UMVE studied the factors implicated in the three steps that led to Ebola virus and Marburg virus diseases emergence in humans. These steps include: the identification of reservoir species, the circulation within the natural host, the crossing to intermediary animal species, and finally the direct transmission to humans from great apes and fruit bats. Antibodies and nucleotide sequences specific for Ebola virus were detected in the liver and spleen of fruit bat belonging to three species (Hypsignathus monstrosus, Epomops franqueti, Myonycteris torquata) in Gabon and Republic of the Congo (Figure 4 ). Antibodies and nucleotide sequences specific for Marburg virus were found in the Egyptian fruit bat (Rousettus aegyptiacus) in Gabon, suggesting that bats might be reservoirs for filoviruses [3] [4] [5] . We showed that Ebola virus caused extensive epizootics among gorillas and chimpanzees, killing thousands of animals during the last decade in parts of Gabon and Republic of the Congo [4] . We characterized the viral variants associated with all Ebola virus disease outbreaks that occurred between 1996 and 2008 and developed new epidemiological models of Ebola virus disease epidemics, based on the identification of several independent epidemic chains. The identification of multiple variants during the 2001 Gabon/Republic of Congo outbreak and two phylogenetically divergent lineages suggest independent introductions into great ape and human populations following multiple viral spillovers from a reservoir host [6] [7] . In this "multi-emergence" hypothesis, Ebola virus disease outbreaks would occur episodically during certain ecological conditions caused by habitat disturbances or climatic phenomena. This hypothesis also implicitly assumes that Ebola virus was present in Equatorial Africa long before the first documented disease outbreak in 1976, as supported by various serological surveys. Furthermore, we recently showed that the 2007 Luebo outbreak in the Democratic Republic of the Congo was linked to massive fruit bat migration, strongly suggesting that humans could be infected directly by bats or by consumption of bats [8] .