Rift Valley fever

Rift Valley fever [′rift ¦val·ē ′fē·vər]

(medicine)

A toxic generalized febrile virus disease of humans and animals in South and East Africa, transmitted by a mosquito, and characterized by headache, photophobia, myalgia, and anorexia.

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Rift Valley fever

An arthropod-borne (primarily mosquito), acute, febrile, viral disease of humans and numerous species of animals. Rift Valley fever is caused by a ribonucleic acid (RNA) virus in the genus Phlebovirus of the family Bunyaviridae. In sheep and cattle, it is also known as infectious enzootic hepatitis. First described in the Rift Valley of Africa, the disease presently occurs in west, east, and south Africa and has extended as far north as Egypt. Historically, outbreaks of Rift Valley fever have occurred at 10–15-year intervals in normally dry areas of Africa subsequent to a period of heavy rainfall.

In humans, clinical signs of Rift Valley fever are influenzalike, and include fever, headache, muscular pain, weakness, nausea, epigastric pain, and photophobia. Most people recover within 4–7 days, but some individuals may have impaired vision or blindness in one or both eyes; a small percentage of infected individuals develop a hemorrhagic syndrome and die.

Rift Valley fever should be suspected when high abortion rates, high mortality, or extensive liver lesions occur in newborn animals. The diagnosis is confirmed by isolating the virus from tissues of the infected animal or human. Control of the disease is best accomplished by widespread vaccination of susceptible animals to prevent amplification of the virus and, thus, infection of vectors. Any individual that works with infected animals or live virus in a laboratory should be vaccinated. See Animal virus, Vaccination