The deadly H5N1 strain of bird flu has been found in seabirds in two Australian states .
But don’t be fooled by the name: this virus also rapidly infects other animals. It has caused havoc in poultry farms and backyard chicken flocks in the northern hemisphere. And it can also infect, and even kill , cats.
Domestic pet owners, particularly homes that keep backyard chicken flocks, should be on alert for signs of this highly infectious virus. Now is the time to think about how you will respond.
A deadly strain of the virus
I have been working on the H5N1 since 2004. In more than two decades it has evolved into a highly infectious “zoonotic” disease – able to jump between several animal species and occasionally to humans.
The tipping point occurred in the United States in 2023-24, when the virus was transmitted from wild birds into poultry farms and high-density dairy farms in Texas, Kansas, Michigan and Idaho. Transmission has also occurred between cattle and cats, with cats feeding on infected cow colostrum (the first milk after a mammal gives birth), and some later dying.
In the past three years, we have seen many cases in Peru , Chile and southern Antarctica, including the deaths of thousands of seal pups on Heard Island.
How long has it been here?
Initially, Australian authorities were concerned the virus would come predominantly from the north during the annual migration of migratory shorebirds . There was uncertainty about whether sick birds would be strong enough to fly here from far-off Antarctica.
But two of the sick birds in Western Australia and South Australia were found alive. Given this virus was first identified on June 20, it’s possible it arrived in Australia much earlier since these species tend to make their way from the sub-Antarctic region from March onwards.
It makes sense this virus has arrived in winter – it is most easily transmitted during cold weather. In China we saw it typically emerge around Chinese New Year – a time when low temperatures coincide with high demand for poultry for celebratory meals.
How quickly can it move from wild birds?
The World Organisation for Animal Health tracks where the virus is reported for different countries ( WAHIS ).
Analysing this data, we find it takes between 2 and 6 weeks, on average, for the virus to be move into poultry species following the first report in wild birds. Of course, this differs according to the comprehensiveness of a country’s surveillance and the level of data aggregation provided by different countries reporting to the system.
For example, considering data reported between 2020 and 2024 in Denmark , it took a little more than three weeks between finding the virus in wild birds and reporting it in poultry.
In Australia, and considering data from other countries it is possible we will see outbreaks in poultry in the next 4-5 weeks. This obviously depends on the role bridging species will play on bringing infection into Australian poultry facilities, as well as the level of biosecurity of Australian poultry husbandry systems. Everyone is on high alert, and state and federal agriculture departments have ramped up surveillance and public messaging for producers and the public.
In the past few years, an avian influenza surveillance system has tested the faeces of wild birds at nesting sites to watch for the virus. Now this surveillance is likely to be expanded to include poultry. Testing will also be informed by farmers, producers and backyard chicken owners reporting suspected illness.
What’s the risk to my household pets?
Poultry
The risks are very real. When this virus ends up in a densely housed commercial farm, mortality rates of close to 100% are likely. The greatest risk of exposure is when free-range hens spend some time outdoors and are exposed to contact with wild birds. This is the same for backyard chickens.
If you have a flock of chickens, keep them housed as much as possible. “Bridging species” like crows, magpies and other urban birds can bring infection into backyard flocks.
Keep an eye on your chooks and monitor their health for lethargy and neurological signs. If you notice a bird seems disoriented or unwell you should call the Emergency Animal Disease Hotline on 1800 675 888.
If warranted, a biosecurity officer will come and take nasal swabs and bird droppings away to be tested. In the meantime, you will be asked not to move your poultry and to keep them housed.
Unfortunately, all poultry in a farm or backyard flock where H5N1 infection is identified will have to be euthanised.
This virus can infect humans, though it is rare. Do not approach the bird or animal, just call the hotline on 1800 675 888. If there is a need to move the animal, wear gloves and a PPE mask, and dispose of them carefully afterwards.
Cats
Evidence from the US suggests cats are at much greater risk of severe disease than dogs. Where cats ingested contaminated material, such as milk from cattle, there were fatalities. Australian cat owners should be vigilant about what their cat is “investigating” outside, including dead birds.
Dogs
The evidence for serious illness is not as strong as cats. We know they can be exposed, but they don’t seem to be an at-risk species. Other terrestrial carnivores, such as skunk and foxes, have shown neurological illness and respiratory distress. We will have to watch the dingo population closely, because they scavenge on dead wild birds.
Caged birds
Caged birds such as budgerigars are unlikely to come into contact with wild birds. But if this is possible, and there are signs of illness, these should be reported.
Emergency Animal Disease Hotline – 1800 675 888
