The savagery of African swine fever was starkly illustrated to Kiwi epidemiologist Dr Eric Neumann when he visited a 1000-pig farm in Vietnam.
The fever’s presence had been confirmed in the housed piggery two weeks before his visit but by time he got there 600 animals had died and most of the survivors were sick.
“They had fevers. Some would stand up walk 1.5m then lie down, others would roll onto their sides, all clinical signs of African swine fever.”
Neumann, who owns epidemiology consultancy Epi Insight, specialises in the pig industry and dealing with population-scale disease in animals.
Born and educated in the United States he is now based at Taieri south of Dunedin and has spent his career specialising in infectious pig diseases, initially in the US then last 15 years or so in New Zealand.
He has adjunct appointments at Iowa State University, Massey University and Otago University and works for NZ Pork.
He has 25 years’ epidemiology experience and helps international clients on biosecurity, animal health, livestock production and public policy aspects of animal disease
Half his year is spent overseas and the other half supporting clinical research at Massey and Otago and, as a qualified vet, doing some clinical work.
Before his academic career Neumann was veterinary services manager for Heartland Pork Enterprises in Iowa, which ran 65,000 sows, and was the director of swine health and research at the National Pork Board in Des Moines, Iowa.
One of Neumann’s international roles is to deliver foreign aid projects and he is in Vietnam helping them deal with the fever while also learning as much as he can to aid the preparedness of the US Department of Agriculture should the disease find its way to the US.
Having devastated the pig population in China, the fever has now reached East Timor and the Philippines, inching ever closer to Australia.
It was discovered in Africa, reached Europe in 2014 and is now present in much of Africa, central and eastern Europe and central and southeast Asia.
Despite being surrounded by infected countries Thailand remains disease-free but is preparing for its arrival.
It has been estimated 200 million pigs have been killed though Neumann says the exact number is difficult to quantify.
Freezing does not kill the virus. The only way to is to cook it or to change its pH level through curing or processing.
“African swine fever is a very hardy disease,” he says.
Humans are not susceptible but have a huge influence on its spread.
Neumann says the risk of it arriving in Australia is rising though its commercial pig farms are well away from the likely entry through its northern coast.
The fear is Australia’s feral pig population will become infected, making eradication a major challenge.
While the fever has behaved as scientists expect, it has moved rapidly in the last six months making the threat to NZ very real.
Neumann warns NZ’s relative security from being an isolated island nation and with modern biosecurity and surveillance systems could be compromised.
NZ imports 60% of the pork meat it consumes, which comes from 25 countries including Australia, in-part due to reciprocal trade access agreements.
The fever has been found in some of those countries from which NZ imports pig meat, such as Belgium, and NZ relies on internal biosecurity measures to keep that imported product disease-free.
Belgium has isolated the area where the fever has been discovered and is not sourcing pig meat from that region but Neumann says that policy is only as good as the monitoring to ensure infected pigs do not breach the cordon.
“My concern is that your infection zone border is only as good as the last known report of the disease.”
NZ has about 100 commercial piggeries but he believes the biggest threat for spreading the disease is the way the 8000 to 10,000 non-commercial piggeries are managed.
The fever can be introduced to pigs by feeding uncooked or under-cooked food scraps containing contaminated or cross-contaminated pork products.
The risk is that owners of non-commercial pigs can be lax in what they feed their pigs and might not be as careful with animal husbandry or monitoring animal health as a commercial operator.
“There is a perfect storm in NZ with lots of fresh product coming from overseas, lots of non-commercial farms with not a lot of contact with vets or animal husbandry rules and thirdly, a robust waste-food feeding culture.”
Neumann says given the fever’s steady advance the Ministry for Primary Industries needs to act now to acknowledge that heightened risk.
“The risk will continue to rise and I think we need to encourage MPI to think about that increased risk and not decide that because it has been safe in the past that is going to be adequate in the future.
“The risk has changed but the pathways haven’t changed.”
Neumann urged non-commercial pig owners to ensure they know the origin of their pigs, to adhere to feeding guidelines, which stipulate any meat in feed scraps must be cooked at 100C for one hour, and to watch carefully for any sick stock.
He also urges pig owners to implement biosecurity measures, such as introducing quarantine systems for anyone who might have been in contact with pigs while overseas and cleaning clothes and footwear.
Whenever Neumann returns from overseas he self-imposes a week-long quarantine and ensures all clothes are thoroughly washed before coming into contact with livestock.
Scientists have unsuccessfully been searching for a vaccine for the fever for 40 years but Neumann says success has been stymied by the ability of the disease to change its structure.
“Nothing is certainly imminent.”
He is also looking at how farms can restock once the disease has gone and he believes if a surface can be disinfected then animals can return after 60 days or so.
Neumann says significant disease outbreaks in animals occur regularly around the world, a fact that is a reason for NZ to stay vigilant.
