Clinical aspects of African viral hemorrhagic fevers.

Three hemorrhagic fevers occur in southern Africa: Rift Valley fever, Marburg virus disease, and Crimean-Congo hemorrhagic fever. The patient's history of travel in Africa, visits to rural areas, contact with sick animals or their carcasses, or contact with a tick-infested environment or tick bites is important. Rift Valley fever is characterized by an incubation period of approximately 3 or 4 days, sudden onset of fever with a biphasic course, and signs and symptoms of liver and kidney disorder. The commonest complication is retinitis with a central scotoma. Severe cases may develop a hemorrhagic state, which may be fatal. Marburg virus disease was studied in two Australian students after a tour of Rhodesia (now Zimbabwe) and in a nurse who cared for them. The incubation period of approximately 7 days is followed by sudden onset of fever (typically lasting 7 days) and the appearance of a maculopapular petechial rash on the 5th day. A hemorrhagic state develops about the same time and may be fatal. Crimean-Congo hemorrhagic fever is widespread in South Africa; it may be transmitted by tick bite of the species Hyalomma, by contact with the tissues of animals, or by contact with infected patients.