The deadly H5N1 bird flu has jumped species in Antarctica. It's getting closer to 'pandemic potential'

Australia Broadcast Center

17-05-2025

Australia is "surrounded" by the deadly H5N1 strain of bird flu. And it is morphing as sea animals and birds bring it ever closer to these shores.
Warning: This story contains images that may upset some readers.
Soaking up the Antarctic summer sun, a herd of crabeater seals lay oblivious to the impending threat.
The killer virus that infiltrated Earth's most remote ecosystem continues to jump between animals, leaving a trail of death and devastation in its wake.
Dead young southern elephant seals and king penguins on Possession Island, Crozet archipelago, October, 2024. ( Supplied: Jérémy Tornos/Mathilde Lejeune/CNRS/IPEV )
Fifteen species have been detected with the virus in the region so far, from flying seabirds to penguins.
Now, a disturbing revelation.
A dead elephant seal on the shore. ( Supplied: Jérémy Tornos/Mathilde Lejeune/CNRS/IPEV )
The virus is now attacking pinnipeds — or as we know them, seals.
"We've definitely now had detections in most of the seal species in Antarctica," said Dr Meagan Dewar, who recently returned from her fourth research expedition to the continent this year.
"Other teams found Antarctic fur seals and elephant seals are heavily impacted, crabeater seals and Weddell seals have also died from the virus, and some leopard seals were detected as well."
A bird pecks at a dead baby seal. ( Supplied: Dr Michelle Wille )
From Antarctica's plagued peninsula to previously untouched archipelagos, the infamous highly pathogenic H5N1 strain of avian flu has now moved across thousands of kilometres of ocean and settled in new locations and colonies.
"It's quite hard to see a lot of these species dying, or already dead," Dr Dewar told 7.30.
A.dead skua in the snow. ( Supplied: Dr Michelle Wille )
An Antarctic giant petrel devours a penguin chick. ( Supplied: Dr Michelle Wille )
The H5N1 bird flu has infected pinnipeds. ( Supplied: Jérémy Tornos/Mathilde Lejeune/CNRS/IPEV )
Many animals experience respiratory distress before they die. ( Supplied: Dr Michelle Wille )
Virus Ecologist Dr Michelle Wille said the impacts on the animals before death are shocking.
"It's really targeting the brains of these animals," she said.
"Animals are having neurological [symptoms], and that's not just the marine mammals like the elephant seals, that's the birds too," she explained.
"Some of the sea lions are having really big respiratory distress, they're really struggling to breathe, and they are dying in large numbers.
"To see the number of sick animals in distress, and dead animals, is very confronting."
Through her work with the Scientific Committee on Antarctic Research Dr Dewar was one of the first scientists to detect the virus in the region after its jump from South America in 2023, spread by scavenging birds.
Dr Meagan Dewar was among the team that detected highly pathogenic avian flu for the first time in Antarctica more than a year ago. ( Supplied: Dr Meagan Dewar )
Dr Dewar returned to the icy continent this year. ( Supplied: Dr Meagan Dewar )
There were fears bird flu would have wiped out entire penguin colonies following Antarctica's harsh winter. ( Supplied: Dr Michelle Wille )
When Dr Dewar returned this year to track the evolution of the frigid continent's first outbreak, she expected to see "hundreds, if not thousands" of dead penguins, but that was not the case.
Scientists are concerned that penguins could now be asymptomatic carriers, noting that the virus "is not spreading the way we thought it would".
As H5N1 continues to march across the Southern Ocean, there are concerns that Antarctic seals are now also spreading the virus, adding a new layer of complexity and putting the deep south's mammalian population at greater risk.
"The only consistency with avian influenza is that it is unpredictable," Dr Wille told 7.30.
"It just keeps surprising us, and it keeps doing things that we didn't think would happen."
"There's an arms race, of sorts — the host is always trying to find a way to evade the virus, and the virus is always evolving new ways to infect the host," Dr Dewar said.
Employing the same tools and processes used to track COVID-19, Dr Wille is now testing hundreds of samples taken from skuas, penguins and seals at the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne.
The work will take months but is crucial for confirming where and how high pathogenicity avian influenza H5N1 (HPAI H5N1) is spreading through the continent.
Samples were collected in Antarctica over nine weeks. ( ABC News: Tom Hartley )
Virus Ecologist Dr Michelle Wille uses the same processes as those used to track COVID-19. ( ABC News: Tom Hartley )
Dr Wille says their initial findings suggest the virus "is all in the same places as it was last year," but noted other groups had identified cases "really far away" from the original detection point, proving it's on the move.
Even more concerning is the potential that some species may be able to carry the virus asymptomatically — remaining healthy enough to travel vast distances while infectious.
There are concerns penguins could be asymptomatic carriers of H5N1. ( Supplied: Dr Meagan Dewar )
Adèlie penguin chick with a mohawk in Antarctica. ( Supplied: Dr Meagan Dewar )
A springboard into Australia
The virus's jump to the sub-Antarctic archipelagos of Crozet and Kerguelen is a remarkable example of just that.
The strain detected on Kerguelen was determined to have originated 7,000 kilometres away, at the South Georgia Islands.
A French team of researchers reported H5N1 in late 2024, describing "unprecedented and alarming mortalities of southern elephant seals", noting King penguins, Gentoo penguins, brown skuas were also among the casualties.
From Kerguelen, Australia's remote Heard and McDonald Islands are less than 500 km away, and richly biodiverse with an array of potential new hosts. If the virus makes that jump, the next incursion could be direct to the mainland.
The Australian Antarctic Division told 7.30 it is sending a research vessel to those islands later this year, but in the absence of eyes on the ground, what's happening there and in many parts of Antarctica remains a dangerous unknown.
It is feared a localised outbreak is already underway.
"There's a lot of areas where we just don't know if bird flu has hit there or if it hasn't — and to what scale that effect is," Dr Dewar said.
"And from Heard and McDonald, it's only a short distance to Macquarie Island and the New Zealand sub-Antarctic islands as well."
The other probable pathway for the virus to enter Australia is from the north, with long-distance migratory birds returning from the northern hemisphere in spring, stopping in H5N1 hotspots along the way.
"It's a concerning situation — we're basically surrounded by highly pathogenic H5N1 avian influenza now," Dr Wille said.
Her research suggests an incursion is an inevitable matter of 'when' not 'if'."
How ready are we?
While different avian flu strains are already in Australia, none are as dangerous as the H5N1 clade 2.3.4.4b.
Its genomic properties allow it to keep jumping species. It has recently infected cats, dolphins, pigs, sheep, and humans.
Australia's Chief Veterinary Officer Dr Beth Cookson confirmed the risk to Australia has increased.
"That's due to the number of different bird species that can now be affected by the strain and potentially disperse it [domestically] over longer distances," Dr Cookson said.
Currently, not much is known about the scale of bird flu in Antarctica. ( Supplied: Australian Antarctic Division )
Dr Cookson told 7.30 that the Australian government has ramped up its surveillance and preparedness across all sectors.
More than $100 million has been committed to preparing for an incursion, focussing on agriculture, health, and environment sectors. The government is also updating its Avian Influenza Plan after a desktop simulation found shortcomings in agency and department responses.
"Our level of preparedness has really escalated," Dr Cookson said.
"We've got well-established emergency response arrangements … and we've tested those recently through the H7 outbreaks of 2024 and 2025," referring to the epizootic that crippled production at several Australian egg and poultry farms.
A quarantine area sign is attached to a tree at a quarantine zone after an outbreak of bird flu in Victoria. ( AAP/Department of Energy, Environment and Climate Action )
An outbreak of the H7 bird flu crippled production at several Australian egg and poultry farms. ( ABC News: Morgan Timms )
Farms under quarantine restrictions due to positive cases of the HPAI H7N8 strain of avian influenza being detected. ( ABC News: Marcus Stimson )
The goal is early detection and containment. But for all the planning, one reality remains.
"Once this H5 avian influenza virus is in wild bird populations, there are limited options available to prevent or limit the spread," she said.
And while no one knows what it will mean for our endemic animals — marsupials like koalas and kangaroos, and mammalian sea animals including the Australian fur seal — there are genuine fears that already endangered species could be wiped out.
"We also have to be cognisant of the human health risks," Dr Cookson said.
'Pandemic potential'
Since 2020, there have been 112 human cases, including an Australian toddler who contracted the virus while visiting India before making a full recovery.
Other countries where cases have been recorded include Laos, Cambodia, Vietnam, China and India, a few in Europe, as well as the United Kingdom, South America, Canada and Mexico. But almost two-thirds have occurred in the United States this past year.
Person-to-person spread isn't considered an issue yet but scientists argue the virus is one mutation away from 'pandemic potential'.
In its latest Avian Flu assessment, the World Health Organization said vigilance and testing is "warranted" in pigs, as they "act as mixing vessels for genetic re-assortment of avian and human influenza viruses, potentially creating new strains with pandemic potential."
Dr Wille says in the US context, it is concerning that there are so many cases in dairy cattle because we are seeing cow-to-cow transmission.
"As there is more spread from mammal to mammal to mammal, there are more opportunities for the virus to get better at infecting mammals," Dr Wille said.
Delays in containing the US outbreak have allowed H5N1 to rip through every state.
The virus has been detected in millions of poultry and more than 1,000 dairy herds. Americans on the frontline say it is out of control.
H5N1 has been detected in more than 1,000 dairy herds across the United States. ( Reuters: Jim Vondruska )
A cow is kept in an isolation pen at a farm in Rockford, Illinois, as a precaution amid the outbreak. ( Reuters: Jim Vondruska )
"This outbreak started in 2022 and we're still in it," explained Dr Kay Russo, a veterinarian consultant who has been on the frontline of the cattle outbreak.
"So it feels a little bit hopeless, and that's not a good feeling to have when you don't have the tools you need to get in front of it."
Dr Russo says there were "a lot of internal tug of wars" happening between government agencies in the US, which significantly delayed the response and allowed the virus to spread.
She also suspects many cases in migrant dairy workers are going unreported, for fear they'll lose their jobs or be deported — which could lead to the first human-to-human outbreak going unseen.
"We are in the throes of the worst animal disease outbreak that our country, and perhaps the world, has ever seen.
"But I think what we've learned, and what flu continues to teach us, is to expect the unexpected."
Credits
Reporter: Tom Hartley
Producer: Richard Mockler
Photos and videos: Dr Meagan Dewar, Dr Michelle Wille, Australian Antarctic Division
Digital production: Jenny Ky
Editor: Paul Johnson
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