A virus disease, caused by a phlebovirus and transmitted by mosquitoes, at one time confined to sub-Saharan Africa and predominantly found in domestic animals such as cattle, sheep and goats. In the 1970s the disease flared up in Egypt, probably owing to a more virulent virus. The illness in humans is characterised by fever, haemorrhages, ENCEPHALITIS and involvement of the EYE. An effective vaccine protects both animals and human beings against the disease (see IMMUNISATION).