It’s only taken 30 years, but information about Ebola in nature is finally starting to snowball. First, after almost 15 years of disappearing from the human population, Ebola returned with a vengeance in the mid 1990s, causing illness in 6 separate outbreaks in Gabon, Ivory Coast, Democratic Republic of Congo (DRC), and South Africa (imported case) between 1994 and 1996. As doctors and scientists rushed in to contain the outbreaks, they were also able to collect viral samples, and trap animals and insects in the area, searching for a reservoir for the virus. In this decade, there have been almost yearly outbreaks of Ebola and/or the closely related Marburg virus in Africa, resulting in the discovery of both Ebola and Marburg infection in species of fruit bats–suggesting these animals may be a reservoir species for filoviruses (though more work remains to be done to confirm this).
As I blogged about previously, prior work has suggested that the most deadly Ebola subtype, known as Ebola-Zaire (EBO-Z) after its initial site of isolation, has been spreading steadily eastward across the central African continent. This was tracked by examining isolates of the virus obtained during human epidemics, which introduces a bias into the sample. However, viral isolates from other sources have been quite difficult to obtain, despite many years of searching. A new paper examines viral isolates collected from dead gorillas and reconstructs their phylogeny in an effort to fill in some of these gaps.
(Continued over at Aetiology).