9 Sep 2021

MPI expecting small number of M bovis infections this Spring

4:44 pm on 9 September 2021

More cases of the cattle disease M bovis are expected this spring, with bulk tank milk testing last month picking up 61 farms requiring further investigation.

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Photo: RNZ / Richard Tindiller

The government has been working to eradicate Mycoplasma bovis since 2018. As part of that work, so far 172,000 cattle from 268 farms have been culled and $209.4 million has been paid in compensation to affected farmers.

Figures from the Ministry for Primary Industries show at moment there are just two farms, both in Canterbury, actively infected with M bovis.

MPI's director of the M bovis eradication programme Stuart Anderson said it wouldn't be surprised to see a small number of new cases this spring.

Anderson said in August, bulk tank milk testing involving 8000 farms nation-wide picked up the possible presence of M bovis on 61 properties. These properties were now undergoing more accurate testing work.

"Thirty of those 61 farms have already been ruled out ... so far there haven't been any confirmed infections come out of that August screening," Anderson said.

"We are expecting that we might we pick up a few, with the direct of travel [of the eradication programme] we would be expecting that it's a smaller number rather than a large number."

The same milk screening programme in August 2020 identified 48 dairy farms requiring further investigation, compared to 43 in August 2019.

According to the ministry, more than 95 percent of farms with a 'detect' result are found to be clear of infection after on-farm investigation is completed.

He said when cows calve their immune systems became a little bit suppressed, making it more likely for the antibodies to come through in screening.

"So yes, spring is a time of year when we do pick up more from the bulk milk screening and some of those do to go through to actually become confirmed infected properties. So we we do think there's still probably a few more out there to find."

Anderson said the higher number of detections this August was not "overly surprising". He said he was confident the eradication programme was making good progress.

"The trajectory is certainly heading the right direction for the eradication."

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