How African Horse Sickness spreads in South Africa, what the OBP vaccination programme involves, and the management steps owners discuss with their vet.
Horse Care · 2026-02-08 · 7 min read
African Horse Sickness (AHS) is a controlled animal disease in South Africa under the Animal Diseases Act, 1984 (Act 35 of 1984). It is caused by an orbivirus spread by biting *Culicoides* midges, and it is one of the most serious infectious disease risks facing horses in the country. This article is general information, not veterinary advice — your vet or your local state vet is the authority on your horse and your area.
AHS is caused by an orbivirus with nine recognised serotypes, with limited cross-protection between most of them. It is transmitted by *Culicoides* midges and is not directly contagious from horse to horse. Risk is seasonal and highest in the warm, wet late-summer and autumn months, though the exact pattern varies by region and by year.
Reported case fatality rates differ between studies, forms of disease and vaccination status. Treat published figures as indicative rather than exact.
The registered South African AHS vaccine is produced by Onderstepoort Biological Products (OBP). It is a live attenuated polyvalent vaccine supplied in two bottles that are given as separate injections some weeks apart, rather than a single shot. The combination does not contain every one of the nine serotypes, so vaccination reduces risk — it does not guarantee immunity.
Timing, intervals, booster schedules and which horses should or should not be vaccinated (for example young foals, pregnant mares or horses in particular zones) are set out in the manufacturer's directions and in current veterinary guidance, and are commonly planned so that the course is completed well before the higher-risk season. Confirm the current schedule and the price with your own veterinarian before ordering vaccine — protocols and product availability change.
South Africa maintains an AHS controlled area in the Western Cape. Movements into, out of and within that area require an AHS movement permit from the responsible state veterinarian, and specific vaccination, identification and health-certification conditions apply. Movements elsewhere in the country are not automatically subject to those permit conditions. Check the current requirements with the state veterinary services before planning any move that touches the controlled area.
Horses arriving from countries where AHS does not occur have no prior exposure to the virus. Discuss an appropriate vaccination and management plan with your vet before and after arrival.
Vector control is a supporting measure alongside vaccination, not a replacement for it. Commonly recommended steps include:
AHS is a notifiable controlled disease. If you suspect AHS, contact your vet immediately — there is no specific antiviral treatment, and care is supportive. Your vet is also responsible for the reporting obligations that follow a suspected case.
More SAHorseSales articles · Browse horses for sale in South Africa