Black market cattle sales and lack of compliance with animal tracking rules have undermined the fight against the spread of Mycoplasma bovis.

Biosecurity officials say that the unauthorised movements of cattle has made containment difficult and led to the spread of the illness.

The disease, which has already led to the culling of thousands of cows, has spread "beyond all expectation" in the last six days, biosecurity officials say.

The number of farms under regulatory control for Mycoplasma bovis disease has jumped from 130 properties to 290 over that period, Biosecurity New Zealand head Roger Smith told MPs at a briefing at Parliament this morning.


That meant movement of cattle was being restricted while testing for the disease was being carried out.

It is now possible that Mycoplasma bovis may not be eradicated, and officials will instead have to work on containing it instead.

So far, 38 properties have tested positive for the disease in the North and South Islands. It can cause serious conditions in cows including untreatable mastitis, pneumonia, arthritis and late-term abortions.

The first case was detected 300 days ago in Oamaru. But Smith said the number of farms requiring testing had hugely increased in the last week.

"The spread has, in the last six days, gone totally above all expectations in modelling," he said.

It was unclear whether it was a one-week blip or whether the disease was reaching epidemic proportions, he said.

Biosecurity NZ's director of response services Geoff Gwyn said the extent of the disease's spread would become clear in the six to 12 days.

For now, biosecurity officials were still focusing on eradicating the disease. But Gywn conceded that focus may have to switch to containment.


"What's happened over the last six days is that long-term management or containment is probably getting a little bit more of our thinking than perhaps it was six days ago."

It was not still known where the disease originated from.

DNA strands need to be compared to strands held in overseas laboratories, and because M. Bovis was not of great concern to other countries there were limited places where this could take place.

Testing for the disease was slow and complicated, sometimes taking up to 60 days. Cows could test negative for the disease multiple times before showing up as positive.

Eradication efforts were also complicated by poor record-keeping by some farmers, in particular those who sold calves for cash – making it almost impossible to trace cattle movements.

"We do have, unfortunately, quite a black market of cows sold for cash," Gwyn told the primary production committee at the parliament today. "We're looking at bank records, taking affidavits."

Primary Industries Minister Damien O'Connor said it was always expected that more infected farms would be found.

"[However], officials tell me that the numbers will likely exceed their earlier modelling.

"That modelling work is continuing and we will have a clearer picture in the next couple of weeks."

The Ministry for Primary Industries now has 250 staff working on the response to Mycoplasma bovis.

Where are the infected properties?

Hawkes Bay (near Hastings) – 1
Manawatu – 1
Canterbury – 3
North Canterbury (Cheviot) – 1
Mid-Canterbury (Ashburton) – 7
South Canterbury/North Otago – 12
Otago (Middlemarch) – 2
Southland (Winton, Lumsden, Invercargill, Gore) – 13

- Additional reporting from BusinessDesk