Thanks to Greg Folkers for sending the link to this long, informative New York Times report: Ebola Lying in Wait. Excerpt:
A growing body of scientific clues — some ambiguous, others substantive — suggests that the Ebola virus may have lurked in the West African rain forest for years, perhaps decades, before igniting the deadly epidemic that swept the region in the past year, taking more than 10,000 lives.
Until recently, Ebola had been considered a threat mostly to Central African nations. Yet studies tell of possible Ebola antibodies in human blood samples drawn in West Africa long before the current outbreak. And genetic analysis suggests the West African virus broke off from a parent strain in Central Africa at least 10 years ago, possibly as long as 150 years ago.
“My gut feeling,” said Dr. Peter Piot, the director of the London School of Hygiene and Tropical Medicine, who helped discover the Ebola virus in 1976, is that the evidence points to “infection before the current epidemic.”
Medical detectives in West Africa are now seeking to establish whether the virus had previously infected people there. The research is part of a broader push to better understand where Ebola might strike next, and to strengthen surveillance and health systems in hopes of preventing future outbreaks.
Beyond the known outbreaks in Central and West African nations, scientists have found signs in human blood that suggest immune reactions to Ebola in 14 other countries: 12 in Africa, as well as Panama and the Philippines.
Zeroing in on African rain forests, a team of scientists from Oxford University, Harvard and other institutions recently used ecological data and patterns of known human and animal outbreaks to construct a detailed prediction of other likely Ebola danger zones.
It stretches across 22 nations from West Africa as far east as Madagascar. The team stressed the low probability of humans picking up the virus, which can be transmitted only by direct contact with bodily fluids like blood and vomit.
But the scientists also warned of new dangers because of encroachments on primal forests and sharp rises in populations and mobility.
Stuart Nichol, the chief of the viral special pathogens branch at the National Center for Emerging and Zoonotic Infectious Diseases, said there was a growing consensus “that in this broad area of Africa, we should be doing all we can to improve surveillance.”