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PostPosted: Mon Sep 08, 2014 3:45 pm 
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How deadly is Ebola? Statistical challenges may be inflating survival rate



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By Gretchen Vogel 8 September 2014 1:00 pm 0 Comments
The Ebola virus that is causing the raging epidemic in West Africa is famously lethal. In previous outbreaks it has killed as many as 90% of the people it infects. That’s why the figures in World Health Organization’s (WHO’s) latest “Situation Report” look like they might be a rare glimmer of good news. Although the rate of infections is picking up speed at an alarming rate, the report says the fatality rate is 53% overall, ranging from 64% in Guinea to just 39% in Sierra Leone.

But there’s a catch: The apparent low proportion of deaths probably depends more on the way health officials are calculating the number than on the deadliness of the virus—or the quality of care patients are receiving. Indeed, the dramatic increase in cases in recent weeks is one of the main reasons the reported death rate appears to be artificially low.

There are several ways to calculate what officials call the “case fatality rate,” or CFR, of a disease outbreak. One of the simplest is to divide the number of deaths by the number of total cases. That is what WHO does in its recent CFR calculations.

But that method doesn’t take into account that many living patients—recently diagnosed and very ill—will not survive. So it underestimates the death rate. And that effect is exaggerated when an outbreak is expanding quickly. The calculation also misses patients who were confirmed as Ebola cases, but then left the hospital before being discharged, says Andrew Rambaut, an evolutionary biologist who studies infectious disease at the University of Edinburgh in the United Kingdom. Many of those patients later died but are not counted in the death statistics.

Another way to calculate the rate is to ignore current patients and count only patients who have officially recovered and been released from treatment or who are known to have died. Those numbers seem to paint a more sobering picture. According to the 7 September update from the Sierra Leone Ministry of Health and Sanitation, 268 patients have been treated and released, and 426 confirmed Ebola cases have died. Those numbers suggest a 61% fatality rate. But that isn’t completely accurate either, notes Marc Lipsitch, an epidemiologist at the Harvard School of Public Health in Boston: Survivors may have longer average hospital stays than patients who die. That would lead to a CFR that is artificially high.

A more accurate way to calculate the rate is to compare the outcomes in patients who were infected around the same time and wait long enough until all have either recovered or died. Rambaut notes that there were 23 survivors among the 77 patients included in a recent paper looking at the evolution of the virus. That’s a CFR of 70%.

Christopher Dye, director of strategy for the WHO, says the organization is moving toward that method and is working to compile data for each patient recorded as a case. “We do need valid estimates,” Dye says. “We want to know if CFR is different in this epidemic from previous ones in central Africa, [and] whether different approaches to patient care in the current epidemic lead to different outcomes.”

Even that method is imperfect. In almost all outbreaks, cases are missed because the patient never seeks care at a health facility, and therefore is not recorded in any statistics. Such missed cases can potentially bias the CFR in either direction, Lipsitch notes. If many cases are relatively mild—in which infected people recover without ever seeing a doctor—then relying on health care records overstates the death rate. (That was the case for the H1N1 pandemic flu in Mexico, and experts suspect it is the case for the MERS virus as well.) A mild case of Ebola is less likely to go unnoticed than a mild case of influenza, Lipsitch says, but given the overall lack of health care in the region, there could be significant numbers of undetected survivors.

On the other hand, researchers already know that many Ebola victims never made it to hospitals and died at home (often infecting family and other caregivers). That means their deaths aren’t counted—reducing the CFR.

Exactly how many unrecorded Ebola deaths have occurred will never be known. Health officials are keeping track of suspected and probable cases, many of which are people who died before they could be tested. Whether to include those numbers in CFR calculations is another source of potential bias. And there are different patterns of testing in different regions: Some places have done more testing on post-mortem cases, for example. “How these biases balance is always the big question,” Lipsitch says.

“We are not naïve about the difficulties of estimating CFR,” Dye writes in an e-mail. “I’m not yet ready to believe … that CFR is much higher in Guinea than Sierra Leone. This is what the data say, taken at face value, but we need to exclude all possibility of ascertainment bias before believing this to be the truth.”

*The Ebola Files: Given the current Ebola outbreak, unprecedented in terms of number of people killed and rapid geographic spread, Science and Science Translational Medicine have made a collection of research and news articles on the viral disease freely available to researchers and the general public.

*Correction, 8 September, 1:53 p.m.: The fatality rates in Guinea and Sierra Leone have been corrected.

http://news.sciencemag.org/africa/2014/ ... vival-rate

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PostPosted: Sat Sep 13, 2014 12:46 pm 
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PostPosted: Sat Sep 13, 2014 12:49 pm 
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niman wrote:
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2400 deaths and 342 survivors linked to MSF, which represent MOST of the real Ebola survivors.

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PostPosted: Mon Sep 15, 2014 1:39 pm 
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There’s no good way to treat Ebola, which the World Health Organization says has infected more than 4,700 people and killed 2,400 of them since the outbreak started in February in West Africa. Patients like Brantly lucky enough to be treated in more modern facilities have done well with balanced rehydration salts. But even a little saline and careful care has saved the lives of half the patients — a good sign for a virus that has been known to kill up to 90 percent of its victims.

http://www.nbcnews.com/storyline/ebola- ... gy-n202486

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PostPosted: Mon Sep 15, 2014 3:47 pm 
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MSF International ‏@MSF 3m
Sianneh, our 100th survivor was discharged from ELWA3 in Monrovia today, free of #Ebola & with the world at her feet!

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PostPosted: Tue Sep 16, 2014 7:05 am 
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Based on the latest data from the MoHSW, the number of beds in existing ETUs could hold only 15 per cent of the total reported cases (suspected, probable and confirmed).

http://reliefweb.int/sites/reliefweb.in ... 202014.pdf

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PostPosted: Thu Sep 18, 2014 10:04 pm 
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WHO has removed the 47% survive from Ebola page

http://www.who.int/csr/disease/ebola/en/

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PostPosted: Fri Sep 19, 2014 12:47 pm 
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EDITORIAL
Ebola — An Ongoing Crisis
Lindsey R. Baden, M.D., Rupa Kanapathipillai, M.B., B.S., M.P.H., D.T.M.&H., Edward W. Campion, M.D., Stephen Morrissey, Ph.D., Eric J. Rubin, M.D., Ph.D., and Jeffrey M. Drazen, M.D.
September 19, 2014DOI: 10.1056/NEJMe1411378

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ArticleReferences
In March 2014, an outbreak of a febrile illness associated with a high case fatality rate was identified in the Guéckédou region of Guinea–Conakry, a remote part of West Africa. An international field investigation was initiated. On April 16, the Journal published a preliminary report identifying the outbreak as due to Ebola virus.1 The initial sequence data showed that the outbreak strain was Zaire ebolavirus, but a strain distinct from those identified in prior outbreaks, such as those in the Democratic Republic of Congo (DRC) and Gabon. In Guinea there appeared to be ongoing human-to-human transmission. Over the next 4 to 8 weeks, the outbreak seemed to be resolving, as over 20 previous outbreaks have, with a substantial decline in new cases. We and many others thought it would soon be over.2
We were wrong. Cases started to appear over the summer, and the number increased exponentially as this viral infection spread more widely in Guinea–Conakry and in Liberia and Sierra Leone.3 Cases associated with travel have been identified in Senegal and Nigeria, and there is evidence of ongoing transmission in Nigeria.4 Recently, Ebola transmission has been identified in the DRC, although molecular data suggest that this event is unrelated to the ongoing West African outbreak.5,6 These molecular data provide the information we need to define important aspects of ongoing transmission dynamics and to guide control strategies. Currently, there is no effective treatment, but human vaccine trials have been initiated.7
As of September 18, 2014, there were 5335 identified cases of Ebola virus disease, with more than 2622 associated deaths, which is more than in all previous Ebola outbreaks combined.4 These numbers are nonetheless likely to be underestimates, given the limitations of case identification, and the fraction of deaths probably underestimates the case fatality rate, because the interval between case identification and death has been just over 2 weeks. Although clinical data remain sparse, it seems likely that effective basic supportive care may make the difference between life and death for an infected patient. Unfortunately, health care workers have been disproportionately affected owing to the tremendous demands of patient care and the difficulty of implementing the infection-control measures required to prevent transmission.8 The Ebola outbreak is having serious adverse effects on travel, commerce, and routine health care, such as care for malaria, which threaten to further disrupt the already precarious conditions in which millions of people in the region live.9
The fear associated with a virulent and potentially deadly contagious infectious disease, which respects neither borders nor social status, has captured the attention of the world. The responders, both local and international, have been dedicated and brave. But far more is needed. It is critical that all members of the global health community — health care workers, scientists, regulators, funders, governments, and local communities — collaborate in responding as rapidly as possible if we are to control this enlarging outbreak. For example, the move by regulators to allow vaccine trials to proceed quickly shows flexibility and good judgment.
We, as a global health care community, must move decisively to bring this dangerous epidemic under control and then to improve the health care systems in the affected region.10 This will require more resources and more health care workers on the front lines (see the Ebola Outbreak page at NEJM.org for volunteer opportunities). It will also require communication and teamwork to win the trust of those in the affected communities. The Journal will continue to report on this unprecedented outbreak with updates on the efforts to control it, the biomedical findings emerging from it, and the difficult stories of those who are suffering through it.
Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.
This article was published on September 19, 2014, at NEJM.org.

http://www.nejm.org/doi/full/10.1056/NEJMe1411378

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PostPosted: Fri Sep 19, 2014 12:48 pm 
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Joined: Wed Aug 19, 2009 10:42 am
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niman wrote:
EDITORIAL
Ebola — An Ongoing Crisis
Lindsey R. Baden, M.D., Rupa Kanapathipillai, M.B., B.S., M.P.H., D.T.M.&H., Edward W. Campion, M.D., Stephen Morrissey, Ph.D., Eric J. Rubin, M.D., Ph.D., and Jeffrey M. Drazen, M.D.
September 19, 2014DOI: 10.1056/NEJMe1411378

Share:
ArticleReferences
In March 2014, an outbreak of a febrile illness associated with a high case fatality rate was identified in the Guéckédou region of Guinea–Conakry, a remote part of West Africa. An international field investigation was initiated. On April 16, the Journal published a preliminary report identifying the outbreak as due to Ebola virus.1 The initial sequence data showed that the outbreak strain was Zaire ebolavirus, but a strain distinct from those identified in prior outbreaks, such as those in the Democratic Republic of Congo (DRC) and Gabon. In Guinea there appeared to be ongoing human-to-human transmission. Over the next 4 to 8 weeks, the outbreak seemed to be resolving, as over 20 previous outbreaks have, with a substantial decline in new cases. We and many others thought it would soon be over.2
We were wrong. Cases started to appear over the summer, and the number increased exponentially as this viral infection spread more widely in Guinea–Conakry and in Liberia and Sierra Leone.3 Cases associated with travel have been identified in Senegal and Nigeria, and there is evidence of ongoing transmission in Nigeria.4 Recently, Ebola transmission has been identified in the DRC, although molecular data suggest that this event is unrelated to the ongoing West African outbreak.5,6 These molecular data provide the information we need to define important aspects of ongoing transmission dynamics and to guide control strategies. Currently, there is no effective treatment, but human vaccine trials have been initiated.7
As of September 18, 2014, there were 5335 identified cases of Ebola virus disease, with more than 2622 associated deaths, which is more than in all previous Ebola outbreaks combined.4 These numbers are nonetheless likely to be underestimates, given the limitations of case identification, and the fraction of deaths probably underestimates the case fatality rate, because the interval between case identification and death has been just over 2 weeks. Although clinical data remain sparse, it seems likely that effective basic supportive care may make the difference between life and death for an infected patient. Unfortunately, health care workers have been disproportionately affected owing to the tremendous demands of patient care and the difficulty of implementing the infection-control measures required to prevent transmission.8 The Ebola outbreak is having serious adverse effects on travel, commerce, and routine health care, such as care for malaria, which threaten to further disrupt the already precarious conditions in which millions of people in the region live.9
The fear associated with a virulent and potentially deadly contagious infectious disease, which respects neither borders nor social status, has captured the attention of the world. The responders, both local and international, have been dedicated and brave. But far more is needed. It is critical that all members of the global health community — health care workers, scientists, regulators, funders, governments, and local communities — collaborate in responding as rapidly as possible if we are to control this enlarging outbreak. For example, the move by regulators to allow vaccine trials to proceed quickly shows flexibility and good judgment.
We, as a global health care community, must move decisively to bring this dangerous epidemic under control and then to improve the health care systems in the affected region.10 This will require more resources and more health care workers on the front lines (see the Ebola Outbreak page at NEJM.org for volunteer opportunities). It will also require communication and teamwork to win the trust of those in the affected communities. The Journal will continue to report on this unprecedented outbreak with updates on the efforts to control it, the biomedical findings emerging from it, and the difficult stories of those who are suffering through it.
Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.
This article was published on September 19, 2014, at NEJM.org.

http://www.nejm.org/doi/full/10.1056/NEJMe1411378

REFERENCES
1Baize S, Pannetier D, Oestereich L, et al. Emergence of Zaire ebola virus disease in Guinea — preliminary report. N Engl J Med 2014. DOI: 10.1056/NEJMoa1404505.
2Center for Disease Control and Prevention. Outbreaks chronology: ebola hemorrhagic fever (http://www.cdc.gov/vhf/ebola/resources/ ... table.html).
3World Health Organization. Ebola Response Roadmap situation report 1: 29 August 2014 (http://apps.who.int/iris/bitstream/1066 ... g.pdf?ua=1).
4World Health Organization. Ebola Response Roadmap update: 18 September 2014 (http://apps.who.int/iris/bitstream/1066 ... g.pdf?ua=1).
5Gire SK, Goba A, Anderson KG, et al. Genomic surveillance elucidates Ebola virus origin and transmission during the 2014 outbreak. Science 2014;345:1369-1372
CrossRef | Medline
6Virological analysis: no link between Ebola outbreaks in West Africa and Democratic Republic of Congo. Geneva: World Health Organization, September 2, 2014 (http://www.who.int/mediacentre/news/ebo ... er-2014/en).
7Cohen J. Ebola vaccines racing forward at record pace. Science 2014;345:1228-1229
CrossRef | Medline
8Unprecedented number of medical staff infected with Ebola. Geneva: World Health Organization, August 25, 2014 (http://www.who.int/mediacentre/news/ebo ... st-2014/en).
9Ebola: Economic impact already serious: could be “catastrophic” without swift response. Washington, DC: World Bank Group, September 17, 2014 (http://www.worldbank.org/en/news/press- ... world-bank).
10Investing in global health systems: sustaining gains, transforming lives. Washington, DC: Institute of Medicine, September 16, 2014 (http://www.iom.edu/Reports/2014/Investi ... Lives.aspx).

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PostPosted: Sat Sep 20, 2014 3:18 pm 
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That last time I was in Liberia I must have moved hundreds of bodies but only three people survived during the month that I was there. I don't think you can see that many bodies without viewing death in a different way.

http://www.bbc.com/news/magazine-29245149

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