The Ministry for Primary Industries (MPI) and its dairy industry partners will extend the Mycoplasma bovis milk testing underway in Canterbury, Otago and Southland into a national milk surveillance programme from February.
Mycoplasma bovis is commonly found in cattle globally, including Australia. It does not infect humans and presents no food safety risk, but can have serious effects on cattle, including mastitis, pneumonia, arthritis and late-term abortions.
In July, MPI said the disease had been detected in a dairy herd in South Canterbury, the first known outbreak in New Zealand, on two of 16 farms belonging to Van Leeuwen Dairy Group.
Around 4,000 cows have been culled and thousands of tests completed. Earlier this week, it was found on a farm in Ashburton, bringing the total number of infected properties to 14.
In a statement, MPI said that "while there is no indication that the disease is present beyond the areas currently identified, checking for other possible regional clusters is essential to building a complete picture of the disease in New Zealand."