Two sick seabirds found on a remote beach near Esperance, Western Australia have tested positive for highly pathogenic avian influenza H5N1, marking the first confirmed detections of the virus in Australia.
According to a report by Phys.org, the birds, a brown skua and a giant petrel, both species commonly found in the Southern Ocean, carried the strain identified as HPAI H5N1 clade 2.3.4.4b. That specific strain has been circulating globally for several years and has killed millions of wild animals and poultry across every continent except Australia until now.
The coming weeks will determine whether these are isolated cases or the beginning of a wider outbreak.
Since 2021, this strain of H5N1 has spread rapidly worldwide. It has devastated bird colonies, caused mass die-offs in marine mammals including seals and sea lions, and repeatedly crossed into dairy cattle herds. It spreads more quickly than earlier strains and can infect a much wider range of species, including mammals.
The two confirmed cases offer clues about how the virus arrived in Australia. Brown skuas and giant petrels are long-distance fliers that travel across the Southern Ocean and may scavenge carcasses of infected animals along the way. Their detection in Western Australia suggests the virus arrived through Southern Ocean wildlife movements rather than through northern migratory shorebird routes. Research has shown that migratory seabirds have carried this virus thousands of kilometers across the Southern Ocean from South America since 2023.
Genetic sequencing of the virus will be needed to confirm how closely this strain is related to viruses found at Heard Island, in Antarctica, or in South America.
The virus transmits through close contact with infected animals or contaminated environments, including scavenging carcasses. Birds that nest in large colonies, such as gannets, terns, and albatrosses, face the highest risk. Scavengers like the Tasmanian devil are also considered vulnerable.
For humans, the risk remains low. Infections in people are rare and are typically connected to direct or indirect exposure to infected animals or contaminated environments such as live poultry markets, dairy farms, or beaches where sick or dying wildlife are present.
In the United States, the same strain has caused severe damage to the poultry and dairy industries, leading to mass culling of commercial flocks. Australian authorities will be watching the situation closely to see whether additional cases emerge in wildlife or whether the virus reaches commercial farms.
