Three new properties have been identified as being infected with the Mycoplasma bovis bacterial cattle disease, bringing the total to 17, but the Ministry of Primary Industries still believes eradication is possible.
"Eradication still remains our prefered option. We have containment at the moment of the infected places to prevent further onward spread. Our belief is that the infection hasn't been in the country for a large number of years and eradication is still firmly on the table," David Yard, MPI incident controller, told BusinessDesk.
"Clearly if it had been established and been silently dormant for 10 years or so, spreading from animal to animal, we would find it on a lot more farms or herds," he said.
Mycoplasma bovis was first confirmed in July on two farms in South Canterbury, marking New Zealand's first official outbreak of a disease that is present in many other countries.
While the disease presents no food safety risk, it can cause a range of symptoms in cattle including mastitis that doesn't respond to treatment, pneumonia, arthritis and late-term abortions. There are now nine infected properties in South Canterbury, five in Southland, two in Ashburton and one in Hawkes Bay.
Given it was detected seven months ago, 17 confirmed farms is "not a huge number" when you look at the number of dairy and even beef farms across the country, Yard said.
There are about 12,000 dairy herds in New Zealand but some farms will have more than one herd.
According to Yard, a national milk testing programme will help determine whether there are any other pockets of infection in the country.
Under the testing regime - slated to start in February - every dairy farm will provide three milk samples, one from bulk milk and two from discarded milk unsuitable for collection, for example, from cows with mastitis.
Yard said the results should be ready by the end of March and "if we suddenly found that we have another 10 different pockets then that might change the ball game. We might say eradication is off the table and we are moving to containment or long-term management but that's a very long bow to draw at the moment," he said.
Agriculture Minister Damien O'Connor also said the goal is eradication. "There is a willingness out there to do whatever it takes to eradicate Mycoplasma bovis. This remains our focus," he said in a statement.
MPI's Yard said the ministry is not "chasing the disease as it spreads" but rather the increased number of infected farms is a reflection of MPI's tracing and testing: "We are actually picking out properties that were probably already infected and we just now know about them."
However, MPI expects to find more. "We do logically expect that because of the severity of the disease, in some areas, particularly down in the Southland area, further properties because the animals were quite heavily infected and there are have been large number of movements of young susceptible animals," he said.
In an earlier email Thursday MPI said "we expect that more properties will become positive as our tracing and testing programmes continue to ramp up. From one farm in Ashburton alone, we anticipate tracing some 30 additional properties." Not all, however, are necessarily infected.
Yard also said MPI is progressing with compensating affected farmers but that there is a process to be followed. He declined to give a dollar figure but said "obviously the cost escalates on a day-to-day basis because every time we serve a notice, those people are entitled to compensation."
While it is difficult to estimate the final amount "it's going to be quite a large sum," he said.