The recent news that the first case of the deadly H5N1 strain of Highly Pathogenic Avian Influenza (HPAI) has been detected in Australia has, despite its potential for serious consequences, a degree of inevitability about it. In June 2026 the Australian authorities confirmed the isolation of the virus from a migratory sea bird, a brown skua. Other sick birds were noted and the virus had been previously detected in Antarctica in 2024. The current Australian case was detected on the coast, near Esperance, Western Australia.
Various strains of avian influenza have regularly infected the world, with various degrees of severity and risk to humans. This current strain of HPAI emerged in 2020 and has spread steadily around the globe with, Australia, and New Zealand, having previously been the only major countries to escape. New Zealand remains free to date: the strain of virus which resulted in the depopulation of a large poultry farm in Otago in 2024 was of the H7N6 strain ; but New Zealand remains vigilant with its Ministry of Primary Industries (MPI) recently commenting:
“While we can’t prevent wild birds bringing this virus here, we can work together to limit its impact. If H5N1 bird flu arrives, it is likely to spread in our wild bird population and will not be able to be eradicated, so it’s important for farmers and backyard bird owners to have good biosecurity practices in place.”
New Zealand’s unique avian fauna, some species of which are highly endangered, are particularly at risk from a widespread epidemic of this highly pathogenic virus.
Concerns have been also expressed about the ability of this strain of virus to cross over into mammalian species including humans. Since the initial cases in 2020, the virus has been detected in numerous mammals including seal lions, bears foxes and mink. One case which attracted considerable publicity earlier this year concerned the sudden deaths of 72 captive tigers in Thailand. Initially HPAI was blamed for these deaths but subsequent testing proved canine distemper and Mycoplasma sp. to be the primary causes. As the general public have become increasingly aware since the global COVID epidemic, there are many more viruses, including currently Ebola and Hanta, which are capable of giving rise to serious concerns. During the first half of 2025, a total of 26 human deaths were reported as being linked to HPAI worldwide with 11 deaths, including 7 children in Cambodia.
We have written before of the HPAI situation in the USA, following its crossover into dairy cows and proven spread within dairy herds and a few cases reported in dairy workers. During 2026 there have been relatively few new cases reported in dairy herds and no new human infections. Surveillance continues but the Centre of Disease Control (CDC) in the USA currently reports the risk as ‘Low’.
Somewhat ironically, the U.K. decided to relax measures against bird flu in June 2026, with Chief Veterinary Officer Christine Middlemiss commenting:
“The evidence clearly shows that the risk of avian influenza to poultry across Great Britain has reduced, making this the right time to lift the prevention zones.
“This has been possible because of the hard work of all bird keepers, who have upheld high biosecurity standards for many months. It remains vital that keepers remain vigilant and maintain high levels of biosecurity to keep flocks safe. Low risk does not mean no risk.”
It is tempting to conclude that the worst is over; that this strain of HPAI has had its day but the pending situation in Australia and New Zealand gives cause for concern and vets and all members of the public in those countries, and elsewhere, are advised to remain highly vigilant. However there is no case for relaxation. New virus strains will emerge, and some of them will undoubtedly prove to be zoonotic. And as many western governments reduce or remove their levels of international aid, the potential for delayed diagnosis and inadequate control unfortunately remains.
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