10 Deadly Agents the CDC Works With

Marburg Hemorrhagic Fever
A newspaper chronicles the Marburg virus outbreak in the Ugandan capital Kampala in October 2014. © James Akena/Reuters/Corbis

Unlike its close cousin Ebola, we know the reservoir host for Marburg hemorrhagic fever: the African fruit bat, Rousettus aegyptiacus. Scientists don't know for sure how bats transmit the RNA filovirus (a filament-like virus that encodes its genetics using RNA), but they suspect it happens in bat-infested mines and caves, where humans come in contact with bat feces or small droplets of bat fluids, like urine, suspended in the air. Once in humans, it spreads like Ebola, via direct contact with an infected person's bodily fluids. Marburg occurs mainly in Africa [source: CDC].

Following an incubation period of five to 10 days, the infected person will experience a sudden attack of fever, chills headache and muscle pain, followed roughly five days later by a maculopapular rash (a rash with raised, spotted lesions), most noticeable on the torso. Nausea, vomiting, chest pain, sore throat, abdominal pain and diarrhea often accompany the rash. Finally, symptoms will grow worse, branching into jaundice, inflamed pancreas, severe weight loss, delirium, shock, liver failure, massive hemorrhaging and multi-organ dysfunction [source: CDC].

Marburg HF, like Ebola, has no known cure, and fatality rates can range widely depending on the outbreak (23-90 percent) [sources: CDC; WHO]. Diagnosis also can prove difficult, as the virus's effects resemble other those of infectious diseases, such as malaria and typhoid fever. Some experimental treatments show positive results in nonhuman primates tests, but are not yet approved for human trials [source: CDC].