The beginnings and progress of this particular circovirus outbreak, for seven years or more, have been recorded on the UK newsgroup uk.business.agriculture - fully searchable through Google Groups.
There were two incursions of PMWS. The strains in North and South Islands were different.
Like the British veterinary establishment, the closely associated NZlanders preferred IIIIM (imaginary illegal imported infected meat) and smallholders, rather than veterinary indiscipline and greed, as an explanation for all outbreaks of everything.
As a result of closing the wrong stable doors, the mess gets worse.
You will notice that the NZ government are now trying to de-emphasise IIIIM and border controls. They know that IIIIM does not stand scrutiny as a source.
They have, as usual, had some superbug outbreaks in humans in New Zealand. Pigs ill with circovirus quickly become a human health risk, not least antibiotic resistant diseases such as MRSA caused by the use of excessive antibiotics to control co-infection.
Full report from the New Zealand Herald here (the date is incorrect it should be March 24.)
Devastating pig disease still spreading - NZ Pork
8:17 PM Saturday Mar 26, 2011
A devastating pig disease which broke out in the North Island in 2003 and crossed to the South Island in 2006 is still spreading, farmers say.
Post-weaning multi-systemic wasting syndrome (PMWS) does not affect humans but attacks young pigs, causing emaciation, diarrhoea and breathing problems, and can kill up to 40 per cent of a piggery's weaners in its early stages.
Found worldwide, apart from Australia, the disease inflicts a high death rate on pigs aged six to 12 weeks, and continuing illness for survivors, including infertility.
"PMWS is still infecting new farms ... and even some with very stringent biosecurity practices," New Zealand Pork chief executive Sam McIvor told NZPA...
...When the disease was first found on Ted and Irene Graham's Orini piggery, 24km east of Huntly in 2003, the industry argued that the outbreak occurred only after an unidentified infectious agent was fed to pigs in uncooked pork...
...The disease later "exploded" across farms which kept pigs outdoors: "Spread, we believe, by gulls, sparrows, flies, an errant truck driver and weaner pig movements before it was recognised," Mr McIvor told the primary production select committee probing the Biosecurity Law Reform Bill.
"In the South Island, we now have about 80 per cent of the herds with it and the initial mortality was 18 per cent of pigs on those farms."...
..."I haven't put a figure on the depression, marriage break-ups, business failures, two deaths and a severe heart attack that were believed to be related to the issue," he told MPs...
...But Mr McIvor told the committee that research had shown that a virus that cause a worse disease, incurable porcine reproductive and respiratory syndrome, could arrive in the meat of imported animals.
Though the virus did not have human health implications, it could be transmitted to the New Zealand pig herd with devastating effects on animal health, and pig farmers had been at odds with MAF since 2006, when the ministry proposed a health import standard for pigmeats.
NZ Pork also had some "fundamental concerns" around sections of the biosecurity bill, including a shift of focus away from trying to manage risks offshore and at the border.