Gauteng officials have warned farmers of a new outbreak of African swine fever, after it was detected in an informal set up in the Swaniesville area.
A group of about five pig owners were affected, the Gauteng Department for Agriculture and Rural Development said in a statement on Wednesday night.
There around 1 000 pigs in the area and the culling process was still pending.
African swine fever is a virus that affects both domestic and wild pigs. Wild pigs, such as bush pigs, warthogs and European wild boars are considered reservoirs for the disease as they don't show signs of infection, but are able to infect other pigs they come into contact with.
The disease is also spread by soft ticks that are found in warthog burrows.
Signs of the disease in animals are, among others, fever, loss of appetite, lack of energy, vomiting, diarrhoea, swollen red eyes, laboured breathing, coughing and sudden death.
Fin24 reported that outbreaks had been found in Gauteng, North West, Mpumalanga and Free State.
The first reported outbreak in the province was in April this year, when some informal pig keepers on the outskirts of Daveyton bought pigs at an auction and reported unusual deaths a few days later.
A total of 257 pigs belonging to 19 communal pig farmers were culled.
The department said the next outbreak was reported in May when a small-scale farmer in Vanderbiljpark introduced infected pigs he had bought into his farm.
A total of 96 pigs were culled on this farm and disposed of.
A further three outbreaks were reported, with the last at the start of the month on a farm in Nigel.
The department, together with other affected provinces, directed that no pigs be sold at auctions until the outbreak was declared over in Gauteng.
"The unintended consequence of this disease control measure was curtailing the sale of pigs other than through registered abattoirs," it said.
A system was also introduced for issuing movement permits for farmers who wished to get their pigs to abbatoirs for slaughter.
Pig farmers should contact their local state vet for these permits.
The department was in the process of procuring pig feed to small-scale farmers to buffer against losses resulting from the inability to sell their pigs.
There was also an ongoing awareness drive.