New Zealand’s Mycoplasma bovis eradication campaign has now been running for almost three years, with no decline in the number of farms newly detected as being infected. Can the disease be stamped out?

It is now more than five months since I last wrote about Mycoplasma bovis in late October 2019. Since then, another 44 farms have gone positive, bringing the total to 245 farms since the disease was discovered in July 2017. All of these farms have been required to slaughter their herds. There are 31 farms where that process is still ongoing.

During this latest five-month period, farms infected with Mycoplasma bovis have been identified at the average rate of two per week. This is slightly higher than the overall average rate of 1.75 farms confirmed per week since the disease was first discovered in July 2017.

This raises a legitimate question as to whether it is the Ministry of Primary Industries (MPI) or the disease that is running faster? Has MPI got better at their job of finding infected farms, or is it because the disease is running ahead and leaving increased calling-cards behind?

I am often asked as to whether or not Mycoplasma bovis can be eliminated. I have always been sceptical. Right now, I still do not know. There is definitely a chance, but the evidence remains murky.

Ever since the Government gave the full steam ahead decision back in April 2018, the official line has been that the program is going well. Then, in April 2019 we learned that things had in fact not been going well at all, but would supposedly go well thereafter. That was when MPI announced that there would be a big ‘surge’ in activity.

April 2018 was also when we learned that the official figures had been fudged over at least the previous five months, with MPI using one criterion to decide whether herds should be considered infected and slaughtered, but using another criterion, and hence a totally different number, to disclose to the public. Quite simply we had been manipulated and lied to.

Those of us close to the on-farm action had known for many months, indeed right from the outset, that MPI had been fudging and hiding their gross inefficiencies. However, we found it more than a little challenging to communicate our concerns to the authorities. It was something the Director General of MPI at that time, a former military man who by instinct and training relied on information passed to him through the formal system, did not wish to acknowledge.   He did respond, but through personal attacks on the messenger rather than dealing with the issues.

A problem with fudged figures, including mid-level underlings hiding their own inefficiencies, is that top officials themselves can get misled. In many organisations, the top people are the last people to know when things are going wrong unless they also have informal networks. 

In the case of MPI and Mycoplasma bovis, it also meant that the Minister was not getting the full story. But the Minister did inform me very firmly one day in his office that he believed the formal information that he was getting was correct, and anything I might say publicly about program defects was not helpful, and risked the ongoing social licence from the community to keep the program going.

When the new Director General of MPI took over in late 2018, he quickly recognised by talking to farmers and other people in the field that there were many problems, but it still took time for full recognition to develop that he was getting fed the same mushroom treatment (animal fertiliser and darkness) as the rest of us.

Since then, MPI has had a major makeover and the public face of MPI in relation to Mycoplasma bovis is a different set of people than previously. The people away from the public eye have also changed considerably.

One of the advantages of the new guard is that they no longer have to dig bigger and bigger holes for themselves while trying to defend and cover up prior fudgings.  However, those matters of fudgings and laying blame for the past do still have to be handled with discretion. Anything else would not be a good career move.

Those of us from an older generation who used to watch ‘Yes Minister’ and then ‘Yes Prime Minister’ got many a laugh from the parodies of government and bureaucracies. A friend of mine who was himself a mandarin within that English system tells me it was all so true.  In fact, the traits are universal.

So the question becomes, when the new guard says that they are cautiously optimistic about eradicating Mycoplasma bovis, can we trust them given the way the old guard behaved? My judgement is that we can, as long as due weight is given to the fact that these people at the top are indeed still cautious in their assessment, and there are still lots of unknowns.

In contrast, when the messaging comes from within the industry organisations, they are still driven by maintaining social licence from their members. In any case, the industry spin doctors don’t really know themselves, as they are simply communicators.

So, now a little more as to where we are in a technical sense.

The key question is whether or not the ‘estimated dissemination rate’ (EDR) between herds, which is essentially the same concept as R, the transmission rate for COVID-19 between people, has been driven down below ‘1’? An EDR of ‘1’ is the crucial separation point that determines whether or not the disease will proliferate or fade away.

Alternatively worded, does each infected farm on average infect more or less than one other farm?  Eventual outcomes depend totally on what is the correct answer to that question.

One thing we do know is that the bulk-milk ELISA testing of every dairy farm each month is a powerful tool for filtering out those dairy farms that are likely to be infected and therefore need closer scrutiny. That tool was not available until around August 2018. Even then it still had to be validated in the field. Without it, we would have been stuffed.

It is notable that in the last five months only five dairy farms have gone positive, with 25 newly diagnosed farms being beef farms and 12 further farms being ‘other’ (mainly dairy youngstock). But some caution is appropriate with MPI sometimes shifting farms between categories and even transferring farms between islands! 

The biggest current unknown relates to whether Mycoplasma bovis has got into beef breeding-herds as well as finishing-herds, where it has been highly prevalent. With hindsight, we will be able to answer that question, but only with hindsight.

The biggest weakness right now is that too many service bulls with uncertain backgrounds are still coming back onto dairy farms from beef finishing-farms, where their purpose is to have some fun with the cows before being sent to slaughter. I am trying to get MPI to put more focus on that part of the system.

We also should never forget the distress that the program continues to impose on affected farm families. In contrast to diseases like tuberculosis that we continue to fight against for good reason, or the currently endemic Johne’s disease that we will have to fight in the future, Mycoplasma bovis is a minor disease that farmers elsewhere in the world simply live with.

*Keith Woodford was Professor of Farm Management and Agribusiness at Lincoln University for 15 years through to 2015. He is now Principal Consultant at AgriFood Systems Ltd. One of his interests is the epidemiology of both animal and human diseases. He can be contacted at kbwoodford@gmail.com. Keith’s previous COVID-19 articles are available here.