African Bats a Reservoir for Marburg Virus?

Hemorrhagic fevers caused by the Marburg and Ebola filoviruses have a case fatality rate of up to 90% in humans and apes. The natural host of the Ebola virus was recently identified as African fruit bats (see Journal Watch Infectious Diseases Dec 21 2005).

Although the closely related Marburg virus was discovered 40 years ago, when laboratory workers in Germany developed hemorrhagic fever after handling African green monkeys, its natural reservoir has remained unknown. During the past decade, outbreaks of Marburg hemorrhagic fever have occurred in Angola, Uganda, and the Democratic Republic of the Congo. These outbreaks were often linked to caves or mines, and bats roosting in such places have long been suspected of harboring or transmitting the virus. To investigate this possibility, researchers tested 1138 bats representing 10 species for Marburg virus infection. The animals were collected from four locations throughout Gabon and one in northwestern Republic of the Congo.

PCR assays revealed Marburg virus RNA in tissue samples from four bats (all Rousettus aegyptiacus). Serum specimens were available for 438 bats (including 3 of the PCR-positive ones); 29, including the 3 PCR-positive animals, tested positive for Marburg antibody. Again, all were R. aegyptiacus. Overall, seroprevalence among R. aegyptiacus bats was 12%, with infection more likely in adults than in juveniles. Whether the virus causes morbidity in bats remains unclear: The captured animals all were apparently healthy.