There are 140 000 chickens on the affected farm in the Paardeberg region, according to the provincial department of agriculture head of communication, Petro van Rhyn.
She confirmed that at least 30 000 have died and said the rest would be culled.
The virus has not yet been confirmed as the highly pathogenic avian influenza (HPAI) type H5N8, which is the strain in outbreaks in other parts of the country.
However, the H5 typing, and the nature of its effect on chickens, is indicative of it being the H5N8 strain, according to the department.
In Heidelberg, three ostrich farms have tested positive for avian flu. No birds have died on the farms but they remain under quarantine. The two farms each have about 1000 ostriches.
Van Rhyn said no decision to cull ostriches has been taken yet. She also said chicken in stores was safe for consumption.
Bronwynne Jooste, spokesperson for Tourism, Economic Development and Agriculture MEC Alan Winde, said culling of the rest of the chickens and composting of mortalities had already been started.
Last week, the department’s Veterinary Services programme confirmed the disease had spread to the farm.
“The cause is most likely through contact with wild birds. Since then, meetings with poultry veterinarians and stakeholders such as the National Institute for Communicable Diseases have taken place,” Jooste said.
The farm has been placed under quarantine.
She said farms within a 3km zone of an infected farm would be monitored closely and subjected to the control measures as laid out by the national Department of Agriculture, Fisheries and Forestry (Daff)
“It is strongly recommended that any movement of pet birds, racing pigeons, breeding birds and show birds be limited as far as possible and covered by a movement permit if coming from within 30km of an infected farm,” said Jooste.
Sick or dead birds - both wild birds and poultry - must be reported to local state vets, and exports of poultry and poultry products have been suspended except from poultry compartments registered with Daff, or where a country’s import permit contains clauses that are able to be signed by a certifying veterinarian.
Winde said the virus presented a challenge to control, but the vets were working hard to contain the spread.
“This is a priority for the poultry industry, and the entire agriculture sector. The outbreak and the current drought have made agriculture a tough space to be in.
“This is a particularly difficult time for those affected farms, which are important employers. This is why we ask all stakeholders to continue working with us to mitigate the impact of this outbreak on our economy,” Winde said.
Avian flu is a viral respiratory disease among birds, believed to be transmitted by wild migratory birds. The H5N8 strain of the disease has already wreaked havoc in the poultry industry in Zimbabwe, where thousands of commercial birds have died or had to be culled.
Bomikazi Molapo, spokesperson for Daff Minister Senzeni Zokwana, said South Africa had reported eight further cases of HPAI H5N8 to the World Organisation for Animal Health.
This brings the total number of outbreaks to 24 since June this year.
“All affected properties have been placed under quarantine and disease control measures have commenced,” she said.
The poultry industry raised concerns relating to the principles and guidelines of compensating affected farms during a meeting with Zokwana last week.
The draft guidelines have been completed and are subject to ministerial approval, Molapo said. The approved guidelines will be released by September 1.
“The industry also requested to be given permission to import fertile eggs to close the supply gap as a result of culled birds. Only one company has submitted an application for the importation of hatching eggs; the department is still performing the prescribed risk analyses to determine the appropriate level of risk.
“We need to conduct a thorough risk assessment in order to avoid exposing the country to other disease risks,” Molapo said.
There are two options which will be presented to the poultry industry - the first is for risk mitigation to be conducted in SA through stringent quarantine measures on arrival of the hatching eggs from their country of origin.
The second option is for stringent quarantine measures in the country of origin where eggs will come from compartments free of specified diseases that Daff will approve, with less stringent post-arrival quarantine measures.