Australia has confirmed its first detected case of highly pathogenic avian influenza (HPAI) H5N1, specifically the clade 2.3.4.4b lineage, in a brown skua found in Cape Le Grand National Park near Esperance in Western Australia.A southern giant petrel discovered in the same area is also suspected to have been infected.

Samples were tested and confirmed by CSIRO, marking a significant development after years of Australia remaining free of this strain despite its global spread.

H5N1 originated from avian influenza viruses that have existed for thousands of years, but a highly pathogenic form emerged in 1996 and became established in poultry populations worldwide.

Since 2021, the virus has caused a major global animal pandemic, killing millions of wild birds and affecting numerous mammal species, including seals.The virus spreads through contaminated faeces, water, direct contact, aerosols and scavenging or predation of infected animals.The virus has reached every continent except Australia until now.

Researchers believe Australia was protected because migratory duck species, which are major carriers of H5N1 in the Northern Hemisphere, do not regularly travel between Australia and affected regions.

Instead, seabirds such as skuas and giant petrels may have transported the virus across the Southern Ocean after it became established in Antarctica and subantarctic regions.Experts caution that the detection does not necessarily mean the virus will become widespread in Australia.

The greatest concern is transmission from infected seabirds to native wildlife and freshwater ducks, which could greatly increase the risk of broader spread.Authorities are continuing surveillance and testing to determine whether additional animals have been infected.

Members of the public are advised not to handle sick or dead wildlife and to report suspected cases immediately, while poultry owners should follow biosecurity guidance and report unusual bird deaths.