TB leaders meet Otago farmers to plan eradication

Date 4 September 2019

Otago farming leaders gathered in Middlemarch recently to plan the end of bovine tuberculosis in the Strath Taieri-Maniototo area.

Bovine TB has affected both domestic herds and wildlife in the Strath Taieri for more than 30 years, and still affects a few herds in the wider area.

OSPRIi committee chairman Marty Deans, of Barewood, said a fresh energy at the farmer-funded disease management company would lead to TB being eradicated from livestock herds in the area by 2026, and from possums and other wildlife by 2030.

The Strath Taieri Tb Management Area covers 175,170ha and encompasses the drylands around Middlemarch and the eastern faces of the Rock and Pillar Range through towards the Pigroot in the northeast.

It features a mix of tussock, scrub and improved farmland.

Bovine TB and the risk it still poses to farming in the region has come into fresh focus now the TBfree eradication strategy, adopted in 2016, focuses on getting rid of the disease rather than just managing it.

When biological eradication of TB from New Zealand became the objective, the Strath Taieri-Maniototo area became a Tb focus area and is now highlighted as a priority for achieving TBfree's goals.

After a long spell with no broad-scale possum control being conducted within the Strath Taieri-Maniototo area, due to this locality not being a priority under the 2011 TB Plan, intensive possum control was implemented during 2018-19 for the first time in many years.

Several thousand possums have been caught so far by both pest control contractors and by research staff working on TB-related projects in the area.

While the sheer numbers of possums being caught has surprised both contractors and researchers alike, local farmers have known for a long time through their own hunting efforts that this drylands country can support high possum populations and this was confirmed during the Middlemarch gathering.

Surveys of ferrets and pigs as sentinels of TB infection in possums, New Zealand's primary maintenance host of TB, have also been implemented over 126,000 ha of Strath Taieri-Maniototo during the past two years with 302 ferrets and 180 pigs recovered, and nine ferrets and four pigs were infected with Tb.

This information, along with herd and wildlife infection TB strain typing matching, and confirmation of high-density possum populations easily able to maintain TB within the area, have all pointed to the fact that TB was established in wildlife.

Working with TBfree programme veterans Phill Hunt and Peter McNab, Marty Deans hosted the August meeting in Middlemarch so the farming community and OSPRI could listen and work together to plan eradication activity.

''The meeting was called to inform the farmers in the area about the OSPRI plan for the next couple of years to be on track to eradicate TB in this area, remembering that this area was also going to be one of the last areas to have Tb eradication,'' Mr Deans said.

The committee led a tour of Rocklands Station in Strath Taieri and a visit to Strathavon Station near Middlemarch.

The meeting heard from OSPRI's disease team led by Kevin Crews, chief executive Steve Stuart, scientific research leader Graham Nugent and contractors who manage possum control and ferret research.

Manaaki Whenua Landcare Research has led work on the role of ferrets in spreading TB and researchers said OSPRI needed to conservatively assume ferrets could lengthen the time taken to eradicate TB in this type of landscape once Tb was eradicated from possums. A recommended tactical approach would be to implement ferret population reduction, where TB is found in ferrets, once OSPRI was confident that possum populations had been controlled to a level that would break the Tb cycle within possums.

The Middlemarch gathering confirmed the unique and complex nature of this drylands landscape from a TB-eradication perspective and that a custom-made tactical approach would be required.

Otago TB meet 1

Farmers and farming leaders got together at Rocklands Station, Strath Taieri, to plan the end of bovine tuberculosis.