South African Horse Sickness
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What is (South) African Horse Sickness (AHS)? It is a highly infectious non-contagious, vector born viral disease. It is characterised by respiratory and circulatory damage, accompanied by fever and loss of appetite. Animals affected are all breeds of horses (mortality rate of 70-90%), mules and donkeys. The vector host which spreads the virus is a midge.
AHS does not spread directly from one horse to another, but is transmitted by the midge, which becomes infected when feeding on other infected animals. Most animals become infected in the period associated with sunset and sunrise, when the midges are most active. [This is an abbreviated description of AHS taken from Google. In the early 20th Century AHS was thought to be spread by biting flies or mosquitoes. But it was already understood that it was non-contagious. ]
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South African Horse Sickness first appeared in Aden in 1879; it was said to have been brought in from Mauritius. In October that year the Aden Troop lost 17 horses.
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The Glanders & Farcy Act of 1899 provided for horses affected by the Glanders and Farcy disease or other epidemics such as South African Horse Sickness. Inspectors appointed by the Government under this Act would arrange for a vet to examine the affected animal. Whereas the killing of diseased animals was obligatory for Glanders and Farcy diseases, for African Horse Sickness, the Inspector had the option of either killing or treating the animal.
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In 1907 Aden was not subject to the 1899 Act and was therefore under no obligation to control the export of animals or hides. Between October 1906 and May 1907 there were 130 cases of South African Horse Sickness in Aden, only 30 of which survived. 78 died from the sickness and the remaining 22 were destroyed. This was the first major epidemic since 1879. The sickness usually appeared in the autumn and would continue through to early summer.
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Various measures were taken which in subsequent years would contain the spread of the disease to a great extent. One advantage of Aden was that the topography lent itself to being divided into a number of areas, with entry and exit from each area controlled through one of the Gates. So an obvious measure was to ban movement of horses between areas once an outbreak had been identified. Another was for sick horses, or those suspected of having the sickness, to be quarantined, the minimum period being 15 days. An additional measure was the automatic quarantining of all horses arriving by sea from Mukalla, Somaliland and Jibuti. This proved to be a very worthwhile precaution as two horses developed the sickness in quarantine in 1910, three in 1911 and eight in 1913. That year there was a fairly serious epidemic with 40 horses dying in either Aden or Sheikh Othman. The stables of the Aden troop at Khormaksar were pretty isolated and only one horse succumbed there. There were cases every year at Dthala and Lahej so control measures were required at the border between Aden and its hinterland. At the end of the 1907 outbreak the carriage stand at Khormaksar was reopened from 1 June for carriage traffic between Aden and Sheikh Othman, this being 15 days after the last case had developed.
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At that time Aden had no resident vet, which was perhaps why the Glanders & Farcey Act was not applicable to Aden. On the next outbreak in November 1908 Aden asked for a vet to be sent from India. As he was a civilian and not a military vet all his costs including travel had to be met from the Aden budget. Aden was not amused.
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AHS is prevalent today on the African continent. In 2007-2008 the outbreak in South Africa itself lasted from October 2007 to May 2008. In these eight months there were 707 cases, of which 404 horses died.