The Ministry for Primary Industries' testing programme for Mycoplasma bovis continues at pace with over 15,000 tests now completed by MPI's Animal Health Laboratory at Wallaceville.
Response Incident Controller Dr Eve Pleydell says the overwhelming majority of the tests have come back negative, with positive results so far only being found on the 6 known infected properties.
"Farm testing may be carried out up to 3 times at 3-4 week intervals before there is a definite result for each farm but the results so far are encouraging.
"All the current infected properties have direct links to each other through animals moving from one farm onto another and disease passing between animals that are in close, repeated and prolonged contact. There have been no cases of infection by any other means. Despite intensive testing, no neighbouring properties have as yet been identified as infected", she says
The tracing and testing programme
"As part of our tracing and testing programme we are continuing to contact individual farms where there may be a higher chance of the disease being present because they have received cattle from an infected property in recent months.
"We are also testing animals on farms that are neighbours to an infected property, to make sure we get a complete picture of any local spread of this disease. So far, no positive results have been returned from any neighbouring farms, which is very good news."
Dr Pleydell says MPI has a wide range of checks and testing underway to make sure they get as complete a picture as possible of where this disease is. As well as the checks on the infected properties, neighbours and trace properties, the Ministry also has a regional and national testing programme.
Comprehensive regional and national testing
"We are taking a multi-layer approach to testing to find out how wide spread Mycoplasma bovis is", she says.
"This approach has 3 layers that we are calling response surveillance, district surveillance and national surveillance.
"Response surveillance is focussed on the infected properties, stock movement traces from and to those properties, and the neighbouring properties.
"District wide, there is a Waimate/Waitaki survey run as a collaborative programme between MPI and a number of industry groups to screen the milk from animals in those districts. Bulk and discard milks are being collected from approximately 260 farms in the area and being tested. No positive results have been found on uninfected farms in the area.
"National wide testing is also multi-layered. Firstly, any farmer who has contacted their vet about possible Mycoplasma bovis disease in their herds are tested. Vets across the country are identifying any farms on their books with a history of recurrent mastitis and other signs that could be a result of Mycoplasma bovis infection. In addition to this, samples of mastitic milk are collected from regional labs for testing. To date approximately 1000 samples have been received, these tests have also not identified any other infected farms."
"Taken together, these initial surveillance results are encouraging and suggest that this disease is not spreading in the local area around the infected farms and is not widespread across the country. We will continue with our testing programme until we have enough evidence to be highly confident that the disease has not spread elsewhere.
"If farmers have not been contacted by us, then it means they are not in any of these groups and are at considerably less risk of the disease being on their property. It's a case of 'no news is good news'. If you don't hear from us, it means this disease is not of immediate concern for you".
Supporting farmers in the affected areas
"We've heard there have been cases of farms in South Canterbury and North Otago having contracts cancelled with customers looking at sourcing stock from other parts of New Zealand. This is disappointing and is not justified based on what we know of the current pattern of disease.
"What the South Canterbury and North Otago farming communities need right now is support. As much as possible, business needs to continue as usual. We realise that this is a worrying situation for farmers across New Zealand but business decisions need to be evidence-based and grounded in fact.
"We have no evidence of any means of disease spread other than from close animal contact on a farm at this stage. This includes no evidence that the disease has jumped fences and infected animals on neighbouring farms. Our scientists and vets also tell us this is unlikely to occur because the disease is usually spread by repeated and prolonged contact between animals.
"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 are confident our control measures are sufficient to contain it there as we continue to gather the evidence necessary to assess whether this disease can be eradicated".
Contain and eradicate
"Along with the animal industry bodies, we remain committed to continuing the biosecurity response, finding any further infected properties if they are out there, controlling the disease and, if possible, eradicating it from the country.
"We encourage all farmers and rural contractors to help protect their farms and businesses by following standard farm hygiene best practice."