Australia Detects Highly Pathogenic H5N1 Avian Influenza in Migratory Seabirds

Australian authorities have confirmed the presence of the H5N1 2.3.4.4b strain of avian influenza in two migratory seabird species found along the southern coast of Western Australia. The detection, involving a brown skua and a giant petrel found near Esperance, marks the first time this highly pathogenic virus has been identified in Australia. According to Australia’s Department of Agriculture, Fisheries and Forestry, officials have launched enhanced surveillance protocols to monitor the movement of these species and mitigate potential risks to native wildlife and commercial poultry sectors.

How the Virus Reached Australia

The transmission route is currently the subject of genomic sequencing, but experts point to subantarctic islands as the likely origin. While initial biosecurity concerns focused on migratory shorebirds arriving from the north, the H5N1 strain has been tracked moving through the Southern Ocean. According to research published by the French National Centre for Scientific Research (CNRS), species like brown skuas and giant petrels are highly susceptible to the virus due to their scavenging behavior and extensive long-range movements between subantarctic breeding grounds and Australian waters. These birds can travel from the subantarctic region to the Western Australian coast in approximately one month.

Why Scavenging Behavior Increases Transmission Risk

The ecological habits of skuas and giant petrels make them efficient vectors for the virus. Ecologist Marcel Klaassen from Deakin University notes that these birds often engage in kleptoparasitism—stealing food from other animals—and scavenging on carcasses, which exposes them directly to infected mucous, saliva, and feces. Unlike many migratory shorebirds that remain in specific wetlands, these seabirds typically roost on the water and only approach the shore when sick or injured. This behavior complicates surveillance efforts, as sick birds are often found in isolated, inaccessible coastal areas.

Potential Risks to Native Wildlife

The primary concern for Australian biosecurity is the potential spillover into local wildlife populations, particularly scavengers and marine mammals. According to BirdLife Australia, if infected carcasses wash ashore, scavengers like silver gulls, eagles, and ravens could contract the virus. Furthermore, Australian sea lions—which are known for their curiosity and physical interaction with debris—could be exposed to infected remains. Experts are also monitoring the risk to freshwater systems, where the virus could spread rapidly among waterfowl such as mallards if they intermingle with infected migratory species.

Current Biosecurity and Surveillance Measures

In response to the findings, the Australian Chief Veterinary Officer, Dr. Beth Cookson, has convened an expert wildlife advisory group to map the co-mingling sites of high-risk seabirds. The government is currently managing an influx of reports from the public regarding dead or sick birds. Officials emphasize that the virus’s impact on Australian carnivorous mammals, such as quolls or dingoes, remains unknown, though feral cats and foxes are known carriers in other global regions.

Key Takeaways for Public Safety

• Report Sightings: Do not touch sick or dead birds. Report them immediately to the Emergency Animal Disease Hotline at 1800 675 888.
• Geographic Scope: While initial cases were confirmed in Western Australia, the migratory paths of these seabirds extend along the entire southern coastline to Queensland.
• Virus Characteristics: The H5N1 2.3.4.4b strain is highly pathogenic, with high mortality rates observed in poultry and wild bird populations globally since 2020.
• Monitoring: Genomic sequencing is ongoing to determine if the virus arrived directly from subantarctic islands or through an intermediate population.

While the current detection may be isolated to a few individuals, researchers warn that the arrival of H5N1 in Australia was likely inevitable given the global spread of the virus. Ongoing surveillance remains the primary tool for determining whether the pathogen will establish a foothold in the Australian ecosystem.