The potential for the spread of livestock epidemic diseases over vast distances was, unfortunately, clearly demonstrated late this year when Pan-Asian type O foot-and-mouth disease (FMD) entered South Africa. It was the first outbreak of FMD in South Africa's free zone since 1957; it is also the first time that the Pan-Asian strain of FMD type O has been detected on the African continent.
On 4 September 2000, a farmer near Pietermaritzburg (KwaZulu-Natal Province) presented two pigs - one dead, one alive - to the Regional Veterinary Laboratory at Allerton. At first, FMD was not recognized; it was only some days later when more cases were presented that local veterinarians suspected FMD. By the time the diagnosis was confirmed, 247 pigs were clinically infected, of which 83 had died. Stamping-out was applied immediately, and all animals on the farm were destroyed - in all, the remaining 643 pigs, ten goats, five sheep and six cattle.
A quarantine zone with a radius of 10 km around the initial focus was instituted; no animals were allowed to leave this zone. A surveillance zone with a 20-km radius was declared, and a control zone comprising some 16 districts around the infected focus was implemented. No products originating from the control zone could be certified for export.
On 21 September a cow on the adjoining farm was reported as having FMD which was then confirmed; this farm was also depopulated, involving the slaughter of a further 53 cattle and 3 500 pigs. Serological investigations and physical inspections continued, all reporting negative results.
On 10 October the preliminary results of serological testing of cattle and goats in the nearby communal grazing area known as the Valley of a Thousand Hills appeared to indicate that these animals had been infected. With the disease apparently spreading, it was decided to institute a limited vaccination programme to assist in reducing virus transmission. The vaccination programme (type O) began on 9 November. It was later discovered that in fact there was actually no serological evidence of infection in the communal grazing area. The small number of Liquid Phase Blocking ELISA positive results was not confirmed by the Virus Neutralization Test or 3ABC ELISA (for antibody to virus infection associated antigen) at either Onderstepoort Institute for Exotic Diseases or the World Reference Laboratory for FMD. Intensive investigations demonstrated that the disease had been contained within the originally declared 10-km critical control area. As of end January 2001, the last cases were those detected in early November, yet vaccination was continuing in the communal area.
Coincidentally, in November 2000, FMD caused by serotype SAT 1 was recognized in Swaziland in a group of cattle imported from South Africa. Lesions were discovered during the process of slaughter at an abattoir. All 110 imported cattle were slaughtered and buried. Subsequently intensive surveillance in the quarantine zone detected clinical disease and cattle, sheep and goats in a 10-km radius "high risk" area of a declared quarantine zone were vaccinated with trivalent SAT vaccine. This outbreak was within the FMD-free area that is subject to trade agreements with the European Union. A limited spread of infection was still occurring in January 2001, including outbreaks in the traditionally FMD-free area. In some of the later outbreaks the disease was associated with cattle which had illegally crossed into Swaziland. In January 2001, a stamping-out policy was applied with compensation and the outbreak area was fenced in an attempt to limit the spread. A temporary loss of trade is to be expected until the disease can be contained. Trace-back studies disclosed the source to be inside the FMD surveillance zone, which surrounds the FMD control zone around Kruger National Park in South Africa, at a feedlot in Mpumalanga Province that was thought to have been affected by bovine virus diarrhoea. It appears that the infection was introduced to the feedlot from farms in the control zone where clinical disease or serological evidence of inapparent infection were found. The virus involved was genetically similar to SAT 1 viruses isolated previously from wildlife in the southern Kruger National Park, suggesting the origin. Vaccination with trivalent SAT vaccine was repeated in the FMD control zone and its extension to take in the newly infected area. No further cases were detected in this area after early December.