A strain of bird flu has caused ‘mass mortality events’ on every continent but Australia. Scientists say an outbreak is … – ABC News
May 21, 2024
A deadly strain of avian influenza has breached the fragile ecosystem of the world's most remote continent. Scientists say it's only a matter of time before it reaches Australia.
Antarctica is home to some of the world's most unique animals.
Now, scores of them are dying in "mass mortality events", the likes of which the continent has never seen.
The bodies of Adliepenguins and skuas are lined up on the snow and ice as adeadly, mutating pathogen continues its unrelenting spread, infecting new species of birds and mammals across the globe.
It was quite devastating, every couple of metres youre finding another dead bird," Australian researcher Dr Meagan Dewar told 7.30.
A multinational crew of scientists led by Dr Dewar made the grim Antarctic finding on their most recent disease surveillance expedition in March.
Among the casualties were dozens of skuas the big brown seagull-like birds had suffered a sudden death.
"It's devastating that we may have lost a population, just as we've discovered it," Dr Dewar told 7.30.
With a theory in mind, they ran experiments to be sure.
Taking tissue samples from the skua carcasses aboard their yacht, they performed tests, similar to the sequencing of COVID-19.
Their findings, while not unexpected, did come with a heavy reality.
A mutated strain of the virus we know as "bird flu" had penetrated the world's most remote continent.
"Sadly, it's something we predicted; it was something that was going to happen."
While the extent of the pathogen's spread in Antarctica remains unknown, tests are being conducted to find out what killed thousands of Adliepenguins on nearby Heroina Island.
Dr Dewar said there were clues to indicate sudden death as their bodies appeared healthy and many had food in their stomachs.
"It indicates most likely [the cause of death was] an infectious disease of some sort," she told 7.30.
Samples from the penguins are still being analysed.
Heroina is classified as the third-largest Adliepenguin colony in the world.
There are now concerns for all bird and mammal species across the continent.
"Now that it's moved onto the peninsula, there's a greater risk it'll spread to other parts of Antarctica," Dr Dewar said.
Skuas are known to frequently move between animal populations across Antarctica,and could potentially spread the virus to penguin colonies next season.
"We do know there are species that mix with similar species from different populations during winter, so there's a chance of [further] spreading the virus and taking it back to their colonies," Dr Dewar said.
The working theory for the Antarctic spread is relatively simple, and commonly attributed to most other bird flu outbreaks: wild birds.
In this case, it's suspected infected skuas carried the virus from the sub-Antarctic Falkland Islands and South Georgia Island, where there were several known hotspots including infections in mammals.
Those sub-Antarctic cases were introduced by birds who carried the deadly strain from South America, which has seen bird populations decimated in recent years.
Developments have been closely monitored and logged by the Scientific Committee on Antarctic Research (SCAR), and show a clearly defined route.
Virus Ecologist Dr Michelle Wille has been tracking bird flu for years.
"If we look at what's happening around the world this virus has arrived and left a trail of destruction, we're talking species-level consequences," she told 7.30.
"The worst-case scenario is arriving at penguin colonies that are silent, arriving at places where there should be abundant wildlife and having nothing.
"It's very hard to predict what's going to happen in the next season, or even this winter."
Bird flu isn't anything new.
It became a well-known virus in the late 1990s, when an outbreak in a Hong Kong poultry market resulted in the deaths of several people.
The disease then appeared in other birds and poultry throughout Asia, before breaching Europe, spreading into Africa and reaching the Americas.
There have been more strains between then and now but since 2020, a mutated strain of bird flu has had unprecedented impacts on poultry and wild birds on a global scale.
It's officially labelled HPAI (Highly Pathogenic Avian Influenza) H5N1 clade 2.3.4.4b.
It is often referred to as "H5N1".
In the context of infectious diseases, scientists agree this is the worst ecological disaster yet.
"I don't think any of us could have imagined it's been as bad as it is now, but since 2020-21, things have gotten to a whole new level," Dr Wille told 7.30.
"The scale of the mortalities is also something we've never seen before and there's no evidence that it's stopping any time soon."
Arguably, the most confronting supporting evidence comes from South America.
In Peru, at least 40 per cent of the native pelican population has been wiped out.
More than 10 per cent of the penguin species have been affected as well.
And this strain is not just killing birds more than 10 per cent of sea lions have died across the continent.
The list goes on.
Globally, more than 500 bird species have been affected, and more than 60 mammalians.
In poultry, some of the worst outbreaks have been recorded in the United States. The Centre for Disease Control estimates total losses exceeding 90 million chickens and turkeys across 48 states.
And the most recent unexpected developments with bird flu have come in the US.
Authorities there are dealing with the fallout from a peculiar "spillover" event which is when animals pass the virus to other species.
Somehow, a herd of dairy cattle became infected, spreading it to other bovines, and to at least one person a farmer who reported having mild flu symptoms and conjunctivitis.
The transmission to multiple species and humans has raised questions.
While this strain has jumped species and finds new hosts with ease, scientists say there is little concern for humans at present.
A team of Australian scientists at the CSIRO's Centre for Disease Preparedness (ACDP) are an authority on the matter and back that statement.
Dr Frank Wong, who is a global authority on avian flu, described humans as "dead-end hosts", which means an infected person cannot pass it on to others.
"In the few cases where people have got infected, they've mainly been people at the front lines dealing with the outbreak or infection," Dr Wong told 7.30.
"The virus still hasn't been able to easily transmit from a mammalian host from person-to-person or mammal-to-mammal."
Dr Wong and others know this because of their research, which takes place inan airtight high-biosecurity laboratory where they're growing the latest H5N1 strain to study it more closely.
The virus is injected into eggs and replicates itself before being harvested.
This is also how some vaccines are developed.
So if the day ever comes when we need one for bird flu, they already know how to develop it.
No one is certain, but the highest risk period for Australia is theorised to be from September the start of Spring.
That's when migratory birds are expected to make their return from Europe.
The first place of incursion depends on which birds (species and populations) are involved.
Shorebirds stop along the top end of Australia first where places like Broome are important sites.
But some fly directly to the country's southern parts, bypassing the top end.
If it arrives with seabirds, like muttonbirds, it would first arrive at their colonies, and this could be across many places.
Some sectors are watching more closely than others.
Australia's poultry industry, which has fallen victim to a number of past deadly outbreaks, including previous strains of bird flu, has increased biosecurity to its strictest level yet.
A bleak picture has been painted in Australia's Avian Influenza Plan, written by a National Biosecurity Committee.
It suggests our domestic economy could suffer from a widespread outbreak and disruptions within the poultry sector.
Export markets for chicken products would "likely close immediately".
It predicted other industries, including tourism, would be affected.
There are grave concerns for wildlife too, with a widespread outbreak potentially reversing "decades of conservation efforts".
There are currently 163 bird species considered either critically endangered, endangered, or vulnerable and those could be pushed closer to extinction.
"Sometimes that's the last nail in the coffin for some species," Dr Wille said.
"They never recover from something like that, it can be catastrophic.
"The most important thing we can do is monitor ... but I don't think there's any way to stop it once it's in Australian wild birds."
Admitting an outbreak is unavoidable doesn't mean the outlook is hopeless.
For several years, state, territory and federal governments have been preparing and considering an incursion to be inevitable.
You can't stop wild birds at the border, so enhanced surveillance is the key to spotting and controlling any outbreaks.
"Our teams here keep a close eye on genetic evolution of the virus and we know what new strains are emerging as the virus spreads in different parts of the world particularly in our region," Dr Wong told 7.30.
"With influenza, we never say never, but we are confident that we're well prepared for any possible incursion."
In a country as vast as Australia, the public plays an important role too.
We're being asked to immediately report any unusual bird deaths to the Emergency Animal Disease Hotline on 1800 675 888.
Health authorities have also warned against handling sick or dead birds.
Those now in charge, watch, wait and hope.
Reporter: Tom Hartley
Photos and videos: DrMeagan Dewar, Dr Michelle Wille, Ben Wallis
Digital production: Jenny Ky
Editor: Paul Johnson
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A strain of bird flu has caused 'mass mortality events' on every continent but Australia. Scientists say an outbreak is ... - ABC News
