In short:
It is virtually impossible to completely monitor Northern Australia’s biosecurity border.
The threat is increasing as wild birds that can carry avian influenza change migration patterns in response to climate change.
What’s next?
As spring approaches, authorities are urging people to report sick animals.
With its red dirt deserts to rainforests and rugged coastlines, the terrain of northern Australia is vast and varied but presents a uniform threat.
The remote stretch of land spanning the Northern Territory, Queensland, and Western Australia is an entry point for migratory birds, container vessels, and tourists.
With them comes the threat of new pests and diseases as economic growth and climate change alter how people and animals move.
As spring approaches, authorities fear activity in the north could lead to an outbreak in the south.
Veterinarian Regan Lynch grew up in Far North Queensland and has researched ways to improve biosecurity in the beef industry as part of a Nuffield scholarship, a program that funds practical study to improve agriculture.
Ms Lynch found climate change was impacting wild animal movements.
“We’re seeing different migration changes and patterns with animals and changes in insect populations,” she said.
“We’re getting animals into places that they haven’t necessarily been before.”
Distance no barrier
As southern states battled outbreaks of the H7 strain of avian influenza, Australia’s acting Chief Veterinary Officer Sam Hamilton said loss of habitat and urbanisation also affected bird migration.
Dr Hamilton said as populations of birds fell during droughts and boomed during wet seasons, the abundance of animals increased the spread.
“These birds regularly migrate to Australia each springtime, travelling thousands of kilometres all the way from Siberia, or even further north, down to wetlands across Australia,” he said.
“When these birds do migrate through northern Australia and bring a disease, that does impact southern Australia, particularly agriculture.”
Australia remains free of the deadly H5N1 bird flu strain, but there are fears that could change in spring.
Dr Hamilton, whose office advises the federal government on animal health issues, said wild bird populations were being surveilled, but it was difficult work.
“There are many diseases that wild birds can carry, but we can’t prevent wild birds from coming to Australia,” he said.
Piggy in the middle
For 30 years, the federal government’s Northern Australian Quarantine Strategy has been surveilling the border between Broome in WA and Cairns in Queensland.
It watches for early signs of targeted pests, diseases, and weeds, works with neighbouring countries such as Indonesia and Papua New Guinea, and encourages the reporting signs of disease in animals.
But while it looked to prevent new incursions, Heather Channan said an old foe was still a significant threat.
As the National Feral Pig Management coordinator, Dr Channan works with governments and landholders to control the population.
She said pigs interacted with livestock in remote parts of the country that were not frequently monitored by producers.
“There’s opportunity for them to transmit diseases to beef cattle without people recognising or realising,” Dr Channan said.
She said feral pigs were “amplifying hosts” and could cause human and animal diseases to spread quickly.
That included Japanese encephalitis virus, which spread from Far North Queensland to southern Australia in 2022.
It was believed to have been transmitted by mosquitoes biting infected birds and pigs.
Dr Hamilton said maintaining strict biosecurity controls was crucial to international trade, Australia’s food security, tourism, and the environment.
“Many of the countries that accept high-value Australian products require Australia to be free from certain diseases,” he said.
But he said that could only be maintained by good biosecurity standards on farms and by people who interacted with wildlife being aware of the signs of disease.
Dr Lynch said lameness, sudden death, skin lesions, or salivation could be signs of disease in animals.
She said unwell animals such as birds, feral pigs, or livestock should be reported to the Emergency Animal Disease Hotline on 1800 675 888.
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