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This award-winning blog supplements the articles in Hospital Infection Control & Prevention.

Ebola man Tom Geisbert: This is not his first rodeo

Tom Geisbert, PhD, has been studying Ebola for more than a quarter of a century, but when you ask him a question he pauses thoughtfully, acknowledging there is much to learn before we have anything close to certitude about this deadly virus. The unknowns are intriguing, and Geisbert is willing to think off the cuff and artfully riff about why the current Ebola outbreak in West Africa is unfolding so differently than its predecessors.

Here’s an excerpt from a Q&A session we did with Geisbert coming up in the September 2014 issue of Hospital Infection Control & Prevention

HIC: This outbreak has many troubling aspects, including the ability to sustain itself and spread and cause infections in health care workers using full barrier precautions. Is there anything different about this particular strain of Ebola?

“This outbreak is caused by the Zaire species, which is associated with the highest case fatality rates. ‘Strain’ is kind of taking it down defining it even further. It does appear to be a slightly different strain of the Zaire species than some of the outbreaks. I don’t think at this point there’s any evidence that suggests that there’s something different about this strain that’s causing it to be more transmissible. However, I don’t think that we really know for sure. I think the probability is low but I don’t think we are able to rule it out yet. An example would be a small genetic change in the virus that can cause it to be more or less pathogenic. Historically these Ebola outbreaks have really not been transmitted through the air like influenza or something like SARS. There’s really been no evidence that Ebola is transmitted that way and we don’t really see any evidence from this outbreak. I think the only thing that we don’t know that could potentially make it more transmissible -- person-to- person through close contact -- would be if there’s something about this particular strain that makes it shed higher levels [of virus]. We know that Ebola from this species and all the other ones can be found in all kinds of body fluids. Obviously blood, but also feces, urine, sweat -- things like that. So it’s theoretically possible that for some unknown reason this strain maybe is found at higher levels or higher concentrations in body fluids. So for example if you had a drop of some kind of body fluid with this strain maybe you had ten thousand particles in there and with another strain maybe you have 10. Your absolute exposure would be higher, but this is all hypothetical. We don’t know that yet.”