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Disease Archive Rift Valley Fever	Back to Disease Archive Index

News 2000 2001 2002 2003 Outbreaks     First Out of Africa: 2000

Rift Valley Fever is a member of the sand fly fever group (Phleborivus genus, Bunyaviridae family), but is the only fever of this group vectored by mosquitoes. It is transmitted from animals to humans, by bite or by exposure to infected animal tissues. Initial clinical signs of the disease in animals are not precisely described. It is often the case that the disease is suspected by a confluence of events - spontaneous abortions, human deaths - after animals die 24-36 hours from the first observance of their appetite loss and listlessness. The mortality rate in animals less than a week old is 90%. In humans, there are symptoms similar to those in Dengue fever – fever, headache, joint and muscle pain, weakness – plus a rash. Complications include hemorrhage, encephalitis and blindness. The mortality rate varies widely. Prior to the 2000 outbreak of Rift Valley fever in Saudi Arabia and Yemen, the disease was confined to the African continent, e.g., Egypt, Kenya, Tanzania and South Africa. While some Western experts claim to have found the reservoir of the virus in wild rodents in the 1970s in Egypt, South African scientists contend that the reservoir is not yet known. Thus, research is still pursued. Rift Valley Fever - First Out of Africa