Mycoplasma tests uncover low numbers

Mass testing of milk from all dairy farms this spring has so far turned up only three properties with the cattle disease Mycoplasma bovis.

The testing has been carried out over the past 12 weeks, starting at the top of the North Island, and is nearly finished in the South Island.

Ministry for Primary Industries principal scientist Dr John Roche conceded that several months ago there were some doubters within MPI and elsewhere over the possibility of eradication.

‘‘If you went back a couple of months before we started the spring milk testing, there were a number of people who were concerned we would learn stuff this spring that would make us change our minds.

‘‘Even those of us confident we could eradicate it expected to see a greater outbreak. But now you won’t find too many dissenting views,’’ Roche said.

Part of the reason why so few cases were being detected was the time between infection and identification had become so short that animals were not spreading beyond infected farms.

Roche said he was personally committed to eradication after his experience in the United States a decade ago when he was working on a dairy farm with the disease.

Roche said scientists were confident M bovis was a recent arrival, despite persistent claims it has been in New Zealand for more than a decade.

Two threads of evidence support the official narrative. One is a bulk milk sampling across the country carried out in 2007, which failed to detect the disease, the other recent DNA testing of the bacteria.

In 2007 scientists and officials from the former Ministry of Agriculture random-tested the milk of 244 herds for the presence of the disease, but detected nothing. Other evidence related to the DNA testing of the bacteria.