Ebola virus disease is a viral haemorrhagic fever of humans and other primates caused by ebolaviruses, RNA viruses in the Filoviridae family. The natural host is thought to be megabats. The virus spreads by contact with body fluids, such as blood. After an incubation period of 2–21 days, nonspecific symptoms including fever, sore throat, muscle pain and headache develop, followed by vomiting, diarrhoea, rash, liver and kidney impairment, and sometimes internal or external bleeding. On average, around half of those infected die, often from hypovolaemic shock. The virus sometimes persists in semen or breast milk for several weeks or months after recovery.
The disease was first identified in 1976 by Peter Piot and others in two simultaneous outbreaks, one in Nzara, Sudan and the other in Yambuku, then in Zaire, near the Ebola River, for which the disease is named. Outbreaks have occurred intermittently in tropical regions of sub-Saharan Africa, with a few thousand cases documented before the epidemic in Western Africa of 2013–16, in which nearly 29,000 cases with more than 11,000 deaths were reported. More than 3000 cases were documented in a subsequent epidemic in the Democratic Republic of the Congo in 2018–20, with more than 2000 deaths. Prevention of outbreaks focuses on limiting virus transmission from infected animals to humans, for example, by taking precautions when handling bush meat. Ebola vaccines are now available. Monoclonal antibody treatments can improve outcomes, and a combination of three monoclonals has been licensed.