Rift Valley Fever in Southern Rhodesia

Abstract

Rift Valley fever is a virus disease characterised by a short incubation period, typical liver lesions and heavy mortality in young lambs and calves. The aetiological agent is an arthropod- borne pantropic virus exhibiting marked hepa- totropism. It is chiefly a disease of ruminants, but man and monkeys are highly susceptible, as also several rodent species. Daubney and Hudson (1931) first recognised the disease as an entity, and as a result of their investigations concluded it was a filterable virus and probably mosquito transmitted. It was not, however, until Smithburn, Haddow and Gillett (1948) isolated the virus from wild caught mosquitoes in the Semliki Forest of Western Uganda that the mode of transmission was definitely established. Apart from Kenya and Uganda, the virus has been isolated from the Union of South Africa during the course of an outbreak of heavy mortality amongst sheep and cattle in the Western Free State, Southern and Western Transvaal and North-Western Cape Province (Alexander and Dickson, 1951).