Animal diseases caused by retroviruses: enzootic bovine leukosis, equine infectious anaemia and caprine arthritis-encephalitis.

This article presents the essential features of three retroviral infections of animals: enzootic bovine leukosis, equine infectious anaemia and caprine arthritis-encephalitis. A unique feature of these diseases is persistent infection, maintained throughout the life of the host animal by the presence of a provirus integrated into the cells of the host, thereby making an infected animal a continuous source of the pathogen. Information currently available on the epidemiology and detection of these diseases is sufficient to institute effective disease control measures.