Domestic animals may be next source of Ebola infection

• Seven such outbreaks have hit Gabon and the Republic of Congo since 1994, leading to 445 cases resulting in 361 deaths.
• Ebola virus thus constitutes a grave public health problem in these countries.
• No medicine or vaccine is currently available, only prevention and rapid control of epidemics by isolation of disease victims can limit its spreading.
• Since 2001, IRD research scientists and their partners (1) have been working to unravel the virus's biological cycle, in other words the whole range of ways in which the virus circulates in its natural environment, from its natural host (or reservoir) right up to humans.
• They showed that strong epidemics of Ebola have decimated populations of large primates over the past several years in the border regions between Gabon and the Republic of Congo.
• Human infection appears to occur only in a secondary way, through contact with carcasses of dead animals (2).
• It is quite possible that several reservoir species co-existent and that many other animal species can become infected, thus contributing to propagation of the virus in nature.
• A serological investigation conducted from 1980 to 2000 on 790 nonhuman primates from Cameroon, Gabon and the Republic of Congo, belonging to 20 different species, hence revealed that 12.9 % of wild chimpanzees carry Ebola virus antibodies, several of the positive samples dating from before the first epidemics in these countries.
• The presence of specific antibodies in the animals taken before the epidemics means that the Ebola virus has probably been circulating for a long time in Central African forests.
• These observations also show that an epidemic or sporadic cases can appear at any moment in the sub-region of Central Africa as a whole.
• Moreover, during the latest epidemics in Gabon and the Republic of Congo, there were many cases where dogs had eaten remains of dead animals infected with the virus, nonetheless without showing visible clinical signs.