Descriptive study of an outbreak of equine sarcoid in a population of Cape mountain zebra (Equus zebra zebra) in the Gariep Nature Reserve

An outbreak of equine sarcoid occurred in a population of Cape mountain zebra (Equus zebra zebra) at the Gariep Nature Reserve located in the southern Free State Province of South Africa in 1996. The course of the outbreak during 1996 to 2003 is described. During this period the average population size was 69 animals. Initially (1996) all affected animals were removed from the population. New cases continued to manifest and the incidence varied between 4.6% and 17.6%. Prevalence reached 24.7% in 2002. No sexual predilection was noticed in the 39 recorded cases. Of the affected individuals, 64% had a single lesion and no animal had more than 4 lesions. In males, the majority of lesions occurred in the inguinal area (55.17%), whereas in females they mostly occurred on the head and neck (41.38%). Lesions can increase 260% in size annually and may impede movement.