The study, published in the Public Library of Science journal PLoS ONE, suggests that Marburg may be more common than previously thought.

"Furthermore, this is the first report of Marburg virus being present in this area of Africa, thus extending the known range of the virus," the researchers wrote.

"These data imply that more areas are at risk for Marburg hemorrhagic fever outbreaks than previously realized and correspond well with a recently published report in which three species of fruit bats were demonstrated to be likely reservoirs for Ebola virus."

The study suggests that controlling these bats may help reduce the threat.

The World Health Organization said last week that Uganda had contained an outbreak of Marburg fever among gold miners there after two men became infected and one died.

A major outbreak of Marburg occurred among gold miners in the Democratic Republic of Congo between 1998 and 2000, killing 128 of 154 people infected. An outbreak that started in Uige, Angola, in 2004-05 killed 348 people out of 386 cases.

Ebola has also infected gorillas.

There is no vaccine or specific treatment for either disease, which cause a severe headache and fever followed by rapid debilitation. Death can follow within eight to nine days.

Like Ebola, the Marburg virus kills before it can spread far, and while bats have been suspected as the source, no one had been able to show this.

The CDC team has been testing bats across several regions of Africa.

They found a common species of fruit bat, Rousettus aegyptiacus, was the only one infected with the virus.