The farms are under quarantine and the affected animals will be slaughtered.
The National Animal Health Forum (NAHF) said it had been notified of the positive brucellosis tests only on Tuesday night and was still gathering information.
Nelson Mandela Bay councillor Andrew Whitfield, who heads up the metro’s agriculture portfolio, said this was the first he had heard of it.
“We have not received any information about quarantined farms, but we will look into the matter urgently,” he said.
“We will also be in contact with the Department of Public Health so that it is made aware of the situation.”