Provisional confirmation of pig disease

A provisional diagnosis of Post-weaning multisystemic wasting syndrome (PMWS) has been made on a Waikato piggery which is under investigation by the Ministry of Agriculture and Forestry (MAF).

Clifton King, MAF’s Programme Coordinator Exotic Disease Response said that although final results on tissues samples will not be available until the end of the month, clinical and pathological criteria had been met.

“It has been difficult to get a definite diagnosis as PMWS is a complex disease associated with two viruses that are already present in New Zealand – porcine parvovirus (PPV) and porcine circovirus type 2(PCV2).

“Final confirmation of the disease is dependent upon finding PCV2 DNA in tissues samples sent overseas. However, clinical signs and New Zealand pathology results suggest that we do have PMWS in this farm,” he said.

Mr King said that MAF had requested a second round of tests after results from tissue samples sent to Seoul National University in Korea in September were inconclusive.

A Technical Advisory Group (TAG) made up of representatives from MAF, pork industry and national experts has been established to consider further investigation and control options now that a provisional diagnosis has been made.

Tracing of pigs and other risk items on and off the affected farm has been completed. Six farms have been identified that may have come in direct or indirect contact with this farm. Results from the tracing will be analysed within the month but there have been no reports of disease found on any of the identified farms to date. Once this analysis is completed the TAG will meet again to decide possible next steps.

“Given that PCV2 and PPV are endemic in New Zealand, MAF needs to consider the possibility that the conditions for PMWS have been present in New Zealand for some time. In the meantime the restricted place notice will remain in place while the investigation is underway,” he said.

Mr King said that while PMWS is of concern to the pig industry, the impact on our trade would be negligible, as the viruses are present in virtually every pork producing country in the world.

MAF became involved in the investigation in early in September after being contacted by a veterinarian concerned that weaner pigs had failed to thrive even after veterinary care and farm management advice.

PMWS 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 high morbidity and mortality and no known treatment.

The New Zealand Food Safety Authority confirms that there are no food safety issues associated with this disease, which is specific to weaner pigs aged six to 12 weeks.

To report suspected PMWS please call the MAF Exotic Disease and Pest Emergency Hotline on 0800 809 966.

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