New Zealand seems to be winning so far in its world-first attempt to eradicate the serious cattle disease Mycoplasma bovis, but there's more than a year's hard work still ahead, says the agriculture ministry's chief science advisor.
Dr John Roche said 14 months into the near-$1 billion eradication drive, he's still optimistic of a win because none of the alarm signals that could be expected have shown up.
"I can only answer that question at a point in time but yes, all the indications are that we are winning.
"But it's important that people realise this is a long game. We have another 12 to 18 months of heavy lifting ahead, tracing and casing farms, depopulation and from there we enter into longer-term background surveillance."
Roche said the technical advisory group assisting the ministry, comprising some of the world's top mycoplasmologists and veterinary experts, assess all information gathered to provide their best ongoing estimates on whether the disease can be eradicated.
"All indications are that is true. We have not found a massive cluster of farms we didn't anticipate. We haven't found an alternative strain we didn't anticipate. We haven't got any evidence it was here prior to late 2015.
"All of these things give us confidence that we can still eradicate."
Latest available ministry data says 108,182 cattle have been killed and 179 farms have been confirmed as infected. Of 1233 farmer claims for compensation, 878 have been paid in full or part, totalling $83 million. The value of assessed claims so far is $97.6m.
Claims are taking an average 28 days to be paid and 795,359 tests have been completed.
The Government, in agreement with the dairy and beef sectors, decided in May last year to try to eradicate M. bovis at an estimated cost of $870m over 10 years.
Taxpayers are down to pay $591m, the dairy sector $262m and beef farmers $17.4m. Farmers will pay through levies agreed with their industry-good sector organisations.
Recent reports suggest the taxpayer bill has passed $200m.
Separate to the eradication budget, the ministry has allocated $30m to fund the science effort over two years. Roche, who had yet to join the ministry when the eradication decision was made, said a science plan has been developed within that allocation, with diagnostics work a priority.
Unless "something absolutely genius comes out of that which greatly increase the opportunity to eradicate", he's confident the team won't have to go back to the Government for more money.
He said the science programme has sufficient resources but noted many of the expert advisors in New Zealand and from overseas were donating their time and work to help.
M. bovis causes incurable mastitis, arthritis and respiratory issues and is endemic in the herds of New Zealand's trading partners. It is highly resistant to antibiotics and cannot be passed to humans.
Roche said New Zealand has only one identified strain of M. bovis. The ministry is working with researchers in Australia, the US and Europe to try to determine where it came from. How it got into New Zealand is still not proven.
Because the disease is endemic around the world there hasn't been much research on it and the knowledge around its genetics is sparse, he said.
The decision to try to eradicate the disease through killing infected cattle rather than managing it as overseas farmers do has caused Kiwi farmers huge distress and financial difficulty as their animals and herds, some bred up over many decades, have been ordered to be killed. The trauma has been amplified by the fact many animals had not shown any physical illness but were identified by ministry testing.
Federated Farmers dairy chairman Chris Lewis has said the "why" of the campaign has become lost this year in farmer anger over a ministry testing and movement restriction upsurge just as the June dairy season was about to start.
The Herald asked Roche to recap why eradication was being attempted.
"Mycoplasma bovis is an incredibly debilitating disease. From an animal welfare perspective that's a key reason for eradication.
"The economic analysis done ... suggested it would be cheaper to eradicate than to live with it over the 10-year timeframe.
"And third, it's important to remember that under the Biosecurity Act we are compensating people for losses ... if we were to just go to long-term management, people would be dealing with the losses themselves.
"Yes it is tough and I don't for a second want to belittle the angst and some of the suffering that people caught up in the response are going through.
"But if we didn't eradicate you'd have people equally challenged and anxious having to deal with an outbreak on their farm on their own, at their own cost."
The ministry was keeping an eye on vaccine developments around the world but no Government science work on vaccines was being done here, Roche said.
Vaccine use would be a problem in an eradication response because it wouldn't be possible to tell the difference between naturally infected animals and those vaccinated.
Also, using a live vaccine in the place you were attempting to eradicate a disease wasn't a good idea.
Research on the use of dead or attenuated vaccines, where the virulence of the pathogen was much reduced, had shown they were basically non-effective, Roche said.
And just as a human flu vaccine didn't stop people getting the flu but prevented them getting very sick with it, M. bovis vaccines used overseas didn't stop animals getting infected or halt the spread. The aim was to reduce sickness and limit productivity loss.
If eradication is successful, what's to stop the disease getting back into the country?
Roche said live animal shipments were the greatest risk and they had been stopped by the Government.
Strict biosecurity regulations around importation of equipment used in the livestock sector would limit that risk.
Another possible entry pathway was through imported semen and embryos.
"Everyone seems to talk about that being the route but there's no confirmation that has been the route of infection (here).
"We have a research programme which is looking for scientists in New Zealand or anywhere in the world to provide us with a mechanism to allow us to test with confidence semen or embryos in a non-destructive way. We don't want to damage them. But that would give us confidence it won't come in by any legal means."