No other country has done it before, but New Zealand is on the brink of eradicating the cattle disease mycoplasma bovis. It's come at a heavy emotional and financial cost to farmers - what lessons can be learned?
The first day of winter is a big day in the dairy farming calendar: moving day.
1 June is when dairy farmers around the country move thousands of cows to new pasture for winter grazing or new sharemilking contracts.
But unlike the past few years, the threat of mycoplasma bovis won't be looming so large, with just one farm - a large beef feedlot near Ashburton - still infected with the disease.
The Detail talks to Professor Richard Laven from Massey University's School of Veterinary Science - an expert in farm animal production.
What is mycoplasma bovis?
It's a bacterium found mostly in cattle and occasionally other animals like deer and sheep. Laven says it lives in the lungs and respiratory tract, and it's usually passed on through nose-to-nose or other close contact between cattle.
M. bovis can also get into the udder and cows can pass the disease on to calves through their milk. Laven says this is almost certainly what happened in New Zealand.
In calves, M. bovis can cause pneumonia and it's difficult to treat. In adults it can cause mastitis and arthritis.
But the majority of cattle show no symptoms of the disease.
It hadn't been found in New Zealand previously.
When was it discovered in New Zealand?
M. bovis was first found on a farm in south Canterbury in 2017.
However, the disease was spreading on farms before that - the Ministry for Primary Industries believes it may have arrived in the country in late 2015 or 2016.
Laven says the majority of infected farms have shown no clinical signs of the disease, which is likely why it took so long to be detected.
Do we know how it got in?
No. The Ministry for Primary Industries has looked into it but hasn't been able to pin down the source. Laven says all of the possible scenarios are considered low risk.
"We won a very bad lottery where we had a disease that was very unlikely to come in and it came in."
New Zealand wasn't importing live animals - the most obvious way M. bovis would arrive in the country. It could have come in on semen, but again, Laven says that's also very low risk.
Genetic analysis shows the disease didn't come from Australia and Laven says it's most likely it came from Europe.
"How, we don't know and I suspect we'll never know."
Why did New Zealand try to eradicate it?
The plan to eradicate M. bovis was announced in 2018. It was expected to take 10 years and cost just under $900 million, with the price tag split between the Government and industry bodies.
No other country in the world had attempted to eradicate the disease. At the time, Prime Minister Jacinda Ardern said the decision was taken to "protect the national herd from the disease and protect the base of our economy".
The Government said not acting would have cost the industry $1.3 billion in lost production over 10 years, with ongoing productivity losses across the farming sector.
All cattle on infected properties were culled and farmers were able to access compensation for loss of stock and production.
To date, 272 farms have been found to have the disease and more than 176,000 have been culled. More than $220 million has been paid out to farmers.
There is one last farm infected with M. bovis. It's not clear at what stage New Zealand would declare itself free of the disease, but Laven says ongoing testing and monitoring will be required.
Has it been worth it?
A few weeks ago, Ardern said: "Had we not though chosen to undertake this programme of eradication, the cost to the economy and the primary sector would have been in the billions".
However, it's taken a heavy emotional and financial toll on farmers.
An Otago University study found the Government's response to the M. bovis outbreak was poorly managed and caused significant and lasting trauma for farmers who had their herds culled.
The Ministry for Primary Industries has previously apologised to farmers for the handling of the response.
"I think the issue hasn't been anything to do with the science of the programme, it's been to do with the implementation of the programme and the not listening to farmers...the dealing with the people wasn't good enough," Laven says.
"Any farmer who has his cows culled because of a disease on a farm that hadn't shown any clinical signs, if that's not heart-breaking for them, then they shouldn't be doing dairy farming.
"Cows are not just machines that can be replaced, they are living, breathing animals and part of being a good farmer is understanding that."
Find out how to listen and subscribe to The Detail here.
You can also stay up-to-date by liking us on Facebook or following us on Twitter.
