Domestic and wild mammals may be amplifying and reservoir hosts. Rift Valley Fever Virus Rift Valley fever appears as epizootics in sheep, cattle, camels, and goats in Africa. Massive outbreaks have been recognized in South Africa, Kenya, Uganda, Sudan, Egypt, and Mauritania. Human cases usually are restricted to veterinarians, butchers, and others in close contact with blood of domestic livestock. However, in Egypt in l977 and again in Mauritania in l987, widespread human epidemic disease was recognized.
Transmission is via aerosolized infected blood and mosquitoes.
Epizootics in the Rift Valley arise periodically after heavy rains. There is evidence that the virus is maintained in nature in the dried eggs of Aedes mosquitoes that hatch only in very moist years. It is propagated in baby mice or mosquitoes or in vertebrate or invertebrate tissue cultures. The RNA has been detected in lung tissue from cases of hantavirus pulmonary syndrome postmortem. Serologic tests used to diagnose bunyavirus infections include the enzyme-linked immunosorbent assay and complement fixation, fluorescent antibody, neutralization, and hemagglutination inhibition tests.