#19,292
This week OFFLU - the WOAH/FAO joint network of expertise on avian influenza - published a 33-page statement which serves as both a detailed account on the opening 6 weeks of the first incursion of HPAI into Australia/New Zealand, and a One-Health technical briefing on the likely implications of H5 HPAI for the region.
This statement has an excellent pedigree, and many of the authors will be familiar names to regular readers of this blog.
10 August 2026OFFLU WILDLIFE STATEMENT IV:
Thijs Kuiken — co-chair, OFFLU Wildlife Technical Activity, Lineke Begeman — lead, OFFLU Wildlife Technical Activity, Andrew Breed — co-chair, OFFLU Wildlife Technical Activity, Ruth Cromie, Jolene Giacinti, Manabu Onuma, Laura Roberts, Yoshi Sakoda, David Stallknecht, Marcela M. Uhart — chair, OFFLU Steering Committee, Jonas Waldenström, Michelle Wille
Executive summary
What was long expected, has now come to pass: high pathogenicity avian influenza H5 (HPAI H5) has been detected for the first time in wild birds in Australia in June 2026 and in New Zealand in July 2026.
HPAI H5 has a high burden of disease for poultry and wildlife, as well as a zoonotic risk for humans. Since the emergence of HPAI H5 (specifically, the A/Goose/Guangdong/1/1996 lineage)in Asia in 1996, it has been detected in ever more continental regions. It spread from Europe to North America in 2021, to South America in 2022, and to the Antarctic region (Antarctica and sub- Antarctic islands) in 2023. Since its incursion in the Antarctic region, it spread nearly 6,500 km eastwards in two years, from South Georgia in the South Atlantic Ocean in October 2023 to Heard Island in the southern Indian Ocean in October 2025.
It is likely that HPAI H5 was carried from the Antarctic region to Australia and New Zealand by migratory seabirds. Between 14 June and 31 July 2026, HPAI H5 was detected in 1 Brown Skua (Stercorarius antarcticus) and 17 giant petrels (Macronectes sp.) on the coast of Australia, and 1 Brown Skua on the coast of New Zealand. These species breed in spring in the Antarctic region, where they are known to have been infected by HPAI H5. In the non-breeding period, these species may disperse widely, including northwards to waters off the coasts of Australia and New Zealand. Preliminary phylogenetic analysis shows that the HPAI H5 virus detections in wild birds in Australia are closely related to viruses from Heard Island in the Antarctic region.
HPAI H5 has subsequently spilled over from these seabirds to resident bird species in Australia and New Zealand. In Australia, HPAI H5 has been detected in 34 Greater Crested Terns (Thalasseus bergii) as of 31 July 2026. The Greater Crested Tern is a largely resident species in Australia and occurs widely along the coast and offshore islands, a habitat shared with many other seabird species. In New Zealand, HPAI H5 has been detected in one Swamp Harrier (Circus approximans) as of 31 July 2026. The Swamp Harrier is a resident species in New Zealand. In winter it feeds largely on carrion, which is a likely source of infection in avian scavengers.
Based on the sequence of events in other continents, HPAI H5 is likely to spread among wild birds and mammals in Australia and New Zealand. The main wildlife groups at risk are seabirds (e.g. gannets, terns and albatrosses), other waterbirds (e.g. ducks, swans and grebes), pinnipeds (e.g. seals and sea lions), and predatory and scavenging birds and mammals (e.g. raptors, corvids, Dingoes (Canis familiaris dingo) and quolls). From Australia and New Zealand, HPAI H5 may spread to other parts of Oceania (Melanesia, Micronesia, Polynesia), most likely via medium- or long-distance movements of wild birds.
The potential conservation impact from HPAI-H5-associated wildlife morbidity and mortality in Oceania is enormous. Oceania contains many geographically restricted and threatened wildlife populations. For susceptible species, particularly colony-nesting seabirds and pinnipeds, additional mortality associated with HPAI H5 could compound existing pressures on populations.
Although it is not possible to stop the geographical spread of HPAI H5, there are response options to reduce its spread and impact on wildlife, as well as the risk of such HPAI panzootics occurring in the future. Short-term response options include expanding and improving avian influenza surveillance in wildlife, coordination of surveillance across Oceania, removal of infected wildlife carcasses, management of human activities in regions with affected wildlife, vaccination of threatened wildlife species, and avoidance of activities that harm or disturb wildlife and theirhabitats. In case of HPAI H5 spillover to poultry (which has so far not been reported in Australia or New Zealand), short-term response options include rapidly controlling outbreaks and limiting concurrent infections in poultry populations, thereby reducing opportunities for continued viral evolution and recurrent spillback into local wildlife. Medium- and long-term response options include long-term monitoring of impacted wildlife populations, increasing resilience of susceptible wildlife populations (including by actively reducing other threats and promoting actions to enable recovery of populations) and reducing the risk of HPAI emergence and spillover from poultry in the future.
Post scriptum (10 August 2026): Following the drafting of this statement, further cases of HPAI H5 have been detected in wild birds in Australia. These include: a mass mortality event in Greater Crested Terns in South Australia involving over 80 sick or dead individuals. Several detections have been made in Silver Gulls (Chroicocephalus novaehollandiae), a widespread resident species in Australia and New Zealand that occurs both on the coast and inland, including wetland habitats and urban environments. A single detection has been made in an Australian Magpie (Gymnorhina tibicen), a widespread resident species in Australia, member of the Artamidae family and is omnivorous. As of 10 August 2026, there have been 231 confirmed detections of H5 HPAI in wild birds in Australia (10 in Western Australia, 163 in South Australia, 53 in Victoria, 4 in New South Wales and 1 in Queensland), while there the number of confirmed detections in New Zealand has remained at two.
(SNIP)
The potential conservation impact on the wildlife of Oceania is enormous. According to the IUCN Red Data List, a disproportionately large number of mammalian and avian species in Oceania face high extinction risks. In part this is due to island biogeography, and threats such as invasive species and climate change. The IUCN Red Data List shows 248 avian species in Oceania at the top three levels of extinction risk: 48 Critically Endangered, 67 Endangered and 133 Vulnerable (Appendix 1). Of these species, 90 occur in Australia, 83 in New Zealand and 150 in the rest of Oceania. Similarly, 158 mammalian species are listed at the top three extinction risk levels: 28 Critically Endangered, 58 Endangered and 72 Vulnerable (Appendix 2). Of these species, 76 occur in Australia, 14 in New Zealand and 90 in the rest of Oceania. These appendices are not intended to imply that all listed species are equally susceptible to HPAI H5 virus infection or mortality. Rather, they identify species for which additional mortality could have important conservation consequences and provide a starting point for prioritizing species for further HPAI risk assessment.
The history of HPAI's global expansion suggests that as it conquers new territories, it encounters new host species and previously unseen LPAI viruses, which can promote both adaptation and reassortment.
In the first three years after H5N1's arrival in North America more than 100 new genotypes were identified - and while most were no improvement on its ancestors - at least three new reassortants of note emerged:
- B3.13 aka the `bovine' strain affecting dairy cattle in at least 19 states and infecting dozens of humans
- D1.1 a wild bird/poultry strain which has spilled over into > a dozen people in Washington State and a teenager in British Columbia
- D1.2 a wild bird/poultry strain which recently detected in poultry and 2 pigs in Oregon
As any kid with an erector set can tell you (yes, I'm showing my age. Feel free to substitute Lego (tm)), the larger and more varied supply of components you have, the more complex things you can build.
The same logic seems to apply to viruses. And by reaching Oceania, HPAI H5 has just accessed a fresh supply of new building blocks to play with.
While what it may eventually create is unknown, we should be prepared for surprises.
