Importance

Rift Valley fever (RVF) is a zoonotic viral disease that can affect a variety of species, including ruminants and camels, causing high mortality in young animals and/or abortions in adults. The RVF virus is endemic mainly in subSaharan Africa, but it has also been seen in North Africa, and may have become established in Egypt. There are concerns that this virus might be spreading, after outbreaks were reported in Saudi Arabia and Yemen in 2000. Rift Valley fever tends to occur in periodic epidemics, which typically occur after heavy rainfalls and may be devastating to domesticated livestock. These outbreaks are thought to begin when dormant, infected mosquito eggs hatch in flooded areas. However, the epidemiology of Rift Valley fever is incompletely understood, and low levels of infection have now been identified during interepidemic periods. Rift Valley fever outbreaks in domesticated animals are often accompanied by human disease. Many human cases are caused by occupational exposure to blood and tissues from infected animals, but mosquito-borne transmission can also occur. The most common form of the disease is a self-limiting, flu-like illness. Complications i