The Department of Agriculture, Forestry and Fisheries announced on Monday that an outbreak of African swine fever has hit a fourth province and has now been found in Gauteng, North West, Mpumalanga as well as the Free State Province.
The department said African swine fever was detected in Heilbron in the Free State.
The World Organisation for Animal Health describes African swine fever as a severe viral disease affecting domestic and wild pigs which can cause serious production and economic losses. There is currently no known approved vaccine for African swine flu.
"Veterinary services together with the industry are conducting follow-up investigations to trace the origin of the disease and to identify other farms that may possibly be affected," the statement said.
The statement said while African swine fever does not affect humans and the consumption of pork is safe, any meat and products from affected pigs can be a source of infection to other pigs.
"Farmers should therefore ensure that, if any swill is fed to pigs, [that it] must be pre-cooked for at least an hour. This will ensure the inactivation of the African swine fever virus, as well as other diseases of concern," the statement said.
The department said farmers are requested to be vigilant and report any sudden illness and deaths of their pigs to the local state veterinarian.
The department advised that pigs should be bought only from reputable owners, and that buyers should insist on a declaration from sellers that the pigs come from a healthy herd. Pigs should also be enclosed to prevent contact with other pigs whose health status may not be known.