The Ministry for Primary Industries' testing programme has identified one new property as positive for the bacterial cattle disease Mycoplasma bovis.
The newly identified property is a Van Leeuwen Dairy Group farm which was already under a Restricted Place notice under the Biosecurity Act.
"We've said all along that we fully expected the possibility for further farms within this enterprise testing positive. The nature of this disease is that it spreads between animals that are in close, repeated and prolonged contact", says Response Incident Controller Stephen Bell.
"The disease doesn't always present symptoms and often doesn't show up through just one test. This is why we developed a testing protocol which tests herds up to 3 times at 3 to 4 week intervals. Testing like this, over 2 to 3 months gives us the confidence we need that we have definite results for each farm. This latest detection is evidence of that protocol working.
"It has meant there has been a long period of disruption and uncertainty for farms that are being tested but we have to be absolutely thorough in diagnosing positive and negative farms. It's important for New Zealand that we take that time to get accurate results", he says.
The testing programme
The testing programme for Mycoplasma bovis continues at pace with over 26,000 of the planned 39,000 tests now completed by MPI's Animal Health Laboratory at Wallaceville. These tests have been focused on the infected properties, stock movement traces from and to those properties, and the neighbouring properties. Mr Bell says no adjacent properties have, as yet, been identified as infected.
"We're not just relying on these tests though, we've been taking a multi-layer approach to testing to find out how widespread Mycoplasma bovis is.
"District-wide surveillance in Waimate/Waitaki has been part of this. Bulk and discard milks were collected from approximately 260 farms in the area and tested. All these results are now back and no further infection outside the Van Leeuwen Group has been found on farms in this area.
"There has also been a nationwide testing programme. Samples of mastitic milk have been collected from regional labs across the country for testing. To date approximately 2,300 samples have been received, these tests have also not identified any other infected farms elsewhere in New Zealand.
"Taken together, these results are encouraging and suggest that our surveillance plan is working and this disease is not spreading in the local area around the infected farms and is not widespread across the country".
Mr Bell says that while the sampling and testing programme continues MPI is also preparing for what might happen next.
"This involves preparing plans for the different possible scenarios. Eradication is one of the scenarios we are looking at, but before we can make decisions we need to have enough evidence to be confident that the disease has not spread elsewhere", he says.
"We cannot make long-term decisions that potentially have huge impacts on people’s lives without that knowledge. We need to be confident the disease is limited to the outbreak on the farms where we have detected it.
"As our picture grows and as more and more test results come back, the greater our confidence that the disease is being well contained on the known infected properties.
"We hope to have a clear picture by mid-October.
"If samples continue to test negative for Mycoplasma bovis and if the evidence is pointing to the infection being contained to the current properties and not having spread wider, we would expect to have sufficient confidence to assess whether this disease can be eradicated.
"We know this is an enormously stressful time for the impacted farmers and also for the wider farming community. We are carrying out all our work with urgency to limit the impact on the farming community as much as possible.
"We will be very open about the status of the response and whether eradication will be possible or not. In the meantime we continue to encourage all farmers and rural contractors to help protect their farms and businesses by following standard on-farm hygiene best practice."