Rift Valley Fever (RVF) is an acute, fever causing disease caused by RVF virus, a bunyavirus that is transmitted via mosquitoes to domestic livestock. Human infections can result from mosquito bites as well as direct or indirect contact with the blood or organs of infected animals (care or slaughter of infected animals and possibly from ingestion of raw milk). It was first recognized in the 1900's in Kenya, Africa among domestic sheep. In 1931, the agent causing RVF was isolated from infected sheep.
RVF is endemic to parts of Africa with tropical and sub-tropical environments. Outbreaks typically occur or peak in late summer especially after periods of heavy or unusual amounts of rainfall. In East Africa, outbreaks have been closely associated with the heavy rainfall that occurs during the warm phase of the El Niño/Southern Oscillation (ENSO) phenomenon. In 1997-1998, Kenya and Somalia experienced the largest outbreak reported and in the first outbreak outside of Africa occurred in Saudi Arabia and Yemen in 2000-2001.
The virus is typically recognized in domestic animal populations through symptoms consisting of elevated temperatures, increased rates of abortions, and high mortality rates among young animals.
Methods of prevention of RVF and other mosquito borne diseases outbreaks include taking proper protective measures against mosquitoes.
Centers for Disease Control and Prevention Rift Valley Fever Fact Sheet
World Health Organization
Sissoko, Daouda. et. al. Rift Vally Fever, Mayotte, 2007-2008. Emerging Infectious Disease. Vol.15, No.4; 568-570: 2009.
Hartley DM, Rinderknecht JL, Nipp TL, Clarke NP, Snowder GD; National Center for Foreign Animal and Zoonotic Disease Defense Advisory Group. Potential effects of Rift Valley fever in the United States. Emerg Infect Dis. 2011 Aug