Independent review on M. bovis spread in Wakanui is published

An independent expert review into Mycoplasma bovis infection in Wakanui, mid-Canterbury, shows appropriate steps are being taken to remove infection in the area, says programme director Simon Andrew.

The review was commissioned by the Programme’s partners, MPI, DairyNZ, and Beef + Lamb New Zealand, in mid-2022 after it became apparent that infection was circulating in a small geographical area despite the use of disease control measures, which have proven successful in other areas around New Zealand.

“The review, carried out by independent epidemiologist Dr Jonathan Happold, has endorsed the approach we are taking in the Wakanui area,” Mr Andrew said.

“While the review did not confirm the sources of infection in Wakanui it notes that the area has been unique to other parts of New Zealand, which have experienced M. bovis infection.

“Wakanui had a large, concentrated and dynamic population of infected animals within the local feedlot and there was a small cluster of Confirmed Properties, most of which have paddocks within 1.5 km of the feedlot.”

Dr Happold concluded the unusually high amount of infection on the Five Star Beef feedlot could have allowed for airborne transmission that is highly unlikely to have occurred in other areas of New Zealand.

“The review has not determined the transmission routes occurring in Wakanui with any certainty, and it is possible we may never be able to categorically say what the transmission route is,” Mr Andrew said.

“What we do know is, eradication is not dependent on knowing the transmission route. What is important is that we remove the infection from the area which is exactly what we’re doing.”

As part of the review, Dr Happold also looked at a range of transmission routes including mechanical vectors such as birds and flies, manure, effluent, and groundwater. He has concluded infection is unlikely to have occurred via these routes.

“Dr Happold supports the depopulation plan for Five Star Beef and the use of a Controlled Area Notice (CAN). He made several recommendations and most of these have already been implemented.”

Mr Andrew said the eradication effort continues to make good progress. The high-risk area of the CAN is now free of cattle and the CAN is on-track to be lifted in mid-March.

“It is expected all current Confirmed Properties are likely to be cleared within the first half of this year,” Mr Andrew said.

“While the job is far from over, we are as close to moving to the next phase of the eradication as we have ever been and the collective effort from farmers, industry and Programme staff has helped us get to where we are today.”

Source: Ministry for Primary Industries




Author: Bob Edlin

Editor of AgScience Magazine and Editor of the AgScience Blog