African horse sickness surveillance systems and regionalisation/zoning: the case of South Africa.

Central and Southern Africa are generally regarded as being endemic areas for African horse sickness (AHS). With the advent of the concepts of risk analysis and regionalisation/zoning, however, the possibility has now arisen of establishing 'zones' within South Africa for AHS surveillance purposes. In 1993, a protocol was submitted to the European Community (now European Union: EU), proposing the establishment of an AHS-free zone in the Cape peninsula. The proposal is based on historical evidence that AHS virus overwinters (in zebra) only in the Kruger National Park, from where it spreads westwards and southwards every year. The infection only extends to the Western Cape Province once every fifteen years. A ban on vaccination in the proposed AHS-free zone has been suggested, together with strict control of the movement of horses into and through this zone. The entire equine population of this zone (some 8,000 animals) would serve as sentinels. All equine mortalities would be notifiable, with mandatory post-mortem examinations. The establishment of an insect-free quarantine station in this zone would enable the movement of certified AHS virus-free horses from South Africa to the EU and the rest of the world.