Feral animal role in FMD Australian outbreak: what the science says

The federal government has downplayed the role of feral animals in a domestic FMD outbreak, often pointing to international examples where pest populations had little to no effect on the overall outbreak.

However, the domestic research conducted by Professor Michael Ward, chair of the University of Sydney's school of Veterinary Public Health, suggests the danger of feral animals should not be dismissed.

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After extensive field work in the nation's north, Prof Ward modelled an FMD outbreak in a mixed wild pig-domestic cattle ecosystem.

It found in regions with high concentrations of feral pigs, it was likely the disease would get into the pests and set up "an ongoing transmission cycle" with cattle, with the virus going back and forth between the two species.

"You have to expect if livestock get infected, it's going to get into feral species.... if that [transmission cycle] got going, it would be much harder to eradicate," Prof Ward said.

The one silver lining of the research is the modelling expected the virus to die out naturally in a feral pig population after several months.

The effect of feral deer in an FMD outbreak is yet to be modelled in Australia - despite requests for funding - but Prof Ward said research he'd conducted in Texas was a good point of reference.

In southern parts of Australia, where deer are established in their thousands, they would act as vectors and reservoirs, however unlike pigs, the disease is more likely to survive in wild populations.

Prof Ward said in the event of an outbreak, the focus would be on domestic livestock - and rightly so - but there could be a reservoir of the disease lurking in wild species and "at some point we have to do something about that".

"It would be incredibly disappointing to get rid of it in livestock populations, only for it to keep popping up in feral animal populations," Prof Ward said.

"Can you imagine the pain of slaughtering a herd, only to be told, 'by the way, look behind you, it's in the pigs and deer'. It would be a real kick in the guts."

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Prof Ward cautioned against using global examples to downplay the threat, as Australia had a huge number of feral animals by international standards.

Bulgaria has been held up as an example of where FMD got into the feral pig population with little effect on the overall outbreak. However, the eastern European country only has 100,000 feral pigs, compared to Australia's 26 million.

"Our livestock production is extensive, while in Bulgaria, it's village based, so there are a lot more opportunities for interactions between livestock and feral animals in Australia." Prof Ward said.

"You can regularly see feral pigs mixing with cattle in many places, so pathways definitely exist.

"If you're looking for international examples of exotic disease in feral populations, in Romania classical and African swine fever is in the wild boar population and they can't do anything about it."

The lingering legacy of an FMD outbreak in feral animals could be the most devastating, preventing Australia from regaining the trust of its trading partners.

"The whole thing with FMD is it's a trade disease," Prof Ward said.

"To get back in the marketplace, you have to show you're FMD free - we know how to do that with domestic animals, how do we do it in wild species?

"How long that will take is the big unknown, and the unknown is a killer in trade."

When equine influenza got into Australia in 2007, there was limited sampling of the brumbies in Kosciuszko National Park.

"We tested 40 to 60 and they were all negative, we were lucky the rest of the world believed that was enough," Prof Ward said.

"It's much harder to prove eradication of FMD in pigs, which are in much higher populations, and deer, which live in hard-to-reach places."

Globally, there is a trend of buck passing responsibility of feral animals between levels of government and different departments, Prof Ward said, because there were no easy answers or cheap solutions.

Culling is extremely expensive and to be effective, it's estimated 40 per cent of the region's population must be eradicated.

"In the north, keeping the cattle away from feral pigs, destocking and waiting until the FMD died in wild pigs is a possible solution," Prof Ward said.

"But down south with deer and pigs, that's not as feasible. Keeping feral and domestic populations separate is your best bet, but ferals don't respect fences.

"We could try to get vaccines into wild populations, but how do you distribute it? We're really scraping the bottom of the barrel to stop this."