Rift Valley fever (RVF) is a zoonotic, mosquito-borne disease that primarily affects ruminants such as cattle, goats and sheep. The disease is caused by an RNA virus that has been classified in the family of Bunyaviridae and genus Phlebovirus.
Humans are usually infected by direct contact with uncooked animal products or by body fluids from infected animals, although infection may also occur from the bite of an infected mosquito. Person-to-person transmission does not occur. The virus is endemic over much of Africa, including Southern Africa, East and Central Africa, up to Egypt and across to the Arabian peninsula extending up into Saudi Arabia.
Outbreaks of RVF in livestock in South Africa were reported in February 2010, and cases have again been occurring in 2011. Human cases have been reported from a number of provinces, particularly Eastern and Western Cape, and most have exposure related to occupation or hunting. Although the risk to most travellers is considered to be low, travellers may be infected and present in healthcare facilities in the UK.