Bovine tuberculosis (TB) has turned up in a small dairy herd near Matamata, in the Waikato.
The identification of a cow showing symptoms of bovine TB infection late in 2016 triggered a programme of responsive testing of dairy cattle and the slaughter of a small number of calves, OSPRI - an organisation formed to eradicate the disease - said.
OSPRI national disease manager Kevin Crews said the animal was found at a routine post-mortem inspection at a slaughter facility.
The infection was confirmed with laboratory testing and herd tests continue to be conducted on the farm concerned.
OSPRI immediately introduced measures to restrict animal movements in the area, it said.
The area had been considered TB-free, with no recent history of infection.