African Horse Sickness in Aden: A Century-Long Struggle

African Horse Sickness first made its presence known in Aden in 1879, believed to have been brought in from Mauritius. In that year, the Aden Troop lost 17 horses to the disease. The Glanders & Farcy Act of 1899, which addressed horses affected by Glanders and Farcy diseases, also provided for those suffering from AHS. Under this Act, government-appointed inspectors would arrange for veterinary examinations of affected animals. While the killing of animals was mandatory for Glanders and Farcy diseases, for AHS, inspectors had the discretion to either euthanise or treat the animal.

African Horse Sickness (AHS) is a serious viral disease, highly infectious but not directly contagious between horses. It's transmitted by a vector – typically a midge – and not through direct contact between horses. The disease is characterised by respiratory and circulatory damage, causing fever and a loss of appetite. AHS affects all breeds of horses, with a high mortality rate of 70-90%, and also impacts mules and donkeys.

The disease is most prevalent during times around sunset and sunrise when the midge vectors are most active. Interestingly, in the early 20th Century, it was thought that AHS was spread by biting flies or mosquitoes, though it was already understood to be non-contagious.

In 1907, Aden witnessed a significant outbreak of AHS. During this period, the region was not governed by the 1899 Act and hence had no obligation to control the export of animals or hides. This outbreak resulted in 130 cases of AHS, with only 30 surviving. A total of 78 horses died from the sickness, and 22 were euthanised.

Various measures were subsequently implemented to control the spread of AHS. Aden's topography, divided into several areas each with controlled entry and exit points, facilitated containment efforts. Restrictions on horse movement between areas during outbreaks, quarantine measures for sick or suspected horses, and mandatory quarantine for horses arriving from Mukalla, Somaliland, and Djibuti were key strategies. These measures proved effective in subsequent years, significantly reducing the spread of AHS. In 1910, two horses developed AHS while in quarantine, followed by three in 1911 and eight in 1913. That year, a serious epidemic saw 40 horses dying in Aden or Sheikh Othman.

During the 1907 outbreak, Aden lacked a resident vet, which may explain why the Glanders & Farcy Act was not applied. In the subsequent outbreak of November 1908, Aden requested a vet from India, with all costs borne by the Aden budget, leading to some dissatisfaction.

Today, AHS remains prevalent in Africa. For instance, a major outbreak in South Africa from October 2007 to May 2008 resulted in 707 cases, with 404 horse fatalities. The ongoing challenge of AHS underscores the importance of vigilant veterinary practices and effective disease control measures.