At-risk bird species (such as the far eastern curlew) are the priority as Australia grapples with the likely impacts of the deadly H5N1 avian influenza strain that’s reached our shores. Photo: DCCEEW.
For the past six years, Australia managed to be free of the highly contagious and deadly H5N1 avian influenza strain.
It arrived on Western Australia shores on 22 June and has since spread to resident birds in South Australia, Queensland, Victoria and NSW.
The Commonwealth Government has acknowledged that eradication will be impossible and the focus is on trying to keep it out of the agricultural industries for as long as possible and to protect vulnerable native species.
So what is the likelihood that bird species will be wiped out? Can it be passed to livestock and people (which has occurred in the USA)? And what can we expect to see as the virus continues to spread?
Region took part in a briefing with experts from CSIRO’s Australian Centre for Disease Preparedness to find out what’s happening behind the announcements and press conferences.
How does this strain compare to others around the world?
Australia has seen some variations of bird flu in the past – such as the H7 outbreak that impacted the poultry industry in 2024.
Viruses constantly mutate, but around 2020/21 the avian flu essentially exchanged gene segments (called reassortments) with local low-pathogenic influenza viruses in North Africa and Europe.
This became the H5N1 plate 2.3.4.4B lineage (similar to how we had different strains of the COVID-19 virus) that has been ravaging the rest of the country for the past six years, decimating not only bird populations but some marine mammal species as well (such as sea lions and elephant seals).
World Organisation for Animal Health (WOAH) avian influenza expert and CSIRO senior research scientist Dr Frank Wong explained Australia’s strain was known as genotype B3.2 and originally arose from reassortment of the virus in North America.
“[It] then spread to South America in late 2022, moving down the entire west coast of South America in the space of six months, causing great impact to South American poultry industries as well as to wild birdlife and to marine mammals,” he said.
“So that’s why we’re concerned about the introduction of this virus to Australia.”
Dr Wong said “sporadic spillover events” of the virus from birds had occurred in more than 55 mammalian species, categorised into scavenger species, domestic/farm animals and colony mammals.
Wait, so can the virus spread into our livestock and people?
Not at the moment.
The H5N1 strain in Australia has only been detected in resident wild bird species, and hasn’t made its way into poultry or other animals.
But based on what’s happened overseas, it is a possibility.
Dr Wong said the infections in dairy cattle and people in America had been linked to the B3.13 and B1.1 strains of the virus, but reiterated the one in Australia was known as B3.2
“It certainly can infect marine mammals – so, for example, in South America it has impacted colonies of southern elephant seals and sea lions … and when it was detected in Heard Island in late 2025 and early this year, it was observed that it had significant impact to the resident southern elephant seal population … they counted up to 75 per cent of the season’s pup or juvenile population have succumbed to H5N1 infection due to this genotype,” he said.
“The risk with this genotype is still considered low for infection of livestock, and I would add that, aside from just the makeup of the virus or the genotype, you would need an ecological perfect storm for the virus to spill over and impact livestock.”
But given viruses’ predisposition to keep mutating, it’s not out of the question.
“When a virus goes into a new area and it picks up gene segments from local viruses, it could provide a new genotype or a new strain with better host-fitness for host species in that new area,” Dr Wong said.
“[So can transmission to people] occur in Australia? The answer is yes, and that’s why it’s important we keep tracking it.”
CSIRO Australian Centre for Disease Preparedness director Dr Debbie Eagles added this was why a close eye was being kept on every single case to make sure the strain wasn’t changing into something that could cross over.
“If we don’t test, then we’re not able to look for the changes in the sequence that can help to inform if there’s any mutations to the virus that increase the risk of spread to people,” she said.
Is it likely Australian species could go extinct because of this strain?
As the virus has never been in Australia before, we can’t predict exactly how it will interact with the biology of our native species.
But it’s already well documented to have devastating impacts on poultry populations, and a mass extinction event of greater crested terns at Baudin Rocks, south of Cape Jaffa in South Australia, has already been reported.
Dr Wong said the level of an extinction event in Australia would come down to the species that had been infected.
“In species that are pretty healthy in terms of their population status, and have a lot of big numbers, there’s been reports that, over subsequent seasons, that population … has had signs of recovery,” he explained.
“But in populations where there’s already critical [low] numbers and are already hammered by other conservation impacts … then you could risk an extinction-level impact because those particular species would find it much more challenging to recover from … highly pathogenic bird flu on top of that.”
What about vaccines? What’s going to be protected?
Vulnerable bird species that are in captivity are being prioritised to receive two shots of a bird flu vaccine.
These are sourced from overseas and Australia doesn’t have the capability to produce them here at the moment.
And it’s unclear if poultry farms will be given access to the vaccine either.
“There’s ongoing discussion between government and industry about whether that might be feasible, sort of what opportunities and risks there might be around that,” Dr Eagles said.
“Obviously there’s a number of measures that can be implemented as needed, such as the Victorian housing orders that have been put in place … all of those additional biosecurity measures can help where they’re specifically needed.”
Anyone who encounters sick or dead wildlife should avoid touching the animal, record it with a phone and report it to the Emergency Animal Disease Hotline on 1800 675 888. More information can be found at Agriculture.
Original Article published by Claire Fenwicke on Region Canberra.
