Rabies-related viruses.

Five viruses related to rabies occur in Africa. Two of these, Obodhiang from Sudan and kotonkan from Nigeria, were found in insects and are only distantly related to rabies virus. The other three are antigenically more closely related to rabies. Mokola virus was isolated from shrews in Nigeria, Lagos bat virus from fruit bats in Nigeria, and Duvenhage virus from brain of a man bitten by a bat in South Africa. The public health significance of the rabies-related viruses was emphasized in Zimbabwe where in 1981 a rabies-related virus became epizootic in the dog and cat population. It is postulated that the ancestral origin of rabies virus was Africa where the greatest antigenic diversity occurs and that the ancestor may have been an insect virus. Questions are raised why rabies has not evolved more rapidly in the New World, given the frequency and ease with which antigenic changes can be induced in the laboratory, and how the virus became so extensively established in New World bats.