The Marburg virus is in the same family as Ebola and causes severe hemorrhagic fever in humans. Case fatality rates in Marburg outbreaks have ranged from 24% to 88%.

The Centers for Disease Control and Prevention reports laboratory confirmed cases have been reported in Uganda, Zimbabwe, the Democratic Republic of the Congo, Kenya, Angola, and South Africa.

The virus has not been found in West Africa–until now. Scientists have discovered live Marburg virus in fruit bats in Sierra Leone.

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Five Egyptian rousette fruit bats tested positive for active Marburg virus infection. Scientists caught the bats separately at locations in three health districts: Moyamba, Koinadugu and Kono. There have been no reported cases of people sick with Marburg in Sierra Leone, but the virus’s presence in bats means people nearby could be at risk for contracting Marburg virus.

The Marburg virus discovery came through two projects – one led by the Centers for Disease Control and Prevention and Njala University, and another by the University of California, Davis, and the University of Makeni, funded by USAID.

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“We have known for a long time that rousette bats, which carry Marburg virus in other parts of Africa, also live in West Africa. So it’s not surprising that we’d find the virus in bats there,” said CDC ecologist Jonathan Towner, who led the CDC team. “This discovery is an excellent example of how our work can identify a threat and help us warn people of the risk before they get sick.”

Scientists have shown that the Egyptian rousette bat (Rousettus aegyptiacus) is the natural reservoir for Marburg virus, which means the bats can carry the virus for a long time without getting sick themselves. They can then pass it on to humans or other animals through their saliva, urine, or feces.

Infected Egyptian rousette bats may shed Marburgvirus in their saliva, urine and feces as they feed on fruit. Contaminated fruit may then be eaten by people or other animals, raising the possibility of spreading Marburg virus to them. People might also be exposed to Marburg virus through bat bites when they capture bats to eat.

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