What's really happening with the spread of the cattle disease Mycoplasma Bovis is about as transparent as a plane-grounding Wellington fog.

OPINION: Brian Rudman: Farmers should cope with bug on their own

Coincidentally, that's the city where the Ministry for Primary Industries (MPI) does whatever it is they do. They are good at professional spin and obfuscation, and all designed to make it hard to know where to point the bone.

But, while we're on the subject of MPI, I do have a few words to say. Myrtle Rust, Velvetleaf, Bonamia ostreae in flat oysters, kauri dieback, Psa in kiwifruit, herbicide-tolerant swedes causing cow deaths... the list goes on.

MPI officials have assured apoplectic farmers and vets that if, heaven forbid, foot-and-mouth disease hit these shores, they'd be far better prepared than they have been for M. bovis. They have a plan, you know.

Which is somewhat ironic given MPI's go-ahead last year for mud to be imported from a known foot-and-mouth region of South Korea for Rotorua's "Mudtopia" event. It's pretty telling when a lowly columnist single-handedly breaks the story and, in doing so, put the kibosh on any chance of the disease entering the country via that particular pathway.

Feeling reassured?

On former MPI Minister Nathan Guy's watch, a host of biosecurity risks emerged. It's not a great legacy for him, or the nine years of his National Government. Neither is his widely-recognised slow start out of the blocks on M. bovis. He hesitated on immediate eradication, and that has no doubt contributed greatly to the crisis farmers are facing today.

Of course, in the middle of all this, along came an election. The foot never even looked like hitting the gas while the coalition was being formed, and then came Labour's Damien O'Connor. Consequently, Nathan Guy now gets to spend much of his spare time blaming the new minister. Which feels cheap and nasty somehow.

Having said that, O'Connor has also caused many to shake their heads – mine included – given his predilection for cosying up to BigAg. He hasn't quite decided whether he's blue or red, and I suspect he will prove to be Labour's biggest weakest link.

Speaking to dairy farmers in Hamilton last week he said, "We are doing our very best to eradicate it but I have to say the slow start and the absence of a robust NAIT [national animal identification tracing scheme] have complicated things immensely. And it will cost us a hell of a lot more money."

O'Connor absolutely has a point. But MPI – his ministry - has also absolutely failed to robustly enforce the NAIT system since its inception, and rogue farmers, stock agents, and trucking companies have abused it.

Nathan Guy also had more than enough of time at the top to address such well-known non-compliance issues. They can share this failure.

So how did M. bovis get here? Was it here much earlier than last year, but effectively manifested when the cows were under stress due to overstocking, or a hard winter?

Is PKE, which must be stopped as a supplementary feed on its environmental record alone, a potential M. bovis pathway? I mean, it's not beyond the realm of possibility that a ground-up pig's leg could find its way into a shipment. Am I drawing a long bow? Maybe, but funnier things have happened at sea.

None of it really matters right now. On Monday another farm tested positive in Cambridge. This is fast becoming a runaway train, and any window for the eradication of the disease is slamming shut.

Perversely, there could still be some silver linings in all of this.

Environment Minister David Parker's vision of cow numbers declining, despite the industry's protestations, may yet be borne out. Dairy farmers may return to self-containment, and closed systems. Off-farm supplementary feed may become a thing of the past. Compliance with NAIT may become something that is taken seriously, rather than treated like a casual fling.

Fewer cows, fewer problems, less stress on animal and human. Farmers may discover they can earn the same income with fewer cows. Who knows, maybe a complete cultural shift is imminent? Because, by crikey, if ever one was needed it's needed now.

More than anything, MPI needs a complete rebore. Farmers can always change and adapt - given decent leadership, and scientific guidance they trust. But turning around an entire ministry that's now failed on biosecurity under two governments?

The tactic from MPI will be to blame farmers first, and themselves never. We're seeing it already, and it's an easy option because there's some truth to it. But the bigger truth?

What's the point of any regulation without enforcement?

MPI needs to take a good hard look in the mirror, and pray they don't ever see foot-and-mouth disease staring straight back at them.

It'd be ugly, and the mirror would crack.

• Rachel Stewart on Twitter: @RFStew