MPI ramps up cow disease investigation

Investigators will start tracking the movement of cows on the Morven farm. Photo / File

The response team charged with containing New Zealand's first known outbreak of the bacterial cattle disease Mycoplasma bovis may know by the end of today if it has spread from the Waimate district dairy farm where it was first detected.

About 65 Ministry for Primary Industries (MPI) staff are working on the outbreak and that number was expected to expand rapidly over the next week.

MPI regional controller Dr Chris Rodwell acknowledged at the weekend there was a chance the bacteria had already left the farm, given the time between the first health issues being noticed in March, when vets were unable to culture anything from test samples, and the official identification of the disease on July 22.

''There's always a chance. That's the difficulty with this particular bacteria,'' he said.

The infected farm, known as ''Tainui'', is in the Morven area and belongs to the Van Leeuwen Dairy Group.

It is one of 16 properties owned by Aad and Wilma van Leeuwen which are now under restricted place notices controlling the movement of animals. It may be months before the notices are lifted.

Sample analysis of about 50 neighbouring farms to the properties in the Van Leeuwen Dairy Group was also under way and those test results were expected to be known by the end of the week.

''We're still only at one confirmed farm at the moment. We're now moving into the surveillance,'' Dr Rodwell said.

The investigators would now start tracking the movement of cows on the Morven farm over the past six months.

Dr Rodwell said that was to see where they might have gone and what they were in contact with.

The farm where the disease was detected has about 1000 cows and ''around 10 to 20% are showing clinical signs that they may contain this bug''. Between 10 and 15 cows have been put down so far.

Dr Rodwell said the test results would be used to help guide the investigation.

Public speculation about how the disease arrived and its location would be rife, but ministry staff could only deal in fact. he said.

The disease, which affected milk production, was made up of complicated bacteria that have no cell walls, making the disease extremely difficult to treat with antibiotics.

He urged farmers to report any suspect cattle to the ministry and when dealing with other farm users to make sure anything entering their properties was clean.

''Clean your equipment. We're not talking about things being shiny, brand new, gleaming in the sunlight. We're talking about getting rid of any gross fecal contamination or any gross mud material then just using a disinfectant spray over.

''We're currently recommending a citric acid. The good thing about this particular bacteria is it's relatively easily killed by that particular product.''

Response team veterinarian Richard Laven told a meeting in Glenavy last Friday, attended by about 200 people, the disease was primarily spread by animal to animal contact.

''Everything else is much less risk. If you've got an animal on one side of your fence and your cow is on the other side of the fence and they're snorting at each other, they're going to be spreading the disease to each other.

''If one cow walked down the road last week and your cows walk down the same road next week, even if there's still dried manure on the road, the risk is extremely small.''

- Otago Daily Times