Mycoplasma bovis 'not highly contagious' says MPI vet

Government officials have sought to allay the fears of North Canterbury farmers about Mycoplasma bovis.

Nearly 200 farmers turned out at the Amberley Pavilion recently to receive an update from Ministry for Primary Industries (MPI) and industry representatives, who addressed some myths about the bacterial infection which the Government hopes to eradicate.

MPI incident response controller David Yard acknowledged the response had been slower than farmers would like, but the biggest challenge was tracing cattle movements from infected herds, as farmers' Nait records were not always up to date.

Farmers raised concerns about the risk of the disease arriving on-farm from bought-in stock or from transport trucks or contractors.

Fellow MPI official and qualified vet Dr Paul Bingham said a commercially available blood test for Mycoplasma bovis was not far away but he warned this could produce "false positives" as there were other Mycoplasma diseases and the only way to be sure was through regular testing.

Swab testing was also available, but taking a swab from a bull's throat was not easy.

MPI officials Dr Paul Bingham (left) and David Yard (right), were joined by DairyNZ's Tony Finch to address farmer concerns about Mycoplasma bovis at a meeting in Amberley. Photo / David Hill

He said 38 infected properties had been identified at that point and MPI modelling predicted about 190 herds would need to be eradicated out of more than 20,000 dairy and beef cattle herds across the country. Just one infected property has been confirmed in the Hurunui district.

M.Bovis was "not highly contagious" and the risk of spreading the disease from cattle trucks was low, Dr Bingham said.

"It does require pretty prolonged contact with infected animals, so walking over the same path or travelling in a truck after infected animals would present a low level of risk."

A bigger risk was feeding infected milk to calves, so testing milk was essential.

The lack of certainty around test results and the resources needed to repeatedly test every cow or bull meant the only way to be certain of eradication was to cull an entire herd which had confirmed cases, Dr Bingham said.

"We are trying to eradicate it because we don't want it," Mr Yard said.

"And if we don't eradicate it, and it's possible we won't succeed, the costs to manage it will be ongoing."

Mr Yard said MPI would work alongside farmers when culling herds "to minimise the impact" and compensation was available.

"Farmers on IPs (infected properties) can complete the season or keep bull calves for six months to fatten them, but it will be controlled and when they come to move stock to the works it will be by permit."

There was no evidence of any risk to human health, and other livestock such as sheep and deer appeared to be unaffected.

While there had been no directive preventing cattle from being transported to agricultural shows or calf days, Mr Yard questioned whether "the benefit would outweigh the risks".