Two poultry farms in the southern Australian State of Victoria have been quarantined for high pathogenicity avian influenza A/H7N8 infections, but spread to additional farms has not been observed so far.

The Australian Government’s Outbreak website notes that the two farms were connected and that the 2025 A/H7N8 strain is not the same A/H7N8 strain involved in the 2024 outbreaks. An Agriculture Victoria’s update noted:

The first 2025 poultry farm avian H7N8 outbreak occurred in a farm on 8-FEB-2025, less than a week after quarantine restrictions had been lifted following the 2024 outbreaks of three different avian influenza H7 viruses, H7N8, H7N3 and H7N9.

Due to related tracing activities, the second 2025 H7N8 poultry farm avian H7N8 outbreak was reported on 13-FEB-2025.

It’s likely the initial infection of poultry originated in wild birds.

In 2024, a different H7N8 strain was involved in News South Wales and Australian Capital Territory poultry outbreaks. It doesn’t look like A/H7N8 sequences from Australia’s 2024 or 2025 outbreaks are in the public domain, so it’s hard to speak more specifically on how they differ: subtle sequence changes, different genes…🤷‍♂️

Transport restrictions were implemented in response to the latest outbreak, and a control area of roughly 5km around an infected farm was set up. Poultry owners…

“..cannot move birds, products (including eggs and manure) or equipment into, out of, or within the area without a permit. ‘This includes selling or giving away eggs from your poultry – these must not leave your property.’”

After the second farm was identified, a requirement was announced to keep poultry indoors for anyone with 50 or more birds within the restricted area. For backyard owners, the Department advised:

• Restrict contact between pet birds, poultry and wild birds.
• Prevent access by wild birds to food and water sources for your birds.
• Keep equipment and yards or aviaries clean.
• Limit visitors to your birds.
• Bird owners should wash their hands before and after handling birds.
• Monitor your birds’ health and report sudden death in your poultry.

It should go without saying—, but it is said in every article, so I’ll add it here, too—that this H7N8 avian influenza virus is not that H5N1 avian influenza virus. Both are subtypes of the influenza A virus. Also, avian influenza viruses are different from seasonal influenza viruses. The latter are well-adapted for human-to-human transmission, whereas avian influenza viruses are not.

Poultry exposed to wild birds, even those in poorly biosecure sheds, have an increased risk of being exposed to avian influenza-infected wild birds.

Interestingly, in wild birds, the H7 subtypes are usually low-pathogenicity avian influenza (LPAI) viruses. But mutation in response to their transmission to and among poultry species means they become high-pathogenicity variants to poultry, causing sickness and death. This has been nicel visualised by Dr Michelle Wille in the image below from Update on avian influenza in Australia.

Avian influenza continues to travel worldwide, perhaps a candidate for a Time Cover as Virus Collective of the Year! And so long as these spillovers between wild and farmed birds keep happening, we’re in for a fundamental longing for the good old days of cheap and available eggs.