular physical activity, maintaining a normal body weight and avoiding tobacco use can prevent or delay the onset of type 2 diabetes.  

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World health statistics 2012 reports data on people with raised blood glucose levels. One in 10 adults has diabetes. While the global average prevalence is around 10%, up to one third of populations in some Pacific Island countries have this condition. Left untreated, diabetes can lead to cardiovascular disease, blindness and kidney failure. Already, diabetes extracts a high cost in health care dollars, economies’ financial stability, lost productivity, and it destroys lives and families.

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The International Diabetes Federation (IDF) — the umbrella organization for 200 diabetes associations in more than 160 countries — just released its 2013 Diabetes Atlas. It cites current statistics and the rise of diabetes worldwide. If you’ve been following the trend in diabetes, it will not surprise you to know diabetes continues to rise, unabated, around the world. Type 2 diabetes, which many consider an epidemic currently, is increasing worldwide predominantly due to poor diet, sedentary lifestyle and the fact that we are living longer. The research, published by the American Heart Association’s journal Circulation, found that eating fast food two or more times a week increases the risk of developing Type 2 diabetes by 27 percent.

 

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New wealth and development in the Middle East has already led to one in 10 adults having the disease. The greatest number of people with diabetes worldwide is between the ages of 40 and 59. Every six seconds someone dies from diabetes. Diabetes imposes unacceptably high human, social and economic costs on countries at all income levels. In Africa, three quarters of diabetes deaths are in people under 60 years old, handicapping Africa’s ability for development. In 2013, the world spent $548 billion (US) on diabetes health care — 11 percent of the total spent for health care worldwide. 175 million people are currently undiagnosed and progressing toward complications unaware. The number of people with diabetes globally will increase by 55 percent by 2035. 

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Diabetic death rates:

Diabetes causes 4.6 million deaths and costs over 465 billion US dollars in global healthcare expenditure every year. Diabetes is already the world’s most costly epidemic. By 2020, in countries such as the US, Malaysia and Indonesia over 10% of the population will be diabetic and there will be over 300m diabetics worldwide. Up to 5% of GDP and over 25% of many public healthcare budgets globally will be typically being spent on dealing with the consequences of diabetes.  

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Diabetic awareness:

46 % of diabetics are unaware that they have diabetes.

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The incidence of both type 1 and type 2 diabetes mellitus is increasing; the former has been attributed to an increase in environmental factors, whereas the latter is strongly associated with increasing rates of obesity. Alarmingly, during the past 10 years, type 2 diabetes has been diagnosed more frequently in patients younger than 44 years. In this context, physicians face a dual challenge: not only are there more patients with diabetes, but also the disease is being increasingly diagnosed in younger patients who will require lifelong management. Adding to this burden is the increasing complexity of caring for patients with type 1 diabetes and the expanding armamentarium of medications for patients with type 2 diabetes. The chronic hyperglycemia of diabetes is associated with both micro- and macrovascular complications, which result in significant increases in morbidity and mortality. Improving glycemic control in diabetic patients has been shown to reduce these complications. The main goal of treatment is to keep blood sugar levels in the normal or near-normal range. Checking one’s blood sugar is one of the best ways to know how well the diabetes treatment plan is working.

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Diabetes mellitus is a condition characterized biochemically by increased blood glucose concentrations and associated with both small blood vessel complications in the eyes (retinopathy), kidneys (nephropathy), and peripheral nerves (neuropathy) and large blood vessel complications of the heart (causing heart attacks), head and neck (causing strokes), and legs (leading to gangrene and amputations). Diabetic retinopathy is the leading cause of blindness in industrialized countries in people between the ages of 20 and 74 years. Diabetic nephropathy is the leading cause of people requiring dialysis for kidney failure. Diabetic neuropathy underlies most cases of lower extremity amputations, much more so than the large vessel complication in the legs. There is overwhelming evidence that keeping blood glucose near normal will have a marked beneficial effect of limiting (and possibly preventing) the small vessel complications. Although one recent article showed that lowering blood glucose concentrations in type 1 diabetic patients had a beneficial effect on coronary artery disease (CAD) many years later, five previous articles in type 2 diabetic patients did not.

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What is the DCCT?

The Diabetes Control and Complications Trial (DCCT) was a major clinical study conducted from 1983 to 1993 and funded by the National Institute of Diabetes and Digestive and Kidney Diseases. The study showed that keeping blood glucose levels as close to normal as possible slows the onset and progression of the eye, kidney, and nerve damage caused by diabetes. In fact, it demonstrated that any sustained lowering of blood glucose, also called blood sugar, helps, even if the person has a history of poor control. The DCCT involved 1,441 volunteers, ages 13 to 39, with type 1 diabetes and 29 medical centers in the United States and Canada. Volunteers had to have had diabetes for at least 1 year but no longer than 15 years. They also were required to have no, or only early signs of, diabetic eye disease. The study compared the effects of standard control of blood glucose versus intensive control on the complications of diabetes. Intensive control meant keeping hemoglobin A1C levels as close as possible to the normal value of 6 percent or less. The A1C blood test reflects a person’s average blood glucose over the last 2 to 3 months. Volunteers were randomly assigned to each treatment group.

What is the EDIC?

When the DCCT ended in 1993, researchers continued to study more than 90 percent of participants. The follow-up study, called Epidemiology of Diabetes Interventions and Complications (EDIC), is assessing the incidence and predictors of cardiovascular disease events such as heart attack, stroke, or needed heart surgery, as well as diabetic complications related to the eye, kidney, and nerves. The EDIC study is also examining the impact of intensive control versus standard control on quality of life. Another objective is to look at the cost-effectiveness of intensive control.

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DCCT Study Findings:

Intensive blood glucose control reduces risk of

  • eye disease
    76% reduced risk
  • kidney disease
    50% reduced risk
  • nerve disease
    60% reduced risk

EDIC Study Findings:

Intensive blood glucose control reduces risk of

  • any cardiovascular disease event
    42% reduced risk
  • nonfatal heart attack, stroke, or death from cardiovascular causes
    57% reduced risk

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Large, long-term, randomized controlled trials in both type 1 diabetes (T1DM) and T2DM have shown that ag­gressive treatment of hyperglycemia significantly reduces the development and progression of microvascular com­plications. A weaker relationship is observed in most studies between hyperglycemia and the development/ progression of macrovascular disease. However, in a systematic review with meta-analysis including 6 randomized controlled trials involving 27,654 patients, tight blood glucose control reduces the risk for some macrovascular and microvascular events, without effect on all-cause mortality and cardiovascular mortality. Recent RCTs have not shown a benefit of tight glucose control on macrovascular disease in people with T2DM of long duration and high cardiovascular risk. In the earlier studies, the benefits of tight control on macrovascular outcomes were seen only many years after the initial trial had ended and when levels of glycemic control in the intervention and control arms had converged. This so called ‘metabolic memory’ or ‘legacy effect’ suggests that, while the short-term benefits of tight glycemic control for macrovascular disease have not been shown in RCTs, the longer-term benefits may be substantive particu­larly when good HbA1c levels are achieved and maintained early in the course of the disease. The longer-term findings suggest that greater benefits (clinical and economic) are obtained when simultaneous control of glycemia, blood pressure and lipid levels has been achieved. Diabetes is a significant and growing worldwide concern with potentially devastating consequences. Numerous studies have demonstrated that optimal management of glycemia and other cardiovascular risk factors can reduce the risk of development and progression of both microvascular and macrovascular complications.

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Proper glycemic control, including self-monitoring of blood glucose (SMBG) is key to managing diabetes. It has been shown that microvascular complications, such as neuropathy, nephropathy, and retinopathy, are reduced 40% for every percentage reduction in hemoglobin A1c values. Furthermore, a survey of 1,895 diabetic patients suggested that decreased blood glucose monitoring compliance was observed in patients who had more than two hospitalizations in a 2-year period. Yet, despite current evidence of the importance of daily SMBG, many patients who have diabetes do not regularly check their blood glucose at home. For example, up to 67% of patients do not check their blood glucose regularly for reasons such as sore fingers, inconvenience, and the fear of needles.  Hence, some patients choose to avoid these unpleasant aspects by simply not checking blood sugars on a regular basis, especially since hyperglycemia is often asymptomatic in the early stages of diabetes mellitus. In addition to the difficulties posed by SMBG, maintaining proper glycemic control can be a challenge, especially for patients who are on insulin therapy. Patients who use short-acting insulin to help control blood glucose during a meal must constantly estimate their insulin doses by counting the carbohydrate content of the meal. Since most of us do not eat the same meal every day for breakfast, lunch, and dinner, counting carbohydrates can become a cumbersome process. Furthermore, improperly estimating an insulin dose can potentially result in undertreatment or overtreatment, which may have grave consequences. Based on discharge data of Californian hospitals, hypoglycemia was found to be responsible for approximately 1.7% of hospitalized diabetic patients. In today’s society, even with better understanding of the importance of glycemic control, only 41% of people with diabetes have the ability to calculate an insulin dose based on carbohydrate intake and blood glucose levels. Controlling blood sugar with fast-acting insulin is difficult because it poses the risk of hypoglycemia or hyperglycemia if insulin is not administered in a correct manner. It is difficult to estimate the amount of insulin required with varying portion sizes and fluctuating sugar levels throughout the day.

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Screening for DM:

Widespread use of the FPG or the A1c as a screening test for type 2 DM is recommended by experts because (1) a large number of individuals who meet the current criteria for DM are asymptomatic and unaware that they have the disorder, (2) epidemiologic studies suggest that type 2 DM may be present for up to a decade before diagnosis, (3) some individuals with type 2 DM have one or more diabetes-specific complications at the time of their diagnosis, and (4) treatment of type 2 DM may favorably alter the natural history of DM. The ADA recommends screening all individuals >45 years every 3 years and screening individuals at an earlier age if they are overweight [body mass index (BMI) >25 kg/m2] and have one additional risk factor for diabetes. In contrast to type 2 DM, a long asymptomatic period of hyperglycemia is rare prior to the diagnosis of type 1 DM. A number of immunologic markers for type 1 DM are becoming available, but their routine use is discouraged pending the identification of clinically beneficial interventions for individuals at high risk for developing type 1 DM.

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Note:

I have seen many patients who have normal FPG but higher PPG and these patients ultimately develop frank type 2 DM. I therefore recommend only PPG as a screening test for T2DM (vide infra).

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History of SMBG:

In 1957, Kohn showed that Clinistix could also give approximate results for blood glucose. In 1965 an Ames research team under Ernie Adams went on to develop the first blood glucose test strip, the Dextrostix, a paper reagent strip which used the glucose oxidase/peroxidise reaction but with an outer semipermeable membrane which trapped red blood cells but allowed soluble glucose to pass through to react with the dry reagents. A large drop of blood (approximately 50–100 μL) was applied to the reagent pad, and after one minute the surface blood was gently washed away and the pad colour visually assessed against a colour chart to give a semiquantitative blood glucose value. However, the colours were difficult to visualise as the colour blocks were affected by ambient lighting conditions, and variation in individual visual acuity made it difficult to obtain accurate and precise readings. Although the Dextrostix was designed for use in doctors’ offices, the concept of diabetic patients undertaking the measurements had not been considered. Around the same time, the German company Boehringer Mannheim developed a competitive blood glucose strip, the Chemstrip bG. This was easier to use because the drop of blood was wiped off using a cotton wool ball, and, as it had a dual colour pad (one beige, the other blue), it was easier to visualise the colour. The visually monitored blood glucose test strips, Dextrostix (Ames) and Chemstrip bG (Boehringer Mannheim), were widely used in clinics, surgeries and hospital wards, notably intensive care units, for adults and neonates. However, colours were prone to fade and it was realised that there were highly significant visual variations in the assessment of colours across the range of glucose concentrations using Dextrostix. These limitations became the trigger to develop an automatic, electronic glucose test strip reader to improve precision and give more quantitative blood glucose results.  The development in the 1950s of the oxygen electrode by Clarke for the measurement of pO2 was the forerunner in the development of the first biosensor electrode. The first description of a biosensor, an amperometric enzyme method for glucose measurement, was made by Clarke and Lyons in 1962. This concept was incorporated in the measurement of blood glucose in the Yellow Spring 24AM ‘desktop’ analyser, which became commercially available in the mid-1970s. The first blood glucose biosensor system, the ExacTech, was launched in 1987 by MediSense. It used an enzyme electrode strip developed in the UK at Cranford and Oxford universities. The strip contained glucose oxidase and an electron transfer mediator, ferrocene, which replaced oxygen in the original glucose oxidase reaction; the reduced mediator was reoxidised at the electrode to generate a current detected by an amperometric sensor. The meter was available in two highly original forms, a slim pen or a thin card the size of a credit card. Evaluation reports showed that accuracy, precision and error grid analysis were satisfactory. The use of electrode technology thus heralded what became designated the third-generation BGMS. In 1987, with the increased use of SMBG systems, the American Diabetic Association (ADA) lowered the preferred glucose meter deviation compared to laboratory reference methods to 15%. A useful evaluation statistical tool, error grid analysis, was developed by Clarke et al. and applied by Kochinsky et al., which gave an improved measure of accuracy related to clinical significance and decision making.

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Four generations of glucometer:

The figure above shows four generations of blood glucose meter. Sample sizes vary from 30 to 0.3 μl. Test times vary from 5 seconds to 2 minutes (modern meters typically provide results in 5 seconds).

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Body fluid sample for glucose measurement:

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The figure below shows overview of body fluid glucose measurement by various techniques and from various sites:

 

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Three of the major factors that influence glucose test results are the type of chemical analysis used for the test, the type of sample analyzed (whole blood verses plasma), and the source of the blood (venous, capillary, or arterial).

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Whole blood vs. plasma glucose:

Glucose is measured in whole blood, plasma or serum. Historically, blood glucose values were given in terms of whole blood, but most laboratories now measure and report plasma or serum glucose levels. Because red blood cells (erythrocytes) have a higher concentration of protein (e.g., hemoglobin) than serum/plasma, serum/plasma has higher water content and consequently more dissolved glucose than does whole blood. To convert from whole-blood glucose, multiplication by 1.15 has been shown to generally give the serum/plasma level. Under usual circumstances, the concentration of glucose in whole blood is about 15% lower than in plasma or serum, but the difference will be less in patients with low hematocrits. Collection of blood in clot tubes for serum chemistry analysis permits the metabolism of glucose in the sample by blood cells until separated by centrifugation. Red blood cells, for instance, do not require insulin to intake glucose from the blood. Higher than normal amounts of white or red blood cell counts can lead to excessive glycolysis in the sample, with substantial reduction of glucose level if the sample is not processed quickly. Ambient temperature at which the blood sample is kept prior to centrifuging and separation of plasma/serum also affects glucose levels. At refrigerator temperatures, glucose remains relatively stable for several hours in a blood sample. Loss of glucose can be prevented by using Fluoride tubes (i.e., gray-top) since fluoride inhibits glycolysis. However, these should only be used when blood will be transported from one hospital laboratory to another for glucose measurement. Red-top serum separator tubes also preserve glucose in samples after being centrifuged isolating the serum from cells. If you have so far been using a blood glucose monitoring system calibrated for whole blood and are now switching to one calibrated for plasma or vice versa, you may need new target values. You will have to re-adjust though when interpreting the results: since glucose concentration in plasma is approx. 10-15 per cent higher than in whole blood, the levels indicated by meters with plasma-calibrated test strips are approx. 10-15 per cent higher. All the manufacturers will probably switch to plasma in future and in many European countries it has already taken place. Diabetics will find the information about how their meter has been calibrated on the leaflet accompanying the test strips or also in the operating instructions for the meter.

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Is plasma glucose measurement best?

Conversion of glucose concentrations determined in different sample systems by use of factors is an oversimplification and probably leads to unpredictable rates of discordant disease classifications. These problems are becoming more relevant with the widespread use of point-of-care testing instruments, including blood gas analyzers with integrated glucose sensors that measure glucose in the plasma water fraction. The only solution for this dilemma is to use only one sample system. The experimental data clearly indicate that the use of plasma should be preferred to diagnose glucose intolerance, including diabetes. The logistic disadvantages are the centrifugation step and the prevention of glycolysis. Chan showed that delays in processing blood specimens in hospital practice may lead to misclassification in up to 7% of GTTs. Stahl proposed storage on ice for not more than 1 h until centrifugation. However, this recommendation may not be acceptable for many hospitals. The use of capillary hemolysate together with a reduced decision limit thus may be a second choice for the detection of diabetes.

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IV fluid and blood glucose measurement:

To prevent contamination of the sample with intravenous fluids, particular care should be given to drawing blood samples from the arm opposite the one in which an intravenous line is inserted. Alternatively, blood can be drawn from the same arm with an IV line after the IV has been turned off for at least 5 minutes, and the arm has been elevated to drain infused fluids away from the vein. Inattention can lead to large errors, since as little as 10% contamination with a 5% glucose solution (D5W) will elevate glucose in a sample by 500 mg/dL or more.

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60 % of body weight in men and 50 % of body weight in women is water. Total body water is distributed between 3 fluid compartments in body. Intracellular water (intracellular fluid-ICF) makes up about two- thirds of total body water, with remaining one-third, the extracellular water (extracellular fluid- ECF) being distributed between intravascular (25 %) and interstitial (75 %) compartment. The pores between endothelial cells in capillary allow free movement of water and solutes but do not allow proteins to pass through. So glucose readily passes through intravascular compartment to interstitial compartment. When any glucose-containing IV drip is given, each pint (500ml) of D5W/D5NS contains 25 gm glucose. If you give each pint slowly in 8 hours, body gets 52 mg of glucose every minute. This 52 mg glucose is distributed in 13.8 liter of extracellular water in a 70 kg man (blood water plus interstitial water). So blood glucose value will rise by 0.38 mg/dL every minute if there is no insulin.  So if you have given glucose containing IV drip to a diabetic who has near zero insulin secretion, blood glucose will rise by 0.38mg/dL every minute when drip duration is 8 hour. If the same drip is given in 4 hour, the rate of glucose rise is 0.76mg/dL every minute.  However, if the same drip is given to a normal non-diabetic person, slight increase in blood glucose will stimulate insulin secretion and therefore blood glucose will be reasonably maintained provided drip rate is 4 to 8 hours per each pint of fluid. The corollary is that if you have collected blood from the arm opposite the one in which an intravenous line is inserted, and if you are getting high glucose level, do not blame IV drip but patient may be diabetic.

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Every day average person eats 900 to 1300 Kcal of carbohydrates in 2000 Kcal diet. If you divide it in three meals, breakfast, lunch and dinner equally, you eat approximately 300 to 430 Kcal of carbohydrate in each meal. Even if half of carbohydrate is converted into glucose, every meal contains 150 to 215 Kcal from glucose [the other being fructose/galactose]. In other words, every meal generates minimum 37 to 53 gm of glucose to be assimilated in body. Yet in normal non-diabetic person, insulin secretion does not allow the blood sugar to rise much and maximum blood sugar 2 hr after meal is < 140 mg/dL. If normal person can dispose off 50 gm glucose in 2 hours with blood sugar < 140 mg/dL; sure it can dispose off IV D5W/D5NS 500 ml containing 25 gm glucose without rise in blood sugar provided drip rate is not very fast. So drip rate of 125ml/hr to 60 ml/hr would not cause hyperglycemia in normal non-diabetic person.

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Why have I not taken renal glucose loss into consideration in the above formula?

First let me discuss normal non-diabetic person. His GFR is 125 ml/min and blood glucose 100 mg/dL. His kidneys would filter 180 gms of glucose in 24 hrs and more than 99.9 % of filtered glucose is reabsorbed resulting in urine glucose of < 130 mg/24 hr. Now let me discuss uncontrolled diabetic with GFR 125 ml/min and blood glucose 450 mg/dL. He will filter 810 gms of glucose in 24 hrs. Since his blood sugar is far higher than renal threshold, he would have massive renal glycosuria with osmotic diuresis and polyuria. I have gone through various studies on osmotic diuresis in diabetes. For blood glucose of 450mg/dL, when urine output is 5 liter/24 hr, urine glucose concentration is about 8 gm/liter. Further increase in urine output reduces urine glucose concentration, so urine output of 12 liter/24 hour has urine glucose concentration 5 gm/liter. In other words, maximum urine glucose loss in uncontrolled diabetes is 40 to 60 gm glucose in 24 hours. So approximately 6 % of blood glucose is lost in urine and 94 % of filtered glucose is still reabsorbed in uncontrolled diabetes. Therefore, rate of rise of blood glucose after IV D5W/D5NS even in uncontrolled diabetes will change slightly due to renal glucose loss.

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Note:

Excess water infused through routine IV drip would be excreted by kidneys and would not dilute blood glucose concentration.  

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Artery vs. capillary vs. vein vis-à-vis blood glucose:

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Artery to capillary to vein:

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Home glucose monitoring has traditionally relied on a drop of capillary blood from the finger. Blood glucose is generally measured as the venous plasma level. There is a 3–5 mg/dL difference between arterial and venous levels, with higher differences in the postprandial state. Levels are higher in the arterial blood because some of the glucose diffuses from the plasma to interstitial fluid (IF) as blood circulates through the capillary system. Arterial blood glucose and capillary blood glucose have been shown to be almost identical in concentration, even though the distribution of the glucose to the systemic capillaries does not occur instantaneously. The finger-prick blood sampling is to collect blood in peripheral capillaries and the blood glucose concentration approximates to the level of arterial blood glucose (Rasaiah, 1985). Despite few differences between fasting capillary blood glucose and fasting venous blood glucose, postprandial venous blood glucose is lower than postprandial capillary blood glucose by 7 % because glucose absorbed by the human tissues and remaining glucose returns to veins. Accordingly, the level of arterial blood glucose or postprandial capillary blood glucose is higher than that of postprandial venous blood glucose.

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Glucose test values may not match with different blood samples because glucose is being consumed by the body:

Glucose diffuses through the capillaries and is consumed by the cells, so arterial glucose concentration (the capillaries’ source) should be higher than venous glucose concentration (the capillaries’ drain) unless capillary diffusion or muscle glucose consumption has been stopped. It has been shown that in fasting subjects the glucose levels in arterial, capillary, and venous samples are practically the same (venous glucose is generally 2-5 mg/dL lower than fingerstick capillary or arterial blood glucose). It is only after meals, when glucose uptake in the periphery is rapid, that glucose levels in fingerstick capillary blood samples can exceed those in concurrently drawn venous samples. A typically quoted value is up to 80 mg/dL difference between venous and fingerstick capillary blood glucose values one hour after ingestion of 100 grams of glucose. Current literature has attempted to determine exactly how glucose levels in venous, arterial and fingerstick capillary blood vary so comparisons can be made. Venous blood is usually employed for laboratory analysis and is preferable in diabetes testing. However, because of the widespread use of SMBG instruments, fingerstick capillary blood samples have also become a standard. Fingerstick capillary blood has been shown to be predominantly arterial and so approximates the concentration of arterial blood. Somogyi compared the glucose content of blood samples simultaneously drawn from the femoral artery and the fingertip of non-diabetics one-hour after ingestion of 50 grams of glucose. The ingested glucose would produce a substantial difference between the arterial and venous glucose levels, and so should indicate whether fingerstick capillary blood was predominantly arterial, venous, or a combination of the two. The discrepancies between arterial and fingerstick capillary blood were less than 1 mg/dL for all three subjects studied and seemed to justify the substitution of fingerstick capillary for arterial blood glucose. Somogyi also studied the difference between fingerstick capillary and venous glucose levels during the fasting state on 100 healthy individuals (fasting for 10-14 hours). The average fasting glucose value in fingerstick capillary blood samples was 89 mg/dL (78 – 97 mg/dL) with the average venous blood glucose value 5 mg/dL lower (84 mg/dL).  In the same study, both venous and fingerstick capillary blood glucose values were followed for a period of 4 hours in 44 healthy individuals that had ingested a 100-gram glucose load (see figure below). A substantial increase in the fingerstick capillary to venous blood glucose difference were measured after an oral administration of glucose, and this difference remained consistently higher than the initial fasting level until the blood glucose returned to the fasting blood glucose level. The paper also found that the larger the glucose load ingested, the higher the glucose peaks, and the greater the maximal difference between the fingerstick capillary (paper assumed this to be arterial) blood glucose level and the venous blood glucose level.

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The difference between capillary and venous blood in the postprandial state is due to muscles removing more glucose from the blood than the liver in the presence of adequate insulin action.  It has been shown that a lack of insulin (in the de-pancreatized animal) shows an arterial to venous glucose difference that is extremely small and that injection of insulin produces an increase in this difference. As such, glucose uptake by the tissue is dependent on the sensitivity of the tissue to insulin, the circulating insulin level and the local blood flow. Diabetics may have various degrees of peripheral insulin resistance or various blood insulin levels or both, so a single patient’s nonfasting difference may not be seen in other patients. The nonfasting difference will depend on meal size, meal content, time of sample collection, and individual patient variability. In summary, glucose levels in arterial and fingerstick capillary blood have been so closely correlated that most studies refer to arterial glucose measurements even if they measure fingerstick capillary samples. When studies are performed with the patient under fasting conditions, glucose levels in fingerstick capillary blood gives reliable quantitative estimates of the venous glucose concentration as determined in the laboratory for most patients. However, when the patients are under a glucose load the venous and fingerstick capillary glucose levels diverge in a similar but unpredictable manner where the venous value may be anywhere from 2% lower during fasting to 26% lower within one hour after a glucose load. Unfortunately, empirical conversion factors have been applied to generate equivalent glucose values for different blood sample compartments without adequate data to show equivalence. One such conversion is that fingerstick capillary blood has a glucose concentration that is 7-8% higher than the concurrently drawn venous concentration. Others have presented charts showing the equivalence of venous and capillary glucose levels that differ between 0% to 13% depending on the glucose level. The validity of these conversion factors has been called into question since individual differences between capillary and venous blood glucose values are too great to allow for a meaningful transformation to be applied. It can be reasonably concluded that there is no simple conversion factor available to explain differences between glucose values in the various blood compartments.

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Glucose test values may not match because the body is consuming oxygen:

A study by Liu measured arterial, fingerstick capillary, and venous blood samples from six healthy males for oxygen saturation and glucose. Each subject’s right hand was placed in a warm air box at 55-60 degrees C to determine if warm air would arterialize the venous blood obtained from a cannula inserted into the dorsal right-hand vein. The oxygen saturation measured in the arterial blood was 97%. The oxygen saturation measured in venous blood on a nonheated hand was 80%. The oxygen saturation measured in the heated ‘arterialized’ venous blood was 94% or approximately 3% below the average arterial value. Glucose levels also showed equilibration between the two blood compartments with heating. The difference between fasting arterial glucose levels and venous glucose levels with no heating of the hand ranged between 4-9 mg/dL (6% – 9%), and this glucose difference significantly correlated with the differences in oxygen saturation between the two blood supplies. The difference between the arterial glucose levels and ‘arterialized’ venous glucose levels obtained by heating the hand averaged less than 2 mg/dL difference, and this glucose difference had a low correlation with the differences in oxygen saturation between the two blood supplies.

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Many analytical procedures are used to measure blood glucose but the most common techniques are enzymatic. Enzymes commonly used in commercial test strips are glucose oxidase, glucose dehydrogenase, or hexokinase combined with glucose-6-phosphate dehydrogenase. Glucose oxidase has historically been the preferred enzyme because of its excellent specificity for glucose, good room temperature stability, and relatively low cost. However, the reaction requires an adequate oxygen supply, and this leads to an oxygen dependence problem in certain measurement systems. Electrochemical measurement combined with glucose oxidase involves a mediator to transfer electrons between the electrodes. The mediator attempts to replace oxygen in the reaction sequence. This makes oxygen in the blood sample a competitor in the reaction and produces varying results with varying oxygen concentrations (oxygen dependence). Electrochemical test strips that are calibrated using fingerstick capillary blood can read up to 30% higher when tested with venous blood because of its 50-60% lower pO2 values. A similar situation exists with some optical reflectance methods. Generally, atmospheric oxygen is sufficient to meet the glucose oxidase reaction requirements, but different test strip design can block the diffusion of oxygen to the reaction site. Commercial analyzers attempt to circumvent oxygen effects by pre-dilution of the sample into an oxygenated buffer. Glucose dehydrogenase can be made oxygen independent when it is combined with a cofactor called pyrroloquiniline quinone (PQQ). Using this enzyme combination effectively eliminates oxygen competition and enables the use of venous or arterial samples where extremes of pO2 may occur. The trade-off is reduced specificity for glucose in that it also detects maltose, galactose, and metabolites of maltodextrins. There is also reduced operational stability when compared to glucose oxidase. Hexokinase combined with glucose-6-phosphate dehydrogenase also avoids oxygen dependence, but the test strip is inherently more sensitive to heat and moisture, and therefore special attention is paid to packaging. Glucose comparison studies between arterial, capillary, and venous blood must consider the significant differences in oxygen tension between the blood compartments when using analytical systems that are oxygen dependent. Ideally, the effect of pO2 needs to be examined by monitoring oxygen concentrations and determining if a correlation exists for glucose.  

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Glucose test values may not match because of low blood flow in the forearm:

Glucose consumption and oxygen variation concern physiological parameters that would lead to a bias between glucose test results taken simultaneously from two different blood compartments during either fasting or the meal cycle. A third physiological parameter that would cause glucose in one blood compartment to lag or lead another is flow or circulation problems in a capillary bed. Many medical and physical conditions can affect capillary blood flow with the problem being either systemic or localized. Localized variations in blood flow associated with the capillary beds would be a major contributing factor to erroneous comparison data between two capillary blood supplies such as within the finger and forearm. A localized variation in blood flow would also be a contributing factor in glucose differences measured within capillary, arterial, and venous blood.  Lower flow in the capillaries will lead to greater exchange of nutrients and metabolites. Simplistically, a drop of blood moving slowly will have more time to lose glucose to the consuming tissue compared to a drop of blood moving quickly. In tissues like the heart, all capillaries are normally open to perfusion, but in skeletal muscle and intestine only 20% – 30% of capillaries are normally open. As an example, it is possible that only 70% of the forearm capillaries are flowing normally at any one time, and 30% have slower-moving blood that is being depleted of glucose and oxygen by diffusion into the cellular space. Lancing into such a location would produce glucose readings lower than both arterial and venous blood glucose since more glucose consumption would occur in areas with no flow. If the measurement technique were oxygen sensitive, then the measurement would also be lower because of oxygen consumption by the surrounding tissue. Ideally, blood collection from sites such as the forearm and thigh should target a highly perfused capillary bed, and either compensate for or be independent of temporal changes in blood flow.

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Simultaneous measurements of arterial and venous blood samples should produce different glucose values in healthy people due to glucose utilization by peripheral tissues. Unfortunately, the magnitude of this glucose difference cannot be predicted due to the large number of variables that affect it. Since capillary blood has been expanded to refer to blood collected from the finger, forearm, ear, heel, calf, and stomach, questions have arisen if each of these is predominantly arterial or venous. Published studies have justified equating arterial and fingerstick capillary glucose levels under most conditions but no other capillary blood source has been equally studied. Local, rhythmic changes of blood flux within capillary beds play a larger role in the variation of forearm capillary blood glucose vs. fingerstick capillary blood glucose than the differences between arterial and venous values. It is not to say that forearm capillary is more like venous, but that the independent temporal changes in select capillary beds affect the venous value because it is upstream.   

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A Comparison between Venous and Finger-Prick Blood Sampling on Values of Blood Glucose: a 2012 study:

The purpose of this study is to investigate changes in fasting and postprandial blood glucose values of 12 healthy voluntary subjects, who were asked to take 50g glucose solution, during 2 hours and compare correlations and differences based on two types of blood samplings, venous blood sampling and finger-prick blood sampling. It can be seen from experimental results that (1) there is no significant difference between the fasting venous blood glucose value (87.4±0.4 mg/dL) and the fasting capillary blood glucose (91.6±4.4 mg/dL) (0 min); (2) there is significant difference between the postprandial venous blood glucose concentration and the postprandial capillary blood glucose concentration, both of which reach the maximum levels at 30 min (postprandial venous blood glucose value=122.0±1.2 mg/dL; postprandial capillary blood glucose value=163.8±1.3 mg/dL), with glucose solution ingested by subjects; (3) the mean capillary blood glucose concentration is higher than the mean venous blood glucose concentration by 35%; (4) the correlation coefficient r=0.875(p<0.001) suggests statistical discrepancy and positive correlation between two groups of blood glucose concentrations which imply the venous blood glucose concentration is a better indicator to clinically test blood glucose due to higher stability and fewer interference factors. The blood glucose is defined as venous plasma glucose according to the criteria of WHO to diagnose diabetes but the whole blood glucose on the peripheral capillary basis is available in a glucose meter. As one simple and convenient tool, the glucose meter is applicable to self-monitoring of blood glucose values which are accurate enough but proportional to venous plasma glucose values by a stable factor of 1.12 due to a different numerical benchmark rather than an error.

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Comparability of Blood Glucose Concentrations Measured in Different Sample Systems for Detecting Glucose Intolerance: A study:

The interconversion of glucose values for venous and capillary blood is further complicated by the arteriovenous difference. In the fasting state, the glucose concentrations in arterial, capillary, and (forearm) venous blood are supposed to be almost indistinguishable. In contrast, arterial blood glucose values may differ by 20% or as much as 70% in the postprandial state. The mean arteriovenous differences are largest in lean nondiabetic individuals, smallest in diabetic individuals, and larger in deep veins than in superficial vessels. Other factors can influence the differences in glucose concentrations among the various samples. Thus, the conversion of concentration values from one system (or sample type) to another is subject to unpredictable errors. Several authors have already rejected the practice of converting glucose concentrations and have recommended that plasma be used for all glucose determinations. In a recent editorial, glucose measurement in whole blood was considered anachronistic, but only whole blood is used by home monitoring and near-patient monitoring devices. Many laboratories measure the glucose concentration in whole blood, especially in capillary whole blood, for therapeutic monitoring and for diagnosing hypo-, normo-, and hyperglycemia. However, the applicability of whole blood for determining glucose intolerance is still a matter of debate. Many practitioners tend to use capillary blood (CB) for diagnostic purposes. The decision limits usually applied for whole blood are those recommended by WHO and the American Diabetes Association, which are based on epidemiologic studies with venous plasma (VP). In practice, either measured values or decision limits are converted from one sample system to another.

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Blood glucose vs. Interstitial fluid (IF) glucose:

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Interstitial fluid (IF):

IF constitutes approximately 45% of the volume fraction of human skin, with blood vessels contributing to the 5% of the skin volume. IF is a relatively passive medium that has one-third of the total protein concentration as compared to plasma with an average albumin/globulin ratio of 1.85  The total body volume of the interstitial space is three times that of plasma; however, IF compartments around the cells are microscopic. IF bathes the cells and feeds them with nutrients, including glucose, by providing a corridor between the capillaries and the cell. There is less IF in the subcutaneous tissue than in the dermis. Adipose tissue, just below the dermis, is richly vascularized with capillary walls that are relatively thinner (0.03 μm vs. 0.1 μm) than the capillaries of the dermis. The basal membranes of the capillaries are in direct contact with the adipose cell cytoplasmic membrane. The size of adipocytes might affect the amount of IF in the subcutaneous tissue, suggesting that adiposity might have an effect on IF glucose concentrations.

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The Relationship between Plasma Glucose and Interstitial Glucose:

Plasma and IF have different characteristics and should be considered as separate glucose compartments. Glucose is transferred from the capillary endothelium to the IF by simple diffusion across a concentration gradient without the need of an active transporter. Blood flow to the area dictates the amount of glucose delivered. Interstitial glucose values are determined by the rate of glucose diffusion from plasma to the IF and the rate of glucose uptake by subcutaneous tissue cells. Thus, the metabolic rate of the adjacent cells and other factors, like insulin, affecting glucose uptake by cells, the glucose supply from the blood vessel, blood flow to the area, and the permeability of the capillary that can be altered by many factors, including nerve stimulation, influence the interstitial glucose levels. The time required for glucose to diffuse from the capillary to the tissue plays an important role in the lag time between changes in plasma and interstitial glucose levels, but the lag during rapid changes of blood glucose is likely due to the magnitude of concentration differences in various tissues at a time of rapid change. A major confounding factor in evaluating the dynamics of changes in IF glucose concentrations has been the complexity of direct sampling methods, including insertion of wicks, blister formation, lymph sampling, and ultrafiltration. Microdialysis is an indirect method of estimating IF glucose values. Lönnroth et al. was the first to use this method to show that IF glucose was almost identical to venous plasma glucose in healthy individuals during steady state. Jannson et al. demonstrated an increase in lag time between IF and plasma glucose when there is a rapid rise in the plasma glucose level. The data of Jensen et al. revealed lower IF glucose levels than plasma glucose during clamp experiments extracting IF by suction blister technique. There are relatively limited data on dermal IF glucose levels. Bantle and Thomas demonstrated no significant difference between the dermal and plasma pre- and postprandial glucose levels in subjects with type 1 diabetes. A plasma and dermal interstitial glucose concentration lag time of 10–20 min was reported by Stout et al. In general, IF and plasma glucose variations were evaluated in two different conditions: steady state and non–steady state. Under steady-state conditions, IF glucose generally correlated with the blood glucose with a lag time reported to be between 0 and 45 min and an average lag of 8–10 min. Increasing the blood flow to the interstitial glucose sampling site by applying controlled pressure has been shown to decrease the lag time between the blood and interstitial glucose at times of increasing plasma glucose levels. The reported gradient between interstitial and plasma glucose concentrations has varied between 20% to 110%. During the time of decreasing glucose, interstitial glucose may fall in advance of plasma glucose and reach nadir values that are lower than corresponding venous glucose levels. Interstitial glucose levels have been shown to remain below plasma glucose concentrations for prolonged periods of time after correction of insulin-induced hypoglycemia. These findings could be explained by the push–pull phenomenon during which the glucose is pushed from the blood to the interstitial space at times of increased blood glucose, and later on glucose being pulled from the IF to the surrounding cells during decreasing blood glucose levels. This phenomenon has been a matter of debate for some time, in light of data failing to support the push–pull phenomenon and instead reporting compensation of enhanced uptake of glucose in the IF by increased plasma glucose delivery and lack of glucose removal effect of insulin in the adipose IF. Current continuous glucose monitoring systems have the advantage of direct insertion of electrochemical sensors into the IF space rather than transporting the sampled fluid outside the body to detect glucose concentrations. Software programs have been designed to accommodate the lag in IF glucose readings.  Recent advances in glucose sensor technology for measuring interstitial glucose concentrations have challenged the dominance of glucose meters in diabetes management, while raising questions about the relationships between interstitial and blood glucose levels.

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For glucose meter measurements, a skin-pricking device is used to access the dermal capillary plexus. Human skin consists of two layers—epidermis and dermis—residing above the adipose and muscle tissue. Epidermis is an avascular epithelial membrane. It has enzymes with glucose metabolizing effect. Moreover, glucose is formed from the breakdown of ceramide at the stratum granulosum–corneum interface. Dermis comprises many arterioles, venules, and capillaries, including a deep vascular plexus interfacing dermis and the subcutaneous tissue as seen in the figure below. Another vascular plexus located 0.3–0.6 mm from the skin surface is formed by the feeding vessels arising from the deep vascular plexus. It supplies the blood flow to the dermis and epidermis with the help of small capillary loops branching from the superficial plexus. The blood sampled from the skin prick comes from the capillaries of dermis with a small amount of blood from cut arterioles and venules providing a mix concentration. Blood flow to the skin is controlled by many factors, including autonomic nervous system, temperature, hormonal changes during menstrual cycle for females, and chemical inputs.

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The figure above shows skin layers with the magnified IF space. (a) Vasculature in different skin layers with the CGM inserted into the subcutaneous tissue. (b) Diffusion of glucose from plasma to IF is in proportion to the concentration in each compartment. IF glucose is cleared by the surrounding cell uptake. Insulin may increase cellular glucose uptake after binding its membrane receptor.  

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Methods of monitoring glucose:   

Intermittent vs. continuous glucose monitoring:

The difference between an intermittent and a continuous monitor for monitoring blood glucose is similar to that between a regular camera and a continuous security camera for monitoring an important situation. A regular camera takes discrete, accurate snapshots; its pictures do not predict the future; it produces a small set of pictures that can all be carefully studied; and effort is required to take each picture. A continuous security camera, on the other hand, takes multiple, poorly focused frames; displays a sequential array of frames whose trend predicts the future; produces too much information for each frame to be studied carefully; and operates automatically after it is turned on. The two types of blood glucose monitors differ in much the same way: 1) an intermittent blood glucose monitor measures discrete glucose levels extremely accurately, whereas a continuous monitor provides multiple glucose levels of fair accuracy; 2) with an intermittent monitor, current blood glucose levels do not predict future glucose levels, but with a continuous monitor, trends in glucose levels do have this predictive capability; 3) with an intermittent monitor, it is easy to study every measured blood glucose value over most time periods, but with a continuous monitor, too many data are generated to study all data points; and 4) an intermittent blood glucose monitor requires effort to operate, whereas a continuous monitor does not. Returning to the camera analogy, just as the best tool for closely monitoring a situation when the outcome is important often may be a continuous security camera rather than a regular camera, likewise the best way to monitor diabetes often may be a continuous glucose monitor (CGM) rather than an intermittent monitor.

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Various methods of glucose monitoring are available, including HbA1c measurement, blood glucose monitoring and urine glucose testing.

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Basic approaches for blood glucose measurement:

There are three basic approaches to the laboratory measurement of blood glucose concentration: reducing methods, condensation methods, and enzymatic methods. Reducing methods are the oldest and take advantage of the reducing properties of glucose to change the state of a metal ion while glucose is being oxidized. Reducing methods are nonspecific, and any strong reducing agent can cross react to yield spuriously elevated values. While steps can be added to remove most cross-reacting reducing agents, this approach has largely been abandoned in the clinical laboratory. The aldehyde group of glucose can undergo condensation with aromatic compounds to yield a colored product. In the most commonly used condensation reaction, o-toluidine reacts with glucose to form a glucosamine that has an intense green color. The color is then measured spectrophotometrically to estimate the glucose concentration. The reaction is rapid, and the intense color allows a high degree of sensitivity. Other aldoses can cross react, but only mannose and galactose give a highly colored product. These sugars are not found in great concentrations in the blood and their cross reactivity is ordinarily not significant. o-Toluidirie has the drawback of being highly corrosive and toxic. For this reason, this method is rapidly being phased out of the clinical laboratory. More precise blood glucose measurements are performed in a medical laboratory, using hexokinase, glucose oxidase, or glucose dehydrogenase enzymes.

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The enzyme glucose oxidase reacts with glucose, water, and oxygen to form gluconic acid and hydrogen peroxide. The hydrogen peroxide can then be used to oxidize a chromogen or the consumption of oxygen measured to estimate the amount of glucose present. Glucose oxidase is specific for β-d-glucose, so cross reaction with other sugars is not a problem. In aqueous solution, approximately 66% of d-glucose is in the β state and 34% exists as α- d-glucose. The rate of interconversion is pH and temperature dependent. Some methods add a glucomutarostase to the reagents to speed up the conversion to the beta anomere, but this does not seem to alter the clinical results. The measurement of generated hydrogen peroxide is not as specific as the first glucose oxidase reaction. Numerous reducing substances can potentially inhibit the oxidation of the chromogen. Although uric acid and creatinine, even in uremic patients, seem to have little effect on the results, ascorbic acid will yield spuriously low blood glucose measurements. The high concentration of uric acid found in urine will affect the result and so glucose oxidase methods are not directly applicable to urine samples. The measurement of oxygen consumption using an oxygen-specific electrode avoids the problem of interfering reducing agents. In general, the glucose oxidase method is relatively inexpensive and specific. Many glucose meters employ the oxidation of glucose to gluconolactone catalyzed by glucose oxidase (sometimes known as GOx). Others use a similar reaction catalysed instead by another enzyme, glucose dehydrogenase (GDH). This has the advantage of sensitivity over glucose oxidase but is more susceptible to interfering reactions with other substances.

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Enzymatic methods to measure blood glucose:

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Amperometric and photometric techniques for measurement of blood glucose using enzymatic methods:

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Timing of the test:

Blood sugar is measured at various points of time to give an idea about the body’s blood glucose regulation system. The primary test is the fasting blood glucose (FBG). This is measured after overnight fasting. Blood glucose normally is lowest early in the morning after 6 to 8 hours of fasting overnight. FBG is also called fasting blood sugar (FBS). However, the correct terminology is venous fasting plasma glucose (FPG) as whole blood sugar is obsolete in most laboratories. Two hours post prandial plasma glucose or PPG is the next common test. After a carbohydrate rich, full meal, two hours are allowed to elapse before blood is taken again for estimation of glucose. This test gives an estimation of glucose handling by the body. Other tests include oral glucose tolerance test (OGTT) and intravenous glucose tolerance test (IVGTT) wherein a fixed amount of glucose is administered orally or intravenously respectively and repeated blood sugar tests are performed to check on the body’s glucose handling. Another important test is the glycosylated haemoglobin (HbA1C). This test gives an idea about fluctuations of glucose in blood over a period of last three months.

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These glucose measurements are useful for different reasons:

Fasting plasma glucose levels, taken in the morning before eating, should fall in a normal range. Normal value for FPG is 70 to 100 mg/dL. Measurement of glucose in plasma of fasting subjects is widely accepted as a diagnostic criterion for diabetes.  Advantages include inexpensive assays on automated instruments that are available in most laboratories worldwide. Nevertheless, FPG is subject to some limitations. One report that analyzed repeated measurements from 685 fasting participants without diagnosed diabetes from the Third National Health and Nutrition Examination Survey (NHANES III) revealed that only 70.4% of people with FPG <126 mg/dL on the first test had FPG <126 mg/dL when analysis was repeated ~2 weeks later. Numerous factors may contribute to this lack of reproducibility. 

Two hours after eating:

Blood sugar rises and then falls to a baseline level. By sampling blood sugar levels two hours after eating, you find out if glucose is being removed from your blood in a reasonable time. The sugar level peaks in 30-60 minutes and the falls back to a baseline level. The timing and height of the peak level will vary with the composition of the meal and activity levels. Normal PPG value is 100 to 140 mg/dL.

OGTT:

The OGTT evaluates the efficiency of the body to metabolize glucose and for many years has been used as the “gold standard” for diagnosis of diabetes. An increase in postprandial glucose concentration usually occurs before fasting glucose increases. Therefore, postprandial glucose is a sensitive indicator of the risk for developing diabetes and an early marker of impaired glucose homeostasis. Published evidence suggests that increased 2-h plasma glucose during an OGTT is a better predictor of both all-cause mortality and cardiovascular mortality or morbidity than the FPG. The OGTT is accepted as a diagnostic modality by the ADA, WHO/International Diabetes Federation (IDF), and other organizations. However, extensive patient preparation is necessary to perform an OGTT. Important conditions include, among others, ingestion of at least 150 g of dietary carbohydrate per day for 3 days prior to the test, a 10- to 16-h fast, and commencement of the test between 7:00 A.M. and 9:00 A.M. In addition, numerous conditions other than diabetes can influence the OGTT. Consistent with this, published evidence reveals a high degree of intraindividual variability in the OGTT, with a CV of 16.7%, which is considerably greater than the variability for FPG. These factors result in poor reproducibility of the OGTT, which has been documented in multiple studies. The lack of reproducibility, inconvenience, and cost of the OGTT led the ADA to recommend that FPG should be the preferred glucose-based diagnostic test. Note that glucose measurement in the OGTT is also subject to all the limitations described for FPG. An abbreviated screening glucose tolerance test is recommended for all women between their 24th and 28th week of pregnancy. The test consists of 50 g of oral glucose and the measurement of venous plasma glucose 1 hour later. The test may be administered at any time of day and non-fasting. A 1 hour plasma glucose of 140 mg/dl or greater indicates the need for a full-scale glucose tolerance test as described above.

Checking symptomatic episodes:

You measure blood sugar when you are not feeling well to find out how your symptoms correlate with the blood sugar level. High levels are associated with an intoxicated feeling – drowsy, hard to concentrate, judgment impaired. Levels above 17 mmol or 300 mg are dangerously high – you are likely to want to sleep at this level but the most effective way to reduce the sugar levels is to exercise as vigorously as you can. Levels below 4.5 mmol capillary may be associated with hypoglycemic symptoms – you feel  strange, anxious, irritable; a tremor develops if the blood sugar value falls lower and you become desperate to eat something. If you can take a quick sugar hit – a glass of orange juice will do and measure your sugar immediately you can determine how low the value dropped; as you feel better do another blood sugar check to find the value that feels normal.

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Diabetes and urine glucose monitoring:  

The glucose urine test measures the amount of sugar (glucose) in a urine sample. The presence of glucose in the urine is called glycosuria or glucosuria. After you provide a urine sample, it is tested right away. The health care provider uses a dipstick made with a color-sensitive pad. The color the dipstick changes to tell the provider the level of glucose in your urine. The proximal tubules reabsorb more than 99.9 % of glucose filtered by glomerulus in a normal person. When the blood glucose level exceeds about 160 – 180 mg/dl, the proximal tubule becomes overwhelmed and begins to excrete glucose in the urine. This point is called the renal threshold of glucose. If renal threshold is so low that even normal blood glucose levels produce glycosuria, it is referred to as renal glycosuria.  Although used in the past to self-monitor diabetes control, urine glucose testing has been largely replaced by self blood glucose monitoring using a small, personal meter. The reason for this is the greater accuracy with which blood glucose monitoring reflects your blood glucose level. However, if you have difficulty obtaining a drop of blood, or you have some other difficulty performing blood glucose monitoring, your doctor or diabetes educator may suggest that urine glucose monitoring is suitable for you. A urine glucose test determines whether or not glucose (sugar) is present in the urine. Glucose will overflow into the urine only when the blood glucose level is high, that is, too high for the kidneys to stop it spilling over into the urine. In most people, blood glucose levels above 10 mmol of glucose per liter of plasma will cause glucose to appear in the urine. This level is called the ‘renal threshold’ for glucose.  However, the renal threshold for glucose can be lower in some people who are otherwise healthy, during pregnancy, and in people who have a kidney disorder. In these people, glucose may be present in the urine despite the blood glucose being normal. This can sometimes make urine glucose tests difficult to interpret. 

To perform the test:

1. Collect a small amount of urine;

2. Apply this to the test strip, usually by dipping the strip in the urine sample;

3. Read the test result at the specified time, by comparing the colour change on the test strip with the standard colour range for your brand of test strip. The reference colour chart is usually printed on the container.  

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Advantages of urine glucose monitoring

1. Urine glucose testing is easy to do: just dip the test strip in the urine and read the result at the allocated time.

2. It is less painful than blood glucose monitoring — no finger pricks to collect blood!

3. Urine test strips are less costly than buying a blood glucose monitor and its test strips.

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Limitations of urine glucose monitoring:

If monitoring your diabetes control by testing your urine glucose, it’s important to understand the limitations of this method.

1. A urine glucose test does not reflect your blood glucose level at the time of testing; instead, it gives an indication of your blood glucose level over the past several hours. For example, some of the urine present in your bladder may be 2 hours old, and may show glucose even though your blood glucose may have normalised since then. Compare this to a blood glucose test which gives you a reading of your current blood glucose level.

2. A urine glucose test does not give you any information about low blood glucose levels, as glucose is only found in the urine when the blood glucose level is above 10 mmol/L. That is, a negative urine glucose test may be the result of a normal blood glucose level or a dangerously low blood glucose level, with the urine glucose test unable to differentiate between the 2 situations.

3. The results of a urine glucose test are influenced by the volume and concentration of urine that you pass, which will vary with the amount of fluid you consume and your fluid loss due to such things as heavy sweating or vomiting.

4. Urine glucose tests designed for home use rely on interpreting a colour change to define the result. Subtle colour differences may be difficult to interpret.

5. If a urine glucose test is not read at the specified time after applying the urine to the test strip, then the result is prone to error.

6. Some medications may interfere with the results of urine glucose testing.

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Urine ketone testing:

People with type 1 diabetes should perform urine testing for ketones if the blood sugar level is above 240 mg/dL (13.3 mmol/L), during periods of illness or stress, or if you have symptoms of ketoacidosis, such as nausea, vomiting, and abdominal pain. Ketones are acids that are formed when the body does not have enough insulin to get glucose into the cells, causing the body to break down fat for energy. Ketones can also develop during illness, if an inadequate amount of glucose is available (due to skipped meals or vomiting). Ketoacidosis occurs when high levels of ketones are present and can lead to serious complications such as diabetic coma. Urine ketone testing is done with a dipstick, available in pharmacies without a prescription. If you have moderate to large ketones, you should call your healthcare provider immediately to determine the best treatment. You may need to take an additional dose of insulin, or your provider may instruct you to go to the nearest emergency room.

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Urine protein testing:

Urine is tested for microalbuminuria in diabetes. Microalbuminuria is defined as levels of albumin ranging from 30 to 300 mg in a 24-h urine collection. Overt albuminuria, macroalbuminuria, or proteinuria is defined as a urinary albumin excretion of ≥300 mg/24 h. The presence of albuminuria is a powerful predictor of renal and cardiovascular risk in patients with type 2 diabetes and hypertension. In addition, multiple studies have shown that decreasing the level of albuminuria reduces the risk of adverse renal and cardiovascular outcomes. The pathophysiology is not definitively known, but is hypothesized to be related to endothelial dysfunction, inflammation, or possibly abnormalities in the renin-angiotensin-aldosterone system.

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Glycosylated Hemoglobin: Glycated Hemoglobin:

Glycated hemoglobin (hemoglobin A1c, HbA1c, A1C, Hb1c or HbA1c) is a form of hemoglobin that is measured primarily to identify the average plasma glucose concentration over prolonged periods of time. It is formed in a non-enzymatic glycation pathway by hemoglobin’s exposure to plasma glucose. When hemolysates of red cells are chromatographed, three or more small peaks named hemoglobin A1a, A1b, and A1c are eluted before the main hemoglobin A peak. These “fast” hemoglobins are formed by the irreversible attachment of glucose to the hemoglobin in a two-step reaction. The percentage of hemoglobin glycosylated depends on the average glucose concentration the red cell is exposed to over time. Since the average life of the red cell is 120 days, the percentage of glycosylated hemoglobin gives a good indication of the degree of blood sugar control over the preceding weeks. Hemoglobin A1c is quantifiably the largest peak so that most laboratories measure it selectively, although some laboratories measure all the “fast” hemoglobins. Normal levels of glucose produce a normal amount of glycated hemoglobin. As the average amount of plasma glucose increases, the fraction of glycated hemoglobin increases in a predictable way. This serves as a marker for average blood glucose levels over the previous months prior to the measurement. Glycation of proteins is a frequent occurrence, but in the case of hemoglobin, a nonenzymatic reaction occurs between glucose and the N-end of the beta chain. This forms a Schiff base which is itself converted to 1-deoxyfructose. This rearrangement is known as Amadori rearrangement. When blood glucose levels are high, glucose molecules attach to the hemoglobin in red blood cells. The longer hyperglycemia occurs in blood, the more glucose binds to hemoglobin in the red blood cells and the higher the glycated hemoglobin. Once a hemoglobin molecule is glycated, it remains that way. A buildup of glycated hemoglobin within the red cell, therefore, reflects the average level of glucose to which the cell has been exposed during its life-cycle. Measuring glycated hemoglobin assesses the effectiveness of therapy by monitoring long-term serum glucose regulation. At any moment, the glucose attached to the hemoglobin A protein reflects the level of the blood sugar over the last two to three months. The A1c test measures how much glucose is actually stuck to hemoglobin A, or more specifically, what percent of hemoglobin proteins are glycated. Thus, having a 7% A1c means that 7% of the hemoglobin proteins are glycated. A person’s A1c level will not change significantly over the course of a few days, but it will shift in response to a change in overall glucose control. It is estimated that the past month will account for about 50% of an A1c value, so that value can change within just a few weeks. Some researchers state that the major proportion of its value is weighted toward the most recent 2 to 4 weeks. This is also supported by the data from actual practice showing that HbA1c level improved significantly already after 20 days since glucose-lowering treatment intensification. It has also been noted that at any given time a blood sample contains erythrocytes of varying ages, with different levels of exposure to hyperglycemia. Although older erythrocytes are likely to have more exposure to hyperglycemia, younger erythrocytes are more numerous. Consequently, BG levels from the preceding 30 days have been shown to contribute approximately 50% to HbA1c, whereas those from the period 30–90 days and 90–120 days earlier contribute approximately 40% and 10%, respectively.

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Glycated hemoglobin measurement is not appropriate where there has been a change in diet or treatment within 6 weeks. Likewise, the test assumes a normal red blood cell aging process and mix of hemoglobin subtypes (predominantly HbA in normal adults). Hence, people with recent blood loss, hemolytic anemia, or genetic differences in the hemoglobin molecule (hemoglobinopathy) such as sickle-cell disease and other conditions, as well as those that have donated blood recently, are not suitable for this test. Concentrations of hemoglobin A1 (HbA1) are increased, both in diabetic patients and in patients with renal failure, when measured by ion-exchange chromatography. The thiobarbituric acid method (a chemical method specific for the detection of glycation) shows that patients with renal failure have values for glycated hemoglobin similar to those observed in normal subjects, suggesting that the high values in these patients are a result of binding of something other than glucose to hemoglobin.  In autoimmune hemolytic anemia, concentrations of hemoglobin A1 (HbA1) is undetectable. Administration of prednisolone  will allow the HbA1 to be detected. The alternative fructosamine test may be used in these circumstances and it also reflects an average of blood glucose levels over the preceding 2 to 3 weeks.

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A number of techniques are used to measure A1c:

•High-performance liquid chromatography (HPLC): The HbA1c result is calculated as a ratio to total hemoglobin by using a chromatogram.

•Immunoassay

•Enzymatic

•Capillary electrophoresis

•Boronate affinity chromatography

Point of care (e.g., doctor’s office) devices use:

•Immunoassay

•Boronate affinity chromatography

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Indications and use:

Glycated hemoglobin testing is recommended for both (a) checking the blood sugar control in people who might be pre-diabetic and (b) monitoring blood sugar control in patients with more elevated levels, termed diabetes mellitus. There is a significant proportion of people who are unaware of their elevated HbA1c level before they have blood lab work. For a single blood sample, it provides far more revealing information on glycemic behavior than a fasting blood sugar value. However, fasting blood sugar tests are crucial in making treatment decisions. The American Diabetes Association guidelines are similar to others in advising that the glycated hemoglobin test be performed at least two times a year in patients with diabetes that are meeting treatment goals (and that have stable glycemic control) and quarterly in patients with diabetes whose therapy has changed or that are not meeting glycemic goals. In diabetes mellitus, higher amounts of glycated hemoglobin, indicating poorer control of blood glucose levels, have been associated with cardiovascular disease, nephropathy, and retinopathy. Monitoring HbA1c in type 1 diabetic patients may improve outcomes.

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 The HbA1c level measures glycemic control during the preceding 2 to 3 months, but it does not provide information about day-to-day glucose levels, nor does it provide immediate feedback to patients about medication or lifestyle choices. For these reasons, self-monitoring of blood glucose (SMBG) levels is considered an important adjunct to HbA1c measurements for achieving and maintaining glycemic control and consequently for reducing diabetes-related complications. Self-monitoring of blood glucose represents an important adjunct to HbA1c because it can distinguish among fasting, preprandial, and postprandial hyperglycemia; detect glycemic excursions; identify hypoglycemia; and provide immediate feedback to patients about the effect of food choices, activity, and medication on glycemic control.

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HbA1c as a measure of glycemic control: 

Numerous studies have shown that elevated HbA1c is associated with an increased risk of complications in patients with type 1 and type 2 diabetes mellitus and that lowering HbA1c reduces such risk. In the DCCT, reductions in HbA1c were accompanied by proportional reductions in the risk of complications, with clinically meaningful risk reductions observed even when HbA1c was reduced toward the normal range of less than 6%. Similar findings were observed in patients with newly diagnosed type 2 diabetes in the United Kingdom Prospective Diabetes Study, in which intensive blood glucose control yielded a 25% reduction in the risk of microvascular complications (P=0.0099) and a 16% risk reduction for myocardial infarction (P=0.05) compared to conventional therapy. Analysis of these data in terms of HbA1c levels revealed a continuous relationship between HbA1c and the risk of complications, with each 1% decrease in HbA1c resulting in statistically significant reductions of 37% for microvascular complications and 14% for myocardial infarction (P<0.0001). These findings are similar to those derived from the DCCT and indicate that the much larger number of patients with type 2 diabetes benefit from glucose lowering to the same degree as those with type 1 diabetes. Thus, HbA1c serves as a surrogate for the risk of microvascular and macrovascular complications, and these results firmly establish HbA1c as a useful measure of long-term glycemic control.

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For someone who doesn’t have diabetes, a normal A1c level can range from 4.5 to 6 percent. Someone who’s had uncontrolled diabetes for a long time might have an A1c level above 8 percent. When the A1c test is used to diagnose diabetes, an A1c level of 6.5 percent or higher on two separate tests indicates you have diabetes. A result between 5.7 and 6.4 percent is considered prediabetes, which indicates a high risk of developing diabetes. For most people who have previously diagnosed diabetes, an A1c level of 7 percent or less is a common treatment target. Higher targets may be chosen in some individuals. If your A1c level is above your target, your doctor may recommend a change in your diabetes treatment plan. Remember, the higher your A1c level, the higher your risk of diabetes complications.  Also keep in mind that the normal range for A1c results may vary somewhat among labs. If you consult a new doctor or use a different lab, it’s important to consider this possible variation when interpreting your A1c test results.

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Convert A1c to estimated average glucose (eAG):

The A1c-Derived Average Glucose (ADAG) Study is an international study sponsored by the American Diabetes Association (ADA), European Association for the Study of Diabetes (EASD), and International Diabetes Federation (IDF). The objective of the ADAG Study was to define the mathematical relationship between A1c and estimated average glucose (eAG) and determine if A1c could be reliably reported as eAG, which would be in the same units as daily self-monitoring. The ADAG Study establishes what has long been assumed but never demonstrated… that A1c does represent average glucose over time.  With that relationship demonstrated and defined, health care providers can now report A1c results to patients in the same units that they are using for self-monitoring (i.e., mg/dl) which should benefit clinical care. Reporting glucose control as ‘average glucose’ will assist health care providers and their patients in being able to better interpret the A1C value in units similar to what patients see regularly through their self-monitoring.

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New formula to convert your A1c to estimated average blood sugar in either mg/dl or mmol/L:

This new formula is based on CGMS data and is believed to be more accurate than either the DCCT formula or the Nathan Formula.
Estimated Average Blood Glucose in mmol/L = [(1.583 X A1c) - 2.52]
The conversion factor used to convert mmol/L to mg/dl is 18.

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Many patients who practice SMBG already see an “average glucose” on their blood glucose meters. 

Is eAG the same thing?

No, an eAG value is unlikely to match the average glucose level shown on a person’s meter.  Because people with diabetes are more likely to test more often when their blood glucose levels are low—first thing in the morning, and before meals—the average of the readings on their meter is likely to be lower than their eAG, which represents an average of their glucose levels 24 hours a day, including post-meal periods of higher blood glucose when people are less likely to test.  One advantage of using eAG as a measure of glucose control is that it will help patients more directly see the difference between their individual meter readings and how they are doing with their glucose management overall.  A range of factors has been postulated to influence the relationship between HbA1c and BG. In particular, the time of BG measurement (fasting, postprandial, etc.) and the frequency and timing of BG measurement appear to have significant impact on this relationship. Analysis of data from one clinical study found that among individual time points, the afternoon and evening prandial glucose readings showed higher correlations with HbA1c than the morning time points.

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Estimating A1c from SMBG:

Accuracy and Robustness of Dynamical Tracking of Average Glycemia (A1c) to Provide Real-Time Estimation of Hemoglobin A1c Using Routine Self-Monitored Blood Glucose Data: 2013 study:

Laboratory hemoglobin A1c (HbA1c) assays are typically done only every few months. However, self-monitored blood glucose (SMBG) readings offer the possibility for real-time estimation of HbA1c. Researchers present a new dynamical method tracking changes in average glycemia to provide real-time estimation of A1c (eA1c).  In diabetes, the struggle for tight glycemic control results in large BG fluctuations over time. These fluctuations are the measurable result of the action of a complex dynamical system, influenced by many internal and external factors, including the timing and amount of insulin and other drug therapies, food eaten, physical activity, etc. The macro (human)-level optimization of this system depends on self-treatment behavior. Such an optimization has to be based on feedback utilizing readily available data, such as SMBG. Although HbA1c is the gold standard marker for average glycemia, HbA1c assays typically require a laboratory and are routinely done only every few months. Thus, a method to track changes in average glycemia in between laboratory assessments is needed. SMBG offers this possibility, provided that appropriate algorithms are used to retrieve SMBG data. This report describes a method for tracking changes in average glycemia, based on a conceptually new approach to the retrieval of SMBG data. The principal premise of this approach is the understanding of HbA1c fluctuation as the measurable effect of the action of an underlying dynamical system. SMBG provides occasional glimpses at the state of this system, and, using these measurements, the hidden underlying system trajectory can be reconstructed for each individual. Using compartmental modeling, researchers constructed a new two-step algorithm that includes real-time eA1c from fasting glucose readings, updated with any new incoming fasting SMBG data point, and initialization and calibration of the estimated HbA1c trace with daily SMBG profiles taken approximately every month. A conceptually new, clinically viable procedure has been developed for real-time tracking of average glycemia from self-monitoring data. The average glucose tracing is then converted into running estimates of A1c, which can be presented to the patient daily. This technique allows for simple parameterization of the dynamics of average glycemia and thereby HbA1c, has a robust estimation procedure capable of working on sparse readings of fasting BG and occasional seven-point SMBG profiles, and has an inherent capability for calibration of the algorithm using SMBG profiles and/or reference HbA1c readings. It should be emphasized, however, that this procedure is not intended as a substitute for laboratory assessments of HbA1c—it should be viewed as a surrogate measure that allows convenient tracing of average glucose, readily implementable in a point-of-care SMBG device.

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Potential Alternatives to HbA1C:

Two other analytes, fructosamine and 1,5-anhydroglucitol (1,5-AG), have been evaluated as intermediate markers of glycemia. The fructosamine assay measures glycation of serum proteins, principally albumin, that have a shorter half-life than hemoglobin. Thus, fructosamine provides an index of glycemia over a shorter period (approximately 2 weeks) compared to HbA1c measurements. Each 75 µmol change equals a change of approximately 60 mg/dl blood sugar or 2% HbA1c. Unlike A1c, fructosamine is not affected by the varying length of red blood cell lifespans in different individuals. Fructosamine is especially useful in people who are anemic, or during pregnancy, when hormonal changes cause greater short-term fluctuations in blood glucose levels. The accuracy and clinical utility of fructosamine have been questioned because of interference from various substances. The 1,5-AG assay measures serum levels of a compound that competes with glucose for reabsorption at the renal tubule and was recently approved by the US Food and Drug Administration.  Used in Japan for more than a decade, 1,5-AG levels appear to be less sensitive to small changes in glycemic control at high HbA1c levels. It cannot identify hypoglycemia, and results are influenced by impaired renal function. Future studies may support the use of 1,5-AG as a means to detect postprandial glycemic excursions.

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Advantages and disadvantages of FPG, OGTT and HbA1c vis-à-vis diagnosis of diabetes:

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 FPG for the diagnosis of diabetes:

Advantages:

•Glucose assay easily automated

•Widely available

•Inexpensive

•Single sample

Disadvantages:

•Patient must fast 8 hr

•Large biological variability

•Diurnal variation

•Sample not stable

•Numerous factors alter glucose concentrations, e.g., stress, acute illness

•No harmonization of glucose testing

•Concentration varies with source of the sample (venous, capillary, or arterial blood)

•Concentration in whole blood is different from that in plasma

•Guidelines recommend plasma, but many laboratories measure serum glucose

•FPG less tightly linked to diabetes complications (than A1c)

•Reflects glucose homeostasis at a single point in time

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OGTT for the diagnosis of diabetes:

Advantages

•Sensitive indicator of risk of developing diabetes

•Early marker of impaired glucose homeostasis

Disadvantages:

•Lacks reproducibility

•Extensive patient preparation

•Time-consuming and inconvenient for patients

•Unpalatable

•Expensive

•Influenced by numerous medications

•Subject to the same limitations as FPG, namely, sample not stable, needs to be performed in the morning, etc.

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A1c for the diagnosis of diabetes:

Advantages

•Subject need not be fasting

•Samples may be obtained any time of the day

•Very little biological variability

•Sample stable

•Not altered by acute factors, e.g., stress, exercise

•Reflects long-term blood glucose concentration

•Assay standardized across instruments

•Accuracy of the test is monitored

•Single sample, namely whole blood

•Concentration predicts the development of microvascular complications of diabetes

•Used to guide treatment

Disadvantages:

•May be altered by factors other than glucose, e.g., change in erythrocyte life span, ethnicity

•Some conditions interfere with measurement, e.g., selected hemoglobinopathies

•May not be available in some laboratories/areas of the world

•Cost

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Self monitoring (measurement) of blood sugar (SMBG) definition:

SMBG is checking the level of glucose in their blood regularly by patients themselves with diabetes mellitus. SMBG can be performed at home, work, or elsewhere — the process involves pricking a fingertip to collect a drop of blood, absorbing the blood with a test strip, and inserting the test strip into an electronic glucose monitor (glucometer) which then displays a number on its screen. Glucose meters are widely used in hospitals, outpatient clinics, emergency rooms, ambulatory medical care (ambulances, helicopters, cruise ships) besides home self-monitoring. Glucose meters provide fast analysis of blood glucose levels and allow management of both hypoglycemic and hyperglycemic disorders with the goal of adjusting glucose to a near-normal range, depending on the patient group. As SMBG is invasive and painful, non-invasive techniques are developed to determine glucose level in body fluids. Non-invasive techniques can be used by patients themselves or medical personnel. So if I have to define SMBG today, I would call it measurement of glucose in blood either directly (invasive) or indirectly through other body fluids (non-invasive) by patients themselves or their care givers or medical personnel outside laboratory. So blood glucose measured by nurses by glucometer or non-invasive technique would also fall under umbrella of SMBG as it is not done in a laboratory. 

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SMBG technique:

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First drop vs. second drop of blood for SMBG:

Many insulin-treated patients have to perform SMBG for a lifetime—some of them every day. Discarding the first drop of blood and refraining from squeezing the finger makes measurements more complex and necessitates deeper and more painful punctures. International guidelines and studies about SMBG (e.g., the American Diabetes Association [ADA] and the Diabetes UK guidelines) recommend using the first drop of blood after washing the hands. Some also allow squeezing or milking the finger. The manufacturer’s instructions of the meter used in the study include washing hands with warm water and soap and drying the hands. The first drop of blood can be used after gently squeezing the finger. In daily practice, patients cannot or do not always wash their hands before performing SMBG. In international guidelines, these situations are not discussed.

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The Use of the First or the Second Drop of Blood: squeezing or not: a study:

There is no general agreement regarding the use of the first or second drop of blood for glucose monitoring. This study investigated whether capillary glucose concentrations, as measured in the first and second drops of blood, differed ≥10% compared with a control glucose concentration in different situations. Capillary glucose concentrations were measured in two consecutive drops of blood in the following circumstances in 123 patients with diabetes: without washing hands, after exposing the hands to fruit, after washing the fruit-exposed hands, and during application of different amounts of external pressure around the finger. The results were compared with control measurements. Not washing hands led to a difference in glucose concentration of ≥10% in the first and in the second drops of blood in 11% and 4% of the participants, respectively. In fruit-exposed fingers, these differences were found in 88% and 11% of the participants, respectively. Different external pressures led to ≥10% differences in glucose concentrations in 5–13% of the participants. Authors recommend washing the hands with soap and water, drying them, and using the first drop of blood for self-monitoring of blood glucose. It does not matter which finger is used for glucose measurements. If washing hands is not possible, and they are not visibly soiled or exposed to a sugar-containing product, it is acceptable to use the second drop of blood after wiping away the first drop. External pressure may lead to unreliable readings. Firm squeezing of the finger should be avoided.

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Other two studies investigated the differences between glucose concentrations in the first and the second drops of blood. Both of these studies, however, involved volunteers without diabetes. In one study of 53 volunteers, no differences were found in the readings when the hands were clean. Glucose readings for 25 volunteers in the other study were shown to be greatly affected when the fingers were exposed to glucose (i.e., fruit). Even the third drop of blood cannot be used in these cases.  Fruhstorfer and Quarder also investigated the influence of milking the finger in 10 volunteers without diabetes and concluded that milking the finger gives correct glucose values. In another study, authors used two pressures to explore whether there would be any influence on the capillary glucose concentration. Venous stasis is achieved with a pressure of 40 mmHg. A pressure of 240 mmHg is above the systolic pressure of the participants. This study shows more deviation between the glucose concentrations with the higher pressure.

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Lancet: Finger-pricking (lancing) device:

A finger-pricking device (called a lancet) is used to get the drop of blood. The lancet can often be set at different depths for different people. The adjustable lancets are particularly good for young children who have tender skin and may not need much lancing depth. Remember to change the lancet every day. A sharp lancet helps prevent injury and infection.

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How often do you recommend changing lancets?

In the early days of blood glucose self-monitoring, pricking the finger to get a “hanging drop” of blood often hurt and left a scar. This was because the procedure created a laceration, rather than a puncture. We’ve come a long way since then, with improved spring-loaded devices, strips that require less blood and lancets that are sharper and usually coated with a lubricant. Lancets are now much more comfortable to use and less likely to cause a scar. Today’s lancets are so good that they are commonly reused. The reasons to reuse lancets are obvious: It’s cheaper and quicker not to have to change them each time; it’s easier not to carry extra lancets around; and, for some users, the lancets actually seem more comfortable after being “broken in.” Since the lancet goes into the subcutaneous space and is not being used intravenously, and since blood is flowing out of the body, sterility is generally not an issue. The rate of infections and injury from lancets is extremely low. Many people, however, are not able to reuse lancets because they feel discomfort or they experience scarring if the lancet is not in optimal condition. Once a lancet has been used, its surface is rougher, the lubricant wears off and the point is duller. Any handling of the lancet, such as cleaning with alcohol, tends to worsen it. For these individuals, using a new lancet each time is well worthwhile.

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Fingertip puncture pain:

Although the fingertip possesses well-developed capillaries to provide enough blood for the test, pain receptors concentrated on the fingertip induce significant pain when the skin is punctured. As a result, some patients avoid the self test, which could lead to failure of glucose control. In a survey by Park et al., 55% of the diabetes patients responded to the survey questions, and only 35% performed the self-test. These survey results show that only 20% of the patients may perform the routine self-test to control their blood glucose levels. SMBG using capillary blood sampled from the finger is a standard technique for the management of diabetes. However, it induces pain and may force the patient to avoid the test, thereby leading to a failure in maintaining the appropriate glucose levels. Therefore, the pain experienced during sampling is considered to be a significant problem, and a few alternative methods have been suggested. Noninvasive bloodless glucose measurement techniques have been evaluated; however, their accuracy and consistency have not been proven in clinical application, and the higher costs of commercialization of these techniques may also have to be considered. Capillary blood sampling from an alternative site, such as the forearm, could minimize pain, and perhaps be a practical solution to this problem. While blood sampling from the forearm induces significantly less pain than that from the finger, only a small amount of blood, usually less than a few microliters, can be obtained due to the low degree of capillary distribution in the forearm. This small volume of blood is not sufficient for traditional glucometers. Fortunately, modern high-end but inexpensive glucometers can provide accurate glucose measurements within 5 sec by using less than 1 micro-liter of blood. Therefore, to minimize the pain during glucose self-testing, blood sampling from the forearm is a feasible and practical option.

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Take the pain out of blood sugar checks:

Pricking fingers is a vital part of daily diabetes management. In a recent study, up to 35% of the participants stated that pain is the main reason people with diabetes refrain from regular blood glucose testing. One factor contributing to greater pain sensation when pricking the finger is wrong handling of the lancing device. You can test more comfortably with these 7 easy steps:

1. Ensure hands are clean and dry.

2. Lance on the side of the fingertip rather than the pad.

3. Keep the skin taut by pressing the lancing device firmly against the skin.

4. Select a penetration depth as shallow as possible but still produces blood.

5. Alternate fingers daily and take the necessary steps to ensure good blood circulation.

6. Consider testing beyond the fingertip. If you and your healthcare professional agree that checking from other sites is right for you, you may experience less pain after a blood sugar test if you use your palm, forearm or upper arm instead of your sensitive fingertips.

7. Use a fresh lancet. Today’s lancets are so tiny that just a single use can bend or dull the tips. As a result, they can hurt more if you try to reuse them.

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Laser lancet:

It is a laser lancing device that uses a laser beam to draw a drop of blood rather than using a steel lancet.

How does it work?

The fingertip is placed over the disposable lens cover where the laser beam comes out of. Water in the skin absorbs the energy from the laser beam, instantly vaporizing tissue which draws blood.

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Why alternate site?

During the past decade, several studies have clearly established the importance of frequent daily self-monitoring of blood glucose to control one’s glycemic condition and thereby reduce the onset of complications caused by diabetes. Pain associated with finger lancing is one of the major barriers to frequent daily testing. Consequently, it has been argued that skin lancing at less sensitive parts of the body would increase testing compliance. Suzuki was the first to perform such alternate-site testing. In response to the need for less painful testing, several manufacturers have now released products that are specifically designed to be used at body sites other than the fingertip.

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Finger tip vs. alternate site:

Capillary blood glucose levels at the fingertip have been shown to correlate well with systemic arterial blood glucose levels. During times of blood glucose stability, identical glucose levels were demonstrated from alternate sites (e.g., forearm) as compared with finger tip samples. However, at times of rapid change, mainly due to blood flow variability, levels from alternate sites differ considerably.  Capillary blood glucose measured from the forearm is lower than fingertip values at times of rapid increases (>2 mg/dL/min) in systemic blood and higher during rapid decreases. Samples from the dorsal forearm have been shown to correspond better to fingertip values when compared with volar forearm samples. The only exception for the alternate site testing is the palm. The skin type of the palm is in the same skin category, hairless or glabrous skin, as the fingertip, and they share the same amount of blood flow, which is considerably more (five to 20 times) than the blood flow to most alternate sites like the forearm. In that respect, blood flow to forearm and abdomen upper dermal region has been reported to be comparable.

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Alternate sites:

Many children prick sites other than the fingers or toes because they may not hurt as much. The most common alternate site is the forearm. Other places to get blood include the fleshy part of the hand, upper arm, thigh, and back of the calf. The lancet must be dialed to the maximum depth to get enough blood from these sites. You would need a meter that works for these testing sites. The main problem with not using the fingertips is that the blood flow through the arm is slower than through the fingers. The slower blood flow means the blood sugar value from the arm is 10 minutes behind the fingertip.

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Alternate site testing: 

Several blood glucose meters are now available that use sites other than the finger to obtain blood samples in an effort to reduce the discomfort involved with finger sticks. Monitoring at alternate sites, such as the forearm, palm of the hand or thigh, may give slightly lower results than those taken at the fingertips, since they may sample venous blood rather than capillary blood. While this should not be a problem if the patient uses one or the other site exclusively, the between-test variability will increase if numerous sites (such as fingertips and forearm sites) are used. In addition, during times when the blood glucose concentration is either rising rapidly (such as immediately after food ingestion) or falling rapidly (in response to rapidly acting insulin or exercise), blood glucose results from alternate sites may give significantly delayed results compared with finger stick readings. In comparison, blood samples taken from the palm near the base of the thumb (thenar area), demonstrate a closer correlation to fingertip samples at all times of day, and during periods of rapid change in BG levels.

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Alternate site testing should only be used when blood sugar is stable:

•Immediately before a meal

•When fasting

•Near bedtime

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Always check from your fingertip, however, when blood sugar may be changing:

1. Following a meal, when blood sugar is rising quickly

2. After exercise

3. Whenever you think your blood sugar might be low or falling

4. You have just taken insulin

5. The results do not agree with the way you feel

6. You are ill

7. You are under stress

Also, you should never use results from an alternative sampling site to calibrate a continuous glucose monitor (CGM), or in insulin dosing calculations.

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Forearm meter:

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Whole-Blood Glucose Testing at Alternate Sites: 2001 study:

Glucose values and hematocrit of capillary blood drawn from fingertip and forearm:

In this cross-sectional study of 50 nonfasting subjects whose blood glucose concentration changed to various degrees during the experiment, no significant glucose difference was observed between the capillary beds of the forearm and fingertip, regardless of whether glucose was assayed with HemoCue or the Sof-Tact Blood Glucose System. On the other hand, Hb concentration and Hct were found to be significantly higher in the capillary blood of the forearm. No explanation has yet been given for the occurrence of Hb concentration differences across the integument.

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Forearm blood glucose testing in diabetes mellitus: 2002 study:

Self monitoring of blood glucose plays a vital role in the treatment plan of children with diabetes mellitus. Regular self blood glucose monitoring enables the appropriate changes to be made in the treatment and management of the child’s diabetes to meet individual goals and needs. Barriers to frequent self monitoring include the pain and trauma associated with the finger prick necessary to obtain blood for the test. Non-compliance with blood glucose monitoring is common, especially in adolescents. Although modern blood glucose meters only require a small sample of blood, monitoring remains a problem. Using an alternate site for sampling, namely the forearm, may be beneficial to the patient and reduce the level of pain they experience. The main objective of the study was to assess the accuracy of a forearm testing device (SoftSense) in a paediatric population, in comparison to a standard reference laboratory method. Blood glucose measurements from samples taken from the forearm and the finger were compared in an outpatient setting from 52 children and adolescents with diabetes mellitus aged 6–17 years. Opinions on forearm sampling were collected by questionnaire.  Blood glucose results obtained from forearm sampling correlated well with results from the finger measured by the Yellow Springs Instrument analyser. Error grid analysis showed that 100% of measurements were clinically acceptable; 61% of children reported that forearm testing was painless and 19% that it was less painful than finger prick testing.

Conclusion: Forearm testing is an acceptable alternative to finger prick testing for blood glucose measurement in children and adolescents.

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What if I can’t get a drop of blood?

If you don’t get blood from your fingertip, try washing your hands in hot water to get the blood flowing. Then dangle your hand below your heart for a minute. Prick your finger quickly and then put your hand back down below your heart. You might also try slowly squeezing the finger from the base to the tip. If lancing device has dial-a-depth, increase setting by 1 level. Use a new lancet every time you check blood glucose.  

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Your fingertips may get sore from frequent pricking for blood sugar testing. To help prevent sore fingertips:

1. Always prick the side of your finger. Do not prick the tip of your finger. This increases the pain, and you may not get enough blood to do the test accurately. Also, do not prick your toes to get a blood sample. This can increase your risk of getting an infection in your foot.

2. Don’t squeeze the tip of your finger. If you have trouble getting a drop of blood large enough to cover the test area of the strip, hang your hand down below your waist and count to 5. Then squeeze your finger, beginning close to your hand and moving outward toward the tip of your finger.

3. Use a different finger each time. Keep track of which finger you stick so that you don’t use some fingers more than others. If a finger becomes sore, avoid using it to test your blood sugar for a few days.

4. Use a different device. If you are having trouble with sore fingers, you may want to try a meter that obtains a blood sample from sites other than the fingers, such as the palm of the hand or the forearm.

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What supplies are needed for SMBG? 

Doing a blood test requires a method of pricking the skin to get a drop of blood as well as a method of reading the results. Results are read using test strips that are put in a blood glucose meter.

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HOW TO PERFORM BLOOD SUGAR TESTING:

To test your blood sugar level, collect your blood glucose meter, a test strip and lancing device. The following steps include general guidelines for testing blood sugar levels; you should get specific details for your blood glucose monitors from the package insert or your healthcare provider. Never share blood glucose monitoring equipment or fingerstick lancing devices. Sharing of this equipment could result in transmission of infection, such as hepatitis B.

1. Wash hands with soap and warm water. Dry hands.

2. Prepare the lancing device by inserting a fresh lancet. Lancets that are used more than once are not as sharp as a new lancet, and can cause more pain and injury to the skin.

3. Prepare the blood glucose meter and test strip (instructions for this depend upon the type of glucose meter used).

4. Choose your spot—don’t check from the same finger all the time.

5. Use the lancing device to obtain a small drop of blood from your fingertip or alternate site (like the skin of the forearm). Alternate sites are often less painful than the fingertip. However, results from alternate sites are not as accurate as fingertip samples when the blood glucose is rising or falling rapidly. If you have difficulty getting a good drop of blood from the fingertip, try rinsing your fingers with warm water, shaking the hand below the waist, or squeezing (“milking”) the fingertip.

6. Apply the blood drop to the test strip in the blood glucose meter. The results will be displayed on the meter after several seconds.

7. View your test result and take the proper steps if your blood sugar is too high or low, based on your healthcare professionals’ recommendations.

8. Dispose of the used lancet in a puncture-resistant sharps container (not in household trash).

9. Record the results in a logbook, hold them in the meter’s memory or download to a computer so you can review and analyze them later.

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What affects the Test: 

Reasons you may not be able to have the test or why the results may not be helpful include:

1. Alcohol in the drop of blood. If you clean your skin with rubbing alcohol, let the area dry completely before sticking it with the lancet.

2. Water or soap on your finger.

3. Squeezing your fingertip.

4. A drop of blood that is either too large or too small.

5. Very low (below 40 mg/dL or 2.2 mmol/L) or very high (above 400 mg/dL or 22.2 mmol/L) blood sugar levels.

6. Humidity or a wet test strip. Do not store your test strips in the washroom. When you remove a strip from the bottle, promptly secure the lid back on the bottle to prevent humidity from damaging the unused strips.

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Glucometer overview:

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A glucose meter (or glucometer) is a medical device for determining the approximate concentration of glucose in the blood. It can also be a strip of glucose paper dipped into a substance and measured to the glucose chart. It is a key element of home blood glucose monitoring by people with diabetes mellitus or hypoglycemia. A small drop of blood, obtained by pricking the skin with a lancet, is placed on a disposable test strip that the meter reads and uses to calculate the blood glucose level. The meter then displays the level in mg/dl or mmol/l. Blood glucose meters today are small, portable, and easy to use. The mark of a good meter is one that the patient will use regularly and that returns accurate and precise results. Over the past few years the trend with blood glucose meters has been to maximize patient comfort and convenience by reducing the volume of the blood sample required. The blood sample size is now small enough that alternate-site testing is possible. This eliminates the need to obtain blood from the fingers and greatly reduces the pain associated with daily testing. Accurate and precise results have been increased by using better test strips, electronics, and advanced measurement algorithms. Other conveniences include speedy results, edge fill strips, and illuminated test strip ports, to name just a few. Although the cost of using blood glucose meters seems high, it is believed to be a cost benefit relative to the avoided medical costs of the complications of diabetes.  

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Benefits of glucometer:

There are many benefits of using a glucometer for diabetics:

1. It allows diabetics to take care of themselves sans any need to visit doctors and labs regularly.

2. It works towards promoting well-being of the patient.

3. It helps to detect and confirm hypoglycemia.

4. These meters ensure better understanding of medications.

5. The meters help in altering medications.

6. It also helps in detecting infections. Since high blood sugars may be a sign of infection or illness, timely assistance can save many health problems.

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Disadvantages of home blood glucose testing:

The disadvantages are mainly seen when either the patient lacks motivation to test or does not have sufficient education on how to interpret the results to make sufficient use of home testing equipment. Where this is the case, the following disadvantages may outweigh the potential benefits:

1. Anxiety about one’s blood sugar control and state of health

2. The physical pain of finger pricking

3. Costly affair

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There are several key characteristics of glucose meters which may differ from model to model:

•Size: The average size is now approximately the size of the palm of the hand. They are battery-powered.

•Test strips: A consumable element containing chemicals that react with glucose in the drop of blood is used for each measurement. For some models this element is a plastic test strip with a small spot impregnated with glucose oxidase and other components. Each strip is used once and then discarded. Instead of strips, some models use discs, drums, or cartridges that contain the consumable material for multiple tests.

•Coding: Since test strips may vary from batch to batch, some models require the user to manually enter in a code found on the vial of test strips or on a chip that comes with the test strip. By entering the coding or chip into the glucose meter, the meter will be calibrated to that batch of test strips. However, if this process is carried out incorrectly, the meter reading can be up to 4 mmol/L (72 mg/dL) inaccurate. The implications of an incorrectly coded meter can be serious for patients actively managing their diabetes. This may place patients at increased risk of hypoglycemia. Alternatively, some test strips contain the code information in the strip; others have a microchip in the vial of strips that can be inserted into the meter. These last two methods reduce the possibility of user error. One manufacturer has standardized their test strips around a single code number, so that, once set, there is no need to further change the code in their older meters, and in some of their newer meters, there is no way to change the code.

•Volume of blood sample: The size of the drop of blood needed by different models varies from 0.3 to 1 μl. (Older models required larger blood samples, usually defined as a “hanging drop” from the fingertip.) Smaller volume requirements reduce the frequency of unproductive pricks.

•Alternative site testing: Smaller drop volumes have enabled “alternate site testing” — pricking the forearms or other less sensitive areas instead of the fingertips. Although less uncomfortable, readings obtained from forearm blood lag behind fingertip blood in reflecting rapidly changing glucose levels in the rest of the body.

•Testing times: The times it takes to read a test strip may range from 3 to 60 seconds for different models.

•Display: The glucose value in mg/dl or mmol/l is displayed on a digital display. The preferred measurement unit varies by country: mg/dl are preferred in the U.S., France, Japan, Israel, and India. mmol/l are used in Canada, Australia, China and the UK. Germany is the only country where medical professionals routinely operate in both units of measure. (To convert mmol/l to mg/dl, multiply by 18. To convert mg/dl to mmol/l, divide by 18.) Many meters can display either unit of measure; there have been a couple of published instances in which someone with diabetes has been misled into the wrong action by assuming that a reading in mmol/l was really a very low reading in mg/dl, or the converse. In general, if a value is presented with a decimal point, it is in mmol/l, without a decimal it is most likely mg/dl.

•Clock/memory: All meters now include a clock that is set by the user for date and time and a memory for past test results. The memory is an important aspect of diabetes care, as it enables the person with diabetes to keep a record of management and look for trends and patterns in blood glucose levels over days and weeks. Most memory chips can display an average of recent glucose readings. A known deficiency of all current meters is that the clock is often not set to the correct time (i.e. – due to time changes, static electricity, etc…) and therefore has the potential to misrepresent the time of the past test results making pattern management difficult.

•Data transfer: Many meters now have more sophisticated data handling capabilities. Many can be downloaded by a cable or infrared to a computer that has diabetes management software to display the test results. Some meters allow entry of additional data throughout the day, such as insulin dose, amounts of carbohydrates eaten, or exercise. A number of meters have been combined with other devices, such as insulin injection devices, PDAs, cellular transmitters and Game Boys. A radio link to an insulin pump allows automatic transfer of glucose readings to a calculator that assists the wearer in deciding on an appropriate insulin dose.

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Blood glucose vs. plasma glucose:

Glucose levels in plasma (one of the components of blood) are generally 10%–15% higher than glucose measurements in whole blood (and even more after eating). This is important because home blood glucose meters measure the glucose in whole blood while most lab tests measure the glucose in plasma. Currently, there are many meters on the market that give results as “plasma equivalent,” even though they are measuring whole blood glucose. The plasma equivalent is calculated from the whole blood glucose reading using an equation built into the glucose meter. This allows patients to easily compare their glucose measurements in a lab test and at home. It is important for patients and their health care providers to know whether the meter gives its results as “whole blood equivalent” or “plasma equivalent.”

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Glucose meters vary in their method of analysis. Some meters take a fixed volume of patient whole blood, lyse the cells, and analyze the amount of glucose in that volume of lysate. Other meters utilize a series of absorbent pads to separate the cellular portion of a sample from the serum/plasma portion. This allows only serum/plasma to react with the enzymatic reagents. In order to harmonize glucose results, consensus recommends reporting serum/plasma-based results from glucose meters such that the value will most closely match that of a laboratory method using a serum/plasma sample. Glucose meter whole blood lysate results must therefore be corrected to serum/plasma by either applying a fixed mathematical offset to obtain a “plasma-corrected result” (assuming a normal hematocrit) or correcting the whole blood lysate result using the patient’s actual hematocrit. There are meters on the market that use both types of correction. However, it is more common for manufacturers whose meters separate the cellular portion of the sample to set the calibration of the meter against a laboratory method in order to report a “plasma-calibrated” result. The differences between these various calibration and correction functions are one source of variability among the many glucose meter models when analyzing the same specimen.

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Measurement of glucose content in plasma from capillary blood in diagnosis of diabetes mellitus: a 2003 study:

Overall, there is good correlation between glucose values obtained from ear capillary blood and those from peripheral venous plasma, but there are considerable individual differences. Results obtained with these two methods are generally not interchangeable and the converted values should not be used in the diagnosis of diabetes mellitus, because of the risk of misclassification. The aim of this study was to investigate whether these differences might be less significant if measurements were taken at the plasma phase of capillary blood and expressed directly as capillary plasma results and if finger capillary blood were used instead of ear capillary blood. The Hitachi 717 instrument was used for measurements of glucose concentrations in venous plasma, the Cobas Mira S in capillary whole blood and the Accu-Chek Inform from Roche in capillary plasma. The conclusions drawn were (1) capillary ear blood glucose concentration correlates well with capillary finger blood concentration and the two sites can be used interchangeably, yielding similar results in the individual patient; (2) sampling variation is almost the same (approx. 0.16 mmol/L) on capillary plasma and capillary whole blood from finger and ear. Sampling variation for venous plasma measured on the Hitachi instrument was 0.13 mmol/L; not significantly better; (3) the analytical imprecision of glucose measurements on capillary plasma (Accu-Chek Inform) and capillary whole blood (haemolysate method) is almost the same (approx. 2.0%). The analytical imprecision of glucose measurements on venous plasma is 0.9% using a laboratory method and almost twice as high using Accu-Chek Inform (2.1%); (4) determination of capillary plasma values in the finger did not improve the correlation with venous plasma values. Even though average values were in better concordance, individual differences did not change. For some persons, both ear- and finger capillary blood measurements deviate significantly from results on venous plasma, such that they cannot be used for diagnosis of diabetes mellitus; (5) the main factor for good correlation is the sampling site. Results obtained on plasma and whole blood from the same puncture correlate well; (6) neither capillary blood nor capillary plasma correlates with the venous plasma method recommended by the American Diabetes Association. It is concluded that physiologic differences in glucose content in capillary- and venous blood prohibit the random use of these two materials in the diagnosis of diabetes.

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Meter Types:

There are continuous and discrete (single-test) meters on the market today, and implantable and noninvasive meters are in development. Continuous meters are by prescription only and use a subcutaneous electrochemical sensor to measure at a programmed interval.

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Electrochemical meter:

Single-test meters use electrochemical or optical reflectometry to measure the glucose level in units of mg/dL or mmol/L. The majority of blood glucose meters are electrochemical. Electrochemical test strips have electrodes where a precise bias voltage is applied with a digital-to-analog converter (DAC), and a current proportional to the glucose in the blood is measured as a result of the electrochemical reaction on the test strip. There can be one or more channels, and the current is usually converted to a voltage by a transimpedance amplifier (TIA) for measurement with an analog-to-digital converter (ADC). The full-scale current measurement of the test strip is in the range of 10µA to 50µA with a resolution of less than 10nA. Ambient temperature needs to be measured because the test strips are temperature dependent.

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Optical-reflectometry meter:

Optical-reflectometry test strips use color to determine the glucose concentration in the blood. Typically, a calibrated current passes through two light-emitting diodes (LEDs) that alternately flash onto the colored test strip. A photodiode senses the reflected light intensity, which is dependent on the color of the test strip, which, in turn, is dependent on the amount of glucose in the blood. The photodiode current is usually converted to a voltage by a TIA for measurement with an ADC. The full-scale current from the photodiode ranges from 1µA to 5µA with a resolution of less than 5nA. Ambient temperature is required for this method.

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Meter use for hypoglycemia:

Although the apparent value of immediate measurement of blood glucose might seem to be higher for hypoglycemia than hyperglycemia, meters have been less useful. The primary problems are precision and ratio of false positive and negative results. An imprecision of ±15% is less of a problem for high glucose levels than low. There is little difference in the management of a glucose of 200 mg/dl compared with 260 (i.e., a “true” glucose of 230±15%), but a ±15% error margin at a low glucose concentration brings greater ambiguity with regards to glucose management. The imprecision is compounded by the relative likelihoods of false positives and negatives in populations with diabetes and those without. People with type 1 diabetes usually have glucose levels above normal, often ranging from 40 to 500 mg/dl (2.2 to 28 mmol/l), and when a meter reading of 50 or 70 (2.8 or 3.9 mmol/l) is accompanied by their usual hypoglycemic symptoms, there is little uncertainty about the reading representing a “true positive” and little harm done if it is a “false positive.” However, the incidence of hypoglycemia unawareness, hypoglycemia-associated autonomic failure (HAAF) and faulty counterregulatory response to hypoglycemia make the need for greater reliability at low levels particularly urgent in patients with type 1 diabetes mellitus, while this is seldom an issue in the more common form of the disease, type 2 diabetes mellitus. In contrast, people who do not have diabetes may periodically have hypoglycemic symptoms but may also have a much higher rate of false positives to true, and a meter is not accurate enough to base a diagnosis of hypoglycemia upon. A meter can occasionally be useful in the monitoring of severe types of hypoglycemia (e.g., congenital hyperinsulinism) to ensure that the average glucose when fasting remains above 70 mg/dl (3.9 mmol/l).

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False results:

Probably the greatest concern when using glucose meters is false results. All users should be educated about factors contributing to false results. The Office of In Vitro Diagnostics (OIVD), a service of the FDA, evaluates glucose meters. They evaluate long term safety and effectiveness of the analysers and how devices are used. OIVD, in consultation with manufacturers and users, have produced a table of common problems encountered when using glucose meters as seen in the table below. Causes of false results may be patient/sample based or user/device based. Probably the most important advice for any user of a blood glucose meter is to question any result not consistent with the clinical picture. This needs to be investigated and, at a minimum, the test repeated.

Common problems with glucose meter results.

Results Problem Recommendation
Falsely low results Sensor strips not fully inserted into meter Always be sure strip is fully inserted in meter
Not enough blood applied to strip Repeat test with a new sample
Patient in shock Treat appropriately. Venous sample should be sent immediately to a laboratory
Squeezing fingertip too hard because blood is not flowing Repeat test with a new sample from a new stick
Polycythaemia/increased haematocrit Venous sample should be sent to a laboratory
Falsely high results Patient sample site (for example the fingertip) is contaminated with sugar Always clean test site before sampling
Patient is dehydrated Treat appropriately. Venous sample should be sent immediately to a laboratory
Anemia/decreased haematocrit Venous sample should be sent to a laboratory
Variable results Test strips/controls stored at temperature extremes Store kit according to directions
Sites other than fingertips Results from alternative sites may not match finger stick results
Test strips/controls damaged Always inspect package for cracks, leaks, etc.
Dirty meter Even small amounts of blood, grease, or dirt on a meter’s lens can alter the reading
Error codes Batteries low on power Change batteries and repeat sample collection
Test will not complete Check package details, calibration code, and expiry dates are all compatible

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Variables:

We make decisions based on the results of our blood glucose measurements – it is therefore important to us that the readings we obtain are true. What then, other than glucose, may affect the outcome of the test?

•System variables:

- Batch-to-batch or strip-to-strip variation of strips

 - Meter-to-meter variability

•Testing variables:

- Environment – temperature, humidity, altitude

 - User – technique (note hands should be dry and clean before finger-pricking), timing

•Patient variables:

- Blood sample – capillary or venous, red blood cell count

 - Dehydration of the patient

Extreme hypo- or hyperglycemia (if the blood glucose level falls outside the working range of the meter a ‘LO’ or ‘HI’ message will usually be displayed)

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Calibration:

Each pack of test strips usually comes with a special ‘calibration code’. This is a correction factor for the meter which is derived by comparing meter response with a standardised laboratory assay or ‘reference method’. For accurate readings it is essential that the meter is recalibrated between batches of strips.  If you choose to check the accuracy of your meter using a ‘quality control’ solution then you must use one specially formulated by the meter manufacturer. It may be easy enough to make up a standard solution with known concentration of glucose; unfortunately though, such home-made standards, usually water-based, do not behave the same way as blood on the test strip.

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Considerations for Glucose Meter selection:

Feature Clinical advantages
Smaller sample size requirement Less painful, permits alternate site testing
Alternate site testing Less discomfort for patients who use fingertips regularly (e.g., for typing)
Results in less than 15 seconds Increased convenience

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How do you choose a Glucose Meter?

There are many different types of meters available for purchase that differs in several ways, including:

  • accuracy
  • amount of blood needed for each test
  • how easy it is to use
  • pain associated with using the product
  • testing speed
  • overall size
  • ability to store test results in memory
  • likelihood of interferences
  • ability to transmit data to a computer
  • cost of the meter
  • cost of the test strips used
  • doctor’s recommendation
  • technical support provided by the manufacturer
  • special features such as automatic timing, error codes, large display screen, or spoken instructions or results

Talk to your health care provider about the right glucose meter for you, and how to use it.

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How can you check your meter’s performance? There are three ways to make sure your meter works properly:

1. Use liquid control solutions:

–every time you open a new container of test strips

–occasionally as you use the container of test strips

–if you drop the meter

–whenever you get unusual results

To test a liquid control solution, you test a drop of these solutions just like you test a drop of your blood. The value you get should match the value written on the test strip vial label.

2. Use electronic checks:

 Every time you turn on your meter, it does an electronic check. If it detects a problem it will give you an error code. Look in your meter’s manual to see what the error codes mean and how to fix the problem. If you are unsure if your meter is working properly, call the toll-free number in your meter’s manual, or contact your health care provider.

3. Compare your meter with a blood glucose test performed in a laboratory:

Take your meter with you to your next appointment with your health care provider. Ask your provider to watch your testing technique to make sure you are using the meter correctly. Ask your health care provider to have your blood tested with a laboratory method. If the values you obtain on your glucose meter match the laboratory values, then your meter is working well and you are using good technique.

What should you do if your meter malfunctions?

 If your meter malfunctions, you should tell your health care provider and contact the company that made your meter and strips.

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What other supplies do you need?

All meters require test strips to operate – a small chemically treated strip that slides into the meter. After insertion, a drop of blood is placed on the opposite end of the strip that protrudes from the meter, and the meter reads the glucose level and displays the number on the screen. Some monitors use test strip drums or discs, which are self-enclosed packages of strips that automatically load without user intervention or handling. Small children and adults who have difficulties with their fine motor skills may find this type of monitor easier to use. You’ll also need a lancet (a small, fine needle) to get a blood sample for testing. Lancets are inserted into a lancet device – a spring-loaded mechanism about the size and shape of a pen. A dial allows the user to adjust the depth of the lancet stick. Typically there is a button that you push to release the lancet into a fingertip or other site to draw a blood sample. Lancets come in different gauges; the higher the gauge, the finer (i.e., thinner) the needle. Higher gauge needles are less painful, but they also may create a smaller blood sample. Your blood glucose monitor may also come with control solution (for calibrating the monitor per manufacturer’s directions for use) and a carrying case.

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Glucometer sensor (test strips):

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The sensor used has an electroenzymatic approach, which means that it takes advantage of glucose oxidation with a glucose oxidase enzyme. The presence of glucose oxidase catalyzes the chemical reaction of glucose with oxygen, which causes an increase in pH, decrease in the partial pressure of oxygen, and increase of hydrogen peroxide because of the oxidation of glucose to gluconic acid: The test strip measures changes in one or several of these components to determine the concentration of glucose. A negative voltage of –0.4 V is applied at the reference electrode. When blood or a glucose solution is placed in the strip, a chemical reaction occurs inside it, generating a small electrical current proportional to the glucose concentration. This current is constantly monitored while the strip is in place, allowing the device to monitor when blood is placed. After the chemical reaction stabilizes, 5 s, the voltage is read by the ADC and compared using a look-up table to obtain the proportional glucose value in mg/dL. This value is sent to the host computer to inform the glucose value. When choosing test strips, make sure they work in the meter you are using. Look for strips that need only a small drop of blood and can draw the blood into the strip (capillary action).

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Caring for Strips:

It is important to care for your strips so that you get an accurate reading. To do this, refer to the manufacturer’s instructions. It will include recommendations like:

•Storing them in a dry place

•Replacing the cap immediately after use

•Checking the expiry date is valid.

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Avoiding problems with meter usage:

Blood sugar meters need to be used and maintained properly. Follow these tips to ensure proper usage:

•Follow the instructions in the user manual for your device, as procedures may vary from one device to another.

•Use a blood sample size as directed in the manual because different meters require different sample sizes.

•Change batteries as recommended by the manufacturer.

•Use only test strips designed for your meter because not all devices and strips are compatible.

•Store test strips as directed.

•Don’t use expired test strips.

•Clean the device regularly as directed.

•Run quality control tests as directed.

•Check the manual for additional troubleshooting tips.

•Bring the meter with you to doctor appointments to address any questions and to demonstrate how you use your meter.

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Recent advances in glucometer:

Recent advances include:

1. ‘Alternate site testing’, the use of blood drops from places other than the finger, usually the palm or forearm. This alternate site testing uses the same test strips and meter, is practically pain free, and gives the real estate on the finger tips a needed break if they become sore. The disadvantage of this technique is that there is usually less blood flow to alternate sites, which prevents the reading from being accurate when the blood sugar level is changing.

2. ‘No coding’ systems. Older systems required ‘coding’ of the strips to the meter. This carried a risk of ‘miscoding’, which can lead to inaccurate results. Two approaches have resulted in systems that no longer require coding. Some systems are ‘autocoded’, where technology is used to code each strip to the meter. And some are manufactured to a ‘single code’, thereby avoiding the risk of miscoding.

3. ‘Multi-test’ systems. Some systems use a cartridge or a disc containing multiple test strips. This has the advantage that the user doesn’t have to load individual strips each time, which is convenient and can enable quicker testing.

4. ‘Downloadable’ meters. Most newer systems come with software that allows the user to download meter results to a computer. This information can then be used, together with health care professional guidance, to enhance and improve diabetes management. The meters usually require a connection cable, unless they are designed to work wirelessly with an insulin pump, or are designed to plug directly into the computer.

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Specialized glucometer:

Hospital glucose meters:

Special glucose meters for multi-patient hospital use are now used. These provide more elaborate quality control records. Their data handling capabilities are designed to transfer glucose results into electronic medical records and the laboratory computer systems for billing purposes.

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ACCU-CHEK® Aviva Expert, the first and only stand-alone blood glucose meter system with a built-in insulin calculator:

Roche announced that Roche’s ACCU-CHEK® Aviva Expert system, the first and only blood glucose meter system with a built-in insulin calculator to be approved by the U.S. Food and Drug Administration (FDA), is now available by prescription. The device represents a significant advancement in blood glucose meter technology for people with diabetes who take multiple daily insulin injections. The meter’s integrated bolus calculator provides easy-to-use and reliable dose recommendations based on automated calculations, eliminating the need for manual dosing calculations and estimations. A survey of ACCU-CHEK Aviva Expert users found that 79 percent reported increased confidence with insulin dose calculation, and 52 percent reported a reduced fear of hypoglycemia.  In the United States, approximately 6 million people take insulin to help manage their diabetes. Many people also take multiple daily injections of insulin to help manage their disease, which requires them to calculate proper insulin dosage amounts based on their food intake and blood glucose readings. These calculations are complex, and constant precision is critical to determine the proper insulin dose. A multicenter study found that 63 percent of manually calculated insulin doses were incorrect. As an incorrect insulin dose can lead to serious health complications, including hypoglycemia, accurate calculations are required. Researchers from the U.S. Centers for Disease Control and Prevention (CDC) reported that there were nearly 100,000 emergency room (ER) visits each year between 2007 and 2011 that were attributed to insulin-related hypoglycemia and other errors, and that these visits accounted for roughly 9 percent of all ER visits due to drug reactions during this timeframe. The availability of the ACCU-CHEK Aviva Expert system marks an important, game-changing milestone in diabetes self-management by making the process of calculating insulin dosage easier and less susceptible to error. One of the biggest barriers to optimal self-management is the ability to calculate bolus doses. It is hoped is that the device will become the standard of care for patients on multiple daily insulin injection therapy due to the simplicity of the built-in bolus calculator.

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Glucometer for blind:

If you’ve been certified as legally blind, it’s likely you’ll meet the requirements of most insurers to obtain a blood glucose monitor with speech capability, also called a talking blood glucose monitor. Be aware that talking meters fall into 2 categories – those with partial speech and those with full speech. Those with partial speech may only announce your blood glucose result while meters with full speech not only announce your result but also the results in memory, low battery warning, and audible steps to set the time and other monitor features. I wonder how a blind person would use lancet to pierce finger tip and put drop of blood on test strip.

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Meter to determine glucose plus ketones in blood:

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Integrated Self-Monitoring of Blood Glucose System: Handling Step Analysis: 2012:

Self-monitoring of blood glucose (SMBG) implicates a number of handling steps with the meter and the lancing device. Numerous user errors can occur during SMBG, and each step adds to the complexity of use. This report compares the required steps to perform SMBG of one fully integrated (the second generation of the Accu-Chek® Mobile), three partly integrated (Accu-Chek Compact Plus, Ascensia® Breeze®2, and Accu-Chek Aviva), and six conventional (Bayer Contour®, Bayer Contour USB, BGStar™, FreeStyle Lite®, OneTouch® Ultra® 2, and OneTouch Verio™Pro) systems. The results show that the fully integrated system reduces the number of steps to perform SMBG. The mean decrease is approximately 70% compared with the other systems. Authors assume that a reduction of handling steps also reduces the risk of potential user errors and improves the user-friendliness of the system.  

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Individuals achieve more accurate results with Meters that are Codeless and employ Dynamic Electrochemistry: a study:

Four blood glucose monitoring systems (with or without dynamic electrochemistry algorithms, codeless or requiring coding prior to testing) were evaluated and compared with respect to their accuracy. Altogether, 108 blood glucose values were obtained for each system from 54 study participants and compared with the reference values. Analytical performance of these blood glucose meters differed significantly depending on their technologic features. Meters that utilized dynamic electrochemistry and did not require coding were more accurate than meters that used static electrochemistry or required coding.

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Heel-stick SMBG in neonate:

 Heel stick is a minimally invasive and easily accessible way of obtaining capillary blood samples for SMBG in newborn. The development of newer, more effective and less painful lancing devices may increase the relative utility of heel stick. Heel stick sampling can also help preserve venous access for future intravenous (IV) lines in neonates. The normal range of blood glucose is around 1.5–6 mmol/l in the first days of life, depending on the age of the baby, type of feed, assay method used, and possibly the mode of delivery. Up to 14% of healthy term babies may have blood glucose less than 2.6 mmol/l in the first three days of life. The normal blood glucose level in full-term babies is 40 mg/dL to 150 mg/dL. In premature infants, it is 30 mg/dL to 150 mg/dL. The healthy, term infant experiences a brief, self-limited period of relatively low blood glucose during the first two hours of life. Infants are normally asymptomatic during this time. As this transient drop is physiologic, routine glucose screening is not recommended. Lowest concentrations are more likely on day 1. There is no reason to routinely measure blood glucose in appropriately grown term babies who are otherwise well. Screening should be directed towards those infants at risk for pathologic hypoglycemia. Glucose screening is recommended for infants in the following categories who are at increased risk for pathological hypoglycemia:

  • Born to mothers with gestational diabetes or diabetes mellitus
  • Large for gestational age (LGA) ( >3969g)
  • Small for gestational age (SGA) (<2608g)
  • Premature (<37 weeks gestation)
  • Low birth weight (<2500g)
  • Smaller twin when sizes are discordant
  • Polycythemia (hct >70%)
  • Hypothermia
  • Low Apgar scores (<5 at one minute, <6 at five minutes)
  • Stress (sepsis, respiratory distress, etc)

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Standardization of glucometer:

There are two ways to assess the accuracy of glucose measurement techniques: technical or clinical. Technical accuracy assesses the agreement between the measured and reference glucose values. Clinical accuracy judges how the differences in the measurements impact clinical decision processes. Both have clinical implications.  A review by Krouwer and Cembrowski details the standards and statistical methods used to characterize accuracy of SMBG Devices and highlight the different criteria acceptable for accuracy between standard organizations and professional societies. In 1987, an American Diabetes Association (ADA) consensus statement recommended that the acceptable error for SMBG DEVICEs from all sources (user, analytical, etc.) should be less than 10% for glucoses ranging from 30 to 400 mg/dl at all times. This ADA consensus statement also recommended that glucose measurements should not differ more than 15% from values obtained by a laboratory reference method. The ADA decreased the maximum allowable analytical error to <5% in 1996.  International Organization for Standardization (ISO) 15197 provided different recommendations in 2003. These state that 95% of the individual glucose measurements compared to the reference measurements are required to be in the range ±15 mg/dl for values less than or equal to 75 mg/dl and ±20% for glucose values greater than 75 mg/dl. This is the standard that the FDA normally uses as the goal for approval of SMBG DEVICEs. The standards set by the ADA (ADA 1987/1996), requiring all glucose measurements with SMBG DEVICEs to be within 5% of CLD values, were deemed technically unachievable by the International Federation of Clinical Chemistry and Laboratory Medicine.

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Differing glucometer standards:

Although there is no universal standard for accuracy of glucose meters, several groups have defined acceptable ranges. The U.S. Food and Drug Administration (FDA) requires glucose meters to produce self-monitoring results within 20 percent of a reference measurement but recommends results within 15 percent; the FDA has stated that future meters should achieve results within 10 percent of reference at serum glucose concentrations of 30 to 400 mg per dL (1.7 to 22.2 mmol per L). The American Diabetes Association (ADA) recommends that meters produce readings within 5 percent of laboratory values. All meters currently on the market are considered to be clinically accurate in that they at least meet the FDA standard, although it is important to remember that they are not as accurate as a standard laboratory test. Given this broad range of possible error, making treatment decisions based solely on self-monitoring of blood glucose (SMBG) is not advised. Glucose meters are most accurate when used properly. Thus, educating patients on proper use and what to do with the results is vital. Although the exact procedure for using a meter varies by product, potential pitfalls are similar. Common errors include poor maintenance (e.g., soiled meter), using expired test strips, obtaining an inadequate sample size, and failing to calibrate the meter.

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International Organization for Standardization of SMBG devices:

In a recent study in 2012 of 43 glucose meters, only 34 systems met ISO standards. ISO 15197:2013 specifies requirements for in vitro glucose monitoring systems that measure glucose concentrations in capillary blood samples, for specific design verification procedures and for the validation of performance by the intended users. These systems are intended for self-measurement by lay persons for management of diabetes mellitus. ISO 15197:2013 is applicable to manufacturers of such systems and those other organizations (e.g. regulatory authorities and conformity assessment bodies) having the responsibility for assessing the performance of these systems.  Based on ISO 15197:2013, the blood-glucose monitoring system shall meet both the following minimum criteria for acceptable system accuracy.

1.  95% of the measured glucose values shall fall within the standard:

2.  99% of individual glucose measured values shall fall within zones A and B of the Clarke Error Grid (CEG) for type 1 diabetes. The Clarke Error Grid Analysis (EGA) was developed in 1987 to quantify clinical accuracy of patient estimates of their current blood glucose as compared to the blood glucose value obtained in their meter. The grid breaks down a scatter plot of a reference glucometer and evaluated glucometer into 5 regions; A, B, C, D, and E.

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Why SMBG is done?

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Self-monitoring is an integral part of diabetes management because it puts you in charge. Regardless of how you manage your diabetes — through diet and exercise alone or combined with oral medicines or insulin — regular blood glucose monitoring provides immediate feedback on how your program is working. Checking your blood glucose gives you the freedom to make choices without worry, the confidence to learn from your actions, and the motivation to keep striving to do better.  Monitoring tells you that what you’re doing either is working or isn’t, and it serves as motivation to keep up actions that are working or to make changes. The important thing is to know how to interpret the numbers and take the necessary action. For example, if you take insulin and your blood glucose is high, you may need to bolus, or take more rapid-acting insulin, to bring your levels down into range. If you manage your Type 2 diabetes with diet and exercise, you might treat high blood glucose with a walk around the block. People who use insulin and certain oral diabetes drugs are also at risk of developing low blood glucose, or hypoglycemia, which needs to be treated promptly when it occurs. Regular monitoring may enable you to catch and treat it early, and any symptoms of hypoglycemia should be checked with a meter reading. Over time, blood glucose monitoring records can be analyzed for patterns of highs or lows that may suggest that a change is needed in the treatment regimen. Regular monitoring is especially helpful for showing the positive effects of exercise. Say your readings have regularly been around 140 mg/dl, but you start taking a walk every day and you start getting more readings around 120 mg/dl. That will definitely boost your motivation.

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Self-monitoring blood glucose — provides useful information for diabetes management.

It can help you to:

•Judge how well you’re reaching overall treatment goals

•Understand how diet, stress and exercise affect blood sugar levels

•Understand how as illness affect blood sugar levels

•Monitor the effect of diabetes medications on blood sugar levels

•Identify blood sugar levels that are dangerously high or low

•Help prevent low blood sugar at night

•Reduce the risk of eye, kidney and nerve complications

•Help you make informed decisions about the amount and type of insulin to use

•Help you manage illness at home and alert you if you need to do a ketone test

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Based upon the results of randomized trials, self-monitoring of blood glucose (SMBG) is recommended for in patients who take medications that can cause hypoglycemia and that need to be adjusted based on ambient glucose levels. For example, in order to avoid hypoglycemia and achieve target glucose levels, patients with type 1 diabetes who take mealtime insulin should usually test before meals to adjust doses, based on meal size and content, anticipated activity levels, and glucose levels. Similar guidelines apply to insulin-treated type 2 diabetes, although their glucose levels are characteristically more stable, and they may require less frequent monitoring. Patients treated with sulfonylureas or meglitinides, which can also cause hypoglycemia, should be tested once to twice per day during titration of their doses, but after a stable dose and target glycemic targets are achieved, may only need to test several times per week, usually in the morning or before dinner. All insulin and sulfonylurea patients need to test more frequently before and during long car rides, during sick days, and when there are changes in diet and exercise patterns.

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Clinical utility of SMBG:

Uses of SMBG data include identifying and treating hyper- and hypoglycemia; making decisions about food intake or medication adjustment when exercising; determining the effect of ingested food on blood glucose; and managing glucose fluctuations resulting from illness.  Although the data are somewhat conflicting, larger, better-designed trials have shown that SMBG improves glycemic control when the results are used to adjust therapy. However, the data for reducing long-term complications are more conclusive for patients on insulin therapy. In most hands, the glucose oxidase strip method is accurate and reliable. Since whole blood is used, the results tend to be slightly lower than simultaneous venous samples, but this is balanced by the fact that capillary blood has a higher glucose concentration than venous blood. Most patients can visually estimate the correct value, but a few patients consistently misread the visual charts and must use a reflectance meter. This may be due to an unexpectedly high prevalence of disturbances of color perception in diabetics. Most patients feel more comfortable with the digital readout of the reflectance meter, although it is not necessarily more accurate. The major sources of error are in failing to put a large enough drop of blood on the strip and inaccurate timing. For patients who use reflectance meters, another source of error is failure to keep the machine clean and calibrated. Once the color is developed, it is relatively stable, so patients can be instructed to bring developed strips to the physician’s office so that the accuracy can be checked.

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Optimal use of SMBG:

Establishing a Glucose Profile:

To take full advantage of the benefits of SMBG, patients must collect data at appropriate times during the day, recognize readings that are outside their target range, and take action to improve their glycemic control. This is most easily accomplished by having patients compile a periodic glucose profile by taking a series of blood glucose measurements throughout the day, capturing information from the fasting, postprandial, and postabsorptive (or late postprandial) periods. Conversely, by staggering SMBG measurements at different times on different days, patients can generate an accurate portrait of day-to-day glycemic excursions while avoiding the need to test many times in a single day. Regardless of the testing regimen, patients should be encouraged to collect data on glucose levels relative to meals. Studies that have used meal-based SMBG testing have demonstrated improvements in HbA1c. The ability to download memory meters with a date and time stamp greatly facilitates this process. Some meters have event markers for meal times, insulin doses, exercise, and hypoglycemia, substantially adding to the power of the analysis.

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Pattern Recognition:

Regardless of the monitoring regimen, a key to effective use of SMBG in clinical practice is “pattern management,” a systematic approach to recognizing the glycemic patterns within SMBG data and then taking action based on those results. This approach consists of several key steps: (1) establish both premeal and postmeal blood glucose targets; (2) gather data on blood glucose levels, carbohydrate in-take, insulin dose (when applicable), activity levels, schedule, and physical and emotional stress; (3) analyze data to determine whether any patterns emerge; (4) assess any influencing factors; (5) take action; and (6) regularly monitor blood glucose levels to evaluate the impact of actions taken. By using the data gathered during a specified period, the clinician and patient can review patterns of glycemic excursions and then make adjustments to meals, activities, and medications to better control glucose levels, minimize glycemic excursions, and limit hypoglycemia.

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Inconsistent Highs & Lows:

Sometimes you may get a lower or higher blood glucose reading than usual and you may not be able to figure out the reason. When you are sick with a virus or flu, your blood glucose levels will nearly always go up and you may need to contact your doctor. There are a number of other common causes for blood glucose levels to increase or decrease. These include:

•Food – time eaten, type and amount of carbohydrate for example: bread, pasta, cereals, vegetables, fruit and milk

•Exercise or physical activity

•Illness and pain

•Diabetes medication

•Alcohol

•Emotional stress

•Other medications

•Testing techniques.

Contact your doctor or Credentialed Diabetes Educator if you notice that your blood glucose patters change or are consistently higher or lower than usual.

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A change in attitude:
For many people with diabetes, striving for tight control is a full-time job, and numbers outside the parameters of your goals can make you crazy. Dale, the diabetes educator from the University of Michigan, suggests a shift in perception that can help avoid knee-jerk reactions to high or low numbers: Instead of “testing” your blood glucose, “monitor” it. “When you ‘test,’” she says, “the results can be interpreted to mean that you’ve ‘passed’ or ‘failed.’ It’s emotionally charged. When you ‘monitor’ instead, you gather information and make adjustments as necessary. You just need to ask, ‘What can I learn from this? Was my serving of pasta too large? Do I need to lower my insulin dose before exercise? What can I do better to prevent this from happening in the future?’ That’s how it should be for everyone.”

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Barriers to SMBG:

Barriers to optimal use of SMBG include limited knowledge, both by clinicians and patients, as well as from perceived inconvenience or discomfort with the measurement. Motivational/behavioral issues, particularly in the adolescent subgroup, may also be a barrier. These issues, however, should never distract from the fact that failure to achieve glycemic control with SMBG is often the result of a failure to properly educate patients how to monitor blood glucose levels and the importance of accuracy in doing so. Thus, clinicians must be aware of these potential barriers and be prepared to address them with individual patients and other caregivers, such as families or guardians.

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Barriers and facilitators to SMBG by people with type 2 diabetes using insulin

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Conceptual framework of factors influencing the use of SMBG:

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Rate of daily SMBG among Adults with Diabetes aged 18 Years and Older, 1997-2006: CDC Data & Statistics:

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From 1997 to 2006, rates of SMBG increased overall, in all age groups examined, and in the majority of states examined. Health insurance policy changes and improvements in monitoring devices during this period might have influenced the rate increases. The Balanced Budget Act of 1997 provided Medicare coverage for blood-glucose monitors and testing strips for persons with insulin-treated or non–insulin-treated diabetes. This change in Medicare coverage and its possible influence on the policies of private insurers might have contributed to the increases in SMBG rates. The improvement in monitoring technology makes the monitoring practice more convenient, which might also contribute to the upward trends. Consistent with findings from other studies, lower rates of SMBG were correlated with being male, having less than a high school education, having no health insurance coverage, taking no medication or oral medication only, making two or fewer doctor visits annually, and not having taken a diabetes-education course. The negative associations between SBMG and lower education or lack of health insurance coverage suggest that socioeconomic barriers might impede the practice of SMBG. The cost of blood glucose–monitoring supplies might be a barrier for patients with limited economic resources. Positive associations were observed between SMBG and number of doctor visits, insulin use, or having ever taken a diabetes-education course, which indicates that SMBG might be associated with better disease management or more intensive medical care. Access to health care is an important factor associated with SMBG. Health insurance coverage of monitoring devices and supplies is integral in encouraging self-monitoring and self-management practices. Collaborations to ensure adequate insurance coverage for blood-glucose monitors, test strips, and lancets are essential for increasing the rates and benefits of SMBG. Recommendations from health professionals and the provision of diabetes education can influence the self-management practices of patients. Diabetes-education programs might increase the benefits of self-monitoring by teaching patients the optimal timing and frequency of self-monitoring, how to interpret the results correctly, and how to make appropriate diet, exercise, and pharmacologic-therapy adjustments in response to SMBG readings. Continued surveillance will be important for monitoring future trends in SMBG and the effectiveness of intervention strategies.

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 When to do SMBG?  

The more often you measure your blood sugar level, the more information you and your diabetes care provider will have for making the right decisions about your diabetes management. The most common times to do a blood sugar test include:

1. Before breakfast: This test reflects the blood sugar values during the night and is probably the most important time to test. The rapid-acting insulin dose can be adjusted based, in part, by the value of this test. The dose of Lantus or Levemir insulin is also based on this test.

2. Before lunch: This helps you decide if the morning Humalog/NovoLog/Apidra and/or Regular insulin dosage was correct.

3. Before dinner: This test reflects how well the dose of morning NPH or lunchtime rapid-acting insulin worked. It may also reflect the effect of afternoon sports activities and an afternoon snack. A test should not be done unless it has been at least 2 hours since food was eaten. If it is time for dinner and your child had an afternoon snack 1 hour earlier, it is best to wait and do a test before the bedtime snack. If this is a common occurrence, change to doing a blood sugar test before the afternoon snack.

4. Before the bedtime snack: This test lets you know if the rapid-acting insulin dose given at dinner was correct. This test is important for people who tend to have reactions during the night, children who play outside after dinner, and anyone who did not eat well at dinner. If the bedtime values are low, an extra snack should be given in addition to the usual solid protein and carbohydrate so your child’s blood sugar does not drop too low during the night. Recheck the value 15 or more minutes after the snack to make sure that it has come back up.

5. Testing after meals: Doing a blood sugar test 2 hours after eating a meal is becoming a more common practice. You should check blood sugar values 2 hours after each meal once or twice weekly. The blood sugar value goals are the same for 2 hours after a meal as they are before a meal. Testing after meals is a useful testing time for people who count carbohydrates and inject insulin just before eating based on how many carbohydrates they plan to eat.

6. Testing at night: Occasionally, you may need to do a blood test in the middle of the night to make sure the value is not getting too low. A nighttime blood sugar test is important for people who tend to have low blood sugars during the night. More than half of the severe low sugars occur during the night. It is important to test on nights when there has been extra physical activity (for example, a basketball game in the evening or playing hard outside on a nice summer evening). The best time to do a check varies with each person. For some, between midnight and 2 AM is the best. For others, the early morning hours are better

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Dawn phenomenon and Somogyi effect:

If your fasting readings are consistently higher than these goals, it may be because of the dawn phenomenon or a result of the Somogyi effect. In the dawn phenomenon, hormones released in the very early morning cause increased insulin resistance, resulting in higher blood glucose levels. This occurs in everyone, with diabetes or without. However, in people who don’t have diabetes, extra insulin is secreted, so the rise in blood glucose level is minimal. Common preventive treatments for high morning blood glucose caused by the dawn phenomenon include getting daily exercise, eating a carbohydrate-containing bedtime snack, or adding the drug metformin to the diabetes control regimen.

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The Somogyi effect, which is more likely to occur in people who use insulin, is a phenomenon in which low blood glucose during the night causes the body to release hormones that raise blood glucose levels, resulting in high morning levels. While a person’s first instinct for treating high morning readings may be to increase nighttime insulin, in fact, taking less insulin and going to bed with a higher blood glucose reading may be more effective at preventing the low that leads to the morning rise in glucose. People who are experiencing high morning blood glucose levels are often encouraged to wake up at 3 AM on several occasions to check their blood glucose. High blood glucose at this time may point to the dawn phenomenon as the cause of the high morning readings, while low blood glucose at 3 AM may suggest the Somogyi effect.

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What do my blood sugar levels tell me? 

Time of Test Can be used to adjust meal/medicine
Fasting blood sugar (FBG) and   Nighttime (3-4 a.m.) Adjust medicine or long-acting insulin
Before a meal Modify meal or medicine
1-2 hours after a meal Learn how food affects sugar values (often the highest blood sugars of the day*)
At bedtime Adjust diet or medicine (last chance for the next 8 hours)

*Depends on the size of the meal and the amount of insulin in your medicine

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Frequency of SMBG:

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Although the optimal frequency of monitoring is unknown, the ADA recommends SMBG three or more times a day for patients with type 1 diabetes. Patients with type 2 diabetes still benefit from at least periodic monitoring. Ultimately, the frequency and timing of SMBG should be determined by how the data will be used. SMBG can assist the patient and physician with adjusting diet and medications and maintaining appropriate glucose control. More frequent monitoring is beneficial during insulin dose adjustments. Postprandial monitoring is important to identify the effect of various foods on glucose levels and to monitor the effects of preprandial medications. Other factors, such as desire for tight control and current degree of control, will influence frequency of monitoring.

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A major obstacle to increased SMBG utilization is the lack of clear guidelines for testing frequency. A global consensus conference was convened in 2004 to address this issue. The results of that conference were published as a supplement in the American Journal of Medicine. Table below shows a summary of the recommendations presented.

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When you should test your blood glucose levels and how often you should test varies depending on each individual, the type of diabetes and the tablets and/or insulin being used. Your doctor or Credentialed Diabetes Educator will help you decide how many tests are needed and the levels to aim for.

Possible times to test are:

•Before breakfast (fasting)

•Before lunch/dinner

•Two hours after a meal

•Before bed

•Before rigorous exercise

•When you are feeling unwell

You may need to record all your tests. Even though your meter may have a memory, it is important to keep a record of your readings in a diary and to take this with you to all appointments with your diabetes team. Testing four times a day is usually recommended for people with type 1 diabetes. People using an insulin pump may need to test more often.

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SMBG more often:

There will be times when you need to test more often, however you should first discuss this with your doctor or Credentialed Diabetes Educator. Example of these times include when you are:

•Being more physically active or less physically active

•Sick or stressed

•Experiencing changes in routine or eating habits, e.g. travelling

•Changing or adjusting your insulin or medication

•Experiencing symptoms of hypoglycemia

•Experiencing symptoms of hyperglycemia

•Experiencing night sweats or morning headaches

•A female planning pregnancy or are pregnant.

•Pre/post minor surgical day procedures

•Post dental procedures

Your Credentialed Diabetes Educator can help you work out a testing plan especially for you.

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SMBG vis-à-vis diabetes table:   

Basic SMBG requirements (must be met):
The person with diabetes (or a family member/caregiver) must have the knowledge and skills to use a home blood glucose monitor and to record the results in an organized fashion. The person with diabetes and/or members of the healthcare team must be willing to review and act upon the SMBG results in addition to the A1C results.

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A. REGULAR SMBG is required if the person with diabetes is:

SITUATION SMBG RECOMMENDATION
Using multiple daily injections of insulin (≥4 times per day)
Using an insulin pump
SMBG ≥4 times per day
Using insulin <4 times per day SMBG at least as often as insulin is being given
Pregnant (or planning a pregnancy), whether using insulin or not
Hospitalized or acutely ill
SMBG individualized and may involve SMBG ≥4 times per day
Starting a new medication known to cause hyperglycemia (e.g. steroids)
Experiencing an illness known to cause hyperglycemia (e.g. infection)
SMBG individualized and may involve SMBG ≥2 times per day
B. INCREASED FREQUENCY OF SMBG may be required if the person with diabetes is:
SITUATION SMBG RECOMMENDATION
Using drugs known to cause hypoglycemia
(e.g. sulfonylureas, meglitinides)
SMBG at times when symptoms of hypoglycemia occur or at times when hypoglycemia has previously occurred
Has an occupation that requires strict avoidance of hypoglycemia SMBG as often as is required by employer
Not meeting glycemic targets SMBG ≥2 times per day, to assist in lifestyle and/or medication changes until such time as glycemic targets are met
Newly diagnosed with diabetes (<6 months) SMBG ≥1 time per day (at different times of day) to learn the effects of various meals, exercise and/or medications on blood glucose
Treated with lifestyle and oral agents and is meeting glycemic targets Some people with diabetes might benefit from very infrequent checking (SMBG once or twice per week) to ensure that glycemic targets are being met between A1C tests
C. DAILY SMBG is not USUALLY required if the person with diabetes:
Screen for diabetes complications annually or as indicated
Is treated only with lifestyle and is meeting glycemic targets
Has pre-diabetes

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SMBG vis-à-vis insulin table:

Suggested SMBG Patterns for Patients Using Insulin:
Basal Insulin Only – NPH or long-acting insulin analog, typically given at bedtime. SMBG at least as often as insulin is being given. Optional, less frequent SMBG can be done at other times of day to ensure glycemic stability throughout the day.
BREAKFAST LUNCH SUPPER BED-
TIME
NIGHT
before after before after before after
Insulin NPH/
long
(basal)
SMBG
pattern
SMBG
test
Adjustment Basal insulin
↑ if BG high
↓ if BG low
Premixed – typically given pre-breakfast and pre-supper. SMBG at least as often as insulin is being given. SMBG QID until glycemic targets are met; SMBG BID (alternating times) is usually sufficient once glycemic targets are met.
BREAKFAST LUNCH SUPPER BED-
TIME
NIGHT
before after before after before after
Insulin pre-
test
pre-
test
SMBG pattern 1:
Starting
SMBG
test
SMBG
test
SMBG
test
SMBG
test
SMBG pattern 2:
Stable
SMBG
test
SMBG
test
Alternating daily SMBG
test
SMBG
test
Adjustment Pre-supper insulin
↑if BG high
↓if BG low
Pre-breakfast insulin
↑if BG high
↓if BG low
Pre-breakfast insulin
↑if BG high
↓if BG low
Pre-supper insulin
↑if BG high
↓if BG low
QID (basal-bolus/MDI) – typically given as a rapid-acting analog or regular insulin (bolus) before each meal and NPH or long-acting analog (basal) typically given at bedtime. SMBG should be QID, pre-meal and bedtime, in order to assess previous dose and to adjust next dose. Some patients find that post-prandial checking can also be helpful.
BREAKFAST LUNCH SUPPER BED-
TIME
NIGHT
before after before after before after
Insulin rapid
regular
bolus
rapid
regular
bolus
rapid
regular
bolus
NPH/
long
(basal)
SMBG pattern 1:
Starting or Stable
SMBG
test
SMBG
test
SMBG
test
SMBG
test
SMBG pattern 2:
Stable, Focus on
post-meal BG
SMBG
test
SMBG
test
SMBG
test
SMBG
test
SMBG pattern 3:
Intensive
management
SMBG
test
SMBG
test
SMBG
test
SMBG
test
SMBG
test
SMBG
test
SMBG
test
SMBG
test
Adjustment Basal insulin
↑if BG high
↓if BG low
Pre-breakfast insulin
↑if BG high
↓if BG low
Pre-lunch insulin
↑if BG high
↓if BG low
Pre-supper insulin
↑if BG high
↓if BG low
Basal insulin
↓if BG low
MDI = multiple daily injections
No funding sources were used by the CDA for the development or launch of this document on SMBG.

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SMBG in Type 1 diabetes: 

•Self-monitoring of blood glucose levels should be used as part of an integrated package that includes appropriate insulin regimens and education to help choice and achievement of optimal diabetes outcomes.

•Self-monitoring skills should be taught close to the time of diagnosis and initiation of insulin therapy.

•Self-monitoring results should be interpreted in the light of clinically significant life events.

•Self-monitoring should be performed using meters and strips chosen by adults with diabetes to suit their needs, and usually with low blood requirements, fast analysis times and integral memories.

•Structured assessment of self-monitoring skills, the quality and use made of the results obtained and the equipment used should be made annually. Self-monitoring skills should be reviewed as part of annual review, or more frequently according to need, and reinforced where appropriate.

•Adults with type 1 diabetes should be advised that the optimal frequency of self-monitoring will depend on:

-The characteristics of an individual’s blood glucose control.

-The insulin treatment regimen.

-Personal preference in using the results to achieve the desired lifestyle.

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SMBG in Type 2 diabetes:

National Institute for Health and Care Excellence (NICE) recommendations for patients with type 2 diabetes:

•Offer self-monitoring of plasma glucose to a person newly diagnosed with type 2 diabetes only as an integral part of his or her self-management education.

•Discuss its purpose and agree how it should be interpreted and acted upon.

•Self-monitoring of plasma glucose should be available:

-To those on insulin treatment.

-To those on oral glucose-lowering medications to provide information on hypoglycemia.

-To assess changes in glucose control resulting from medications and lifestyle changes.

-To monitor changes during intercurrent illness.

-To ensure safety during activities, including driving.

•Assess at least annually and in a structured way:

 -Self-monitoring skills.

-The quality and appropriate frequency of testing.

-The use made of the results obtained.

-The impact on quality of life.

-The continued benefit.

-The equipment used.

•If self-monitoring is appropriate but blood glucose monitoring is unacceptable to the individual, discuss the use of urine glucose monitoring.

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At least some studies have found that the more often people monitor their blood glucose with a conventional blood glucose meter, the better their glycosylated hemoglobin (HbA1c) levels. (The HbA1c test is a measure of blood glucose control over the previous two to three months.) Other studies have reported similar benefits for continuous monitoring, in which a sensor worn under the skin transmits glucose measurements every few minutes to a receiver. The GuardControl Trial, for example, found that participants with Type 1 diabetes who used a continuous glucose monitor for three months experienced a 1-percentage-point drop in their HbA1c levels. In a perfect world, people with Type 1 diabetes should monitor six or seven times a day. However, that’s often impractical because of time and resources. A person whose Type 1 diabetes is in stable control should monitor a minimum of four times a day. For people whose Type 2 diabetes in good control, they should monitor twice a day.

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SMBG is currently recommended for all type 1 and type 2 diabetes diabetic patients being treated with insulin. SMBG should be determined individually, and be part of a total treatment regimen that includes diet, exercise, weight loss, and insulin or oral medications when indicated. The optimal frequency and timing of SMBG depends on many variables, including diabetes type, level of glycemic control, management strategy, and individual patient factors. Healthcare professionals will also need to modify SMBG regimens to accommodate changes in therapy and lifestyle. For people with type 1 diabetes, SMBG is an essential component of daily diabetes management and it has been shown that testing 3 or more times a day was associated with a statistically and clinically significant 1.0% reduction in A1C levels. Furthermore, blood glucose measurements taken post-lunch, post-dinner and at bedtime have demonstrated the highest correlation to A1C. Frequent SMGB pre-and post meals several times a day will provide useful information for adjusting insulin and carbohydrate intake. In addition, patients with hypoglycemia unawareness may need to test more frequently, particularly prior to driving or operating any machinery, watching small children, and other activities where compromise of cognitive function may be dangerous. The results of multiple testing each day provide information that is better correlated to A1C than fasting results alone.

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SMBG for people with type 2 diabetes who are not using insulin:

Although self-monitoring of blood glucose has been found to be effective for patients with type 1 diabetes and for patients with type 2 diabetes using insulin, evidence suggests that self-monitoring of blood glucose is of limited clinical effectiveness in improving glycemic control in people with type 2 diabetes on oral agents or diet alone.  A Cochrane review found that the overall effect of self-monitoring of blood glucose on glycemic control in patients with type 2 diabetes who are not using insulin is small up to six months after initiation and subsides after 12 months. There was no evidence that self-monitoring of blood glucose affected patient satisfaction, general well-being or general health-related quality of life.

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Accumulating Evidence for Improved Glycemic Control in Type 2 Diabetes:

The use of SMBG to detect hypoglycemia and hyperglycemia and then adjusting therapy to minimize glycemic excursions is generally considered standard practice in type 1 diabetes. In patients with type 2 diabetes, especially those not taking insulin, SMBG use has been more controversial. The observational Fremantle Diabetes Study, which reported cross-sectional and longitudinal data, found no significant benefit associated with SMBG. Likewise, a small study by Davidson et al found no statistically significant improvements in HbA1c for patients randomized to SMBG vs. controls. Cross-sectional SMBG studies are incapable of demonstrating a cause-and-effect relationship between SMBG and HbA1c because the data do not evaluate changes in HbA1c over time in the presence of an intervention. In the longitudinal arm of the Fremantle Diabetes Study, the mean SMBG testing frequency of less than 1 test per day in patients treated with diet or oral agents or less than 2 tests per day in insulin-treated patients may have been suboptimal for providing actionable feedback to patients. Additionally, the study did not clearly indicate how SMBG was integrated into the diabetes management plan or whether patients were taught how to respond to out-of-target blood glucose readings. Similarly, the study by Davidson et al did not clearly report how SMBG results were used by patients or their health care professionals. The sample size, wide 95% confidence interval, less than 40% adherence to recommended SMBG frequency, and poorly educated study population may have contributed to the failure to achieve a significant difference. Recently, however, 2 meta-analyses demonstrated that including SMBG as part of a multicomponent management strategy results in a statistically significant decrease in HbA1c of approximately 0.40% in patients with type 2 diabetes who are not taking insulin. When extrapolated to findings from the United Kingdom Prospective Diabetes Study, this decrease would be expected to reduce the risk of microvascular complications by approximately 14%. A 4-year longitudinal study that differentiated new users of SMBG from experienced users found a proportional relationship between SMBG frequency and HbA1c reduction regardless of therapy for new users and a similar association among pharmacologically treated experienced users. Finally, a large epidemiological study of patients with type 2 diabetes that spanned 6.5 years showed that SMBG was associated with lower diabetes-related morbidity and all-cause mortality, even among patients not receiving insulin. Hence, a growing body of evidence suggests that daily SMBG has clinical value in type 2 and type 1 diabetes.  

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Synopsis of SMBG vis-à-vis methods of glycemic control:

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In a nutshell, frequent SMBG is indicated all diabetics who take daily insulin and who take oral agents which can cause severe hypoglycemia.

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For those with unstable diabetes:

For those suffering from brittle diabetes (unstable diabetes) along with Type 1 diabetes, should use the CGMS (Continuous Glucose Monitoring System) of monitoring their blood glucose. Unlike traditional meters that provide a one-time snapshot of one’s blood glucose levels, continuous glucose monitors (CGMSs) measure one’s glucose levels every few minutes. This system is essential for people suffering from this kind of diabetes since they need to keep a tab on their blood glucose levels at all times.

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Should I keep written records?

Keeping good records to look for patterns in blood sugars is essential. It is wise to keep written records even if your meter is able to store results (in case the meter breaks). Write down the time of the test, the date, how your child feels, and the blood sugar value. You may also want to note times of heavy exercise, illness, or stress. It may be helpful to record what was eaten for the bedtime snack or any evening exercise to see if these are related to morning blood sugars. Also, keep a record of when your child has low blood sugar reactions and possible causes. Bring these results to your appointments. Good record keeping and bringing the results to clinic visits allow the family and diabetes team to work together most effectively to achieve good diabetes management.  

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SMBG: Accuracy of Self-Reported Data and Adherence to Recommended Regimen: a1988 study:

Reflectance meters containing memory chips were used in a study that addressed several questions concerning routine use of self-monitoring of blood glucose (SMBG), including accuracy of patient blood glucose (BG) diaries, reliability of self-reported frequency of SMBG, and adherence to recommended SMBG regimen. Thirty adults with insulin-dependent diabetes used memory meters and recorded test results in diaries for 2 wk while performing their normal SMBG regimen. Analysis of glucose diaries showed that only 23% of the subjects had no diary errors and 47% had clinically accurate diaries (>10% error rate). The most common types of errors were omissions of values contained in meter memory and additions of values not contained in meter memory, with significantly more omissions than additions. Alterations of test values (e.g., changing a 300-mg/dl reading to 200 mg/dl) were extremely rare. There was no difference in the rate of errors that resulted in a more positive clinical profile (omitting unacceptable values and adding acceptable values) or a more negative clinical profile (omitting acceptable values and adding unacceptable values). Examination of the actual frequency of SMBG showed that most subjects (56.6%) measured their BG an average of two to three times each day. Self-report of SMBG frequency correlated with both actual frequency and HbA1. Although actual frequency of SMBG was not related to physicians’ recommendations, the majority (64%) of subjects were self-testing as often or more often than they had been instructed.

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Structured SMBG:

Self-monitoring should be assessed at least annually and in a structured way:

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If self-monitoring is appropriate but blood glucose monitoring is unacceptable to the individual, discuss the use of urine glucose monitoring.

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SMBG education:

SMBG should be part of an educational program including the patient and close relatives (family members) where necessary. When prescribing the SMBG device, it is essential to explain the issues to the patient and to organise this self-monitoring with the patient, including the frequency, scheduling, blood glucose targets and treatment adjustments to be made by the patient or doctor based on the results. In all cases, the patient should maintain an appropriate diet and physical exercise. Glucose meters are most accurate when used properly. Thus, educating patients on proper use and what to do with the results is vital. Also, lower rates of SMBG are correlated with having less than a high school education; and in my view, uneducated people are unlikely to learn right way to use glucometer.   

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The figure below shows impacts of SMBG as a component of education/treatment program:

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Successful SMBG:

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SMBG Special patient groups:  

While the overall effect of self-monitoring seems modest, there is a paucity of data on special groups, including heavy goods vehicle drivers for whom hypoglycemia may pose an unacceptable occupational risk to themselves and the public. Also, people starting or changing their oral diabetes medication may benefit from self-monitoring.

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Barriers to self-monitoring of blood glucose among adults with diabetes in an HMO: A cross sectional study: 2003:

In addition to logistic barriers to SMBG, some recent evidence suggests that adult diabetes patients who may be at greatest risk for poor outcomes (e.g., minorities, elderly, lower SES) may be least likely to self-monitor. In a study of more than 44,000 managed care patients with type 1 (2,818) and type 2 (41,363) diabetes, Karter et al identified older age, male gender, non-white race, lower socioeconomic status, English language difficulty, higher out of pocket test strip costs, intensity of insulin therapy, greater alcohol consumption, and smoking as independent predictors of less frequent self-monitoring in diabetes patients. This study was the first to move beyond simple reporting of descriptive statistics in order to assess predictors of SMBG in managed care settings. Unfortunately, the validity of the study findings is limited by the reliance on self-reports of self-monitoring, an unreliable measure of actual behavior. The purpose of the current study was to examine the relationship between patient characteristics and SMBG in a large health maintenance organization (HMO) using objective measures of self-monitoring practice. Specifically, we tested the hypothesis that, controlling for type of drug therapy and severity of illness, diabetes patients at greatest risk for poor health outcomes (e.g., older age, multiple chronic conditions, non-white race, lower neighborhood SES) are less likely to practice SMBG. The study population included more than 4,500 adult managed care patients using insulin, oral, or a combination of the two drug therapies. Our use of objective measures of SMBG distinguishes this study from previous attempts to identify predictors of SMBG in managed care. This paper represents the first phase of a larger study to evaluate the effect of distributing free home glucose monitors to diabetes patients at this New England HMO. In multivariate analyses, lower neighborhood socioeconomic status, older age, fewer HbA1c tests, and fewer physician visits were associated with lower rates of self-monitoring. Obesity and fewer comorbidities were also associated with lower rates of self-monitoring among insulin-managed patients, while black race and high glycemic level (HbA1c>10) were associated with less frequent monitoring. For patients taking oral sulfonylureas, higher dose of diabetes medications was associated with initiation of self-monitoring and HbA1c lab testing was associated with more frequent testing. Managed care organizations may face the greatest challenges in changing the self-monitoring behavior of patients at greatest risk for poor health outcomes (i.e., the elderly, minorities, and people living in low socioeconomic status neighborhoods).

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Self-monitoring of blood glucose during pregnancy: indications and limitations:

Approximately 5 percent of all pregnancies are complicated by gestational diabetes mellitus, which increases both maternal and perinatal morbidity. In treating women with this condition, many have advocated minimizing fluctuations in blood glucose concentrations to avert maternal hyperglycemia and thus decrease the risk of fetal hyperglycemia and its consequences, fetal hyperinsulinemia and excess fetal growth. Perinatal morbidity and mortality rates, often affected by maternal diabetes, have dramatically been reduced since the discovery of insulin and its therapeutic implementation. In addition to increased availability of insulin, many important technological advances have been developed over the preceding decades. These advances culminated in a larger array of diagnostic and therapeutic capabilities that contributed to improved outcomes in high-risk pregnancies. The availability of glucose meters has represented an important positive impact in the treatment of pregnant women with any type of diabetes. Data frequently show patients who perform self-monitoring of blood glucose (SMBG) more strictly adhere to treatment programs due to increased comprehension regarding treatment and participation in the prescribed treatment regimen. Treating hyperglycemia during pregnancy reduces adverse pregnancy outcomes. The first step towards a tight glucose control in pregnancy is patient adherence to SMBG.

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Indications for self-monitoring of blood glucose during pregnancy complicated by diabetes:

SMBG is an integral part of standard diabetes care. It allows pregnant women and their healthcare providers to determine the most effective therapeutic modality (e.g. diet, physical activity, or insulin) to control glucose levels and reduce risks of diabetes-related complications. The number of daily tests required to adequately monitor blood glucose levels is specific to the patient and based on the recommendation of the practitioner. Several characteristics, unique to each pregnant woman should be considered. For example, the type of treatment (diet and/or insulin), frequency and intensity of physical activity, and the risk of hypoglycemia. Additionally, SMBG makes patients feel more secure and comfortable using insulin since it allows early recognition of symptoms of hypoglycemia. The indications for, and frequency of SMBG in pregnant women that are not under insulin treatment must be tailored to the individual. Patients must be trained to adjust the amount of food intake with the frequency, intensity, and timing of physical exercise. It is unclear whether SMBG alone leads to improved glycemic control in non-insulin treated subjects with type 2 diabetes. Additionally, there is no data in women with gestational diabetes mellitus (GDM). Measured glucose values need to be frequently checked to ensure both accuracy and the patient’s understanding of any alterations to prescribed treatment. For the vast majority of patients using insulin, SMBG is recommended three or more times per day. A more intensive SMBG regimen is indicated for women with pre-gestational type 1 or 2 diabetes. The aim is to reach adequate HbA1c levels safely without inducing hypoglycemia.

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When to monitor:

Strict monitoring of postprandial glucose levels is paramount during pregnancy. Many studies have shown that postprandial hyperglycemia beyond the 16th week of pregnancy is the main predictor for fetal macrosomia. Peak plasma glucose levels during pregnancy occur between 60 and 90 minutes after eating. It is recommended to perform SMBG one hour after food intake to evaluate potential adjustments in meal composition and/or in the prandial insulin dose. In special circumstances, like women with slowed gastric emptying, a high-fat meal, or women who use regular insulin for a prandial bolus, it might be more appropriate to perform SMBG two hours after meals instead of one. SMBG performed before eating is the most useful parameter to identify optimal basal insulin doses. Evaluating glycemic levels during the night is recommended to diagnose and prevent nocturnal hypoglycemia. One randomized study of 66 women with GDM observed better neonatal outcomes by aiming for 1-hour postprandial glucose levels less than 140 mg/dL as opposed to a preprandial target of 59 to 106 mg/dL. In another study, 61 women with type 1 diabetes were randomly assigned into two groups at 16 weeks gestation. Women either monitored blood glucose levels preprandially or postprandially. Postprandial capillary blood glucose monitoring significantly reduced the incidence of preeclampsia and neonatal triceps skinfold thickness compared to preprandial monitoring. These studies have been criticized for not using comparable target blood glucose levels for pre- and post-prandial monitoring. Regardless, most specialists prefer postprandial testing at least partly, for the physiologic changes discussed earlier.

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Barriers to self-monitoring of blood glucose during pregnancy:

The first step towards a successful SMBG during pregnancy is patient education and an understanding of the importance of SMBG to reducing complications during and after pregnancy. The patient must be properly educated on all aspects of meter use. It is important she be aware of how to properly code her meter, wash her hands prior to the test, and to apply the correct amount of blood to the test strip. It is also critical to educate patients on how glucose from food can affect the test results, to use test strips before the expiration date and not longer than 90 days after the vial was opened. Lastly, it is crucial to educate patients on proper storage of strips and disposal of strips if they are subjected to extreme humidity or temperature. Other common barriers to SMBG include costs of the meters and strips, lower socio-economic status, fewer HbA1c tests, obesity and other comorbidities, poor glycemic control, stigmas of testing in public places, pain, and inconvenience.  

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An association between diabetes in pregnancy and fetal overgrowth has long been recognized. Fetal overgrowth is associated with a number of adverse outcomes for both the mother and her baby, such as a higher rate of difficult delivery. To reduce the rate of fetal overgrowth and its associated complications, women with diabetes in pregnancy undergo a number of interventions. Among these interventions is glucose monitoring. The utility of a hemoglobin A1c value appears to be greatest when performed periconceptionally to estimate the risk of congenital anomalies, but it does not appear to confer substantial benefit for estimating the risk of fetal overgrowth or other adverse pregnancy outcomes. Recent studies suggest that CGMS may be beneficial for certain women with diabetes treated with insulin, particularly in women with diabetes that is difficult to control. However, these data require further evaluation and do not yet support the incorporation of CGMS into routine practice.

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Postprandial versus Preprandial Blood Glucose Monitoring in Women with Gestational Diabetes Mellitus requiring Insulin Therapy: a 1995 study:

In the management of gestational diabetes, various methods of glucose monitoring have been proposed, including the measurement of fasting, preprandial, postprandial, and mean 24-hour blood glucose concentrations.  In a retrospective pilot study comparing the outcomes of pregnancy among women with gestational diabetes who were followed with preprandial or postprandial glucose measurements, authors found that there was less macrosomia (defined as a birth weight greater than 4000 g) among their infants when treatment was based on the results of postprandial measurements.  

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Variability of blood glucose:

Biological Variation:

Fasting glucose concentrations vary considerably both in a single person from day to day and also between different subjects. Intraindividual variation in a healthy person is reported to be 5.7% to 8.3%, whereas interindividual variation of up to 12.5% has been observed. Based on a CV (coefficient of variation) of 5.7%, FPG can range from 112 to 140 mg/dL in an individual with an FPG of 126 mg/dL. (It is important to realize that these values encompass the 95% confidence interval, and 5% of values will be outside this range.)

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The concentration of glucose is highest in the arterial circulation. Laboratory determinations are usually done on venous samples. If the venous circulation is delayed, such as by leaving a tourniquet on for a prolonged period of time, the concentration falls even further. Thus, samples should be obtained after releasing the tourniquet. Studies have shown that blood glucose concentration may fall as much as 25 mg/dl when a tourniquet has been left in place for 6 minutes. The concentration of glucose in capillary samples is intermediate between venous and arterial. Warming the extremity increases the capillary flow and “arterializes” the sample, while cooling or a tourniquet decreases the flow and lowers the concentration of glucose.

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Glycolysis:

Both red cells and leukocytes contain glycolytic enzymes. Therefore glucose will be consumed and the concentration of glucose in a sample of whole blood will decline with time. The rate of loss is generally said to be approximately 5% per hour, but may be as rapid as 40% in 3 hours. Consumption of glucose in whole blood samples can be prevented by adding sodium fluoride to the specimen to inhibit the glycolytic enzymes. This approach is the generally applied method in the clinical laboratory. It is effective except in situations where the system is overwhelmed, such as in specimens from patients with leukemia, which contain large numbers of leukocytes. Sodium fluoride has a major disadvantage in that its use makes the sample unacceptable for other determinations such as sodium and uric acid. However, while fluoride does attenuate in vitro glycolysis, it has no effect on the rate of decline in glucose concentrations in the first 1 to 2 h after blood is collected, and glycolysis continues for up to 4 h in samples containing fluoride. The delay in the glucose stabilizing effect of fluoride is most likely the result of glucose metabolism proximal to the fluoride target enolase. After 4 h, fluoride maintains a stable glucose concentration for 72 h at room temperature. A recent publication showed that acidification of the blood sample inhibits glycolysis in the first 2 h after phlebotomy, but the collection tubes used in that study are not commercially available. Placing tubes in ice water immediately after collection may be the best method to stabilize glucose initially, but this is not a practical solution in most clinical situations. Separating cells from plasma within minutes is also effective, but impractical. Rapid separation of the sample or cooling will also prevent glycolysis and will allow the sample to be used for other determinations. Unhemolyzed samples that have been separated within 30 minutes of drawing are generally considered adequate. Rapid cooling of the sample followed by centrifugation is even more effective in preventing glycolysis.  Blood glucose cannot be determined accurately on postmortem specimens because both glycogenolysis and glycolysis continue after death. A reasonable estimate of the antemortem blood glucose concentration can be obtained by measuring the glucose concentration of the vitreous of the eye, which does not contain glycolytic enzymes.

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Variability of capillary blood glucose monitoring measured on home glucose monitoring devices:

Self monitoring of blood glucose helps achieve glycemic goals. Glucometers must be accurate. Many variables affect blood glucose levels. Factors are analytical variables (intrinsic to glucometer and glucose strips) and pre analytical related to patients. Analytical variables depend on factors like shelf life, amount of blood and enzymatic reactions. Preanalytical variables include pH of blood, hypoxia, hypotension, hematocrit etc. CGMS has the potential to revolutionise diabetes care but accuracy needs to be proven beyond doubt before replacing current glucometer devices.

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Factors that alter blood glucose results by SMBG:

Table above outlines preanalytical, analytical, and postanalytical factors that can alter the glucose result when a SMBG device is used. The FDA accumulated over 400 medical device reports on blood glucose monitors used in hospitals over 2 years. The 4 most frequent errors reported included 2 preanalytical errors (inadequate instrument cleaning; incorrect quality control or proficiency testing procedures) and 2 analytical errors (improper technique; an incorrect match between the glucose monitor for calibration and test strip calibration when required by the manufacturer).

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Preanalytical Variation:

 Numerous factors that occur before a sample is measured can influence results of blood tests. Examples include medications, venous stasis, posture, and sample handling. The concentration of glucose in the blood can be altered by food ingestion, prolonged fasting, or exercise. It is also important that measurements are performed in subjects in the absence of intercurrent illness, which frequently produces transient hyperglycemia. Similarly, acute stress (e.g., not being able to find parking or having to wait) can alter blood glucose concentrations. Samples for fasting glucose analysis should be drawn after an overnight fast (no caloric ingestion for at least 8 h), during which time the subject may consume water ad lib. The requirement that the subject be fasting is a considerable practical problem as patients are usually not fasting when they visit the doctor, and it is often inconvenient to return for phlebotomy. For example, at an HMO affiliated with an academic medical center, 69% (5,752 of 8,286) of eligible participants were screened for diabetes. However, FPG was performed on only 3% (152) of these individuals. Ninety-five percent (5,452) of participants were screened by random plasma glucose measurements, a technique not consistent with ADA recommendations. In addition, blood drawn in the morning as FPG has a diurnal variation. Analysis of 12,882 participants aged 20 years or older in NHANES III who had no previously diagnosed diabetes revealed that mean FPG in the morning was considerably higher than in the afternoon. Prevalence of diabetes (FPG > 126 mg/dL) in afternoon-examined patients was half that of participants examined in the morning. Other patient-related factors that can influence the results include food ingestion when supposed to be fasting and hypocaloric diet for a week or more prior to testing.

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Pre-analytical variables:

Choosing the correct blood sample:

There are several aspects concerning the blood sample that needs attention. Although there are different recommendations, the first choice is to wash the hands with soap and water, dry them, and use the first drop of blood for assessment. Erroneous blood glucose levels (pseudo hyperglycemia) have been recorded when patients did not wash their hands with water after peeling fruits and such false readings were still noted when hand washing was substituted with the use of an alcohol swab. If washing hands is not possible, and they are not visibly soiled or exposed to a sugar-containing product, it is acceptable to use the second drop of blood after wiping away the first drop. Firm squeezing of the finger should be avoided.

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Operator error:

The technique of the user or operator of the glucometer usually is responsible for more inaccuracy than the glucometer itself. Applying insufficient blood to the strip, using strips that are out of date or exposed to excess moisture or humidity, and failure to enter the proper code, can compromise accuracy. Several important technologic advances that decrease operator error have been made in the last few years. These include “no wipe” strips, automatic commencement of timing when both the sample and the strip are in the meter, smaller sample volume requirements, an error signal if sample volume is inadequate, “lock out” if controls are not assayed, barcode readers, and the ability to store up to several hundred results that can subsequently be downloaded for analysis. Together these improvements have produced superior performance by newer meters. Patient education can have significant influence on the accuracy of the readings shown on the glucometer. Operator error such as differences as much as 14.5 mg/dl between lots of test strips has been reported. Most of the glucometers require coding to be done prior to use. A study by Raine et al. have suggested that up to 16% of patients in endocrine practice miscode their glucometers. This can lead to -37% to + 29% errors in clinical practice. The probability of giving additional 3 units of insulin dose when meters are miscoded was as high as 22.5%.

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Hematocrit:

Variation in the patient hematocrit can result in inaccuracies in the blood glucose reading. Abnormal hematocrit concentrations can result in falsely low (hematocrit >50%) or high (hematocrit <40%) glucose levels. In one study, hematocrit effect was studied by adjusting the hematocrit of donor sodium heparin blood at glucose concentrations of 54, 247, and 483 mg/dl.  At low glucose concentrations (54 mg/dl), the mean glucose difference changed by more than 10 mg/dl. At higher glucose concentrations, meters demonstrated more than 10% change in the mean glucose percentage difference between the lowest and highest hematocrit values. Hematocrit variations may occur frequently in daily routine (e.g., due to dehydration/exercise, nicotin and alcohol abuse, pregnancy etc.). The uses of meters with stable performance are recommended under these conditions. 

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Whole blood vs. plasma vs. interstitial fluid:

The estimation of whole blood glucose levels are usually 10-15% lower than plasma glucose alone. The glucose concentration in the water that makes up plasma is equal to that of erythrocytes. Plasma has greater water content than erythrocytes and, therefore, exhibits higher glucose levels than whole blood. The World health Organization (WHO) has devised a conversion factor of 1.12, which has been mathematically, derived assuming a hematocrit of 45% and red- cell to plasma ratio of ~ 0.8. In a critical care setting, multiple variables affecting the blood glucose may be present at one time. Hypotension, hypoxia, pH of blood, temperature are amongst the many variables affecting the blood glucose measurement. Glucose is measured in the interstitial fluid by an electrochemical glucose oxidase method. Each measurement cycle requires 20 minutes to complete. The measured interstitial glucose value lags behind the serum glucose concentration by about 18 minutes, secondary to the time required for a change in serum glucose to equilibrate with the interstitial fluid. Sweat on the skin will dilute the collection fluid. Sweat and/or elevated body temperature will initiate a skipped measurement cycle.

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Hypotension:

Hypotension results in decrease in perfusion and increase in glucose utilization resulting in false results in capillary blood glucose. Atkin et al. assessed the validity of the finger stick glucose measurements in the hypotensive critically-ill patients. They found that the fingerstick glucose values were significantly lower than the values obtained by venous reagent strips or laboratory glucose measurements. Fingerstick glucose values in the hypotensive group were 67.5% of laboratory glucose values and were significantly lower than the values obtained in the normotensive group (91.8%, P less than 0.001).  Juneja et al. aimed to compare the accuracy of capillary bedside glucometry with arterial samples in critically-ill patients with shock through a prospective case-control study. They studied 100 patients on vasopressor support, and the control group had 100 normotensive patients. Mean arterial and capillary sugars (mg/dl) in study and control groups were 164.7 ± 70 and 157.4 ± 68.9 and 167.1 ± 62.2 and 167.5 ± 61, respectively. They concluded that arterial blood glucose is better measurement compared to capillary blood glucose in hypotensive patients. Venous blood glucose values are also stated to be significantly better than capillary blood glucose measurement and correlate better with the laboratory measurements in a critical care setting.  Also, the prandial state accentuated the difference between various measurements in hospital setting. Capillary blood glucose levels were 20-25% higher than venous plasma glucose level in prandial state, whereas it was only 2- 5 mg/ dl higher in fasting state.

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PH:

Like any other enzymatic reaction, change in pH is likely to affect the enzymatic reaction. However, in the range of pH 6.89 to 7.4, it is found to not have much effect on the blood glucose levels measured.

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Alternate site:

Bina et al. studied the differences in the measurement of blood glucose at various site (forearm, palm, and thigh) with respect to the finger tip capillary blood glucose. Also, the effect of prandial state and moderate exercise at the blood glucose levels on the different sites were studied. Significant differences in BG at alternative sites were found 60 min post-meal (P < 0.0003) and post-exercise (P < 0.037). However, no significant differences were observed between sites in either the fasting state or at 90 and 120 min post-meal.  It has been observed that there is a considerable time lag in measurement at alternate sites. It can be particularly dangerous in hypoglycemia situations, and hence clinicians must be aware of this. The effect of oxygen concentration in the sample has already been discussed.

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Drugs:

There are various drugs affecting the capillary glucose readings. Of particular importance were the acetaminophen, dopamine, mannitol, and the ascorbic acid. Glucose meters use enzyme-based amperometric biosensors to measure glucose concentrations. Glucose oxidase oxidizes glucose to gluconolactone while reducing oxygen to H2O2. Other mediators like ascorbic acid, uric acid, acetaminophen, and salicylic acid can falsify the results by nonspecifically oxidizing H2O2. Acetaminophen increased glucose readings with GDH meters but decreased readings with some, but not all, GO-based meters at therapeutic drug levels. Dopamine increased glucose values on GDH-based meters, primarily at high drug concentrations.  Mannitol increased GO-based meter readings, possibly through detection by the analyzer or by a non-specific osmotic effect. At high doses, ascorbic acid increased GDH-based meter readings but decreased those that used glucose oxidase.

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Other interfering substances:

 Some naturally occurring substances in the body tend to interfere in the blood glucose readings. High triglyceride levels cause falsely low blood glucose values as they tend to take up volume reducing the glucose levels. Also, bilirubin has also noted to cause pseudohypoglycemia .

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Implications:

With such vast data regarding the various variables affecting the blood glucose reading in glucometer, the clinician must be alert while interpreting the values while treating a patient. Also, the patients need to be educated regarding their glucometers, which can prevent false readings and inadvertent admission of excess insulin resulting in severe hypoglycemia.

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Analytical Variation:

 Glucose is measured in central laboratories almost exclusively using enzymatic methods, predominantly with glucose oxidase or hexokinase. The following terms are important for understanding measurement: accuracy indicates how close a single measurement is to the “true value” and precision (or repeatability) refers to the closeness of agreement of repeated measurements under the same conditions. Precision is usually expressed as CV (coefficient of variation); methods with low CV have high precision. Numerous improvements in glucose measurement have produced low within-laboratory imprecision (CV <2.5%). Thus, the analytical variability is considerably less than the biological variability, which is up to 8.3%. Nevertheless, accuracy of measurement remains a problem. There is no program to standardize results among different instruments and different laboratories. Bias (deviation of the result from the true value) and variation among different lots of calibrators can reduce the accuracy of glucose results. (A calibrator is a material of known concentration that is used to adjust a measurement procedure.) A comparison of serum glucose measurements (target value 98.5 mg/dL) was performed among ~6,000 laboratories using 32 different instruments. Analysis revealed statistically significant differences in bias among clinical laboratory instruments, with biases ranging from -6 to +7 mg/dL (-6 to +7%) at a glucose concentration of 100 mg/dL. These considerable differences among laboratories can result in the potential misclassification of >12% of patients. Similarly, inspection of a College of American Pathologists (CAP) survey comprising >5,000 laboratories revealed that one-third of the time the results among instruments for an individual measurement could range between 141 and 162 mg/dL. This variation of 6.9% above or below the mean reveals that one-third of the time the glucose results on a single patient sample measured in two different laboratories could differ by 14%.

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Analytical variables:

Detection Method:

Glucometers use predominantly 2 principles: Electrochemical (ameperometry) and reflectance photometry. In glucometers, the enzyme used (glucose oxidase) induces an electric current through the strip, which is proportionate to the amount of glucose. In the reflectance glucometers, the strip changes color according to the amount of glucose in the sample. These glucometers quantify the color change by reflectance photometry. If the drop of blood does not cover the entire testing area of reflectance, glucometers can give falsely low value. Also, they are either automatic (non-wiping) or manual (wiping). The ambient temperature has shown to affect the glucose readings in the reflectance meters. In one study, it was demonstrated that the manual reflectance glucometer overestimated glucose concentrations by 14% at 44°C and underestimated by 12.7% at 25°C.

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Enzymatic reactions:

Glucose meters contain strips that contain two enzymes; glucose oxidase (GO) and glucose dehydrogenase (GDH) or hexokinase. Glucose oxidase meters require oxygen and water for their reaction and hence are susceptible to extremes of hydration or oxygenation. GO-mediated reactions result in generation of gluconic acid and hydrogen peroxide. Capillary blood glucose was measured in mountain climbers at 13500 ft by various glucometers. GO glucometers overestimated blood glucose by 6-15%, whereas the GDH meters were all within 5%. This is because the glucose oxidase biosensor strips are sensitive to the oxygen concentration. But, a recent study shows no such difference. Maltose, galactose and xylose will be misinterpreted as glucose by GDH based methods. So patients on icodextrin peritoneal dialysis using GDH meters will result in falsely high values as it can be metabolized to maltose cross-reacting as glucose.

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Glucostrips:

Glucostrips are another potential source of variability of blood glucose levels. Glucostrips have a finite life; it is usually for 2 years in ideal storage conditions. Exposure of strips to light causes discoloration of test area resulting in falsely elevated glucose levels. Exposure of strips to humidity and temperature by open cap vials decreases their stability by day 14 due to exposure to heat and humidity.

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Accuracy of glucometer:

Accuracy can be defined as the variation from the reference value. When assessing laboratory values for glucose, the testing method is accurate if the measurement is within acceptable error compared to the reference method. Within the range of hypoglycemia, if the values reported by the SMBG device are inaccurate (e.g., reported higher than actual values), this inaccuracy could lead to failure to recognize and treat life-threatening values or even more worrisome result in a different treatment (e.g., increasing insulin infusions) that could pose a serious patient safety risk. The importance of accuracy for clinical treatment assesses whether the measurement value is within a range close enough to the actual value that the clinical approach to therapy remains the same. The current ADA device recommendations for SMBG with SMBG devices include the following: (a) achieve and maintain glycemic control, (b) prevent and detect hypoglycemia, (c) avoid severe hyperglycemia, and (d) facilitate diabetes therapy adjustment to lifestyle changes (activity, diet changes, etc.). The accuracy requirements set by the professional organizations are still rarely met by SMBG devices. With outpatients and other hospitalized noncritically ill patients, most clinicians appear satisfied with SMBG device accuracy when glucose values avoid the extremes of hypoglycemia and hyperglycemia. This is because, in the range of normal glucose, the accuracy in this range is typically acceptable for clinical decision-making. For the care of critically ill patients, accuracy becomes more important as some of the early signs present with hypoglycemia and hyperglycemia may be difficult to detect in this patient population due to decreased mental status, sedatives, and other patient conditions. For optimal glucose control in high-demand states in critically ill patients, SMBG device technology has yet to provide a high enough degree of accuracy and reliability that leads to appropriate clinical decision-making. Continuous glucose monitoring devices based on invasive, minimal invasive, or noninvasive methodology are being developed to improve blood glucose monitoring.  

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Establishing glucose meter accuracy is challenging. Glucose meters only accept whole blood, but existing standards are serum based. Glucose as an analyte is unstable in whole blood, and the process of stabilizing glucose through glycolysis inhibitors can interfere with some glucose meters. Technical accuracy for glucose meters is defined by comparing meter results against clinical laboratory methods that use plasma/serum-based samples. There is no consensus among standards organizations and professional societies, however, for acceptable performance criteria. While technical accuracy defines meter performance, clinical accuracy establishes how treatment decisions agree between meter results and laboratory glucose results. Glucose meters should be evaluated before use, and the specific meter model selected should be based on technical and clinical performance in the intended patient population.

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Accuracy of glucose meters is a common topic of clinical concern. Blood glucose meters must meet accuracy standards set by the International Organization for Standardization (ISO). According to ISO 15197 Blood glucose meters must provide results that are within 20% of a laboratory standard 95% of the time (for concentrations about 75 mg/dL, absolute levels are used for lower concentrations). However, a variety of factors can affect the accuracy of a test. Factors affecting accuracy of various meters include calibration of meter, ambient temperature, pressure use to wipe off strip (if applicable), size and quality of blood sample, high levels of certain substances (such as ascorbic acid) in blood, hematocrit, dirt on meter, humidity, and aging of test strips. Models vary in their susceptibility to these factors and in their ability to prevent or warn of inaccurate results with error messages. The Clarke Error Grid has been a common way of analyzing and displaying accuracy of readings related to management consequences. More recently an improved version of the Clarke Error Grid has come into use: It is known as the Consensus Error Grid. Older blood glucose meters often need to be “coded” with the lot of test strips used, otherwise, the accuracy of the blood glucose meter may be compromised due to lack of calibration.

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Independent accuracy testing is expensive, complicated, and rare. Diabetes Forecast, for example, doesn’t test or recommend products because the American Diabetes Association is a nonprofit organization without a laboratory or expertise in lab comparisons of products. Where the data do exist, in the form of manufacturers’ tests, accuracy is reported in different ways. Some companies report accuracy as a “regression line,” involving correlation coefficients, slopes, and Y-axes. Others report in a friendlier table format using percentages. Those measures of accuracy are apples and oranges. It’s not possible [for a consumer] to do a direct comparison of how accurate one meter is to another. We’ve seen cases where cheaper meters don’t necessarily have all the bells and whistles, but have better accuracy. So users have to evaluate all of the features that are important to them.

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Factors that affect Blood Glucose Meter Accuracy:

Expired test strips:

Always check the expiry date of test strips before performing a test as expired test strips could produce a false reading.

Testing in very warm or very cold temperatures:

Accuracy of blood glucose meters can be affected by temperature.  Blood glucose meters are designed to be at their most accurate at room temperature.  If you need to test in very warm or very cold temperatures, refer to your meter’s user guide to see what temperature range the meter is most accurate at.

Testing in very humid conditions:

Humid conditions can also affect meter accuracy.  Always remember to keep the test strip pot closed after a test has been performed and, where possible, avoid testing in very humid environments.

Coding mistakes:

Some blood glucose meters require test strips which need a code to be entered into the meter before testing with a new batch of test strips. If the wrong code is entered, this can affect accuracy of the result.  A number of blood glucose meters these days do not need coding.

Too little blood applied:

If too little applied is applied to the strip, this can cause a false reading.  A number of blood glucose monitors won’t give a reading if this happens and will instead alert that too little blood has been applied or give an error message.

Contamination on skin:

Dirty or wet hands can make readings very inaccurate in some cases. You should ensure your hands have been cleaned, with soap and water, and dried then before performing a blood test.

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Temperature and SMBG:

In principle, SMBG values are measured with blood glucose meters that use an enzyme reaction. A temperature sensor is built into the main device as a control mechanism for adjusting the enzyme reaction rate to match the ambient temperature, allowing accurate values to be obtained. Differences in SMBG values due to temperature, within the range of usual ambient temperatures, are reported to be negligible to the extent that clinical decisions are not affected. Conversely, one study comparing SMBG values for ground temperatures between 25°C and 8°C re­ported that the meters can either underestimate or overestimate BG values. In addition, when patient skin temperature is cool (15.5°C), lower SMBG values have been reported compared with warm skin temperature (35°C). Par­ticularly during the winter, the SMBG values are higher than the PG values.

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Common User’s Errors:

A tool such as SMBG can contribute substantially to improved glycemic control if reasonably accurate and used appropriately. What if, however, the information is incorrect either because of technical inaccuracies or user error? Confounding issues related to blood glucose testing in the inpatient setting have been well elucidated. In the outpatient setting, common errors in SMBG have been documented in observational studies. I have already discussed technical inaccuracies but SMBG data can be rendered inaccurate by several user errors, including:

• failure to store glucose strips properly;

• failure to set glucose meter codes to match strip codes;

• failure to apply sufficient blood on the meter’s strip;

• failure to use control solutions;

• use of date-expired control solutions;

• use of date-expired strips; and

• failure to wash hands properly.

The frequency of user error relating to meter codes has been reported at approximately 16%.  In one study, exactly half of the patients were elderly. As these patients are often challenged by cognitive and dexterity limitations and frequently have long-standing diabetes requiring insulin, therapeutic interventions based on such erroneous data can be destructive.

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The American Diabetes Association (ADA) assumed in a consensus report published in 1990 that up to 50% of the self-monitored blood glucose readings have more than 20% deviation from the true values. However, more recent studies found the percentage of deviation to be less.  Alto and colleagues conducted a study of 111 patients in two family practice settings to determine the technical skill and accuracy of SMBG in an outpatient population. The patients were observed using a 13-point checklist of critical steps in the calibration and operation of their glucose monitor. Overall, 53% of patient glucose values were within 10% of the control value, 84% were within 20% of the control value and 16% varied 20% or more from the control value. In short, the study showed that despite multiple technical errors when using SMBG, most patients obtained clinically useful values. A study reported by Bergenstal and colleagues found that 19% percent of patients had inaccuracy rates of more than 15% in blood glucose monitoring.  Some of the most common causes of inaccurate readings included: lack of periodic meter technique evaluation, difficulty using wipe meters, incorrect use of control solutions, lack of hand washing (even when under clinical observation), and using unclean meters. These studies demonstrate the need for healthcare providers to monitor patient use of SMBG to help improve the accuracy of test results.

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Error categories:

For the evaluation, an error classification system was developed containing a weighting and interpretation of the errors and the resulting consequences. Errors were classified in the categories F1 to F5:

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Community pharmacy-based intervention to improve self-monitoring of blood glucose in type 2 diabetic patients: a 2006 study:

The objective of this study was to record and assess the errors patients make in preparing, performing, and processing self-monitoring of blood glucose (SMBG). This study shows that the majority of individuals with type 2 diabetes (83%) make at least one mistake in carrying out the measurement of blood glucose levels with their own device. The study revealed two kinds of errors that were quite frequent: errors that falsify the measurement reading as well as errors that can have a negative effect on patient compliance. In the reference literature there is a consensus that individuals with diabetes make numerous mistakes in the self-monitoring of their blood glucose levels and that remedial training sessions are required. The kinds of mistakes observed in the studies, however, were very similar. In other studies, too, the main mistakes were in cleaning of the hands, making adjustments to the settings of the meter and problems with coding. But there is little data on how much impact to expect from these remedial training sessions for type 2 diabetic patients. One problem is that there is no standard method for remedying the errors, so that the kind of error assessment is variable at the time of our study. A validated documentation sheet was not available. The documentation sheets used in various studies are designed to record 13 to 45 sources of error. Thus, no comparability exists among the various studies. The main difference in the evaluations consisted in whether the components of the SMBG were summarized or recorded in a very detailed way. Common to all of them, however, is that it could be shown in principle that diabetes management education sessions instructing how to carry out blood glucose self-testing are both necessary and effective, even if no general statement could be made about the extent of the success. The study presented here was able to show that a one-time, standardized intervention in community pharmacies specialized in diabetes care is able to more than triple the number of patients who carried out the self-monitoring without making any errors: initially 17% compared to 59% at the end of the study. However, a selection bias in the patient population of the study cannot be fully excluded, since such offers are probably accepted more frequently by motivated patients rather than by unmotivated patients. Altogether, the pharmacy setting is suited for carrying out such evaluations along with giving corresponding instructions on how to correctly perform SMBG. Such an intervention comprised verbal instructions as well as practical exercises and took on average about 20 to 30 minutes, including the study documentation.

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Synopsis of SMBG variation and error:

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Efficacy of SMBG:

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Why SMBG is helpful for Patients with Diabetes:

SMBG is helpful to patients with diabetes in four distinct ways.

1.  First, it allows patients and clinicians to detect high or low blood glucose levels, thereby facilitating therapeutic adjustments to achieve long-term A1c goals.

2. Second, SMBG helps protect patients by allowing them to immediately confirm acute hypoglycemia or hyperglycemia.

3. Third, the technology facilitates patient education about diabetes and its management by giving patients more self-care responsibilities.

4. Fourth, SMBG helps motivate people toward healthier behavior.

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SMBG facilitates improved A1c:

Many published studies have demonstrated that regular and frequent SMBG improves glycemic control in T1DM and T2DM patients on insulin treatment. There is also very strong evidence that SMBG improves control in T2DM patients who are not on insulin therapy. Davidson and colleagues showed that there is an inverse correlation between frequency of SMBG and A1c values in T1DM patients. Patients using SMBG have lower A1c than those who do not. The authors found that the more times per day that people check their blood glucose levels, the lower their A1c. However, after reaching a frequency of 6-7 tests per day, the improvement levels off. Strowig and colleagues showed similar results, reporting a 0.25% decrease in A1c for each blood glucose test per day. Again, there was a point of diminishing returns; improvements in A1c leveled off at approximately 8 tests per day. Studies of pediatric T1DM patients have demonstrated similar findings. In a retrospective study of more than 24,000 patients, Karter and colleagues found that increased frequency of SMBG correlated strongly with improved A1c regardless of the type of diabetes or therapy used.

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Non-Insulin-Treated T2DM patients:

There has been much debate on the impact of SMBG on A1c in T2DM patients who are not treated with insulin. Skeptics of the benefits of SMBG use in this patient group often cite small or poorly designed studies that demonstrate no A1c benefit. This perspective often overlooks the fact that many T2DM patients are not adequately trained to interpret and respond to their test results. Utilization of SMBG involves more than simply documenting test results in a logbook; patients must understand and be able to make appropriate changes in therapy or activity based upon those results. SMBG testing in T2DM patients has also been hampered by a lack of consensus on the timing and frequency with which testing should be performed. Most patients who do perform blood glucose monitoring seldom test postprandial glucose. Other factors that inhibit testing frequency include the cost, pain, and inconvenience. All of these factors work against seeing a benefit in T2DM patients. Despite these factors, there is strong evidence that SMBG is, in fact, an effective method for lowering A1c in this patient group. A meta-analysis by Sarol and colleagues found an overall A1c improvement of 0.4% in non-insulin-treated T2DM patients who use SMBG compared with those who do not monitor. To counter potential criticism of their report, the authors critiqued the studies included in their meta-analysis and found no publication bias in their selection. A second meta-analysis conducted by Welschen and colleagues found similar results: an overall 0.39% improvement in A1c in type 2 patients not on insulin. The authors concluded that SMBG lowers A1c levels. Another review of the literature by Saudek in 2006 yielded similar findings.

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SMBG and clinical outcome:

In a recent epidemiologic, non-randomized retrospective study, Martin and colleagues looked at disease-related fatal and non-fatal events in approximately 3,200 T2DM patients. Unlike the meta-analyses cited above, this study directly assessed clinical outcomes relative to SMBG utilization. Fewer patients who used SMBG experienced fatal or non-fatal events than patients who did not monitor their glucose (7.2 versus 10.4%, p=0.002). The authors concluded that SMBG may be associated with a healthier lifestyle and/or better disease management. Significantly, this study did not simply show that SMBG correlates with improved A1c; it demonstrated that SMBG is actually linked to better clinical outcomes. Furthermore, a recent study showed that patients described as being “Uncontrolled Diabetics” (defined in this study by HbA1C levels >8%) showed a statistically significant decrease in the HbA1C levels after a 90-day period of seven-point Self-Monitoring of Blood Glucose (SMBG) with a Relative Risk Reduction (RRR) of 0.18% (95% CI, 0.86-2.64%, p<.001).

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Pros and cons of SMBG:

In contrast to the average blood glucose concentration reflected in an A1c level, the measurement of blood glucose itself, termed self monitoring of blood glucose (SMBG), only reflects what is going on at that moment. This has both advantages and disadvantages. One advantage is that, at least theoretically, interventions can be carried out by the patient at that moment to counter the high (or low) blood glucose concentration. Furthermore, when adjusting insulin doses, it is important to know the pattern of blood glucose values, i.e., when during the day the levels are high, in range, or low, since different parts of the insulin prescription affect glucose concentrations at various times after injection. The disadvantage is that the value only reflects one instance in time and glucose concentrations fluctuate throughout the day and night. Therefore, one value does not accurately portray what the overall levels of glucose are. It is certainly not unheard for patients to manipulate their behavior to ‘look good’ (i.e., have a glucose concentration near normal) when seen by their doctor by restricting their diets several days before, omitting food for 18–24 hours before the visit, taking extra insulin, etc. In that vein, it has been amply demonstrated that up to a quarter of patients will falsify their SMBG values when writing the results in their log books. In that case, they usually conveniently forget to bring in the meter, most of which contain a memory chip. Discrepancies between A1C levels and proffered SMBG values usually flush out this misguided behavior.   

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Most people would agree that treatments, especially those that have invasive components and/or are expensive, should result in improved clinical outcomes. SMBG, as part of a treatment plan, is both expensive and invasive but does have the potential to improve outcomes by helping to lower glucose concentrations and thereby decrease the small vessel complications of diabetes. In patients taking insulin, performing SMBG offers the opportunity to correct high measured values at that moment by injecting additional rapid-acting insulin. More importantly, the pattern of results over longer periods of time enables the physician (or selected patients) to make insulin dose adjustments to counteract blood glucose concentrations exceeding the desired range. Therefore, it is not surprising that in at least eight studies, A1c levels were inversely related to the frequency of SMBG measurements in insulin-requiring patients, i.e., the more frequently that patients tested, the lower their A1C levels. However, simply measuring blood glucose is ineffective. In one of the studies, increased frequency of SMBG resulted in lower A1C levels only in those who self-adjusted their insulin doses, not in the insulin-requiring patients who did not. This strongly suggests that acting on the measured values is necessary.
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At least 19 studies have been carried out to evaluate the effect of SMBG on A1c levels in diabetic patients not receiving insulin. Only five have been positive, i.e., showing that performing SMBG in these patients was associated with statistically significant lower A1c levels than in control groups that did not carry out SMBG. However, in each one of them, factors other than SMBG were probably responsible for the positive results. These include greater attention to education and decision making in the group performing SMBG compared with the control group, self-selection or a preferential drop-out rate. In the first case, those in the SMBG group either received more intensive nutritional counseling or decisions on changing therapy were made more frequently than in their matched control group. In the second case, patients were given the choice of performing SMBG or not. Those who chose to also had better self care practices and healthy lifestyle behaviors documented by a questionnaire, thus invalidating the conclusion that SMBG per se is what led to the lower A1c levels. Finally, in one study, nearly 50% failed to finish it. If the nearly half of the SMBG group that failed to complete the study were enriched in those who were showing the least response, these results could also be due to self selection.
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The gold standard for carrying out clinical studies is randomization and blinding. This means that the subjects are randomly chosen to be placed in the control or intervention group (which avoids self selection) and the person(s) carrying out the study are blinded so that they do not know whether the subject is in the control or intervention group (which avoids preferential treatment of one group). A nurse-directed diabetes disease management program afforded the author the opportunity to carry out such a study evaluating SMBG in type 2 diabetic patients who were taking pills but no insulin. In this program, a nurse (under the supervision of a physician) followed detailed treatment algorithms. Patients on pills were randomized to perform SMBG or not. Both groups were seen by a dietitian who taught the selected patients SMBG and provided nutritional counseling to both groups five times during a six-month period. The dietitian utilized the SMBG values (recommended before and after one meal every day but Sunday and carried out 45% of the time) in his nutritional counseling. Neither the nurse nor the physician when consulted by the nurse knew which patients were performing SMBG. Although A1c levels fell significantly in both groups, the decrease was not statistically significantly different between the groups. In other words, SMBG had no beneficial effect when patients not taking insulin received good diabetes care. There are at least three possible explanations for the lack of an effect of SMBG in patients not taking insulin. First, patients receive little or no feedback on their results. This was not the case in the randomized blinded study described above. Second, related to the first, they are not taught the self-management skills to use to lower the measured glucose values. However, there are a limited number of behaviors possible for patients not receiving insulin to counter a high SMBG value. If the measurement was taken before a meal, options include delaying that meal, eating less (especially carbohydrates), exercising at that point, or increasing the dose of a pill before that meal that rapidly increases insulin secretion. (That medication, however, is used by only a very small minority of patients.) Even if taught, given patients’ usual lifestyles, these self management activities are not very likely to occur. Third, in the author’s experience, the vast majority of patients measure their glucose level before meals, rather than after meals. This limits the two potential benefits of SMBG in patients not taking insulin – motivation and education. Fasting values serve neither to educate (there is no information on the effect of the meal composition or size) nor to motivate well (postprandial values are much higher). Except for early type 2 diabetes, in which the before-meal glucose values are near normal, the most important determinant of after-meal glucose concentrations is the before-meal value. Therefore, in the author’s view, if SMBG is to be recommended in patients not receiving insulin, it should be carried out before and one to two hours after a meal to maximize the educational value of how the size and composition of the meal contributes to the rise of glucose concentrations after eating (from the difference between the two SMBG values) and the motivational aspect by showing the patient how high the glucose level rises.

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In addition to its drawbacks of invasiveness and lack of efficacy, SMBG is expensive. In the Kaiser Permanente Northern California Region, the cost for strips alone in 1998 was the fourth largest out-patient pharmacy expenditure, accounting for 2% of the entire budget. Some of these costs would, of course, be attributed to patients receiving insulin. Although it is not possible to completely isolate SMBG costs for diabetic patients not taking insulin, the Medicare B fee-for-service program run by the government affords a fairly accurate estimate of this cost. The ICD-9 code, 250.00 (type 2 diabetes, uncomplicated, not uncontrolled), is the one most often used for diabetic patients on either diet alone or taking oral antidiabetes medications. The total cost in 2002 for reagent strips, lancets, lancing devices, meters, batteries, calibration solutions or calibration chips was US$465,503,576, which represented 58.8% of the total outlay of the Medicare B program for the ICD-9 code of 250.00 (personal communication, staff, Center for Medicare & Medicaid Services).To the extent that type 2 diabetic patients receiving insulin were given this ICD- 9 code, this cost would be an overestimate. On the other hand, to the extent that type 2 diabetic patients not taking insulin were given another ICD-9 code, this cost would be an underestimate. However, since this cost does not include the 10% of Medicare beneficiaries enrolled in health maintenance organiztion (HMO) Managed Medicare, this figure is certainly an underestimate of the total cost for SMBG in type 2 diabetic Medicare patients not taking insulin. Given that this nearly half a billion dollars is only for Medicare patients, the total cost for SMBG for all type 2 diabetic patients not taking insulin is obviously much, much higher.
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SMBG clinical trials:

Self-monitoring blood glucose (SMBG) improves glycaemic control in patients with type 1 diabetes and possibly also in insulin-treated type 2 diabetes (T2D), especially when treated with multiple insulin injections per day. However, the value and frequency of SMBG in non-insulin-treated patients with T2D is a matter of controversy. A consensus opinion among a group of experts from the UK suggested that patients with T2D using oral antidiabetic drugs (OAD) should monitor their blood glucose at least once daily, varying the time of testing between fasting, preprandial and postprandial levels during the day. A global consensus conference on SMBG recommended eleven measurements a week in these patients and another recent consensus conference noted that patents with T2D on OAD may use SMBG but specific recommendations with respect to frequency were not made. A cross-sectional and longitudinal study of patients with T2D in Australia showed that HbA1c was not significantly different between SMBG users and nonusers, either overall or within diabetes treatment groups such as diet, OAD or insulin, with or without OAD. Although such observational data can be useful in determining the effect of an intervention, conclusive evidence of this assumption is not available from randomized controlled trials. A recent study reported on the effect of a more and less intensive diabetes education combined with recommendations on the frequency of SMBG in patients with T2D. They found that a more intensive education did not result in an improved HbA1c (%) compared to standard information and care.

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Summary of key observational studies on Self-Monitoring of Blood Glucose in Non-Insulin Treated Type 2 Diabetes:

Study Description of purpose Findings/comments
Fremantle Diabetes Study Assessed whether SMBG is an independent predictor of improved outcome in a community-based cohort of T2DM patients.  Used longitudinal data from 1,280 T2DM participants (70% ongoing SMBG users at baseline) and a subset of 531 individuals who attended annual assessments over a 5-year period SMBG was associated with a 48% decreased risk of cardiovascular mortality in insulin-treated patients, but a 79% increased risk in non-insulin-treated patients. Time-dependent SMBG was independently associ­ated with a 48% reduced risk of retinopathy in the 5-year cohort.‘Inconsistent findings relating to the association of SMBG with cardiac death and retinopathy may be due to confound­ing, incomplete covariate adjustment or chance’
Kaiser Permanente Assessed longitudinal association between SMBG and glycemic control in diabetic patients from an integrated health plan.  Followed 16,091 new SMBG users and 15,347 ongo­ing users over a 4-year period Greater SMBG frequency among new users was associated with a graded decrease in HbA1c (relative to non-users) regardless of diabetes therapy.  Longitudinal changes in SMBG frequency were related to significant changes in glycemic control
QuED Assessed impact of SMBG on metabolic control in non-insulin-treated T2DM subjects (41% ongoing SMBG users at baseline).  Followed 1,896 patients over a 3-year period Performance and frequency of SMBG did not predict better metabolic control over 3 years.  Investigators could not identify any specific subgroups for whom SMBG practice was associated with lower HbA1c levels during the study
ROSSO Investigated relationship of SMBG with disease-related morbidity and mortality.  Followed 3,268 patients from diagnosis of T2DM between 1995 and 1999 until end of 2003 (mean follow-up 6.5 years) retrospectively from medical records SMBG was associated with decreased diabetes-related severe morbidity and all-cause mortality.  This association was also seen in subgroup of non-insulin-treated patients.  Medical records contained data on some biochemical parameters, retinopathy and neuropathy for only a small proportion of patients
King-Drew Medical Center Trial Randomized, single-blind study designed to determine whether SMBG improves HbA1c in non-insulin-treated T2DM patients. Clinical management decisions were blinded to SMBG data and use 89 non-insulin-treated T2DM patients were followed for 6 months At 6 months, differences in decrease in HbA1c levels were not statistically significant. The rapid upgrading of medication every two weeks if goals were not met may have obscured the potential of SMBG for supporting self-management
ESMON Prospective randomized controlled trial assessed the effect of SMBG vs. no monitoring on glycemic control and psychological indices in patients with newly diagnosed T2DM. Evaluated 184 non-insulin-treated patients with no previous use of SMBG over 12 months There were no significant differences in HbA1c be­tween groups at any time point. SMBG was associated with a 6% higher score on the depression subscale of the well-being questionnaire. The major improvement of mean HbA1c levels in the con­trol group, from 8.6 to 6.9% indicates a dominant role of medication in disease management
DINAMIC Multicentre, randomized, parallel-group trial was designed to determine if therapeutic management programs for T2DM that included SMBG result in greater reductions in HbA1c compared with pro­grams without SMBG in non-insulin-treated patients.Followed 610 T2DM patients with early or mild dia­betes receiving an identical oral anti-diabetic therapy regimen with gliclazide for 27 weeks There was a major decrease of HbA1c which was significantly larger in the SMBG group than the con­trol group. The incidence of symptomatic hypoglycemia was lower in the SMBG group. The major improvement of HbA1c levels in the control group from 8.1 to 7.2% indicates a dominant role of medication in disease management
German-Austrian Prospective, multicenter, randomized controlled study Investigated the effect of meal-related SMBG on glycemic control and well-being in non-insulin-treated T2DM subjects. Followed 250 non-insulin-treated T2DM patients for 6 months In per-protocol analysis (n=223) use of SMBG sig­nificantly reduced HbA1c levels. SMBG use resulted in a marked improvement of general well-being with significant improvements in the subject’s depression and lack of well-being. The benefit of intense patient care is evident but the con­tribution of intense vs. SMBG cannot be assessed
DiGEM Three-arm, open, parallel group randomized trial designed to determine whether SMBG alone, or with instruction in incorporating results into self-care, is more effective than standardized usual care in improving glycaemic control in non-insulin-treated T2DM patients. Followed 453 patients with a mean HbA1c level of 7.5% for a median duration of 1 year. At 12 months the differences in HbA1c level between the three groups were not statistically significant. Investigators concluded that evidence is not convinc­ing of an effect of SMBG, with or without instruction in incorporating findings into self-care, compared with usual care in reasonably well controlled non-insulin-treated patients with type 2 diabetes.

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Self-monitoring of blood glucose in patients with type 2 diabetes mellitus who are not using insulin:

A 2012 study by Cochrane Collaboration:

Self-monitoring of blood glucose (SMBG) has been found to be effective for patients with type 1 diabetes and for patients with type 2 diabetes using insulin. There is much debate on the effectiveness of SMBG as a tool in the self-management for patients with type 2 diabetes who are not using insulin. The Objective of this study was to assess the effects of SMBG in patients with type 2 diabetes mellitus who are not using insulin. Twelve randomised controlled trials were included and evaluated outcomes in 3259 randomised patients. Intervention duration ranged from 6 months (26 weeks) to 12 months (52 weeks). Nine trials compared SMBG with usual care without monitoring, one study compared SMBG with SMUG, one study was a three-armed trial comparing SMBG and SMUG with usual care and one study was a three-armed trial comparing less intensive SMBG and more intensive SMBG with a control group. Seven out of 11 studies had a low risk of bias for most indicators.  From this review, authors conclude that when diabetes duration is over one year, the overall effect of self-monitoring of blood glucose on glycemic control in patients with type 2 diabetes who are not using insulin is small up to six months after initiation and subsides after 12 months. Furthermore, based on a best-evidence synthesis, there is no evidence that SMBG affects patient satisfaction, general well-being or general health-related quality of life. More research is needed to explore the psychological impact of SMBG and its impact on diabetes specific quality of life and well-being, as well as the impact of SMBG on hypoglycemia and diabetic complications. The aim of this systematic review was to assess the effects of SMBG in patients with type 2 diabetes who are not using insulin. Six randomised controlled trials were added to the six trials included in the original review (Welschen 2005a). In non-insulin treated type 2 diabetes patients with a diabetes duration of at least one year the overall effect of SMBG compared to control groups and a follow-up of six months showed a statistically significant 0.3% HbA1c decrease. In contrast, authors saw a non-significant decrease of 0.1% in HbA1c in patients in SMBG groups compared to control groups over a 12 months follow-up period. Secondly, the overall effect of SMBG compared to SMUG over a follow-up of six months showed a statistically non-significant decrease of 0.2% HbA1c. Thirdly, it was not possible to estimate an overall effect of SMBG over a follow-up of six months for newly diagnosed non-insulin treated type 2 diabetes patients, due to substantial inconsistency in the direction of the effect. However, the overall effect of SMBG with a follow-up of 12 months demonstrated a statistically significant decrease of 0.5% in HbA1c compared to control groups (two trials). Concerning health-related quality of life, well-being and patient satisfaction outcomes, based on a best-evidence synthesis authors conclude that there was no significant evidence available that SMBG had an effect on patient satisfaction (4 out of 4 trials), general well-being (4 out of 4 trials) or general health-related quality of life (3 out of 3 trials). Regarding levels of depression (WBQ-22, sub scale), inconsistent findings were observed (2 out of 2 trials). Lastly, regarding the secondary outcomes authors conclude that based on a best-evidence synthesis periods of both asymptomatic and symptomatic hypoglycaemia are more frequent in patients performing SMBG (3 out of 4 trials); and secondly, there is no statistically significant difference in fasting plasma glucose levels between SMBG and control intervention groups (3 out of 3 trials).

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Results from studies of SMBG use in non-insulin-treated T2DM have been mixed, due to differences in study design, populations, outcome indicators, and inherent limitations of the traditional RCT models used. However, current evidence suggests that using SMBG in this population has the potential to improve glycemic control, especially when incorporated into a comprehensive and ongoing educa­tion program that promotes management adjustments according to the ensuing blood glucose values. SMBG use should be based on shared decision making between people with diabetes and their healthcare provid­ers and linked to a clear set of instructions on actions to be taken based upon SMBG results. SMBG prescription is discouraged in the absence of relevant education and/or ability to modify behaviour or therapy modalities. In summary, the appropriate use of SMBG by people with non-insulin-treated diabetes has the potential to optimize diabetes management through timely treatment adjustments based on SMBG results and improve both clinical outcomes and quality of life. However, the value and utility of SMBG may evolve within a preventive care model that is based on ongoing monitoring and the ability to adjust management as the diabetes progresses over time. In the meantime, more effective patient and provider training around the use of SMBG is needed. Because skilled healthcare professionals are needed now and in the future to address the growing diabetes epidemic, it is hoped that this report will encourage the development and systematic introduction of more effective diabetes self-management education/training and the value-based models of clinical decision making and care delivery.

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A systematic review of self blood glucose monitoring (SMBG) in type 2 patients not taking insulin concluded: “The overall effect of SMBG was a statistically significant decrease of 0.39% in glycated hemoglobin (HbA1c) compared with the control groups. This is considered clinically relevant. Based on the UK Prospective Diabetes Study, a decrease of 0.39% in HbA1c is expected to reduce risk of microvascular complications by 14%. Davidson, on the other hand, in a counterpoint to this study, reviewed several trials and concluded that SMBG fails to reduce HbA1c in type 2 patients not taking insulin and is therefore a waste of money.

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HBA1c as a function of SMBG measurements per day:

The figure above conclusively proves that SMBG improves A1c in all types of DM and consequently reduce diabetic complications and improve clinical outcomes.

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Continuous glucose monitoring (CGM): 

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A continuous glucose monitoring system (CGMS) measures blood glucose on a continuous basis (every few minutes). Two types of devices are available: newer systems that display “real time” glucose results directly on the monitor system, and earlier “non-real time” devices that do not have this result display capability and results are only available for retrospective viewing and analysis when data are downloaded to computer.

A typical “real-time” system consists of:

  • a disposable glucose sensor placed just under the skin, which is worn for a few days until replacement,
  • a link from the sensor to a non-implanted transmitter which communicates to a radio receiver,
  • an electronic receiver worn like a pager (or insulin pump) that displays blood glucose levels on a practically continuous manner, as well as monitors rising and falling trends in glycemic excursions.

Continuous monitoring allows examination of how the blood glucose level reacts to insulin, exercise, food, and other factors. The additional data can be useful for setting correct insulin dosing ratios for food intake and correction of hyperglycemia. Monitoring during periods when blood glucose levels are not typically checked (i.e. overnight) can help to identify problems in insulin dosing (such as basal levels for insulin pump users or long-acting insulin levels for patients taking injections). Monitors may also be equipped with alarms to alert patients of hyperglycemia or hypoglycemia so that a patient can take corrective action(s) (after finger stick testing, if necessary) even in cases where they do not feel symptoms of either condition. While the technology has its limitations, studies have demonstrated that patients with real-time continuous sensors experience less hyperglycemia, hyperglycemia, nocturnal hypoglycemia and even improvement in A1C levels. CGMS do not directly measure glucose levels in the blood, but measure the glucose level of interstitial fluid. This results in two disadvantages as compared to traditional blood glucose monitoring. 

1. Using current technology, continuous systems must be calibrated with a traditional blood glucose measurement and therefore do not yet fully replace “finger stick” measurements.

2. Glucose levels in interstitial fluid temporally lag behind blood glucose values. The lag time has been reported to be 5 minutes in general. This lag time is insignificant when blood sugar levels are relatively consistent. However, blood sugar levels, when changing rapidly (rising such as after a meal, or dropping in case of hypoglycemia), may read in the normal range on a CGMS while in reality the patient is already experiencing symptoms of an out-of-range blood glucose value and may require treatment. For these and other reasons related to this first generation technology, patients using CGMS are typically advised to take traditional finger stick measurements at least twice a day (for calibration), to verify that the sensor readings are accurate, and whenever they wish to self-treat their diabetes. Currently available CGMS are relatively expensive. While changing a subcutaneous cannula every 3–7 days would be less invasive than 3 or more finger sticks per day, the technology is still invasive. Coincidentally, the standard finger stick method must be used alongside the CGM technology to guarantee its functionality and accuracy. CGM technology is a major step in the advancement of diabetes care and has been proven effective. The ultimate goal of CGM technology is to use it in combination with subcutaneous insulin pumps, and in effect create an external “artificial pancreas” thereby providing better overall health and improved HbA1C tests.

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The currently available CGMs measure blood glucose either with minimal invasiveness through continuous measurement of interstitial fluid (IF) or with the noninvasive method of applying electromagnetic radiation through the skin to blood vessels in the body. The technologies for bringing a sensor into contact with IF include inserting an indwelling sensor subcutaneously (into the abdominal wall or arm) to measure IF in situ or harvesting this fluid by various mechanisms that compromise the skin barrier and delivering the fluid to an external sensor. These IF measurement technologies are defined as minimally invasive because they compromise the skin barrier but do not puncture any blood vessels. After a warm-up period of up to 2 h and a device-specific calibration process, each device’s sensor will provide a blood glucose reading every 1–10 min for up to 72 h with the minimally invasive technology and up to 3 months with the noninvasive technology. Results are available to the patient in real time or retrospectively. Every manufacturer of a CGM produces at least one model that sounds an alarm if the glucose level falls outside of a preset euglycemic range. Invasive indwelling intravascular sensors that measure blood glucose directly are also under development for monitoring hospitalized patients. Prolonged use of such devices might cause vascular damage or infection. No articles have been published on their performance.

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Noninvasive CGM Sensor:

A novel noninvasive method introduced by Glucon in 2007 is a CGM sensor called Aprise. This technology uses the photo acoustic properties of blood to measure glucose levels. The technique involves a sensor placed on a blood vessel that emits sound and pressure waves generated with short laser pulses absorbable by human tissue. The absorption causes a rise in temperature, and this creates an acoustic pressure impulse on the tissue surface. This impulse carries information about the properties of the structure underlying the skin. Glucose is known to affect the optical properties of blood, and thus the ultrasonic image changes of the tissue can estimate the blood glucose concentration. A study of 62 inpatients showed similar results with the Aprise CGM system compared with the more invasive CGM systems. Results showed accuracy in measuring glucose in 51%, 67%, and 86% of samples amongst low (<150 mg/dL), mid (151–200 mg/dL), and high (>251 mg/dL) glucose ranges respectively. They were able to directly measure the blood instead of using the interstitial fluid compartment and inferring the systemic glucose levels. The results from this noninvasive CGM trial were promising; however, the Aprise is yet to be marketed to the public.

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According to a recent report the CGM technology is not as reliable as initially anticipated. In a clinical trial following 11 patients with either Type I or Type II diabetes, Mazze and colleagues found that the 2 leading CGM systems, DexCom (San Deigo, CA) and MiniMed Guardian RT (Northhridge, CA), are less accurate than expected due to a delay in the time it takes to monitor glucose in interstitial fluid and display it to the patient. There were lag times of 21 ± 5 min for the Guardian system and 7 ± 7 min for Dexcom. The CGM devices were also found to be less reliable than the traditional finger stick method. While both the Guardian and the Dexcom monitors should display 282 readings per day, the Dexcom averaged 204 ± 37 and the Guardian 229 ± 29. The inaccuracies did not induce episodes of acute crisis, such as diabetic coma, nor did they stop the technology from being marketed. As a result it is recommended that finger sticks continue to be performed to confirm high and low glucose readings before relying solely on CGM. The potential for somewhat continuous detection of glycemic abnormalities and maintaining overall glycemic control was achieved, and the technology was appoved for sale. There is no clear consensus about the clinical indications for CGM in actual clinical practice.  A Cochrane review found that there is limited evidence for the effectiveness of real-time CGM use in children, adults and patients with poorly controlled diabetes. However there were indications that higher compliance of wearing the CGM device improved glycosylated HbA1c level to a larger extent.

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Clinical indications of CGM:

Situations that require detailed information about blood glucose fluctuations that only continuous monitoring can provide include when adjusting therapy, quantifying the response in a trial of a diabetes therapy, assessing the impact of lifestyle modifications on glycemic control, monitoring conditions where tighter control without hypoglycemia is sought (e.g., gestational diabetes, pediatric diabetes, in the intensive care unit), diagnosing and then preventing hypoglycemia (e.g., during sleep, with hypoglycemia unawareness), and diagnosing and preventing postprandial hypoglycemia. The most important use of continuous blood glucose monitoring is to facilitate adjustments in therapy to improve control. Specific therapeutic adjustments include changing from regular to a synthetic ultrashort-acting insulin analog at mealtime, changing from NPH to a synthetic ultralong-acting insulin once or twice per day, increasing or decreasing the mealtime insulin bolus dosage, increasing or decreasing the basal insulin rate, altering the treatment of intermittent hypoglycemia or hyperglycemia, changing the insulin-to-glucose correction algorithm for premeal hyperglycemia, changing the insulin-to-carbohydrate ratio at mealtime, changing the method for counting carbohydrates, changing the carbohydrate composition of the diet, changing the discount in short-acting insulin dosage for exercise, changing the nighttime regimen because of the dawn phenomenon, changing the target preprandial or postprandial blood glucose values, or before referring a patient for psychological counseling to improve adherence to the treatment regimen. The most frequent therapy adjustment by Sabbah et al. (out of eight adjustments) was to increase the mealtime bolus dosage. The most frequent therapy adjustment by Kaufman et al. (out of nine adjustments) was to modify the type of basal long-acting insulin.

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Accuracy of CGM:

A real-time CGM can be programmed to sound an alarm for readings below or above a target range. The most important use of an alarm is to detect unsuspected hypoglycemia (such as during sleep) so that glucose can be administered to prevent brain damage. There is a trade-off between an alarm’s sensitivity and specificity. In general, if the alarm is set to sound at a lower level than the hypoglycemic threshold, then the specificity will be good but the sensitivity may be poor. If the alarm is set to sound at a glucose level higher than the hypoglycemic threshold, then the sensitivity will be good but the specificity may be poor. The greater accuracy a continuous monitor can provide, the less of a trade-off is necessary.

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The Diabetes Research in Children Network (DirecNet) is a U.S. network of five clinical centers and a coordinating center dedicated to researching glucose monitoring technology in children with type 1 diabetes. The network’s investigators, the DirecNet Study Group, assessed the accuracy of the first- and second-generation CGMS and the GW2B in children with type 1 diabetes in concurrently published studies. The second-generation CGMS Gold, compared with the first-generation CGMS, had a lower median relative absolute difference (RAD) between CGMS glucose and reference serum glucose paired values (11 and 19%, respectively). For the GW2B, the median RAD between GW2B glucose and reference serum glucose paired values was 16%. Similar RAD values of 21% have been reported for the first-generation CGMS by Kubiak et al. RAD values of 12.8%  and 12.8–15.7% have been reported for the second-generation CGMS Gold system by Goldberg et al. and Guerci et al, respectively. Bode et al. evaluated the performance of the Guardian Continuous Monitoring System (Medtronic MiniMed) and whether using real-time alarms reduced hypo- and hyperglycemic excursions in a type 1 diabetic population. The mean absolute relative error between home blood glucose meter readings and sensor values was 21.3% (median 7.3%); further, on average the Guardian read 12.8 mg/dl below the concurrent home blood glucose meter readings. The hypoglycemia alert was able to distinguish glucose values ≤70 mg/dl with 67% sensitivity, 90% specificity, and 47% false alerts. The hyperglycemia alert showed a similar ability, detecting values ≥250 mg/dl with 63% sensitivity, 97% specificity, and 19% false alerts. The alerts resulted in a significant (P = 0.03) reduction in the duration of hypoglycemic excursions and a marginally significant (P = 0.07) increase in the frequency of hyperglycemic excursions. The International Organization for Standardization (ISO) standards for accuracy of point blood glucose tests require that a sensor blood glucose value be within 15 mg/dl of reference for a reference value ≤75 mg/dl and within 20% of reference for a reference value >75 mg/dl. Sensor accuracy by this definition is expressed as the percentage of data pairs meeting these requirement. The DirecNet group found that for hypoglycemic blood glucose levels (determined by a reference blood glucose monitor, the OneTouch Ultra), the CGMS Gold met the ISO standards in only 48% of readings and the GW2B met these standards in only 32% of readings. The percentage of data points attaining ISO accuracy standards climbed as the blood glucose level rose, topping out for the highest segment of reference blood glucose levels (i.e., blood glucose values ≥240 mg/dl). In this glycemic category, the CGMS Gold and GW2B, respectively, met ISO accuracy for 81 and 67% of data points. In a separate series of 15 healthy nondiabetic children undergoing continuous glucose monitoring over 24 h, the DirecNet Group reported that the median absolute difference in concentrations for the GW2B was 13 mg/dl and for the CGMS was 17 mg/dl. Furthermore, 30% of the values from the GW2B and 42% of the values from the CGMS deviated by >20 mg/dl from the reference value.

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Continuous glucose monitoring offers advantages over intermittent glucose monitoring when glycemic patterns are poorly understood. The information about direction, magnitude, duration, frequency, and causes of fluctuations in blood glucose levels that can be obtained by continuous glucose monitoring is simply not available with intermittent blood glucose monitoring. When retrospective patterns are needed to adjust therapy or document the state of physiology, CGMs are useful. When real-time recognition of both the absolute magnitude of glycemia as well as trend patterns are needed, then a real-time CGM provides a wealth of information. Technologies for continuous glucose monitoring require patient education for proper use. During hypoglycemia or periods of rapid fluctuation, values provided by CGMs may be inaccurate. Clinical outcome studies suggest that measures of mean glycemia and hypoglycemic burden both improve with the use of continuous glucose monitoring, but more studies are needed to convince payers to reimburse for this technology. In this data-hungry world, it appears likely that CGMs will eventually become a routine part of diabetes management, initially for patients with difficult-to-control diabetes and eventually for most patients with diabetes. Retrospective reporting will eventually give way to real-time readings, and adjunctive use requiring a confirmatory finger-stick blood test will eventually give way to primary use without the requirement of such confirmation. As methods for minimally invasive and noninvasive continuous monitoring advance, diabetic patients will use this technology more routinely. Data printouts from CGMs will increasingly provide a roadmap for effective diabetes management in the 21st century.

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Continuous glucose monitoring systems for type 1 diabetes mellitus: Cochrane review 2012:

Type 1 diabetes is a disease in which the pancreas has lost its ability to make insulin. A deficit in insulin leads to increases in blood glucose levels, these elevated blood glucose levels can lead to complications which may affect the eyes, kidneys, nerves and the heart and blood vessels. Since there is no cure for type 1 diabetes, patients need to check their blood glucose levels often by fingerprick and use these blood glucose values to decide on their insulin dosages. Fingerpricks are often regarded as cumbersome and uncomfortable by patients. In addition, fingerprick measurements only provide information about a single point in time, so it is difficult to discern trends in decline of rises in blood glucose levels. Continuous glucose monitoring systems (CGM) measure blood glucose levels semi-continuously. In this review 22 studies were included. These studies randomised 2883 patients with type 1 diabetes to receive a form of CGM or to use self measurement of blood glucose (SMBG) using fingerprick. The duration of follow-up varied between 3 and 18 months; most studies reported results for six months of CGM use. This review shows that CGM helps in lowering the glycosylated haemoglobin A1c (HbA1c) value (a measure of glycemic control). In most studies the HbA1c value decreased (denoting improvement of glycemic control) in both the CGM and the SMBG users, but more in the CGM group. The difference in change in HbA1c levels between the groups was on average 0.7% for patients starting on an insulin pump with integrated CGM and 0.2% for patients starting with CGM alone. The most important adverse events, severe hypoglycemia and ketoacidosis did not occur frequently in the studies, and absolute numbers were low (9% of the patients, measured over six months). Diabetes complications, death from any cause and costs were not measured. There are no data on pregnant women with diabetes type 1 and patients with diabetes who are not aware of hypoglycemia. There is limited evidence for the effectiveness of real-time continuous glucose monitoring (CGM) use in children, adults and patients with poorly controlled diabetes. The largest improvements in glycaemic control were seen for sensor-augmented insulin pump therapy in patients with poorly controlled diabetes who had not used an insulin pump before. The risk of severe hypoglycemia or ketoacidosis was not significantly increased for CGM users, but as these events occurred infrequent these results have to be interpreted cautiously. There are indications that higher compliance of wearing the CGM device improves glycosylated haemoglobin A1c level (HbA1c) to a larger extent.

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Glucose sensing bio-implants:

A significant improvement of diabetes therapy might be achieved with an implantable sensor that would continuously monitor blood sugar levels within the body and transmit the measured data outside. The burden of regular blood testing would be taken from the patient, who would instead follow the course of their glucose levels on an intelligent device like a laptop or a smart phone. Glucose concentrations do not necessarily have to be measured in blood vessels, but may also be determined in the interstitial fluid, where the same levels prevail – with a time lag of a few minutes – due to its connection with the capillary system. However, the enzymatic glucose detection scheme used in single-use test strips is not directly suitable for implants. One main problem is caused by the varying supply of oxygen, by which glucose is converted to glucono lactone and H2O2 by glucose oxidase. Since the implantation of a sensor into the body is accompanied by growth of encapsulation tissue as seen in the figure below, the diffusion of oxygen to the reaction zone is continuously diminished. This decreasing oxygen availability causes the sensor reading to drift, requiring frequent re-calibration using finger-sticks and test strips.

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Other approaches replace the troublesome glucose oxidase reaction with a reversible sensing reaction, known as an affinity assay. This scheme was originally put forward by Schultz & Sims in 1978. A number of different affinity assays have been investigated, with fluorescent assays proving most common.  MEMS technology has recently allowed for smaller and more convenient alternatives to fluorescent detection, via measurement of viscosity. Investigation of affinity-based sensors has shown that encapsulation by body tissue does not cause a drift of the sensor signal, but only a time lag of the signal compared to the direct measurement in blood. Longer term solutions to continuous monitoring, not yet available but under development, use a long-lasting bio-implant. These systems promise to ease the burden of blood glucose monitoring for their users, but at the trade off of a minor surgical implantation of the sensor that lasts from one year to more than five years depending on the product selected. Products under development include: The Senseonics Continuous Glucose Monitoring System, Implanted Glucose Bio-sensor, The Dexcom LTS (long term system) and The Animas Glucose Sensor.

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Function of an Implanted Tissue Glucose Sensor for more than 1 Year in Animals:

An implantable sensor capable of long-term monitoring of tissue glucose concentrations by wireless telemetry has been developed for eventual application in people with diabetes. The sensor telemetry system functioned continuously while implanted in subcutaneous tissues of two pigs for a total of 222 and 520 days, respectively, with each animal in both nondiabetic and diabetic states. The sensor detects glucose via an enzyme electrode that is based on differential electrochemical oxygen detection, which reduces the sensitivity of the sensor to encapsulation by the body, variations in local microvascular perfusion, limited availability of tissue oxygen, and inactivation of the enzymes. After an initial 2-week stabilization period, the implanted sensors maintained stability of calibration for extended periods. The lag between blood and tissue glucose concentrations was 11.8 ± 5.7 and 6.5 ± 13.3 minutes (mean ± standard deviation), respectively, for rising and falling blood glucose challenges. The lag resulted mainly from glucose mass transfer in the tissues, rather than the intrinsic response of the sensor, and showed no systematic change over implant test periods. These results represent a milestone in the translation of the sensor system to human applications.

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Artificial pancreas:

To overcome the limitations of current insulin therapy, researchers have long sought to link glucose monitoring and insulin delivery by developing an artificial pancreas. An artificial pancreas is a system that will mimic, as closely as possible, the way a healthy pancreas detects changes in blood glucose levels and responds automatically to secrete appropriate amounts of insulin. Although not a cure, an artificial pancreas has the potential to significantly improve diabetes care and management and to reduce the burden of monitoring and managing blood glucose.

An artificial pancreas based on mechanical devices requires at least three components:

  • a CGM system
  • an insulin delivery system
  • a computer program that “closes the loop” by adjusting insulin delivery based on changes in glucose levels

With recent technological advances, the first steps have been taken toward closing the loop. The first pairing of a CGM system with an insulin pump—the MiniMed Paradigm REAL-Time System—is not an artificial pancreas, but it does represent the first step in joining glucose monitoring and insulin delivery systems using the most advanced technology available.

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A Breakthrough in better Glucose Control: MiniMed 530G with Enlite:

As an integrated insulin pump and CGM system, MiniMed 530G with Enlite offers better control than multiple daily injections or conventional insulin pumps. It increases confidence to achieve better control. Bayer’s Contour Next Link allows seamless integration as a part of the MiniMed 530G system, transmitting exceptionally accurate blood glucose results wirelessly to the insulin pump. This makes it easier for you and your doctor to make better therapy adjustments than with logbooks alone.  CareLink is a convenient online tool that collects and organizes information from your system into personalized reports.

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Bionic pancreas:

The device represents a solution that is as close to a cure as some feel possible for now and may be available to the commercial market by 2017. Developed by a collaborative biomedical team between BU and Massachusetts General Hospital, the device is worn externally and consists of two hormone pumps (insulin and glucagon), an iPhone and a continuous glucose monitor that measures blood sugar levels every five minutes. It is a marriage of biology and technology, with a powerful algorithm capable of recommending and delivering instantaneous hormone that balances blood sugar better than any diabetic can replicate on his or her own. It is self-correcting, constantly making little adjustments to keep the blood sugars in the optimal range and learning from the patient’s own history how much insulin or glucagon to provide.  All of the participants in the study had blood sugars that would greatly reduce, if not eliminate, the long-term risks of diabetes.

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ICU and glucose monitoring:

Accuracy of different methods for blood glucose measurement in critically ill patients:

Measurement of blood glucose concentration in ICUs is currently performed almost entirely intermittently, with analysis using either point-of-care glucose meters or blood gas analyzers. Although accurate data are not available, most measurements are probably made on glucose meters and the majority of samples are capillary blood obtained by finger pricks. The use of glucose meters and sampling capillary blood both have the potential to introduce errors into the measurement of blood glucose concentration. Severe sepsis and septic shock are the main causes of death in intensive care units. More than 750,000 cases of severe sepsis occur annually in the United States, amounting to 215,000 deaths/year in that country. Impaired microcirculation plays a leading role in this setting and, unless corrected, it can evolve to multiple organ dysfunction and death. Glucose homeostasis becomes modified in these patients, thereby resulting in insulin resistance, hyperinsulinemia and consequent hyperglycemia. This set of conditions is named stress diabetes, and it is a physiological response that ensures glucose supply to non-insulin-dependent tissues such as hepatocytes, nerve cells and alveolar, endothelial and immune system cells. Hyperglycemia is an independent predictor of adverse outcomes in cases of cardiovascular disease, neurological disorders, respiratory, liver and gastrointestinal disease, malignancy, sepsis and surgical patients. Normoglycemia is related to lower morbidity and mortality because of improvements in systemic inflammatory processes and in immune, endothelial and mitochondrial dysfunctions. Normoglycemic patients are less susceptible to bloodstream infection, renal failure, anemia and transfusion, polyneuropathy, hyperbilirubinemia and prolonged dependence on both mechanical ventilation and intensive care therapy. Additionally, glucose control is cost-effective. Thus, although glucose control is a priority in treating critically ill patients, glucose monitoring can be quite challenging. Considering that many intensive care patients are unable to express signs and symptoms of hypoglycemia, frequent and accurate measurements are pivotal. Given the low cost, easy sampling and prompt results of glucometers, capillary blood glucose levels are often determined using this method, although it has not been validated for intensive care patients. Critically ill patients have multiple relevant conditions that can interfere with measurements such as pH, partial pressure of oxygen, hematocrit, low blood pressure levels and tissue hypoperfusion. Measurement mistakes may lead to unnecessary procedures regarding insulin doses and increase the risk of severe or prolonged hypoglycemia and its complications such as seizures, coma, arrhythmia and irreversible cerebral damage. So fingerstick capillary blood glucose method usually overestimates the true glucose levels and gives rise to management errors in ICU patients. The use of glucometer in intensive care must also be avoided, particularly if noradrenalin is being used. Predominantly, this method overestimates blood glucose levels, which implies procedural errors and exposes patients to more frequent and prolonged hypoglycemic events. There is an increasing volume of evidence that maintaining as close to normal glucose as possible in hospitalized patients, especially those in intensive, surgical, and critical care units, can significantly improve outcomes, decreasing both morbidity and mortality.

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Alternatives to the use of glucose meters are measurement in the hospital’s central laboratory or using a blood gas analyzer in the ICU. Although central laboratory measurement is much more accurate, the time delay in sending samples to the laboratory makes this an impractical solution for the ICUs in most hospitals. The frequency with which the blood glucose concentration is measured in the ICU makes venipuncture impractical, and viable alternatives are to sample from indwelling arterial or venous catheters. Sampling from indwelling vascular catheters may increase the risk of catheter-related bloodstream infection but this risk has not been quantified. Obviously, when sampling from indwelling catheters it is essential to avoid contamination from infusions of glucose-containing fluids. A more practical solution, but one that may have considerable cost implications, is to measure the blood glucose concentration in a blood gas analyzer because the majority of ICUs in the developed world will have such an analyzer in the ICU. Measurements from a properly maintained blood gas analyzer will have similar accuracy to central laboratory measurements. An additional consideration is that the blood glucose concentration varies in different vascular beds and the site from which blood is sampled can introduce further errors. The blood glucose concentration in radial arterial blood will be approximately 0.2 mmol/l higher than that in blood sampled from a peripheral vein, and 0.3 to 0.4 mmol/l higher than that in blood sampled from the superior vena cava. Sampling capillary blood in ICU patients, particularly in those who are hemodynamically unstable and being treated with vasopressors, can introduce large errors when compared with a reference method in which glucose is measured in central venous or arterial samples.

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CGM in ICU:

Numerous techniques are available for continuous glucose monitoring in the ICU, including microdialysis and optical methods such as absorption spectroscopy, optical scattering and fluorescence. The blood glucose concentration can be measured in vitro by sensors that sit in the vascular or interstitial space or ex vivo by drawing blood samples or a dialysate to a sensor from an indwelling vascular catheter or dialysis membrane. Systems that intermittently draw blood to an externally based sensor may be described as automated intermittent monitors rather than continuous glucose monitors. Potential advantages of continuous glucose monitors include the ability to observe trends in blood glucose concentration and to intervene before the blood glucose concentration enters an unacceptable range, and removal of operator error both in the timing of blood glucose measurements and in the sampling and analysis of blood. Almost all monitoring of the blood glucose concentration in critically ill patients is by intermittent measurement. Although intermittent measurement is current standard practice, there is no agreed metric for reporting glycemic control and many of the metrics currently reported are affected by the frequency of measurement. Current systems for continuous or automated intermittent monitoring may measure the blood glucose concentration at a frequency varying from every minute to every 15 minutes. Such monitors will not only increase the number of measurements, but will also standardize the frequency of measurements amongst patients monitored with each device. This may allow for a better reporting of glucose control metrics, and if sufficiently accurate may offer a better understanding of the association between those metrics and outcomes.  

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Limitations of Conventional Methods of Self-Monitoring of Blood Glucose: a 2001study:

Children with type 1 diabetes are usually asked to perform self-monitoring of blood glucose (SMBG) before meals and at bedtime, and it is assumed that if results are in target range, along with HbA1c measurements, then overall glycemic control is adequate. However, the brief glimpses in the 24-h glucose profile provided by SMBG may miss marked glycemic excursions. The MiniMed Continuous Glucose Monitoring System (CGMS) has provided a new method to obtain continuous glucose profiles and opportunities to examine limitations of conventional monitoring.  A total of 56 children with type 1 diabetes (age 2–18 years) wore the CGMS for 3 days. Patients entered four fingerstick blood samples into the monitor for calibration and kept records of food intake, exercise, and hypoglycemic symptoms. Data were downloaded, and glycemic patterns were identified.  Despite satisfactory HbA1c levels (7.7 ± 1.4%) and premeal glucose levels near the target range, the CGMS revealed profound postprandial hyperglycemia. Almost 90% of the peak postprandial glucose levels after every meal were >180 mg/dl (above target), and almost 50% were >300 mg/dl. Additionally, the CGMS revealed frequent and prolonged asymptomatic hypoglycemia (glucose <60 mg/dl) in almost 70% of the children. Despite excellent HbA1c levels and target preprandial glucose levels, children often experience nocturnal hypoglycemia and postprandial hyperglycemia that are not evident with routine monitoring.  These observations have important clinical implications, because recent evidence suggests that postprandial hyperglycemia plays a particularly important role in the development of vascular complications of diabetes. These data also illustrate the potential usefulness of monitoring postprandial as well as preprandial glucose levels in youth with type 1 diabetes. The sensor also detected many more hypoglycemic events during the day than were appreciated clinically. Repeated use of the CGMS may provide a means to optimize basal and bolus insulin replacement in patients with type 1 diabetes.

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Home vs. Hospital Testing:

Most home meters measure glucose in so-called “whole blood” (blood as it comes out of our body). Whole blood consists of a liquid, called plasma, and cells, mainly red cells. The percentage of red cells is called the hematocrit. The standard reference lab test measures glucose in plasma (about half to two thirds of the volume of blood). Home meters are calibrated to give results as though they are measuring glucose in plasma only (called “plasma-equivalent” results). That said, to some degree we’re already on two different playing fields. Second, laboratory tests eliminate virtually all variation, except for manufacturing variation, from their testing. What that means is that hospital standards are much more exacting than testing at home because in hospitals you have: trained technicians, a controlled environment for temperature and humidity, constant maintenance of the machine that performs the test, with checking and refining of the machine’s calibration several times a day, and a much larger sample of blood (5 ml) that’s analyzed for 60 seconds or more, and at much greater expense. Lab tests generally come within about plus/minus 4% of a perfect reading.

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SMBG vs. HbA1c:

Hemoglobin A1c outperforms Fasting Glucose for Risk Prediction:

Measurements of hemoglobin A1c (HbA1c) more accurately identify persons at risk for clinical outcomes than the commonly used measurement of fasting glucose, according to a study by researchers at the Johns Hopkins Bloomberg School of Public Health. HbA1c levels accurately predict future diabetes, and they better predict stroke, heart disease and all-cause mortality as well. The study appeared in the March 4, 2010, issue of New England Journal of Medicine. As a diagnostic, “HbA1c has significant advantages over fasting glucose,” said Elizabeth Selvin, PhD, MPH, the study’s lead author. The A1c test has low variability from day to day, levels are not as affected by stress and illness, it has greater stability and the patient is not required to fast before the test is performed. In the study, people with HbA1c levels between 5.0 to 5.5 percent were identified as being within “normal” range. The majority of the U.S. adult population is within this range. With each incremental HbA1c increase, the study found, the incidence of diabetes increased as well; those at a level of 6.5 percent or greater are considered diabetic, and those between 6.0 and 6.5 percent are considered at a “very high risk” (9 times greater than those at the “normal” range) for developing diabetes. The revised ADA guidelines classify people with HbA1c levels in the range of 5.7 to 6.4 percent as “at very high risk” for developing diabetes over 5 years. The range of 5.5 to 6 percent, according to the ADA guidelines, is the appropriate level to initiate preventive measures. The study measured HbA1c in blood samples from more than 11,000 people, black and white adults, who had no history

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Limitations of monitoring glycemic control using only HbA1c:

HbA1c does not provide information about Glycemic Variability:

As an integrated measure of fasting, preprandial, and postprandial glucose levels, HbA1c may not completely represent the risks that patients with diabetes are exposed to on a daily basis. Although it provides a quantitative measure of mean glucose exposure over an extended period, HbA1c alone does not indicate the degree of glycemic variability (the frequency and magnitude of glucose excursions) that a patient may experience during a given day. The potential importance of glycemic variability is suggested by findings from the DCCT. Even at equivalent HbA1c levels, patients receiving intensive therapy (involving more frequent preprandial insulin injections) had a reduction in the risk of progression of retinopathy over time compared with patients receiving conventional treatment. The DCCT research group speculated that complications might be highly dependent on the extent of postprandial glycemic excursions and that conventionally treated patients were more likely to be exposed to greater glycemic excursions than those in the intensive treatment group.

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The figure below proves that HbA1c misses glycemic excursions:

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The figure below shows that HbA1c misses many lows of glucose:

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HbA1C does not differentiate among Fasting, Preprandial, and Postprandial Glycemia:

Optimal diabetes management involves control of fasting, preprandial, and postprandial glucose levels. However, because HbA1c represents mean glycemic exposure over time, it cannot be used to identify whether a given patient’s abnormal glycemic levels are primarily due to high fasting plasma glucose levels or high postprandial plasma glucose (PPG) levels. Simply put, an elevated HbA1c measurement signals a need for a change in therapy, but it cannot indicate what type of change is necessary. In fact, the relative contributions of fasting plasma glucose and PPG to HbA1c vary according to HbA1c level, with PPG becoming increasingly important as HbA1c decreases toward target levels.

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A considerable body of evidence points to the clinical importance of postprandial hyperglycemia, typically evaluated in clinical studies as postchallenge glucose levels in an oral glucose tolerance test. Although the terms postchallenge and postprandial are not synonymous because of the inherent differences between ingesting a pure glucose solution and eating a mixed meal, postchallenge hyperglycemia is often regarded as a surrogate for postprandial hyperglycemia. Even when HbA1c and fasting glucose levels are within the normal range, postchallenge hyperglycemia has been associated with a 2-fold increase in the risk of death from cardiovascular disease. In the Funagata Diabetes Study, impaired glucose tolerance (IGT), defined as a 2-hour postchallenge plasma glucose level between 140 and 198 mg/dL (7.8-11.0 mmol/L), as opposed to impaired fasting glucose (defined in that study as 110-125 mg/dL [6.1-7.0 mmol/L]) was shown to double the risk of death from cardiovascular disease.

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The increased risk of macrovascular disease among patients with IGT but not impaired fasting glucose, combined with the greater contribution of postprandial hyperglycemia to overall glycemia when HbA1c levels are lower, may help to explain why even newly diagnosed patients have an increased cardiovascular risk. When IGT progresses to diabetes, the patient has been exposed to postprandial glycemic excursions for many years. In the Diabetes Intervention Study, elevated PPG levels after a normal breakfast were associated with significantly higher mortality during an 11-year follow-up of patients with newly diagnosed type 2 diabetes (P<.01).  In support of these findings, prospective interventions that control PPG have been shown to improve endothelial function and reduce carotid atherosclerosis in patients with type 2 diabetes. Postprandial hyperglycemia was recently linked to microvascular complications as well. In a study of 151 Japanese patients, PPG levels correlated better than HbA1c measurements with the risk of retinopathy progression.

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Inaccuracies in HbA1c Test Results:

More than 30 different HbA1c assays are currently available. Differences among these assays as well as variations between and within laboratories can affect HbA1c results. In 1996, the National Glycohemoglobin Standardization Program (NGSP) was established in the United States to certify assay methods as traceable to DCCT reference values. Certification from the NGSP requires an assay method’s reference interval to be within 5% of the normal HbA1c level of 4% to 6%, with variations limited to less than 3% within a laboratory and less than 5% between laboratories.6 The ADA now recommends that laboratories use only NGSP-certified assays. Some medical conditions may cause inaccurate HbA1c test results.  Conditions or factors that shorten red blood cell life span, such as acute blood loss, hemolytic anemia, and some medications used for human immunodeficiency virus-positive patients,  will yield falsely low HbA1c values regardless of assay method. Hemoglobin variants, hemoglobinopathies, conditions that result in increased erythrocyte turnover, and blood transfusions can increase or decrease HbA1c levels depending on the condition and the HbA1c assay method used. Iron deficiency anemia, hypertriglyceridemia, hyperbilirubinemia, uremia, and high doses of acetylsalicylic acid can produce falsely high HbA1c measurements. Dietary supplements and opiate or alcohol abuse can also affect HbA1c results. Vitamins C and E may lower test results by inhibiting glycation of hemoglobin, and vitamin C has also been reported to increase HbA1c values, depending on the assay used.

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Why is hemoglobin A1c unreliable?  

While this sounds good in theory, the reality is not so black and white. The main problem is that there is actually a wide variation in how long red blood cells survive in different people. A study shows that red blood cells live longer than average at normal blood sugars. Researchers found that the lifetime of hemoglobin cells of diabetics turned over in as few as 81 days, while they lived as long as 146 days in non-diabetics. This proves that the assumption that everyone’s red blood cells live for three months is false, and that hemoglobin A1c can’t be relied upon as a blood sugar marker. In a person with normal blood sugar, hemoglobin will be around for a lot longer, which means it will accumulate more sugar. This will drive up the A1c test result – but it doesn’t mean that person had too much sugar in their blood. It just means their hemoglobin lived longer and thus accumulated more sugar. The result is that people with normal blood sugar often test with unexpectedly high A1c levels. So people with completely normal fasting and post-meal blood sugars have A1c levels of >5.4%. In fact this is not abnormal, when we understand that people with normal blood sugar often have longer-lived red blood cells – which gives those cells time to accumulate more sugar. On the other hand, if someone is diabetic, their red blood cells live shorter lives than non-diabetics. This means diabetics and those with high blood sugar will test with falsely low A1c levels. And we already know that fasting blood glucose is the least sensitive marker for predicting future diabetes and heart disease. This is a serious problem, because fasting blood glucose and hemoglobin A1c are almost always the only tests doctors run to screen for diabetes and blood sugar issues. Another condition that affects hemoglobin A1c levels is anemia. People who are anemic have short-lived red blood cells, so like diabetics, they will test with falsely low A1c levels. In my practice, about 30-40% of my patients have some degree of anemia, so this is not an uncommon problem. 

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Using SMBG to Complement HbA1c:

Self-monitoring of blood glucose provides a real-time measure of blood glucose levels and consequently represents a valuable adjunct to the periodic determination of HbA1c values.  Accordingly, SMBG provides patients with instant feedback about the effects of food choices, exercise, stress, and medications on their glycemic levels. Although the optimal frequency and timing of SMBG depend on many variables including diabetes type, level of glycemic control, management strategy, and individual patient factors, SMBG allows clinicians to fine-tune therapy and thus more effectively manage their patients’ glucose levels. When used properly, most modern glucose meters demonstrate a high degree of clinical accuracy compared with laboratory instruments, and average SMBG readings generally correlate well with HbA1c values. Without regular self-testing to provide day-to-day insights, an A1c result can be misleading. Because it gives a long-term view, a person with frequent highs and lows could have an average A1c that looks quite healthy. The only way to get a complete picture of your blood sugar control is by reviewing your day-to-day self-checks along with your regular A1c tests, and working closely with your healthcare team to interpret the results.

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SMBG can identify Hypoglycemic Episodes:

Fear of hypoglycemia often leads to a less intensive management approach by clinicians and patients, resulting in suboptimal glycemic control. Hypoglycemia is a concern to patients with type 1 diabetes and those with type 2 diabetes managed with insulin or oral agents. In a study using CGM in elderly patients with type 2 diabetes, no patients reported symptoms of hypoglycemia, yet 80% had glucose values lower than 50 mg/dL (2.8 mmol/L) on at least 1 occasion. Self-monitoring of blood glucose provides a means of identifying daily hypoglycemic events, allowing immediate treatment and modification of therapeutic regimens to allow tighter glycemic control while minimizing future hypoglycemic risk.

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SMBG detects Glycemic Excursions:

Continuous glucose monitoring studies show that daily blood glucose values range widely in both hypoglycemic and hyperglycemic ranges. Although real-time CGM devices that measure glucose concentrations in interstitial fluid have recently entered the market, they are indicated as adjuncts to standard SMBG, and all therapy adjustments should be based on measurements obtained from a blood glucose meter. Both SMBG and CGM have the ability to identify glycemic excursions. In a study of 600 insulin-treated patients, regular SMBG—an average of 3 times per day for 3 months—revealed a wide range of daily glucose values. When mean minimal and maximal values were determined, blood glucose ranged from 40 to 449 mg/dL in patients with type 1 diabetes and 63 to 382 mg/dL in patients with type 2. The wide variation in glucose levels, particularly the dangerously low values observed in the patients with diabetes, would not have been detected by HbA1c alone. For patients treated with insulin, an occasional SMBG reading in the middle of the night can help detect nocturnal hypoglycemia. It is important to recognize that postprandial glucose excursions may still be present in patients who have achieved their HbA1c target. A study of patients with type 2 diabetes who performed SMBG before and 2 hours after meals showed that many with HbA1c levels lower than 7.0% had postprandial glucose levels in excess of 160 mg/dL and glucose excursions of more than 40 mg/dL. In a cross-sectional analysis of the Third National Health and Nutrition Examination Survey cohort, postchallenge hyperglycemia was identified in 39% of patients with type 2 diabetes who were not using insulin and had an HbA1c level lower than 7.0%. Diabetes management software, with data uploaded from blood glucose meters, can be used to calculate the SDs of blood glucose values. Analyzing SDs is perhaps the simplest method to identify the degree of glycemic fluctuations.

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Management of glycemia in diabetes is crucially important to the prevention of both acute and long-term complications. The two fundamental approaches to assessment, SMBG and HbA1c, provide fundamentally different but complementary information. Regular SMBG is to be encouraged, particularly in patients using insulin, although the frequency can vary widely dependent particularly on the glycemic stability of the patient and the need to follow treatment changes. HbA1c, the criterion standard measure of chronic glycemic control and complication risk, should be measured every 3 to 6 months to assess the success of the treatment regimen. Changes in both approaches are ongoing but with proper control of

glycemia, diabetes can be successfully managed.

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What blood sugar marker is most reliable?  FPG, PPG or A1c?

Testing accurately for blood sugar is like putting pieces of a puzzle together. Fasting blood glucose, A1c and post-meal blood sugar are all pieces of the puzzle. But post-meal blood glucose testing is by far the most reliable and accurate way to determine what’s happening with blood sugar, and the most sensitive way of predicting future diabetic complications and heart disease.

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Why post-meal blood sugar is a superior marker than fasting BG and A1c:

Fasting blood sugar:

According to continuous glucose monitoring studies of healthy people, a normal fasting blood sugar is 83 mg/dL or less. Many normal people have fasting blood sugar in the mid-to-high 70s. While most doctors will tell you that anything under 100 mg/dL is normal, it may not be. In a study, people with FBG levels above 95 had more than 3x the risk of developing future diabetes than people with FBG levels below 90. This study showed progressively increasing risk of heart disease in men with FBG levels above 85 mg/dL, as compared to those with FBG levels of 81 mg/dL or lower. What’s even more important to understand about FBG is that it’s the least sensitive marker for predicting future diabetes and heart disease. Several studies show that a “normal” FBG level in the mid-90s predicts diabetes diagnosed a decade later. Far more important than a single fasting blood glucose reading is the number of hours a day our blood sugar spends elevated over the level known to cause complications, which is roughly 140 mg/dl (7.7 mmol/L).  One caveat here is that very low-carb diets will produce elevated fasting blood glucose levels. Why? Because low-carb diets induce insulin resistance. Restricting carbohydrates produces a natural drop in insulin levels, which in turn activates hormone sensitive lipase. Fat tissue is then broken down, and non-esterified fatty acids are released into the bloodstream. These FFA are taken up by the muscles, which use them as fuel. And since the muscle’s needs for fuel has been met, it decreases sensitivity to insulin. So, if you eat a low-carb diet and have borderline high FBG (i.e. 90-105), it may not be cause for concern. Your post-meal blood sugars and A1c levels are more important.

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Hemoglobin A1c:

In spite of what the American Diabetes Association (ADA) tells us, a truly normal A1c is between 4.6% and 5.3%. But while A1c is a good way to measure blood sugar in large population studies, it’s not as accurate for individuals. An A1c of 5.1% maps to an average blood sugar of about 100 mg/dL. But some people’s A1c results are always a little higher than their FBG and OGTT numbers would predict, and other people’s are always a little lower. This is probably due to the fact that several factors can influence red blood cells (vide supra). A number of studies show that A1c levels below the diabetic range are associated with cardiovascular disease. A study showed that A1c levels lower than 5% had the lowest rates of cardiovascular disease (CVD) and that a 1% increase (to 6%) significantly increased CVD risk. Another study showed an even tighter correlation between A1c and CVD, indicating a linear increase in CVD as A1c rose above 4.6% – a level that corresponds to a fasting blood glucose of just 86 mg/dL. Also earlier study showed that the risk of heart disease in people without diabetes doubles for every percentage point increase above 4.6%. Studies also consistently show that A1c levels considered “normal” by the ADA fail to predict future diabetes. This study found that using the ADA criteria of an A1c of 6% as normal missed 70% of individuals with diabetes, 71-84% with dysglycemia, and 82-94% with pre-diabetes. How’s that for accuracy? What we’ve learned so far, then, is that the fasting blood glucose and A1c levels recommended by the ADA are not reliable cut-offs for predicting or preventing future diabetes and heart disease. This is problematic, to say the least, because the A1c and FBG are the only glucose tests the vast majority of people get from their doctors.

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OGTT / post-meal blood sugars:

The more realistic and convenient way to achieve PPG rather than conventional OGTT is simply using a glucometer to test your blood sugar one and two hours after you eat a meal. This is called post-prandial (post-meal) blood sugar testing. The ADA considers OGTT of between 140 – 199 two hours after the challenge to be pre-diabetic, and levels above 200 to be diabetic. But once again, continuous glucose monitoring studies suggest that the ADA levels are far too high. Most people’s blood sugar drops below 120 mg/dL two hours after a meal, and many healthy people drop below 100 mg/dL or return to baseline. This study showed that even after a high-carb meal, normal people’s blood sugar rises to about 125 mg/dL for a brief period, with the peak blood sugar being measured at 45 minutes after eating, and then drops back under 100 mg/dL by the two hour mark. Another continuous glucose monitoring study confirmed these results. Sensor glucose concentrations were between 71 – 120 mg/dL for 91% of the day. Sensor values were less than or equal to 60 or 140 mg/dL for only 0.2% and 0.4% of the day, respectively. On the other hand, some studies suggest that even healthy people with no known blood sugar problems can experience post-meal spikes above 140 mg/dL at one hour. If post-meal blood sugars do rise above 140 mg/dL and stay there for a significant period of time, the consequences are severe. Prolonged exposure to blood sugars above 140 mg/dL causes irreversible beta cell loss (the beta cells produce insulin) and nerve damage. One in two “pre-diabetics” gets retinopathy, a serious diabetic complication. Cancer rates increase as post-meal blood sugars rise above 160 mg/dL. This study showed stroke risk increased by 25% for every 18 mg/dL rise in post-meal blood sugars. Finally, 1-hour OGTT readings above 155 mg/dL correlate strongly with increased CVD risk.

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Does targeting postprandial hyperglycemia improve overall glycemic control?

In a study of patients with type 2 diabetes with secondary failure of sulfonylurea therapy, Feinglos et al. showed that improvement of postprandial hyperglycemia, using insulin lispro (Humalog) at mealtime in combination with a sulfonylurea, not only reduced 2-h postprandial glucose excursions, but also reduced both fasting glucose and A1C levels from 9.0% to 7.1% (P < 0.0001). Subjects in the lispro group also benefited from significantly decreased total cholesterol levels and improved HDL cholesterol concentrations. Improvements in A1C levels were also reported in a study by Bastyr et al., which showed that therapy focused on lowering postprandial glucose versus fasting glucose may be better for lowering glycated hemoglobin levels. Further, in a study of patients with gestational diabetes, De Veciana et al. demonstrated that targeting treatment to 1-h postprandial glucose levels rather than fasting glucose reduces glycated hemoglobin levels and improves neonatal outcomes. Regardless of whether postprandial glucose is a better predictor of A1C than fasting/preprandial glucose, most researchers agree that the best predictor of A1C is mean blood glucose, which is a composite of both fasting/preprandial and postprandial glucose. Therefore, it is reasonable to conclude that achieving near-normal postprandial glucose levels is essential to achieving overall glycemic control.

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Is postprandial glucose control an independent contributor to diabetes outcomes?

Numerous epidemiological studies have shown elevated postprandial/post-challenge glucose to be independent and significant risk factors for macrovascular complications and increased mortality risk. The Honolulu Heart Study found a strong correlation between postchallenge glucose levels and the incidence of cardiovascular mortality. The Diabetes Intervention Study, which followed newly diagnosed patients with type 2 diabetes, found moderate postprandial hyperglycemia to be more indicative of artherosclerosis than was fasting glucose, and found postprandial but not fasting glucose to be an independent risk factor for cardiovascular mortality. The DECODE Study, which followed more than 25,000 subjects for a mean period of 7.3 years, showed that increased mortality risk was much more closely associated with 2-h post–glucose load plasma levels than with fasting plasma glucose. Similar to these findings, de Vegt et al. found that the degree of risk conferred by the 2-h postprandial glucose concentration was nearly twice that conferred by A1C level. Further, recent studies have demonstrated that even moderate postprandial hyperglycemia (148–199 mg/dl) is not only more indicative of artherosclerosis than is fasting glucose, but also may have direct adverse effects on the endothelium.  

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What is 4 point SMBG?

Fasting, before lunch, before dinner and bedtime SMBG is 4 point SMBG.

What is 7 point SMBG?

Fasting (before breakfast), after breakfast, before & after lunch, before and after dinner, and bedtime is 7 point SMBG.

7 point SMBG takes into consideration post-meal blood glucose and since post-meal blood glucose correlates well with vascular diabetic complications, 7 point SMBG not only improves glycemic control better than 4 point SMBG, but also greater reduction in diabetic vascular complications. 

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So in a nutshell, I would like to have all three: fasting blood glucose, A1c and post-meal glucose. But if I had to choose one, it would definitely be post-meal glucose.  

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SMBG vs. CGM:

Glucose monitoring is an important component of type 1 diabetes treatment. Careful consideration of the advantages and disadvantages of SMBG and CGM can help providers identify the approach that best fits with patient’s lifestyle and treatment goals.

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The advantages of SMBG are that it is relatively inexpensive, easy to train patient to complete, provides an accurate measure of capillary glucose concentrations, and available glucose meters can offer features including memory, downloading software, no coding strips, and small blood sample requirements. Disadvantages are the impact of user error on test accuracy, the need for multiple finger-stick blood samples each day, and the limited data available (e.g., SMBG provides a single snap shot of glucose concentrations, not trending data). Efficacy studies support the use of SMBG in diabetes management and suggest that it likely to remain the most common form of glucose monitoring practiced by patient today.

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The main advantage of CGM is that it can provide a near-continuous read-out of interstitial glucose concentration, which adequately reflects blood glucose concentration and can help to identify trends and patterns in glucose control with only a single needle stick to place the sensor. In addition, in the case of real-time CGM, monitors can be programmed to alarm for either high or low glucose values, thus allowing parents and youth to treat for these abnormal values and potentially reducing fear related to hypo or hyperglycemia. Disadvantages include the cost of CGM, lack of universal insurance coverage for this technology, limited FDA approval for CGM devices, and cosmetic (e.g., additional infusion site/monitor) and psychological concerns (e.g., frustration, helplessness if glucose control is not perceived as adequate). There is also limited evidence supporting use of CGM with type 1 diabetes as a means of improving long-term glycemic control. One barrier to CGM use appears to be patient’s willingness to accept and use this technology for diabetes management, a problem which likely will need to be addressed before it is possible to adequately examine for the efficacy of CGM use on glycemic control.

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Cost effectiveness of SMBG:

The worldwide epidemic of diabetes is producing unacceptable human suffering. This in turn produces economic losses from direct costs and lost production. Therapeutic endeavors must be directed to attenuation of this effect. A cure is not on the horizon; the best tools available to doctors are those that reduce risks and delay or prevent disease progression. In type 2 patients, therapeutic approaches must be progressive, reflecting the gradual loss of b-cell function. SMBG is the singular, immediate, accurate measure available to the patient allowing therapy adjustment. With appropriate education, the patient and healthcare team can adjust therapy to approach glycemic goals. The value of testing, not simply the cost, must be appreciated by patients, doctors, and the healthcare system. Prevention or delay of complications and improvement in daily symptoms and quality of life are priceless. The cost of home blood glucose monitoring is substantial due to the cost of the test strips. In 2006, the consumer cost of each glucose strip ranged from about $0.35 to $1.00. Manufacturers often provide meters at no cost to induce use of the profitable test strips. Type 1 diabetics may test as often as 4 to 10 times a day due to the dynamics of insulin adjustment, whereas type 2 typically test less frequently, especially when insulin is not part of treatment. As described earlier, frequent SMBG results in a statistically and clinically significant improvement in A1c which can range up to reductions of 2.5-4.0%. To determine whether this reduction results in economic benefits, Neeser and colleagues performed a cost-effectiveness analysis of SMBG using a Markov state model of diabetes to assess the clinical impact and related costs when SMBG is provided to patients not on insulin therapy. They assumed an improvement in A1c of 0.39%. The results of the analysis showed a slight increase in life expectancy and a reduced cost of complications, 70% of which was attributable to reductions in microvascular events. The cost per life-year gained was approximately $39,650, which is considered to be an acceptable cost-effective intervention from a health insurance perspective.

An analysis by Simon and colleagues assessed the cost-effectiveness of SMBG in type 2 subjects who participated in the DiGEM study. The average annual cost of intervention was £89 (€113; $179) for standard­ized usual care, £181 for less intensive self-monitoring, and £173 for more intensive self-monitoring, showing an additional cost per patient of £92 (95% confidence interval £80 to £103) in the less intensive group and £84 (£73 to £96) in the more intensive group. Given that there were no significant differences in clinical outcomes (change in HbA1c), the authors concluded that SMBG is unlikely to be cost-effective when additional to standardized usual care.

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A 2008 BMJ study found that self monitoring of blood glucose with or without additional training in incorporating the results into self care was associated with higher costs and lower quality of life in patients with non-insulin treated type 2 diabetes. In light of this, and no clinically significant differences in other outcomes, self monitoring of blood glucose is unlikely to be cost effective in addition to standardised usual care.  Canadian study in 2010 found that routine use of SMBG (one or more test strips per day) in patients with non–insulin-treated type 2 diabetes is associated with an incremental cost of $113,643 per QALY gained, relative to no SMBG. A reduction in the price of blood glucose test strips would improve the cost-effectiveness of SMBG. For patients with insulin-treated type 2 diabetes, SMBG testing frequencies beyond 21 test strips per week require unrealistically large A1C estimates of effect to achieve favourable incremental cost per QALY estimates.

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Self-monitoring of Blood Glucose in Type 2 Diabetes: Cost-effectiveness in the United States: 2008:

Compared with no SMBG, quality adjusted life expectancy increased with SMBG frequency. Increases were 0.103 and 0.327 quality-adjusted life-years (QALYs) for SMBG at 1 and 3 times per day, respectively. Corresponding incremental cost-effective ratios (ICERs) were $7856 and $6601 per QALY gained. Results indicate that SMBG at both 1 and 3 times per day in this cohort of patients with T2DM taking OADs would represent good value for money in the United States, with ICERs being most sensitive to the time horizon. Longer time horizons generally led to greater SMBG cost-effectiveness. The ICER for SMBG 3 times per day was $518 per QALY over a 10-year time horizon, indicating very good value.

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 Self-monitoring of blood glucose (SMBG) in patients with type 2 diabetes on oral anti-diabetes drugs: cost-effectiveness in France, Germany, Italy, and Spain: 2010:

With cost assumptions reflecting current reimbursement levels in France, Germany, Italy, and Spain, SMBG was found to be cost-effective across a 40-year time horizon, with all base case ICERs <16,000/QALY. This study adds to the literature on the country-specific, long-term value of SMBG for type 2 diabetes patients treated with OADs. Under current model assumptions, variations in cost-effectiveness results stemmed primarily from payer reimbursement practices for SMBG within each country

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Counterfeit SMBG: Bogus Diabetes Test Strips Traced to Chinese Distributor:

Batches of counterfeit test strips for some meters have been identified, which have been shown to produce inaccurate results. A global hunt started by Johnson & Johnson has tracked to China some counterfeit versions of the test strips used by 10 million Americans to measure their blood sugar levels. Potentially dangerous copies of the OneTouch Test Strip sold by the company’s LifeScan unit surfaced in American and Canadian pharmacies last year.  J.& J., one of the world’s largest makers of consumer health products, learned of the bogus test strips from patients’ complaints. Tipped off by the company, the Food and Drug Administration issued a consumer alert without disclosing the link to China. No injuries were reported, but inaccurate test readings may lead a person with diabetes to inject the wrong amount of insulin, causing harm or death. The investigation found that a distributor in China was the source of about a million fake test strips that have turned up in at least 35 states and eight countries. The trail, initiated by calls to a LifeScan hot line, led detectives to 700 pharmacies where the products were sold, then to eight American wholesalers, then to two importers. One importer was in the United States and was found in a Las Vegas hotel room. Records seized from the importers showed that the counterfeit strips were bought from Henry Fu and his company, Halson Pharmaceuticals, which is based in Shanghai. Mr. Fu was arrested by Chinese authorities and remains in prison in China.

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Research and newer technology in SMBG:

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Dual-Analyte Detection:

Various clinical situations require the simultaneous monitoring of glucose and of other clinically important analytes, such as lactate or insulin. Such coupling of two sensing elements requires both analytes to be monitored independently at different levels and without cross talk. Wang and Zhang developed a needle-type sensor for the simultaneous continuous monitoring of glucose and insulin. The integrated microsensor consisted of dual electrocatalytic (RuOx) and biocatalytic (GOx) modified carbon electrodes inserted into a needle and responded independently to nanomolar and millimolar concentrations of insulin and glucose, respectively.

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Less Invasive Technology to Monitor Blood Glucose Levels in Patients with Diabetes:

The current standard for self monitoring blood glucose levels is through a lancet device that pricks the finger or forearm. The droplet of blood is placed on an optical disposable strip that is then placed into a glucose meter, or glucometer, giving a reading of blood glucose in milligrams per deciliter. High or low glucose levels can then be corrected using insulin or glucose depending on whether the patient is hyper- or hypoglycemic, respectively. This gold standard of diabetes self testing has been improved upon in recent years and many monitors require less blood and allow more sites than just the fingertip and forearm to be tested. There have also been attempts to make the standard glucometers less noticeable and easier to carry. One example is a cellular phone which can double as a glucose monitor, thus making it something that could be discretely taken anywhere. However, the invasiveness of the procedure persists as there is still a requirement to puncture skin to produce a blood droplet. The gold standard for self monitoring currently involves a small device measuring the blood glucose level in a droplet of blood taken from the fingertip or forearm of a patient. This lancet approach is done on average 3–4 times a day and can be uncomfortable and inconvenient. It is known that monitoring blood glucose more frequently leads to better control and maintaining overall health. However, invasiveness of the finger stick method has caused patients to ignore the need to monitor their blood glucose levels and leave themselves at risk for future complications.

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Non-invasive glucose monitoring:

Non-invasive glucose monitoring techniques can be grouped as subcutaneous, dermal, epidermal and combined dermal and epidermal glucose measurements.  Matrices other than blood under investigation include interstitial fluid, ocular fluids and sweat. Test sites being explored include finger tips, cuticle, finger web, forearm and ear lobe. Subcutaneous measurements include microdialysis, wick extraction, and implanted electrochemical or competitive fluorescence sensors. Microdialysis is also an investigational dermal and epidermal glucose measurement technique. Epidermal measurements can be obtained via infrared spectroscopy, as well. Combined dermal and epidermal fluid glucose measurements include extraction fluid techniques (iontophoresis, skin suction and suction effusion techniques) and optical techniques. The optical techniques include near infrared spectroscopy, infrared spectroscopy, raman spectroscopy, photoacoustic spectroscopy, scatter and polarization changes

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The Biosensor for Blood Glucose Concentration:

There are many methods available for glucose determination, with the majority based on enzymatic reactions. In order of accurateness, the most common are directly measuring glucose in blood (invasive), measuring glucose in the interstitial fluid (minimally invasive), and estimating glucose using other corporal fluids like oral mucosa, aqueous humor of the eye, sweat, urine, saliva, tears, and so forth (noninvasive). The technologies employed could be polarimetry, electromagnetism, ultrasound, Raman spectroscopy, reverse iontophoresis, impedance spectroscopy, and so forth. Why noninvasive measurement is important is evident; the pain caused by finger pricking or invasive sensors is the main reason. It is very common that minimally invasive glucose sensors cause irritation, infections, or even bruising. These sensors have to be renewed every 5 or 6 days, and, at worst, may require that the sensor be recalibrated at frequent intervals with a fingerstick meter. Noninvasive monitoring avoids all these disadvantages but is not as accurate as the invasive technologies. The ideal glucose sensor should be selective for glucose with a fast, predictable response to changing glucose concentrations. It should depend on a reversible and reproducible signal to provide results, and sensor fabrication must be reproducible and cheap on a large scale. It should have a long operational lifetime under physiological conditions, but most of all must be acceptable to the patient. Therefore, it should be noninvasive, should not require user calibration, and would ideally provide real-time continuous information regarding glucose.

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Current continuous glucose monitoring systems have the advantage of direct insertion of electrochemical sensors into the IF space rather than transporting the sampled fluid outside the body to detect glucose concentrations. Software programs have been designed to accommodate the lag in IF glucose readings. Despite the advances in the making of sensors with new and improved designs and materials, sensor insertion causes trauma to the insertion site. It can disrupt the tissue structure, provoking an inflammatory reaction that can consume glucose followed by a repair process. The interaction of the sensor with the traumatized microenvironment warrants the need for a waiting period for the sensor signal to stabilize, and that period varies depending on the sensor type.

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A variety of noninvasive blood glucose monitoring techniques are currently under evaluation as seen in the table below. However, none of them are commercially available at this time. Noninvasive methods will permit real-time bedside glucose monitoring without the requirement of an indwelling intravenous catheter with a glucose sensor located on its tip. The availability of a device for rapidly assessing glucose concentration without skin puncture by retinal or corneal glucose measurement or skin transillumination will revolutionize monitoring of glucose at home and in the hospital. Products under development include: Fovioptics retinal glucose analyzer, Inlight Solutions, NIR glucose sensor, NIR Diagnostics, NIR glucose sensor, Sinsys Medical GTS, Sontra Ultrasonic Symphony Diabetes management system, Solianis Monitoring AG etc.  

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What is intriguing about these initiatives is that, in their final form, they may create a flow of useful diagnostic data reported to clinical laboratories in real time. This would create the opportunity for pathologists and lab scientists to consult with the patients’ physicians, while archiving this test result data in the laboratory information system (LIS). These glucose monitoring methods would also ensure that a complete longitudinal record of patient tests results is available to all the physicians practicing in an accountable care organization (ACO), medical home, or hospital.

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Overview of Non-Invasive Optical Glucose Monitoring Techniques:

Non-invasive optical measurement of glucose is performed by focusing a beam of light onto the body. The light is modified by the tissue after transmission through the target area. An optical signature or fingerprint of the tissue content is produced by the diffuse light that escapes the tissue it has penetrated. The absorbance of light by the skin is due to its chemical components (i.e., water, hemoglobin, melanin, fat and glucose). The transmission of light at each wavelength is a function of thickness, color and structure of the skin, bone, blood and other material through which the light passes. The glucose concentration can be determined by analyzing the optical signal changes in wavelength, polarization or intensity of light. The sample volume measured by these methods depends on the measurement site. The correlation with blood glucose is based on the percent of fluid sample that is interstitial, intracellular or capillary blood. Drs. Roe and Smoller  have devised the following example. The fluid viewed through the limb is 63% intracellular and 37% extracellular, of which 27% is interstitial and 10% plasma. A blood glucose value of 100mg/dl is equivalent to a tissue sample glucose average of 38mg/dl of which 26% is due to blood, 58% is due to interstitial fluid and 16% is due to intracellular fluid. What the tissue sample glucose means clinically in respect, to therapy is still under investigation. Not only is the optical measurement dependent on concentration changes in all body compartments measured, but changes in the ratio of tissue fluids (as altered by activity level, diet or hormone fluctuations) and this, in turn, effects the glucose measurement. Problems also occur due to changes in the tissue after the original calibration and the lack of transferability of calibration from one part of the body to another. Tissue changes include: body fluid source of the blood supply for the body fluid being measured, medications that affect the ratio of tissue fluids, day-to-day changes in the vasculature, the aging process, diseases and the person‘s metabolic activity.

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Dermal and Epidermal Fluid Glucose Measurement Techniques
Technique Definition
Near Infrared Spectroscopy (NIR) Absorption or emission data in the 0.7 to 2.5 µm region of the spectrum are compared to known data for glucose.
Raman Spectroscopy Laser light is used to induce emission from transitions near the level excited.
Photoacoustic Spectroscopy Laser excitation of fluids is used to generate an acoustic response and a spectrum as the laser is tuned.
Scatter Changes The scattering of light can be used to indicate a change in the material being examined.
Polarization Changes The presence of glucose in a fluid is known to cause a polarization preference in the light transmitted.
Mid-Infrared Spectroscopy Absorption or emission data in the 2.5 µm – 25 µm region are examined and used to quantify glucose in a fluid.

The market introduction of noninvasive blood glucose measurement by spectroscopic measurement methods, in the field of near-infrared (NIR), by extracorporal measuring devices, failed so far because at this time, the devices measure tissue sugar in body tissues and not the blood sugar in blood fluid. To determine blood glucose, the measuring beam of infrared light, for example, has to penetrate the tissue for measurement of blood glucose.

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Optical Coherence Tomography:

Optical coherence tomography (OCT) technology is similar to that of pulsatile microcirculation, but it uses infrared light and penetrates deeper into biological tissues. Optical coherence tomography monitors a cylindrical layer of skin in 20μm increments from the skin surface to the subcutaneous tissue. The sensor, trademarked as the GlucoLight Sentris 100 Optical Continuous Glucose Monitor, detects changes in the protein confirmation of collagen and myosin that occur secondary to glucose concentration changes. In a feasibility trial, 33 patients had baseline blood glucose levels sampled via OCT and via capillary derived glucose with subsequent checks every 10–15 min for 2 hours after a 50-g carbohydrate load. The range of blood glucose detected by OCT was 98–442mg/dL. Eighty-three percent of results were within zones A and B of Clark error grid analysis with <1% of values in the clinically unacceptable zones of C and D. Similarly, 83% of the readings were within 20% of reference values obtained with capillary testing. Overall the results of the clinical trial showed that the GlucoLight was safe and effective, and that its reported glucose readings correlate with capillary blood glucose results. However, the trial did not demonstrate the new technology’s ability to accurately monitor blood glucose in the hypoglycemic range and no readings ≤75mg/dL were recorded.

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At Israel’s Bar-Ilan University, a research team led by Zeev Zallevsky, Ph.D., has developed a non-invasive glucose measuring device that is worn like a wristwatch.  This device consists of a laser that generates a wavefront of light to illuminate a patch of skin on the wrist near an artery, and a camera that measures changes over time in the light backscattered off the skin. Unlike other chemicals present in the blood, glucose exhibits a “Faraday effect,”. In the presence of an external magnetic field generated by the attached magnet, the glucose molecule alters the polarization of the wavefront and thus influences the resulting speckle patterns. These changing patterns provide a direct measurement of the glucose concentration.

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Pulsatile Microcirculation:

Measuring blood glucose using an optical signal rather than blood from the fingertip has recently been developed. In a 15 patient study, each patient placed their finger into a slot of the newly developed meter, the TangTest (TG), and waited 30 sec for results. The meter works by using a weak light source shone onto the tested finger. Variations in intensity of the transmitted light are measured and algorithms used to quantify the amount of glucose present. The times measured were fasting, 20 min, and 40 min after a meal. The results of the study showed a linear relationship between glucose measurements using the TG system and a standard glucometer, with a correlation coefficient of r=0.81. Correcting for finger position and pulsatile components of the TG signals, 100% of results fell within zones A and B in a Clark error grid. There were many factors that might potentially limit this technology’s commercial application. Since blood flow must be unimpeded for testing, the ambient temperature must be within a defined range. As diabetics often have circulatory problems, the test results for this technology might be affected. In addition, the body must be relaxed physically and psychologically when testing; therefore tested patients had to be warm and relaxed for 20 min before performing the study. This is especially challenging in real life when a patient is hypoglycemic and a test result is needed as soon as possible. To obtain optimal results the test finger also has to be perfectly positioned in the meter; an odd angle or improper finger position can affect the transmission of light yielding inaccurate results. The TG meter also takes 30 sec to give a test result, in contrast to 5 seconds for standard glucometers.

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Pulse glucometry:

A new approach for noninvasive blood glucose measurement using instantaneous differential near-infrared spectrophotometry:

Authors describe a new optical method for noninvasive blood glucose (BGL) measurement. Optical methods are confounded by basal optical properties of tissues, especially water and other biochemical species, and by the very small glucose signal. They address these problems by using fast spectrophotometric analysis in a finger, deriving 100 transmittance spectra per second, to resolve optical spectra (900to1700nm) of blood volume pulsations throughout the cardiac cycle. Difference spectra are calculated from the pulsatile signals, thereby eliminating the effects of bone, other tissues, and nonpulsatile blood. A partial least squares (PLS) model is used with the measured spectral data to predict BGL levels. Using glucose tolerance tests in 27 healthy volunteers, periodic optical measurements were made simultaneously with collection of blood samples for in vitro glucose analysis. Altogether, 603 paired data sets were obtained in all subjects and two-thirds of the data or of the subjects randomly selected were used for the PLS calibration model and the rest for the prediction. Bland-Altman and error-grid analyses of the predicted and measured BGL levels indicated clinically acceptable accuracy. Authors conclude that the new method, named pulse glucometry, has adequate performance for safe, noninvasive estimation of BGL.

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Vital signs including blood glucose monitoring from arterial pulse:

UFIT, which uses a noninvasive, Web-enabled device that straps around a patient’s wrist, responds to the need for an easy-to-use self-monitoring system that reliably and simultaneously captures key data on heart and blood, including heart rate, blood pressure, blood oxygen and blood glucose. The system is intended to optimize the management of chronic diseases such as high blood pressure, heart disease and diabetes.  The study’s findings were presented at the Institute of Electrical and Electronics Engineers (IEEE) International Workshop on Medical Measurements and Applications (MeMeA). This Biosign-sponsored study assumed that the arterial pulse, a rich source of clinically relevant information (e.g., rate, rhythm, pattern, pressure and oxygen), could also provide information on blood glucose. The study gathered glucose measurements from 120 participants with blood glucose levels ranging between 3.5 and 27.4 mmol/L. The results show a tight statistical correlation (0.998, Pearson substantial equivalence) between UFIT and laboratory analysis of blood glucose, with a low (1.63 percent) average of the mean percent difference between the UFIT measurements and the laboratory analysis. The correlation was obtained post-hoc by comparing a feature extracted from the radial artery pulse with laboratory blood glucose data. The methodology resembles that used to correlate HbA1C with the direct measurements of glucose in drawn blood.

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Pulse gluco-oxymeter: OrSense’s NBM-200G:

This new, noninvasive continuous blood glucose monitoring system, which has already been approved in Europe, measures oxygen saturation, hemoglobin, and blood glucose with very high sensitivity. NBM-200G utilizes occlusion spectroscopy technology that correlates blood glucose levels with light-absorption and scattering measurements. The device is “operated by placing a ring-shaped probe around the patient’s finger, which applies a gentle pressure to the finger, similar to that applied during noninvasive blood-pressure measurement, and temporarily occludes the blood flow. During the occlusion, optical elements in the sensor perform a sensitive measurement of the light transmitted through the finger.  In a recent trial of the NBM-200G, 130,000 glucose-paired readings were taken from 450 patients to determine the accuracy of the device compared to invasive products. There was a strong correlation between measurements derived from the NBM-200G and those from invasive measurements. This method is painless as well as accurate in comparison to invasive devices. Therefore, it is likely to improve compliance in patients who tend to avoid fingersticks and are unable to control their diabetes with invasive products. According to OrSense, the NBM-200G is Conformité Européenne (CE) approved for noninvasive continuous monitoring in patients with demanding need for glycemic control, such as those with brittle diabetes, nocturnal hypoglycemia, and gestational diabetes.

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Azurite: Attempting to develop a Noninvasive Continuous Glucose Monitor using electrical properties of glucose:

Azurite’s approach is apparently quite original. Andrews and Zebrowski intend to measure blood glucose directly through an electromagnetic (EM) sensing system. Current continuous glucose monitors are invasive and rely on the measurement of some secondary characteristic. For example, Google’s contact lens, which is still in the research stage and not yet available on the market, measures the glucose content of tears, not blood. Continuous monitors currently on the market are invasive, requiring a device that attaches to the body with adhesive and a needle that must be replaced every several days. These monitors measure base blood glucose figures on glucose values in interstitial fluid, the liquid that surrounds our cells and tissues. Azurite’s idea is based on the fact that an electromagnetic signal, depending on its wavelength, can bounce off a surface and return to its source with a particular pattern reflective of the surface it encountered. Glucose molecules, like any material, reflect a unique electromagnetic signal based on their inherent electrical properties. So Azurite hopes to bounce an electromagnetic signal off the glucose in your blood, which would then return to a device carrying information about how much glucose it encountered along the journey. Various research groups have successfully ascertained blood glucose levels by observing the electrical properties of glucose in the blood. In an article published in 2011, researchers at the University of Mississippi demonstrated that a microstrip patch antenna could be used to determine the glucose concentration within a sample of blood by measuring its electrical properties. Drawing from this research and the work of other research groups that are examining at the electrical properties of glucose, Azurite has modeled a novel approach that they hope will lead to a device that uses EM technology to measure those electrical properties remotely. Azurite is determined to move beyond the theoretical and make a direct impact on the lives of people with diabetes. Researchers are hopeful that this technology will lead to a product that combines the rich data of continuous sensing and the convenience and ease of a noninvasive meter.

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Iontophoresis Based Monitoring: GlucoWatch:

The GlucoWatch automatic glucose biographer from Cygnus (San Francisco, CA) has been introduced as a means of measuring blood glucose based on iontophoresis. This technology uses electrical polarity to cross the skin into deeper tissues of the body and is frequently used for drug delivery. In the context of blood glucose monitoring, interstitial fluid is brought to the skin surface and glucose levels are measured with an electrochemical enzymatic sensor worn on the skin. The wearable GlucoWatch device (available from Animas Technologies Inc.) contains both the extraction and the sensing functions along with the operating and data-storage circuitry. It provides up to three glucose readings per hour for up to 12 h (i.e., 36 readings within a 12 h period). The system has been shown to be capable of measuring the electroosmotically extracted glucose with a clinically acceptable level of accuracy. An alarm capability is included to alert the individual of very low or high glucose levels. However, the unit requires a long warm up and calibration against fingerstick blood measurement and is subject to difficulties due to skin rash with irritation under the device, long warm up times, sweating, or change in the skin temperature. A similar device has been developed in Korea called the RIGMD. It uses the same technology as that of the GlucoWatch but the enzymatic sensor measures glucose every 5 min instead of every 10 min.

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The GlucoWatch didn’t quite live up to doctors’ and consumers’ expectations. Promises of a new, revolutionary way to continuously monitor blood sugar levels fell short. Some patients found this process very uncomfortable, even painful. Many reported skin irritation. A randomized study from researchers at the University College of London pointed out further shortcomings with the GlucoWatch device. Their results were published in the May 2009 edition of the journal Diabetic Medicine. Though only 6 percent were unable to tolerate wearing the device, participants noted inaccuracies in their readings on the GlucoWatch G2 Biographer. Another clinical study from the Stanford School of Medicine found that the GlucoWatch frequently triggered false alarms, erroneously telling users their blood sugar was too high. Out of 20 alarms sounded, only 10 cases actually correctly assessed a too-high reading, the other 10 were false positives. Now GlucoWatch has vanished from the diabetes care scene and its manufacturer has stopped any further development.

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Exhaled Gases to Measure Blood Glucose:

It has been previously shown that people experiencing hyperglycemia exhale gases such as acetone and ethanol in different amounts than people who are normoglycemic. The concept of analyzing exhaled gases to measure glucose has been pursued by looking at methyl nitrate production. In a research study 18 experiments were conducted among 10 Type I diabetic children. Glucose from plasma and exhaled gases were monitored during euglycemia (normal glucose levels) and during inducement of hyperglycemia and its correction. The study was able to show that methyl nitrate concentrations were around 11 ± 3 parts per trillion by volume (pptv) during euglycemia and increased to 27 ± 6 pptv during hyperglycemia. Methyl nitrate concentrations also normalized and came back to 15 ± 2 pptv after the correction of a hyperglycemic event. The study showed that methyl nitrate concentration correlates with blood glucose fluctuations. Although methyl nitrate was found to be the most significant chemical in glucose fluctuation, there were greater than 50 gases that were detectable. This study shows the potential for the use of exhaled compounds as diagnostic markers for glycemic levels; however, it is far from being ready for commercial use. The authors employed gas chromatography and mass selective detection to monitor the fluctuations in exhalation levels. This is not a method that is feasible for routine patient use in disease monitoring, and the technology must be harnessed into a device that could be marketed and easily used by diabetics in their daily lives. The study also had weaknesses as it only looked at children with Type I diabetes and only looked at hyperglycemia. Finally, algorithms to relate the levels of exhaled gas to actual glucose levels in standard units are undeveloped. Further testing will need to be done on a larger randomized population of people across all different levels of blood glucose measurements. All negative aspects aside, the authors offer a promising avenue to pursue in the methods of noninvasive blood glucose testing.

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Breathalyzer’s Nanosensor detects glucose in exhaled breath:

Glucose Breathalyzer uses Nano-films and Acetone-Sensitive Polymers:

Western New England University (WNE) researchers also announced another breathalyzer that uses nanotechnology to noninvasively detect blood-glucose levels in the breath of diabetics. The researchers unveiled this technology at the 2013 American Association of Pharmaceutical Scientists (AAPS) Annual Meeting and Exposition in San Antonio, Texas. Ronnie Priefer, Ph.D., a Professor of Medical Chemistry at WNE in Springfield, Massachusetts, created the multilayer technology using nanometer-thick films consisting of two polymers that react with acetone. This film crosslinks the polymers and alters the physicochemical nature of the film to provide quantification of acetone, and thus glucose levels, noted the AAPS press release. 

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Glucose Sensing via the Eye:

An exciting potential avenue for less invasive glucose measurement involves ocular testing. One group created a wearable contact lens that has been analyzed in clinical trial. The lens showed promise as it measures increases in glucose levels by a colorimetric response to systemic glucose fluctuations. Increased glucose levels cause a Rhodopsin fluorescent dye to emit from the lens and recordings were obtained with a hand-held photofluorometer. The color change of the lens was only slightly visible to the naked eye and thus would remain aesthetically acceptable to the wearer. A more recent study introduced a wearable amperometoric glucose sensor to measure tear glucose levels. The sensor, connected to an external measurement system displaying results, was able to detect an increasing dose of glucose as it was manually administered to a rabbit. However, the biosensor showed a limited increase in glucose levels from 0.16 to 0.46 mmol/L in comparison to a commercial glucometer, which showed an increase from 3.7 to 7.6 mmol/L, a clear difference in sensitivity. In addition, there was a measurement delay in the sensor, in the order of tens of minutes, which is not desirable in situations of hypo- or hyperglycemia.

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Google develops contact lens glucose monitor:

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Google unveiled a contact lens that monitors glucose levels in tears, a potential reprieve for millions of diabetics who have to jab their fingers to draw their own blood as many as 10 times a day. The prototype, which Google says will take at least five years to reach consumers, is one of several medical devices being designed by companies to make glucose monitoring for diabetic patients more convenient and less invasive than the traditional finger pricks. The lenses use a minuscule glucose sensor and a wireless transmitter to help those among the world’s 382 million diabetics who need insulin keep a close watch on their blood sugar and adjust their dose. The device looked like a typical contact lens when it is held one on index finger. On closer examination, sandwiched in the lens are two twinkling glitter-specks loaded with tens of thousands of miniaturized transistors. It’s ringed with a hair-thin antenna. The Google team built the wireless chips in clean rooms, and used advanced engineering to get integrated circuits and a glucose sensor into such a small space. Researchers also had to build in a system to pull energy from incoming radio frequency waves to power the device enough to collect and transmit one glucose reading per second. The embedded electronics in the lens don’t obscure vision because they lie outside the eye’s pupil and iris. According to Google, the sensor can take about one reading per second, and it is working on adding tiny LED lights to the lens to warn users when their glucose levels cross certain thresholds. The sensors are so small that they “look like bits of glitter.” Google says it is working with the FDA to turn these prototypes into real products and that it is working with experts to bring this technology to market. These partners, the company says, “will use our technology for a smart contact lens and develop apps that would make the measurements available to the wearer and their doctor.” 

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Non-invasive measurement of blood glucose using retinal imaging:

An apparatus carries out measurements of blood glucose in a repeatable, non-invasive manner by measurement of the rate of regeneration of retinal visual pigments, such as cone visual pigments. The rate of regeneration of visual pigments is dependent upon the blood glucose concentration, and by measuring the visual pigment regeneration rate, blood glucose concentration can be accurately determined. This apparatus exposes the retina to light of selected wavelengths in selected distributions and subsequently analyzes the reflection (as color or darkness) from a selected portion of the exposed region of the retina, preferably from the fovea.

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EyeSense:

EyeSense is a noninvasive technology currently in development that measures blood glucose concentrations simply by placement of the measurement device near the eye. This innovative, noninvasive technology utilizes a novel biochemical sensor that is inserted below the conjunctiva in a simple and painless procedure by the ophthalmologist on an annual basis. The technology would replace conventional fingersticking and would probably increase blood glucose monitoring compliance. The methodology hinges on a biochemical sensor that is embedded on a small, hydrogel disk. The chemical in the disk reacts with blood glucose in the interstitial fluid below the conjunctiva of the eye and emits fluorescent light that is quantified by the photometer device. The photo-meter can be placed in front of the eye to obtain the blood glucose results in less than 20 seconds. The advantage of noninvasive technology is that patients have the ability to measure their blood glucose as frequently as they want without having to lance their fingers. The implanted disk is invisible to the naked eye. Additionally, it is generally well tolerated and does not feel like a foreign body in the eye of the user. EyeSense is still in the advanced stages of development and its approval appears promising.  

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Dario: Turning Your Smartphone into a Glucose Meter:

It’s an integrated unit about the size of a cigarette lighter that includes a basic adapter that connects into a smartphone’s audio jack. As soon as you connect the device, your smartphone switches to BG-monitoring mode. You then click open the self-contained lancing device that has disposable lancets inside and an integrated cartridge of 25 propriety test strips, allowing you to poke your finger just like any other meter. The reading you get is transmitted directly to the smartphone through an app that’ll be available for free for both iPhones and Andriod systems. The app will allow patients not only to immediately see and automatically upload BG results, but also to add food information into a database — along with easy access to carb estimations, an insulin calculator, and other features like data-sharing online. Not to mention the array of alerts and reminders that patients could program in at their choosing. Dario uses ultra-thin lancets, and you would buy the 25-strip cartridges with propriety strips from the company (or from a supply provider who will eventually stock them). Dario is unique in that users will be able to analyze data directly on the phone app, send data to caregivers and doctors, and  even have their data examined in clinical research and epidemiology studies about the distribution and patterns of diabetes management. The hope is to have Dario become compatible with electronic health records (EHRs) and other services that would offer interoperability with insulin pumps and CGMS (continuous glucose monitors), and possibly even Pharma-interaction on the app in terms of learning about or ordering prescriptions if users so desire.

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iBG star:

As the “i” in iBGStar suggests, the glucose monitor is specifically made for the Apple iPhone or iPod touch. iBGStar is the first device that has been cleared by the FDA for use on an Apple device, and it is currently available in some European countries. The iBGStar uses its Diabetes Manager App for the iPhone to help users keep track of blood glucose levels on a daily basis, while the application allows patients to send selected data to their physicians to aid in monitoring their progress. The new monitor uses a novel patented technology called dynamic electrochemistry. Dynamic electrochemistry is a technology that uses complex mathematical methods to calculate and adjust for interference that may be caused by changes in temperature, humidity, and hematocrit levels. The device sends out signals of different frequencies and voltage in order to compensate for the interference that may cause inconsistent blood glucose readings. In patients who have abnormal hematocrit levels, which may be due to a disease state, a low hematocrit level may artificially overestimate actual blood glucose levels. This may pose a safety concern to the patient because it may lead him or her to use a higher insulin dose than required, possibly resulting in hypoglycemia and even hospitalization. Therefore, it is important to use a device that can measure blood glucose levels precisely in various conditions. In order to establish the accuracy of the iBGStar, a comparison study evaluated the BGStar, a device using the same dynamic electrochemistry method, against 12 other glucose monitoring systems from various manufacturers. The study specifically observed the consistency of blood glucose readings with varied hematocrit concentrations. The results showed that only four of the 13 devices—the BGStar, OneTouch Verio, Glucocard G+, and Contour—actually met the study criteria for having less than 10% maximal mean percentage deviation (MMPD) from control glucose readings. In addition, another study has supported the accuracy of the device by showing that the iBGStar has 99.5% accuracy. The iBGStar is an excellent device that will provide consistent blood glucose readings and is easier to use than conventional monitors due to portability and compatibility with smartphones, but it still requires the use of needles, which may hinder compliance to glucose monitoring for some patients.

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Apple’s HealthKit:

HealthKit, which is still under development, is the center of a new healthcare system by Apple. Regulated medical devices, such as glucose monitors with accompanying iPhone apps, can send information to HealthKit. With a patient’s consent, Apple’s service gathers data from various health apps so that it can be viewed by doctors in one place. Stanford University Hospital doctors said they are working with Apple to let physicians track blood sugar levels for children with diabetes. In the first Stanford trial, young patients with Type 1 diabetes will be sent home with an iPod touch to monitor blood sugar levels between doctor’s visits. HealthKit makes a critical link between measuring devices, including those used at home by patients, and medical information services relied on by doctors, such as Epic Systems Corp, a partner already announced by Apple. Medical device makers are taking part in the Stanford and Duke trials. DexCom Inc, which makes blood sugar monitoring equipment, is in talks with Apple, Stanford, and the US Food and Drug Administration about integrating with HealthKit. DexCom’s device measures glucose levels through a tiny sensor inserted under the skin of the abdomen. That data is transmitted every five minutes to a hand-held receiver, which works with a blood glucose meter. The glucose measuring system then sends the information to DexCom’s mobile app, on an iPhone, for instance. Under the new system, HealthKit can scoop up the data from DexCom, as well as other app and device makers. Data can be uploaded from HealthKit into Epic’s “MyChart” application, where it can be viewed by clinicians in Epic’s electronic health record.

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Glooko’s new device Bluetooth-enables popular glucose meters:

Glooko, which makes a cable that syncs popular glucose meters to a companion app on smartphones, has always said it plans eventually to replace that cable with a wireless Bluetooth connection. Recently company announced that they’ve finally released that product, the Bluetooth MeterSync Blue. The small box will plug into a patient’s glucose meter and send the information wireless, via Bluetooth, to Android or Apple phones.

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Telcare Glucose Meter:

Recent advances in cellular data communications technology have enabled the development of glucose meters that directly integrate cellular data transmission capability, enabling the user to both transmit glucose data to the medical caregiver and receive direct guidance from the caregiver on the screen of the glucose meter. The first such device, from Telcare, Inc., was exhibited at the 2010 CTIA International Wireless Expo, where it won an E-Tech award. This device is currently undergoing clinical testing in the US and internationally. The Telcare Blood Glucose Meter (BGM) aims to change that, with a color screen and cellular connectivity that automatically uploads your blood sugars to the cloud. While the Telcare device itself might be more on par stylistically with the Blackberry generation, the Telcare BGM serves as an essential transition step for glucose meters by adding cloud storage and analytics while retaining a familiarity for users of all ages and tech-suaveness. With its own cellular 3G antenna, the Telcare automatically uploads blood glucose recordings to its central cloud server using the Verizon network. At this point, users can access their data through any web browser, or use the partner app Diabetes Pal for Android or iPhone. A key advantage of the Telcare is that the MyTelcare portal allows users to grant read-only access to others (family members, caregivers), and to grant full access to health care providers. The full access permitted for health care providers allows them to adjust feedback messages, change target ranges, and target number of readings per day.

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Non-invasive glucose meter (glucometer):

Noninvasive glucose refers to the measurement of blood glucose levels (required by people with diabetes to prevent both chronic and acute complications from the disease) without drawing blood, puncturing the skin, or causing pain or trauma. The search for a successful technique began about 1975 and has continued to the present without a clinically or commercially viable product. A non-invasive glucose meter is a relatively new piece of technology that takes glucose measurements without any finger pricking or skin pricking. The thought of pricking one’s finger several times a day, or even once, makes many diabetics jittery, so a non-invasive glucose meter can be highly desirable. A 2012 study reviewed ten technologies: bioimpedance spectroscopy, electromagnetic sensing, fluorescence technology, mid-infrared spectroscopy, near infrared spectroscopy, optical coherence tomography, optical polarimetry, raman spectroscopy, reverse iontophoresis, and ultrasound technology, concluding with the observation that none of these had produced a commercially available, clinically reliable device and that therefore, much work remained to be done. As of 2014, only two noninvasive glucose meters [GlucoTrack & Orsense] which have obtained CE mark approval are being marketed in a number of countries.

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The GlucoTrack:

GlucoTrack uses ultrasonic, electromagnetic and thermal technologies to non-invasively measure glucose levels in the blood: In a perfect world, blood sugar testing would be quick and painless. The finger-prick, the blood and the coated strips can be messy, complicated to use and painful—and these issues can contribute to patient noncompliance. A goal of the medical device community has been to develop a blood glucose monitoring device that is noninvasive but still highly effective, and thereby remove what are believed to be among the two most significant barriers to frequent monitoring of blood glucose by diabetes patients:  pain and cost. To meet this need, Integrity Applications, based in Ashkelon, Israel, has developed the GlucoTrack® model DF-F non-invasive blood glucose measurement device, which represents a key advance in this area. It is designed to help people with diabetes obtain blood glucose level measurements without the pain, inconvenience, incremental cost and difficulty of conventional (invasive) spot finger stick devices. The GlucoTrack device takes advantage of the natural physiology of the ear lobe and uses an ear lobe clip to deliver blood glucose readings in about a minute, thanks to a trio of technologies: ultrasonic, electromagnetic and thermal.

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GlucoTrack is battery-operated and includes a Main Unit (MU), which contains display and control features, as well as transmitter, receiver and processor, and a Personal Ear Clip (PEC), which is clipped to the earlobe and contains sensors and calibration electronics. The device is small, light and easy to use and handle.  The Main Unit can be shared by up to three users (in model DF-F), although each user requires his/her own (individually calibrated) PEC.  The device includes a USB port for data downloading (enables off-line analysis), as well as battery recharging. As a noninvasive device, GlucoTrack does not measure blood glucose levels directly; instead, it harnesses three independent technologies to measure physiological phenomena that correlate with the user’s glucose level. These measurements—which are transmitted from the PEC to the Main Unit—are subsequently analyzed using an algorithm that translates them into blood glucose level readings. Significantly, GlucoTrack does not use optical technology, which, based on others’ experience, was found to be impractical for use in noninvasive glucose monitoring.  GlucoTrack performs three independent measurements simultaneously, using thermal, ultrasound, and electromagnetic technologies. The results are weighted, using a patented, unique algorithm to provide a reading which is displayed on a color touch screen of the device by large, clear digits.  The result is announced verbally as well, allowing visually impaired users using the device as easy.

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Why the earlobe and not another anatomical location?

The earlobe is a very convenient place on the body to measure one’s blood sugar levels, since doing so doesn’t interfere with one’s activities. From a physiological standpoint, there are also specific benefits to using the earlobe. For example, the earlobe contains a great number of capillary vessels, and blood within it flows relatively slowly. It also contains a relatively small amount of fat and nerves, as well as no bones. All of these facts help to ensure a better reading. In addition, the earlobe is relatively stable in size in adults, which similarly helps to maintain the calibration valid for relatively long period of time. The device also cuts down on costs for the user, as the Personal Ear Clip only needs to be replaced every six months.

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Calibration:

Calibration is required to be performed prior to glucose measurements so that the influence of individual quasi-stable factors, such as tissue structure, can be minimized. The process consists of correlating invasive basal and postprandial BG data, taken from finger capillary blood, with six sequential measurements with the GluocTrack instrument, generating a calibration curve that is exclusive to each individual. Six invasive pre and post-prandial measurements generate individual calibration as seen in the figure below. The first measurement pair is taken in the fasting state. The calibration procedure is easy, lasts about 1.5 hours and more importantly, is valid for a month (a longer period is forecast in the future). 

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The figure below shows that non-invasive glucometer saves money as compared to invasive glucometer:

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Parents hack child’s glucometer:

To deal with childhood diabetes and keep on top of a disease that could turn deadly at a moment’s notice, parents have resorted to hacking medical devices. By creating solutions that help them manage their children’s disease, these innovative parents could push the medical device world in a new direction. Jason Adams, whose eight year old daughter has Type 1 diabetes, was concerned about monitoring her blood sugar at night. Without the ability to monitor her condition, he was forced to keep her home, which prevented her from attending sleepovers with friends. Jason’s daughter Ella uses a Dexcom Inc. glucose monitor, a device that takes blood sugar readings every five minutes, according the WSJ. Unfortunately, however, the monitor has no provision for sharing data over a network. A little internet searching revealed to Jason a system called “NightScout,” a remote-monitoring software developed by other parents of diabetic children. The developers of NightScout, who happen to be software engineers, were frustrated with the limited capabilities of current diabetes monitoring technology. According to the WSJ, the open-source software enables parents to hack the Dexcom glucose monitor and upload its information to the Internet. Two weeks after getting the software setup at home, Ella was able to attend her first sleepover. Other notable successes have occurred as well, according to the WSJ. Kristin Derichsweiler, a nurse and single mother of four, downloaded the software and started using it to help her 15 year old son manage his diabetes. While at work, she noticed his blood sugar dropping to dangerously low levels. When he failed to answer the phone, she rushed home to find he had become unresponsive and needed juice to restore proper sugar levels. Despite the successes, there is justified concern from the FDA. Coming to rely on an untested technology could lead to a potentially deadly false sense of security. Questions that are raised by the FDA related to NightScout center around how users may get support if they run into problems, and how to keep data confidential on the Internet. While questions are raised, the agency is making efforts to facilitate the new software and the parents who are using it.

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The First Remote Mobile Communications Device Used for Continuous Glucose Monitoring (CGM):

Dexcom, Inc., a leader in continuous glucose monitoring (CGM) for patients with diabetes, announced recently that it has received U.S. Food and Drug Administration (FDA) approval for its CGM remote mobile communications device: Dexcom SHARE. Dexcom SHARE, an accessory to the Dexcom G4® PLATINUM Continuous Glucose Monitoring System, uses a secure wireless connection to transmit the glucose levels of a person with diabetes to the smartphones of up to five designated recipients, or “followers.” These followers can remotely monitor a patient’s glucose information and receive alert notifications from almost anywhere via their Apple® iPhone® or iPod® touch. With Dexcom SHARE, parents and personal caregivers can monitor a child’s or loved one’s glucose data from a remote location, giving them peace of mind and reassurance when they are apart. Now critical glucose data from the Dexcom G4® PLATINUM Continuous Glucose Monitoring System can be remotely monitored using a mobile device. So parents need not hack their child’s glucometer as discussed in previous paragraph.  

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My logic on Diabetes Mellitus: 

Since it has been shown that microvascular diabetes complications are due to chronic hyperglycemia per se, I am surprised to know that most experts including ADA, IDF and WHO recommend venous plasma glucose level for diagnosis of diabetes. It is because all the tissues bearing the brunt of diabetic microvascular complications (e.g. kidneys, nerves, and retina) are perfused by high blood/plasma glucose from their arterial blood supply. Venous blood/plasma glucose does not enter in any tissue except liver through portal vein. Remember, it is the portal vein that brings glucose from food along with insulin from pancreas to liver for metabolism. Remember, both glucose from food and insulin from pancreas enter systemic circulation after first-pass metabolism in liver. However, pancreas secret insulin in response to arterial blood glucose and not venous blood glucose including portal vein glucose. So it is the arterial blood glucose that secretes insulin and it is the high arterial blood glucose that causes diabetic complications when insulin secretion and/or action is reduced. Then why rely on venous blood glucose for diagnosis of diabetes?  Since it is difficult to puncture artery every time for blood glucose test and since arterial blood glucose is almost same as capillary blood glucose, why not capillary blood glucose for diagnosis of diabetes mellitus?  Of course we have to change cutoff values for diabetes diagnosis as compared to venous blood but it would be more rational, more physiological and correlate well with diabetic complications. Of course there is marked difference between capillary blood glucose and venous blood glucose in non-diabetic individual post prandial, but since capillary (surrogate arterial) blood glucose determines diabetic complications, cutoff value for diagnosis of diabetes, both fasting and post prandial, must be based on capillary blood glucose measurement (SMBG) rather than venous glucose. I would also recommend HbA1c measurement from capillary blood rather than venous blood for the same reason.

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The moral of the story:

1. Diabetes mellitus (DM) is defined as a metabolic disorder characterized by hyperglycemia due to reduced insulin secretion and/or reduced insulin action and/or increased glucose production. Persistent hyperglycemia is a hallmark of diabetes but transient hyperglycemia can occur a part of stress response in acute illnesses and is brought about by elevated levels of counter regulatory hormones.

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2. One in 10 adults has diabetes. 382 millions have diabetes in 2013 worldwide. Every six seconds someone dies from diabetes.

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3. About half of diabetic population worldwide does not know that they have diabetes.  

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4. Diabetes is not merely a health issue, but also a political issue, one which requires whole society approach. Type 2 diabetes, which many consider an epidemic currently, is increasing worldwide predominantly due to poor diet, sedentary lifestyle, new wealth and the fact that we are living longer. Eating fast food two or more times a week increases the risk of developing Type 2 diabetes by 27 percent.   

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5. Chronic hyperglycemia per se causes chronic diabetic complications by various mechanisms although there is a genetic susceptibility for developing particular complications. There is no way to check genetic susceptibility to diabetic complications.

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6. Numerous studies have demonstrated that optimal management of glycemia along with other cardiovascular risk factors can reduce risk of development and progression of both microvascular and macrovascular complications. It has been shown that microvascular complications, such as neuropathy, nephropathy, and retinopathy are reduced by 40% for every percentage reduction in hemoglobin A1c (HbA1c or A1c) values. 

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7. Tight glucose control decreased the risk of progression of retinopathy, nephropathy, and neuropathy but increased the risk of hypoglycemia 2.4 times. Intensive efforts to achieve blood sugar levels close to normal have been shown to triple the risk of the most severe form of hypoglycemia, in which the patient requires assistance from by-standers in order to treat the episode. Among intensively controlled type 1 diabetics, 55% of episodes of severe hypoglycemia occur during sleep, and 6% of all deaths in diabetics under the age of 40 are from nocturnal hypoglycemia. 

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8. Since hyperglycemia per se causes diabetic complications, since control of hyperglycemia leads to reduction of diabetic complications and since tight control of blood glucose invariably leads to hypoglycemia and its complications; diabetics are therefore recommended to check their blood glucose levels frequently to prevent and/or treat hyperglycemia and hypoglycemia. 

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9. Researchers found that the lifetime of hemoglobin cells (RBC) of diabetics turned over in as few as 81 days, while they lived as long as 146 days in non-diabetics. In a person with normal blood sugar, hemoglobin will be around for a lot longer, which means it will accumulate more sugar. This will drive up the A1c test result – but it doesn’t mean that person had too much sugar in their blood. It just means their hemoglobin lived longer and thus accumulated more sugar. So normal people with normal fasting plasma glucose (FPG) and postprandial plasma glucose (PPG) can have falsely elevated A1c levels. On the other hand, if someone is diabetic, their red blood cells live shorter lives than non-diabetics. That means diabetics will have falsely low A1c levels. So can we rely on A1c alone?  

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10. It is a fact that A1c is a measure of glycemic control and rise/fall of A1c correlates well with rise/fall of chronic diabetic complications. Nonetheless it does not provide information about day-to-day glucose levels, nor does it provide immediate feedback to patients about medication or lifestyle choices. The biggest limitation of A1c is that it misses wide glycemic excursions and also misses many asymptomatic hypoglycemias. Frequent unrecognized hypoglycemia may lead to falsely low HbA1c levels. Postprandial hyperglycemia was identified in 39% of patients with type 2 diabetes who were not using insulin and had an HbA1c level lower than 7.0%.  There is evidence to show that wide glycemic excursions lead to vascular complications despite reasonable A1c. Self-monitoring of blood glucose (SMBG) complements A1c because it can distinguish among fasting, preprandial, and postprandial hyperglycemia; detect wide glycemic excursions; identify hypoglycemia; and provide immediate feedback to patients about the effect of food choices, activity, and medication on glycemic control.

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11. SMBG is measurement of glucose in blood (or plasma) either directly or indirectly through other body fluids by patients themselves or their care givers or medical personnel by any technique without using laboratory.  

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12. Nobody should do urine glucose test as a surrogate marker for blood glucose test. However, I have diagnosed diabetes in some patients by seeing urine glucose test positive incidentally when urine examination was done for evaluation of fever, jaundice or hematuria and not for diabetes. Also urine ketone test is very helpful to patient to judge severity of illness at home when SMBG level is above 240 mg/dL.  

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13. Collection of blood sample must be avoided from the same arm or the same vein where IV drip D5W/D5NS is infused because only10% contamination with D5W/D5NS will elevate glucose in a sample by 500 mg/dL or more. However, when blood sample is drawn from the arm opposite the one in which an intravenous line is inserted, blood glucose will rise by 0.38mg/dL every minute in a 70 kg diabetic man with little or no insulin secretion when drip duration is 8 hour for 500 ml. And if the same drip is given to a normal non-diabetic person, slight increase in blood glucose will stimulate insulin secretion and therefore blood glucose will be reasonably maintained. The corollary is that if you have collected blood from the arm opposite the one in which an intravenous line is inserted, if the drip rate is average (4 to 8 hour for each pint), and if you are getting high blood glucose level, do not blame IV drip (D5W or D5NS) as patient may indeed be diabetic. This is very important because I have seen in emergency situation as well as routine hospital admission; IV drip is started even before blood is collected for investigation although SMBG by nurse must be done before starting IV drip. Also, diabetics on IV drip for various reasons ought to be monitored for glucose levels. 

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14. Whole blood glucose is 15 % lower than plasma glucose because plasma has higher water content and consequently more dissolved glucose than whole blood. The conversion of concentration values from one system (or sample type) to another is subject to unpredictable errors. Several authors have already rejected the practice of converting glucose concentrations and have recommended that plasma be used for all glucose determinations. The blood glucose is defined as venous plasma glucose according to the criteria of WHO to diagnose diabetes. Venous blood is usually employed for laboratory analysis and is preferable in diabetes testing. Laboratory plasma glucose measurement is far more accurate than plasma equivalent of whole blood capillary glucose measurement by glucometer (SMBG) because laboratory tests virtually eliminate all variations except for manufacturing variation from their testing. A standard lab glucose value is within about plus/minus 4% of a perfect reading while SMBG is within plus/minus 15% of the lab test (current ISO standard). However, because of the widespread use of glucometers, fingerstick capillary whole blood glucose tests have also become a standard. Also, some glucometers can measure capillary plasma glucose directly by a series of absorbent pads to separate the cellular portion of a sample from the plasma portion.

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15. Plasma glucose is a biological variable and possesses intra-individual variability of 5.7% to 8.3% and inter-individual variability of up to 12.5%. An individual having FPG of 126 mg/dL can show FPG value from 112 to 140 mg/dL based on coefficient of variation (CV) of 5.7%. The analytical variability is considerably less than the biological variability, still one-third of the time, the glucose results on a single patient sample measured in two different laboratories could differ by 14%.  

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16. In the fasting state, the glucose concentrations in arterial, capillary (SMBG), and (forearm) venous blood are supposed to be almost indistinguishable. Fasting venous glucose is generally 2-5 mg/dL lower than fasting arterial blood glucose. Arterial blood glucose and capillary blood glucose (SMBG) have been shown to be almost identical in concentration in fasting as well as post meal time. However, post prandial (after glucose load) venous glucose could be 7 to 35 % lower than arterial glucose (equivalent SMBG) due to muscles removing more glucose from the blood than the liver in the presence of adequate insulin action. It has been shown that a lack of insulin (in the de-pancreatized animal) shows an arteriovenous glucose difference that is extremely small and that injection of insulin produces an increase in this difference. The mean arteriovenous differences are largest in lean nondiabetic individuals and smallest in diabetic individuals. So in a non-diabetic individual, SMBG post prandial can overdiagnose diabetes because SMBG would be markedly higher than venous blood glucose. So if you were a non-diabetic before and now you want to know whether you have developed diabetes, please test fasting and post prandial blood (plasma) glucose in a laboratory. For established diabetes, SMBG is useful for monitoring fasting blood sugar (FBS) and postprandial blood sugar (PPBS). Lower post prandial venous blood glucose proves insulin action in non-diabetic as well as in type 2 diabetics (T2DM). Therefore in T2DM, concurrent post prandial SMBG and lab venous blood glucose can show arteriovenous blood glucose difference and higher the difference, greater the residual insulin action. In other words, large arteriovenous postprandial blood glucose difference in T2DM suggests that pancreas is secreting some residual insulin and that insulin is acting.   

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17. I recommend 2 hour postprandial plasma glucose (PPG) by laboratory as a screening test for T2DM. An increase in postprandial glucose concentration usually occurs before fasting glucose increases. Therefore, postprandial glucose is a sensitive indicator of the risk for developing diabetes and an early marker of impaired glucose homeostasis. Also, PPG is a better predictor of both all-cause mortality and cardiovascular mortality or morbidity than the FPG. Even when HbA1c and fasting glucose levels are within the normal range, post prandial hyperglycemia has been associated with a 2-fold increase in the risk of death from cardiovascular disease.  Elevated postprandial glucose is independent and significant risk factors for macrovascular complications and increased mortality risk.  Prospective interventions that control PPG have been shown to improve endothelial function and reduce carotid atherosclerosis in patients with type 2 diabetes. PPG levels correlated better than HbA1c measurements with the risk of retinopathy progression.  We have to unlearn that FPG and A1c levels are reliable cut-offs for predicting or preventing future diabetes and its complications. PPG scores over FPG and A1c as the best marker for predicting future diabetes, preventing future diabetes, controlling present diabetes and preventing chronic diabetic complications. Many studies have shown that postprandial hyperglycemia beyond the 16th week of pregnancy is the main predictor for fetal macrosomia and postprandial capillary blood glucose monitoring significantly reduced the incidence of preeclampsia.  In order to avoid hypoglycemia and achieve target glucose levels, patients with diabetes who take mealtime insulin are advised to test SMBG before meals to adjust doses, based on meal size and content, anticipated activity levels, and glucose levels. The biggest limitation of SMBG is that despite excellent A1c levels and target preprandial glucose levels, patients often experience nocturnal hypoglycemia and postprandial hyperglycemia that are not evident with routine SMBG. Since recent evidence suggests that postprandial hyperglycemia plays a particularly important role in the development of vascular complications of diabetes, it is imperative to monitor postprandial blood glucose by SMBG for better clinical outcome.  

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18. Pain associated with finger lancing is one of the major barriers to SMBG. In a recent study, up to 35% of the participants stated that pain is the main reason people with diabetes refrain from regular blood glucose testing. Everybody nowadays uses computer, internet and cell phones; all need finger tip use; painful finger tips can affect handling of all these devices. To reduce lancing pain, forearm testing is an acceptable alternative to finger prick testing for blood glucose measurement provided blood sugar is stable and not rapidly changing.

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19. Do not share glucometer or fingerstick lancing devices. Sharing of this equipment could result in transmission of infection such as hepatitis B. However, the rate of infections from lancets is extremely low because the lancet goes into the subcutaneous space and is not being used intravenously, and the blood is flowing out of the body.

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20. If fingers are not soiled by sugar containing products (biscuits, fruits etc); the first drop of blood can be used after gentle squeezing the finger for SMBG. 

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21. Up to 16% of patients miscode their glucometers. This can lead t