The world's worst fears about the highly pathogenic H5N1 avian influenza virus have been realised as it has now reached every continent on Earth. Confirmed in Australia this month, its presence marks a devastating milestone in the global spread of the disease since 2020, which has led to the culling of millions of poultry birds and significant mortality among wild bird and mammal populations.
Scientists had been monitoring the virus's advance, particularly after its detection in migrating seabirds in the sub-Antarctic in late 2023 and in seal populations on South Georgia in early 2024. Dr Jane Younger, an ecologist at the Institute for Marine and Antarctic Studies at the University of Tasmania, was part of an expedition to South Georgia six months ago. She recounted discovering numerous fur seal carcasses and witnessing giant petrels scavenging on densely packed bodies of dead seals, describing the scene as 'overwhelming'. Another scientific team simultaneously found approximately 13,000 dead elephant seal pups on Heard Island, 6,500km east of South Georgia, with disease tests confirming H5N1.
The virus appears to have reached Australia via migrating seabirds, with three petrels and a skua found dead or sick on southern Australian beaches earlier this month. Subsequent tests confirmed the deadly H5N1 strain, with two further suspect cases under investigation. This development is particularly concerning for Australia due to its exceptionally high levels of endemism; around half of its bird species and approximately 87% of its land-based mammals are found nowhere else on Earth. The potential loss of these species to extinction in Australia would mean their disappearance from the planet entirely.
Australian national and state governments, alongside conservationists and scientists, are now anxiously observing whether this wave of incursions will spread into the country's native wildlife. Dr Fiona Fraser, Australia's threatened species commissioner, emphasised the cultural value of these endemic species to First Nations people and the global tragedy any loss would represent. While the exact impacts on Australia's unique ecosystems are not yet fully understood, experts are clear that significant consequences are anticipated.
Australia established a national response plan to bird flu in 2024 and has been funding projects aimed at reducing the risk. Despite the widespread impact on animal populations, the risk to humans from the H5N1 strain remains low. Since 1997, there have been around 500 reported human deaths across 25 countries, predominantly among individuals with close occupational contact with commercial poultry. For context, Australia recorded approximately 1,700 deaths from influenza last year.