The mystery and terror of Ebola

Tara Smith at Aetiology has a recent post discussing the Ebola virus. Personally, I think it's much scarier than influenza, but that's just me. She points out that much of the fear comes from the mystery -- we just don't know so much about where it comes from or what natural variability may be hiding in some animal reservoir.

But there's plenty of scary stuff there:

Additionally, I mentioned above that there are 4 known distinct lineages of Ebola: Zaire, Sudan, Ivory Coast, and Reston. This study only focused on the most virulent; the Zaire strain. It doesn't answer the question of whether EBO-Z is spreading into a population where other filoviruses already exist, but EBO-Z is out-competing them, or if it's spreading into regions where no Ebola relatives are present. Just based on other epidemiologic data, I'd guess it's the former. Serologic studies in several regions of Africa have shown that many people possess antibodies to the Ebola virus, even though they report never having had a hemorrhagic fever (or experiencing an outbreak of Ebola-like illness in their village). It seems likely that filoviruses are present somewhere in the environment already, but these strains are probably low-virulence, and do not cause overt disease. The Reston strain already has been shown to cause asymptomatic infection with humans; there is no reason to think others like this cannot be out there as well. Are they losing an evolutionary battle with EBO-Z? If so, that suggests that we may see more frequent outbreaks in the future.

The whole blog is excellent for discussion of health and evolution. I'm adding it to my blogroll.