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Australia remains bird flu free as outbreak continues elsewhere
Since 2020, millions of birds from hundreds of species have been struck down by a global outbreak of avian influenza.
But while bird flu has infected many of the world’s nations, new research confirms that Australia has remained virus free.
As an unprecedented outbreak of bird flu continues to spread across the world, leaving millions of dead animals in its wake, one region has remarkably remained virus free.
Oceania has so far managed to avoid the arrival of the strain of highly pathogenic avian influenza (HPAI) that is currently devasting global bird populations. Australia, New Zealand and other Pacific nations have recorded no cases over the past couple of years, most likely due to their location away from major landmasses and migratory routes.
However, with HPAI infecting Antarctica for the first time this year there are renewed concerns that bird flu may rear its head in the Pacific and pose a risk to the threatened birds that live there, like the fairy tern.
The monitoring of migratory birds arriving in Australia has shown that up to 2023 the virus has been kept out. Dr Alex Bond, the Principal Curator and Curator in Charge of Birds at the Natural History Museum, was one of the co-authors of this research.
“Migratory birds are one vector for diseases spreading into new areas, but species migrating into Australia don’t seem to be carrying bird flu,” says Alex. “The migratory shearwaters we looked at mix with other species in the north Pacific, but don’t appear to have contracted the virus.”
“It’s not entirely certain why this is, but it might be because shearwaters spend a lot of time out at sea where they’re less densely packed, making it harder for the virus to spread between them.”
The study was published in the journal Influenza and Other Respiratory Viruses.
With the H5N1 virus having arrived in Antarctica, there are fears it could spread rapidly in the continent's penguin colonies. © vladsilver /Shutterstock.
The bird flu outbreak so far
The origins of the current bird flu outbreak lie in 1996, when a type of influenza A known as H5N1 emerged in southeast Asia. Even though this isn’t the only form of the virus that can cause HPAI, its ability to spread between birds and mammals means it has attracted a great deal of attention.
Like all influenza viruses, it has an extraordinary ability to adapt. The virus regularly mutates and can spread these changes between individual viruses when they infect a cell at the same time. This means that while this H5N1 strain was first detected in geese, it contains other genes that appear to have come from viruses infecting ducks and other birds.
Though H5N1 viruses have been causing sporadic outbreaks since being discovered 20 years ago, a new variant, known as 2.3.4.4b, has killed an unprecedented number of wild birds and poultry around the world.
But it is not just this high bird mortality rate that is of concern. Though it’s not believed the virus is currently spreading directly between mammals, thousands of seals and sea lions have died during the outbreak after being exposed to infected seabirds and their droppings.
This jump to mammals has raised many alarm bells, particularly in the wake of the COVID-19 pandemic.
While ducks and their relatives used to be the main carriers of bird flu, the spread of the virus to south Atlantic and sub-Antarctic islands suggests that seabirds may also be helping the virus to travel.
In February 2024, HPAI was recorded on the Antarctic mainland for the first time, raising fears for the continent’s vast penguin population. As the birds live together in dense colonies it is feared that the virus could spread rapidly between them if some birds get infected.
The research team took samples from a variety of birds, including the short-tailed shearwater. © ivandon /Shutterstock.
Will bird flu spread to Australia?
In contrast to the rest of the world, Oceania has remained largely bird flu free despite the occasional outbreak in poultry. The region’s geographical isolation, and the fact that many Oceanian ducks don’t migrate to other continents is thought to have limited the spread of bird flu.
However, this could change. Migratory seabirds travelling between continents have now been implicated in spreading the current strain of the virus, meaning that the region may no longer be cut off from bird flu in the same way as before.
To confirm this, the researchers took blood, saliva and cloacal samples from almost 1100 migratory seabirds and waders arriving in Australia between October and December 2023. They sampled a variety of different sites, including breeding grounds on Lord Howe Island and Phillip Island.
Incredibly, none of the birds showed any signs of HPAI and no samples contained H5N1. The team suggest that as the route of these seabirds passes through areas where other H5N1 variants are more prominent, this might offer some protection to the current strain.
While this suggests that Oceania is safe from bird flu for now, the detection of the virus in Antarctica may change things. A number of sea bird species, such as albatrosses, are known to travel vast distances throughout the southern oceans and between the sub-Antarctic islands and Oceania.
A recent update from the UN Food and Agriculture Organization and the World Organization for Animal Health warned that this was a plausible scenario, calling for greater monitoring of the birds’ movement and health to prevent it becoming reality.
