Ebola outbreak came from bats, study says

Chuck Bednar for redOrbit.com – Your Universe Online

This year’s Ebola virus outbreak may have originated from contact between humans and infected bats, according to new research published in the journal EMBO Molecular Medicine on Tuesday.

In the study, researchers from the Robert Koch-Institute in Berlin, Germany and their colleagues identify insectivorous free-tailed bats as a plausible reservoir of the infection, thus expanding the range of possible Ebola virus sources to include these flying mammals. They also noted that their findings indicate that larger forms of wildlife were not the original source of the infection

As the study authors explained in a statement, Ebola virus disease epidemics are of zoonotic origin, meaning that they are transmitted to humans through contact with their large animals or bats. While monitoring populations of large mammals around the index village of Meliandou in southeastern Guinea, they reportedly found no evidence for a concurrent outbreak.

Those observations, combined with the fact that direct contact with the bats is common in the affected region, indicate that they are likely the original source of the infection. However, while fruit bats are commonly suspected Ebola virus reservoirs, they would have transmitted the disease through food, but that would have affected adults prior to or along with the two-year-old boy who is the index patient. That was found not to be the case in this instance.

A large colony of free-tailed insectivorous bats living in a hollow tree near the home of that child presented another opportunity for infection, the researchers said. Villagers said that youngsters often played in and around the tree, and lead investigator Fabian H. Leendertz and his colleagues report that this resulted in a massive exposure to these bats.

Leendertz and his fellow researchers conducted a four-week field mission to Guinea in April of this year to examine human exposures to bats, as well as to survey local wildlife and to capture and analyze bats living in Meliandou and in neighboring forest areas. The index village itself is not located in the woods, but is a more modern, heavily-modified type of setting.

According to the researchers, the virus that spread from Meliandou into other areas of Guinea and Sierra Leone, Liberia, Nigeria and Senegal has become the largest Ebola outbreak ever recorded. As of December 17, approximately 7,800 people have died as a result of the disease.

Earlier this month, a team of US researchers revealed that it had successfully completed the first step toward the development of a vaccine for the Ebola virus. They reported that a Phase 1 clinical trial conducted in Uganda between 2009 and 2010 produced promising results towards a vaccine not just for Ebola, but also for its sister pathogen, the Marburg virus.

“The RV247 study represents the first Ebola vaccine trial conducted in Africa. Since immune responses to vaccines can differ around the world, these findings are encouraging for the development of an effective Ebola vaccine for Africa,” said study author Dr. Merlin Robb, the director for clinical research at the US Military HIV Research Program (MHRP). “Given separately and concurrently, both vaccines were safe, well-tolerated, and elicited antigen-specific humoral and cellular immune responses.”

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