As leading Ebola virologist Heinz Feldmann recently said, the discussion of Ebola prevention 'should be fact-based; it should be data-based.' Interpretation of those facts and data is often clouded by politics and opinion. But they are not as ambiguous as debates in media have made them seem.
Earlier this week, The Atlantic ran an interview on the current Ebola epidemic with Steven Hatfill, a former employee of the U.S. Army Medical Research Institute of Infectious Disease (USAMRIID) who is famous for being wrongly accused of the 2001 anthrax attacks. Hatfill, presented as a world-leading expert on Ebola virus, gave his perspective on topics ranging from transmission of the virus to preparedness for an outbreak in the United States. Some of Hatfill's concerns about our preparedness to stamp out outbreaks quickly are sound, but the bulk of the interview, about the virus and the disease it causes, goes well beyond the data.
The misinterpretations and misrepresentations of data that Hatfill espouses can be found in many places online, and especially on TV. In light of this, we can't be surprised so many Americans really don't know what to think and who to believe on Ebola. Going point-by-point through an interview is boring, unnecessary, and would make Hatfill the core issue. He isn't. Misrepresentations of the scientific literature on Ebola aren't unique to him. But I picked some of the most common and dangerous misrepresentations he upheld and dug into the primary scientific literature.
Not only is there no evidence that Ebola virus spreads between primates by an airborne route, there's actually evidence it does not.
The most controversial part of the ongoing Ebola discussion has been the question of transmission, namely, whether it spreads by an airborne route. Other people have painfully detailed the differences between airborne, aerosol, and droplet transmission. That's not my interest, or area of expertise. The question that people have, I think, is whether Ebola spreads like the flu; whether they can get it by breathing the same air as someone who has it. The biggest obstacle to clearly communicating the answer to this question, which is no, is the misinterpretation of a 2012 study in which Ebola virus was transmitted from pigs to monkeys without direct contact.
Hatfill references this study more than once as an example of 'animal data [that] shows this can happen', including in a series of answers culminating with the comment that 'to say it's not aerosol transmitted is irresponsible.' Not only is that untrue, but the data he uses to get there isn't properly interpreted, as has been the case for months in various forms of media.
That 2012 study was conducted by Gary Kobinger's research group at the Public Health Agency of Canada, one of the best Ebola research groups in the world today. Some have attacked this study in such a way as to make it sound useless or irrelevant, but that's not the case. Its findings have simply been applied in the wrong way. The study was done because Reston virus, a filovirus closely related to Ebola virus, has been isolated from pigs in Asia, with evidence that they have spread it to farm workers. Reston virus was made famous by Richard Preston's sensationalized account of its emergence in The Hot Zone, and does not cause disease in people. Nevertheless, Kobinger's group wanted to know if pigs could spread Ebola virus through the air, the way they seem to transmit Reston virus in Asia.
Kobinger's group infected several pigs with Ebola virus and set them loose in a room containing four cynomolgus macaques, a species of Asian monkey. The monkeys got sick, died, and analysis of their respiratory tracts strongly suggested that this was the route of inoculation. We knew monkeys could be infected by aerosol though, and have known it since 1995.
Two critical points are invariably missed when this study is cited to support the notion that airborne transmission of Ebola virus has been demonstrated. The first is that pigs develop a very different course of disease and pathology than primates do following Ebola virus infection. Pigs develop severe lung pathology and significant respiratory distress, which results in them expelling very high concentrations of virus from the nose and mouth. In contrast, primates develop a systemic, hemorrhagic disease in which the lungs do get infected but respiratory symptoms are rare. The second key point is that airborne infection isn't equivalent to transmission. For airborne infection the virus needs to not only be able to get into the airway, it has to get out when a person or monkey breathes or coughs.
In the aftermath of this outbreak we will learn more about Ebola virus than we know now and use this to ready ourselves for its next appearance.
Fortunately, that's been tested. Kobinger's group followed up their pig study by specifically looking at whether Ebola virus could be transmitted between primates by an airborne route. That, after all, is what we're interested in. Most Americans aren't concerned about coming across an infected pig, but they may be worried about sharing breathing air with a person infected with Ebola virus. They set up this study so monkeys would share the same air but be unable to throw feces or other debris between cages, which could easily confound the results. When they did this, none of the control monkeys were infected, despite the experimentally infected monkeys getting sick and dying.
Entities 0 Name: Hatfill Count: 5 1 Name: Reston Count: 3 2 Name: Asia Count: 2 3 Name: Kobinger Count: 1 4 Name: Public Health Agency of Canada Count: 1 5 Name: Heinz Feldmann Count: 1 6 Name: Steven Hatfill Count: 1 7 Name: Gary Kobinger Count: 1 8 Name: United States Count: 1 9 Name: Atlantic Count: 1 10 Name: USAMRIID Count: 1 11 Name: Richard Preston Count: 1 12 Name: Ebola Count: 1 13 Name: Asian Count: 1 14 Name: U.S. Army Medical Research Institute Count: 1 Related 0 Url: http://ift.tt/1DsCcWx Title: 9 Reasons to Fear Ebola Description: The Obama administration and the Centers for Disease Control and Prevention have moved to tamp down worries over Ebola even as the number of cases continues to accelerate. However, many doctors and researchers say there are ominous signs about what the future holds regarding the deadly virus.
Post a Comment for "Assessing the Science of Ebola Transmission - The Atlantic"