Ebola,virus (of the family Filoviridae ) that is responsible for a severe and often fatal viral hemorrhagic fever; outbreaks in primates such as gorillas and chimpanzees as well as in humans have been recorded. The disease is characterized by extreme fever, rash, and profuse hemorrhaging. Fatality In humans, fatality rates range from 50 to 90 percent.

The virus takes its name from the Ebola River in the northern Congo (Kinshasa)basin of central Africa, where it first emerged in 1976. Outbreaks that year in what was then Zaire and in Zaire (now Congo [Kinshasa]) and The Sudan resulted in hundreds of deaths, as did another outbreak in Zaire in 1995. Ebola is closely related to the Marburg virus, which was discovered in 1967, and the two are the only members of the Filoviridae , designated a family in 1987that cause epidemic human disease. A third related agent, called Ebola Reston, caused an epidemic in laboratory monkeys in Reston, Virginia, but apparently is not fatal to humans.

Viewed through an electron microscope, the Ebola virus appears as long filaments, sometimes branched or intertwined. The virion (virus particle) contains one molecule of noninfectious, single-stranded RNA (ribonucleic acid). How It is not known how the Ebola virus attacks cells is not known; however, it has been postulated that the virus produces proteins that suppress the immune system, allowing reproduction of the virus to continue unhindered. Viral hemorrhagic fevers like Ebola typically are carried by arthropods and rodents; however, the natural reservoir for the Ebola virus has yet to be discovered. Ebola can be transmitted through contact with infected blood, semen, body bodily fluids, and possibly urine and respiratory secretions. The virus has also been detected in the organs of patients after recovery from the fever. Unsanitary conditions and lack of adequate medical supplies have been a factor may be factors in the spread of the disease.

