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 http://health.nytimes.com/health/guides/test/antibody-titer/overview.html?inline=nyt-classifier - 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 http://elifesciences.org/content/3/e04395 - 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.