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

This research article discusses an outbreak of equine sarcoid, a skin disease, in a population of Cape mountain zebras in South Africa’s Gariep Nature Reserve from 1996 to 2003. It notes the progression of the outbreak, the affected population, and lesion characteristics and locations.

Overview of Equine Sarcoid Outbreak

• The outbreak took place in the Gariep Nature Reserve located in South Africa’s southern Free State Province. This particular outbreak was monitored over a seven-year period from 1996 to 2003.
• The average population of Cape mountain zebras during this period was reported to be 69 animals.
• In response to the initial outbreak in 1996, all affected zebras were removed from the population, however, new cases continued to manifest in the following years. The yearly incidence rate of the equine sarcoid disease ranged from 4.6% to 17.6% with the highest prevalence reaching 24.7% in the year 2002.

Observations of the Disease and its Impact on Zebras

• The researchers reported that the disease did not show any sexual predilection, indicating that both male and female zebras were similarly susceptible to the disease. A total of 39 cases were recorded during the study period.
• Among the affected animals, most (64%) had only a single lesion, and no animal experienced more than 4 lesions. This points to the fact that the disease typically doesn’t cause multiple lesions in these animals.
• The location of the lesions varied based on sex. In male zebras, the majority of the lesions occurred in the inguinal area (55.17%), whereas in female zebras, most of the lesions were observed on the head and neck (41.38%). This suggests that the patterns of disease manifestation are different for male and female zebras.
• Lesions caused by the disease can increase by an alarming 260% in size annually, and may impede the zebras’ movement. This could significantly affect the animals’ quality of life and their ability to carry on with regular activities like foraging for food and running from predators.