African Horse Sickness Cases Lessen in Western Cape

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. Two cases are awaiting confirmation, with the last death occurring 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)."

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

Affected areas include the Stellenbosch district, Anandale and Bottelary roads just outside of the Stellenbosch district, and the Kalbaskraal and Durbanville-Klipheuwel areas. A quarantine remains in place for the Stellenbosch district and the Somerset West area. There are about 40-50 equine properties outside of these areas under individual quarantine, according to Koen. No movement is allowed in to, out of, or through these areas or properties.

For the rest of the Western Cape, outward movement is allowed from the free zone and the surveillance zone into the infected zone, but once horses leave, they will not be allowed back in to the free and surveillance zones.

Exports out of the country have been halted by the European Union (EU).  Koen said that once midge numbers decrease significantly 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 been either moved, postponed, or cancelled; however, racing has not been dramatically affected, said Koen. Some movement of equine athletes have been allowed with official veterinary permits, with each case being analyzed on an individual basis. Extra precautionary measures were put in place for those horses being brought into racetracks. A disaster management group, which included traffic police, assisted in monitoring, limiting, and reporting movement of horses in the area.

Besides controlling movement, officials have vaccinated about 1,400 bringing the level of vaccination to the affected area to approximately 95% of the horse population, said Koen. A two-dose vaccination series was provided to private veterinarians, who assisted with the vaccination campaign. In addition, officials have visited 1,500 properties with more than 4,000 horses, gathering data on animal movement through questionnaires. This data has helped guide disease control strategies.

In addition, said Koen, owner education through media outlets has been another control measure. Horse owners were advised to move horses from low-lying, marshy areas to higher ground (away from midge breeding grounds); to use insecticides on their horses; and to stable horses from early evening to mid-morning when midges are active (only one of the cases was in a stabled horse).

Clinical signs for AHS include fever, difficulty in breathing, swelling above the eyes (supraorbital swelling) or of the entire head, coughing, discharge from the nose, excess salivation, sweating, restlessness, lack of energy, and general stress and lethargy due to edema (fluid swelling) around the heart and lungs.

African horse sickness is a very serious disease because of the high mortality rate (70-95%) in affected horses, according to the National Department of Agriculture in South Africa. There is no cure for the disease, and medicine to treat the clinical signs is very costly. Affected horses under treatment must be on complete stall rest before gradually returning to activity.

For previous stories on the outbreak, see and For more on AHS, see the African horse sickness category under the Infectious Diseases topic.

About the Author

Sarah Evers Conrad

Sarah Evers Conrad has a bachelor’s of arts in journalism and equine science from Western Kentucky University. As a lifelong horse lover and equestrian, Conrad started her career at The Horse: Your Guide to Equine Health Care magazine. She has also worked for the United States Equestrian Federation as the managing editor of Equestrian magazine and director of e-communications and served as content manager/travel writer for a Caribbean travel agency. When she isn’t freelancing, Conrad spends her free time enjoying her family, reading, practicing photography, traveling, crocheting, and being around animals in her Lexington, Kentucky, home.

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