The Ministry for Primary Industries has now completed more than 20,000 tests for the cattle disease Mycoplasma bovis.
The disease, which causes illness in cattle including mastitis, abortion, pneumonia, and arthritis, was first detected in New Zealand in a South Canterbury farm in July.
The bacterium is an unwanted organism under the Biosecurity Act 1993.
By August 29, six farms were included on MPI's list of infected properties - four farms were part of the Van Leeuwen Dairy Group, where the disease was first detected, one farm was in the Oamaru area, and one in Rangiora.
No farms have been added to the list since and there are 19 properties under MPI restricted place notices. The Animal Health Laboratory at Wallaceville, Wellington, has received 23,181 samples and is expected to receive more than 39,000.
