Filoviruses belong to a virus family called Filoviridae and can cause severe hemorrhagic fever in humans and nonhuman primates. So far, only two members of this virus family have been identified: Marburg virus and Ebola virus. Ebola and Marburg hemorrhagic fevers are acute viral diseases that often lead to severe illness and death in humans and other primates. The infections typically affect multiple organs in the body and are often accompanied by hemorrhage (bleeding). Once the virus has been transmitted from an animal host to a human, it can then spread through person-to-person contact.
Both diseases are rare, but have a capacity to cause dramatic outbreaks with high fatality. Outbreaks of the diseases have been frequently reported since the discovery of the viruses in the 1960s and 1970s, mainly in Africa where the viruses have their origin.
The World Health Organization reports that viral hemorrhagic fever outbreaks (such as those resulting from Marburg and Ebola viruses) have a case fatality rate of up to 90%
Due to their severe fatality rate and ease of transmission, both viruses are considered potential biological weapons. The U.S. government has determined Ebola and Marburg are material threats to national security. Currently, no standard treatment or vaccine exists against the diseases.