Phylogenetic Analysis of Highly Pathogenic Avian Influenza H7 Viruses in Australia and New Zealand Suggests Local Viral Evolution

Avian Influenza, a disease caused by influenza A viruses, primarily affects birds. However, this disease can sometimes spread to humans, particularly through contact with infected livestock, such as poultry, and poses a serious threat to both animal and human health, as well as food security. Highly Pathogenic Avian Influenza subtypes (HPAI), like H5 and H7, spread fast and can cause severe disease with high mortality. Recently, outbreaks of HPAI H7 subtypes have occurred in Australia and New Zealand, posing a significant challenge to livestock production in these countries. While this virus was largely confined to wild birds, multiple outbreaks have been reported in commercial farms since 2024. In this study, we investigated HPAI H7 subtype viruses associated with recent outbreaks in livestock across Oceania, with a particular focus on Australia and New Zealand, to identify their possible links. After genetic relatedness analysis, HPAI H7 subtype viruses from Australia and New Zealand were found to be distinct from those in neighbouring regions of East and Southeast Asia, suggesting they were local. Although more farm outbreaks were reported earlier this year, successful eradication was achieved by mid-year, highlighting the importance of ongoing surveillance, coordinated national response, and improved biosecurity measures.