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close this bookFact sheet No 103: Ebola Haemorrhagic Fever - Revised December 2000 (WHO, 2000, 3 p.)
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Natural Reservoir

· The natural reservoir of the Ebola virus seems to reside in the rain forests of Africa and Asia, but has not yet been identified. Different hypotheses have been developed to try to explain the origin of Ebola outbreaks. Initially, rodents were suspected, as is the case with Lassa fever whose reservoir is a wild rodent (Mastomys). Another hypothesis is that a plant virus may have caused the infection of vertebrates. Laboratory observation has shown that bats experimentally infected with Ebola do not die and this has raised speculation that these mammals may play a role in maintaining the virus in the tropical forest.

· Although non-human primates have been the source of infection for humans, they are not thought to be the reservoir. They, like humans, are infected directly from the natural reservoir or through a chain of transmission from the natural reservoir.

· Extensive ecological studies are currently under way in Cd'Ivoire to identify the reservoir of Ebola. Studies to identify the reservoir of Marburg virus, a closely related filovirus are being conducted in the Democratic Republic of the Congo.

Further information: Please contact the Spokesperson's Office, WHO, Geneva, Tel.: (+41 22) 791 2599, Fax: (+41 22) 791 4858, E-mail: All WHO Press Releases, Fact Sheets and Features as well as other information on this subject can be obtained on Internet on the WHO web site: