Pig disease investigation underway

An exotic animal disease investigation is underway in a New Zealand piggery after weaner pigs failed to respond to veterinary treatment.

Allen Bryce, National Manager Surveillance and Response with the Ministry of Agriculture and Forestry (MAF), says the cause of the illness has not yet been confirmed but Post-weaning multisystemic wasting syndrome (PMWS) is a possibility. PMWS has not been found in New Zealand before.

“This is a complex disease and confirming the diagnosis is difficult – it may be sometime before MAF can say conclusively whether PMWS is involved or not. While the investigation progresses a restricted place notice has been put on the affected farm,” he says.

“There are no public health or food safety issues associated with this disease which is specific to weaner pigs aged 6 to 12 weeks. While certainly its presence is of concern to the pig industry, it will have a negligible impact on our trade because it is wide spread throughout the world, ” he said.

Mr Bryce says the cause of PMWS is still uncertain. Research shows that it is associated with porcine circovirus type 2(PCV2), and the clinical signs can be associated with at least two other pig viruses – porcine reproductive and respiratory syndrome virus (PRRSV) – and porcine parvovirus (PPV). PCV2 and PPV are present in New Zealand. PRRSV is exotic to New Zealand. Diagnostic tests have definitely excluded the presence of PRRSV on the affected farm.

“We are working closely with national and international experts to confirm the diagnosis and the NZ Pork Industry Board has been consulted throughout the investigation,” he says.

The disease is characterised by a progressive loss of weight and appetite, pigs have visibly enlarged lymph nodes, and they may experience respiratory distress, diarrhoea, gastric ulcers and jaundice. It can vary in severity and virulence but generally there is -low morbidity, and high mortality of affected pigs. There is no known treatment. Overseas experience shows that the disease might spread between pig herds through the movement of pigs, and possibly in semen.

Mr Bryce says the affected piggery is isolated from other piggeries and doesn’t pose a risk while the investigation is underway. Management and control options are being explored as part of the investigation.

PMWS is widespread throughout the world; exceptions include Australia and New Zealand.

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