The African horse sickness (AHS) death toll in the Western Cape of South Africa has risen to 15 confirmed cases since the first death on the Elsenburg Agricultural Research Farm was confirmed on Feb. 25. The last case (unconfirmed) was reported on March 28. Pieter Koen, BSc, BVSc, veterinarian and Deputy Director Animal Health in the Western Cape, said, “I think there is a strong indication that the disease has been contained. Our weather is changing, we’re well into autumn and early winter, and this usually stops the cycle (of the Culicoides imicola midge).”

AHS is a lethal virus spread by Culicoides imicola and C. bolitinos midges, which are species of small flies. Once night temperatures fall below 50-59°F (10-15°C) for 10-14 days concurrently, the midge life cycle is usually broken.

At press time, a quarantine remained in place for the Stellenbosch district and Somerset West area. There are 40-50 equine properties outside these areas under individual quarantine, said Koen, with all horse movement restricted. For the rest of the Western Cape, outward movement is allowed from the free and the surveillance zones into the infected zone, but once horses leave, they won’t be allowed back in to the free and surveillance zones. Horse exports out of the country have been halted by the European Union (EU). Koen said that once midge numbers decrease and at least six weeks have passed since the last clinical case, a request will be made to the EU to regain export status. “If nothing changes, we’re aiming for the middle to the end of May,” he said. “This depends on whether further clinical cases appear.” Various equine events have either been moved, postponed, or canceled. Some movement of equine athletes has been allowed with official veterinary permits.

AHS has a mortality rate of 70-95%, according to the World Organization for Animal Health. There is no cure, and treatment is costly. (For the full story and more information, see www.TheHorse.com/ViewArticle.aspx?id=1720 and African horse sickness under Infectious Diseases at www.TheHorse.com)