To prevent the spread and devastating effects of foot-and-mouth disease, owners of farms within a controlled zone of 10 km around a farm where the disease has broken out can apply to have their foot-and-mouth-free herds vaccinated.
This is a new approach the Department of Agriculture animal health directorate is following for the first time in the Eastern Cape. It is not mandatory, and Dr Mark Chimes of Milk SA says the state will not force any farmer to vaccinate.
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Read more here: Foot-and-mouth: Eastern Cape dairy farms are vaccinating preventively
Only applications from farms within the controlled zone of 10 km will be considered, and farms adjacent to those where animals have contracted foot-and-mouth disease will be given priority.
Chimes explains in a letter to producers that farmers need to realise that any farm where animals are vaccinated against foot-and-mouth disease will be considered a foot-and-mouth-positive farm.
Such a farm is then effectively placed under quarantine, and no cloven-hoofed animals may be moved to or from the farm without written permission from the state veterinarian. The quarantine period lasts for 12 or more months.
Under ideal circumstances, animals that will not be slaughtered, such as breeding and dairy cattle, will be vaccinated with a booster dose four to six months after the first vaccination. Slaughter animals, such as those in feedlots, will be vaccinated only once.
Day zero
For clinically healthy herds that qualify for voluntary vaccination, the day the last animal on the farm is vaccinated for the first time is considered day zero.
For the first six months from this date, cloven-hoofed animals may be slaughtered only at a foot-and-mouth-approved slaughterhouse and must be accompanied by a red-cross permit from the state veterinarian when transported. After six months from day zero, animals can be slaughtered at any slaughterhouse, but must still be transported with a red-cross permit from the state veterinarian, as these farms are still under quarantine.
Animals may not be sold or moved for any other reason unless permission is granted by the state veterinarian. This will be considered only under exceptional circumstances and only between farms with the same foot-and-mouth status.
Milk
As long as a vaccinated farm is classified as foot-and-mouth-positive, the milk will also be considered foot-and-mouth-positive and must be handled accordingly, says Chimes.
All milk from “positive farms” must be double pasteurised or treated with UHT, and milk processors receiving milk from clinically healthy vaccinated farms will lose their export status for as long as they process milk from these farms – unless the processing plant can prove to the state that the infected and clean milk lines are kept completely separate.
Trucks collecting milk from vaccinated farms must adhere to strict biosecurity principles. The process of declaring a farm foot-and-mouth-free can take a long time, Chimes warns.
The entire herd’s blood must be tested for antibodies, and while it is possible to distinguish vaccine antibodies from those of infected animals, the tests can sometimes yield false positive results.
This complicates the interpretation of positive tests in a healthy herd that was voluntarily vaccinated. Calves born to cows and heifers that were vaccinated will acquire antibodies through the colostrum and will therefore also test positive for foot-and-mouth disease in serological blood tests until these maternal antibodies have disappeared from their systems.
To prove that a farm where the animals were vaccinated is ultimately free of foot-and-mouth disease, the blood of calves born two months or more after day zero will first be tested nine months from day zero. This should prove whether a vaccinated farm is truly free of foot-and-mouth disease, says Chimes.
