An outbreak of a deadly virus ravaging unique Australian species could wreak havoc by summer, thanks to migratory birds.
More cases are expected to hit the mainland after a migratory bird tested positive for H5N1 bird flu in South Australia, days after the nation's first two confirmed cases were reported near Esperance in Western Australia.
The poultry and agricultural sectors in Australia remain free from the flu but the industry has been on high alert since the cases were confirmed in wild birds.
Scientists warn the threat of a slew of wild birds becoming infected is "more when than if".
"It may not spread in this winter, but it could come from shorebirds ... in the next summer," Birdlife Australia president Hugh Possingham said on Thursday.
"It'll probably get here eventually ... that's unavoidable.
"The way migratory birds are coming to this continent from other continents and other places - something is going to happen."
Australia is better prepared than other countries, says University of Tasmania biologist Jane Younger.
But she concedes migratory birds are the wild card.
"It's almost inevitable that we'll have wildlife outbreaks at some point," Dr Younger said.
"For a lot of these seabirds in the Southern Ocean that are really circulating this virus around, there has not been a lot of tracking ... so it is a really tricky thing for us to model or predict how this will spread."
There was currently no threat to humans, federal Agriculture Minister Julie Collins confirmed.
"Chicken meat and eggs, as prepared normally, are perfectly safe to eat," she said.
Bird flu could rarely spread to humans in close contact with infected birds but had the potential to cause severe illness, University of NSW epidemiologist Raina MacIntyre said.
She said the risk in Australia was low but noted there were several ways for the virus to spread and mutate across species.
"When a human with human flu comes into contact with an animal or bird with bird flu and the virus exchanges genetic segments, then a pandemic virus arises," Professor MacIntyre said.
She recommended farm workers in the poultry industry to wear personal protective equipment and for pet owners not to let their animals stray too far.
WA authorities have received nearly 200 reports of sick birds since the first suspected case.
Ground-based surveillance and drone surveys are being carried out at sea lion breeding sites along South Australian coasts, with testing frequency increased in high-risk areas.
A temporary ban on all poultry products imported from Australia, imposed by Papua New Guinea's National Agriculture and Quarantine Inspection Authority, has been lifted after being put in place on Monday.
PNG is Australia's largest single market for chicken meat exports, accounting for nearly half of the $133 million in sales in 2023/24.
