Nipah virus left a million pigs and a hundred people dead in Malaysia in a 1999 outbreak, and it is on Australia’s doorstep.
The virus, carried by bats, is fatal for 40 to 75 per cent of humans, and about 40 per cent of pigs.
While the risk is considered to be low, it could have devastating impacts if it reached Australia.
Nipah virus is currently found in fruit bat populations in mainland Asia, with past outbreaks in Malaysia and Singapore.
Bangladesh and India are known to have Nipah outbreaks almost annually.
Dr Andrew Breed, a veterinary epidemiologist at the Department of Agriculture, Fisheries and Forestry said changes to bat habitats due to human encroachment was pushing them into new territories, both in Asia and within Australia.
"In various parts of the world, some of these large fruit bat species are finding urban and rural areas they can adapt to survive in," he said.
Within Australia over the past century, big changes in fruit bat distributions have been observed due to changes in land use.
"In the 1930s, the Black Flying Fox didn't occur any further south in Queensland than the Maryborough region, but by the 1960s there was clear evidence of it in Brisbane," he said.
And in the 2000s, it was found as far south as Sydney.
A virus similar to Nipah had already been found in bat populations in Papua New Guinea, with evidence the bats could migrate from Papua through Torres Strait to Australia.
"We know that fruit bats can fly across Torres Strait, we've observed this using satellite transmitters," Dr Breed said.
Dr Breed said the spillover of diseases from bats to livestock or humans is occurring when the systems they live in were disrupted by human activity, causing stress.
"We need to find ways of minimising and avoiding that stress on wild animal populations," he said.
"They play an important role in our ecosystems, they control insect populations, including agricultural pests, and they're really important for pollinating flowers and dispersing seeds, so we do need them."
Limited research
While Nipah has a high mortality rate in humans, it has not been given as much attention as other diseases like foot-and-mouth disease (FMD) and lumpy skin disease (LSD), which are considered more immediate threats.
There could be two possible reasons for that.
Firstly, Nipah wouldn't have as big an impact on the livestock sector.
"FMD and LSD affect livestock, and if they were to enter Australian populations, there would be severe economic impacts in terms of trade," he said.
Secondly, FMD and LSD were moving across Asia and closer to Australia, but there has been no evidence yet of a similar movement for Nipah.
However, the regions of Indonesia, Malaysia, and the nearby islands close to Australia had not been well-studied.
"[The research] is limited if we're talking about Nipah and where it occurs in that region," Dr Breed said.
He said the pattern of spread in humans had been sporadic, with no clear trend.
"We don't really know how well surveillance for Nipah virus in humans works across the areas that it could be present, so we're not really in a position to monitor incidence very accurately," he said.
'Low risk, high impact'
For Australian pig farmers, the outbreak in Malaysia was a blessing, coming at a time when pig farmers were doing it tough.
"It actually helped the Australian pig industry because they took over supplying the Singapore market," said Edwina Beveridge, a pork producer based in Young.
"But it is on the list of diseases we don't want in this country."
That outbreak in Asia may have come as a relief to producers, but biosecurity threats were increasing and their patterns are becoming more unpredictable.
"It's one of those events that probably has low likelihood, but potentially high impacts," Dr Breed said.
