Visitors to the Agritech Expo Zambia 2018 at Chisamba in Central Province entered a declared foot and mouth disease (FMD) zone en route to the expo recently.
The affected areas of Chisama and Chibombo had 5 000 recorded cases of FMD by the 16 April, according to The Times of Zambia. Vehicles driving into the showgrounds stopped to have their tyres sprayed with a viricide and there were checkpoints along the road at which beds of straw were continuously sprayed.
Slaughter of cattle, sheep, pigs and goats has been prohibited and movement of animals and their products in and out of the infected areas stopped. The Zambeef dairy farm, which supplies 40% of Zambia’s raw milk, is closed for milk sales and butcheries in the area are not operating.
The Central Province FMD outbreak had infected (confirmed) 10 farms by 13 April, according to Alex Woodley, farmer in the area and a member of the FMD task team. Woodley said serotype O antigens had been identified in tests and ring vaccination in a 25 km circle from the first incidence of FMD, would commence as soon as vaccine arrived in the district.
Infected cattle were recovering from the disease and there were no mortalities thus far, said Woodley. “The district vet, Dr Sydney Kalinga, is in charge here and he has a good handle on the outbreak,” Woodley added.
VACCINATING AGAINST FMD
FMD is a highly contagious viral disease that is notoriously difficult to contain. It causes production losses and a decline in milk yield, but is generally not fatal. Initial signs of the disease are salivating and limping, and a closer look will show lesions in the mouth and on the feet.
The economic losses during an FMD outbreak are mainly due to a clamp down on animal, and animal product, movement by state vet departments as they try to contain the spread of the disease. Live animals, and animal products, from an FMD zone cannot be exported as no other country will accept them.
The primary drive in an FMD outbreak is to stop the virus from spreading by sanitation, biosecurity, restricted movement, quarantine and culling. The secondary drive is to regain disease-free status as soon as possible.
Since FMD is endemic to Zambia with periodic outbreaks occurring, there can be no disease-free status for the country and it makes sense to vaccinate. Indeed there are regular FMD vaccination campaigns in the country. In 2012 more than a million cattle were vaccinated against FMD in Zambia.
The vaccine must be strain specific which is why it is important to identify the serotype. There are vaccines available that offer protection against 3 and even 4 strains.
There may be a problem with farmer resistance to the FMD vaccine because it elicits an antibody response that cannot be differentiated from the antibody response elicited by the disease. Tattoos customarily used to mark vaccinated animals show that they have been vaccinated rather than infected.
CHECK THE SOURCE
Rumours have circulated in Zambia that buffalo, with carrier status, may have been responsible for the outbreak, but this seems unlikely since buffalo in southern and central Zambia more typically present with FMD SAT (southern African territories) 1, 2 or 3.
Minister of Livestock and Fisheries Kampanda Mulenga said the disease appeared to have come from the east and had spread to northern Zambia and to the Central Province regions. Mulenga stated that serotype O had not been isolated to buffaloes and that it was maintained and spread by cattle.
This is not entirely correct since serotype O has been isolated in buffalo in various sample studies in Zambia and Tanzania. According to a 2015 survey on buffalo in Zambia, published in the Journal of Veterinary Medicine, SAT 1, 2,3 and serotypes O and A circulate in the country’s buffalo populations.
The survey found that most of the outbreaks of FMD in the sub-Saharan region are due to SAT serotypes with fewer introductions of A and O serotypes. Mulenga said this was the first time serotype O had spread southwards into central Zambia.