Introduction by Croakey: Although many of the mass bird deaths from avian influenza are occurring in isolated areas, increasing numbers of Australians are seeing birds that have died or are sick from the virus.
ABC News published photos this week of residents in the south-west Victorian town of Portland removing carcasses from beaches in the area.
Croakey has previously covered some of the wider health impacts of the outbreak, including upon mental health and wellbeing, and rural communities. No doubt people will increasingly be wondering about the direct risks to humans from the virus, and how best to manage these.
The Australian Centre for Disease Control says bird flu rarely spreads to people and the risk of H5 bird flu (H5N1 clade 2.3.4.4b) to people in Australia is low, with no infections of this strain reported in people here.
Still, as infectious diseases expert Professor Allen Cheng writes below, human infections can occur, with more than 1,000 cases reported globally since 2003, including 479 deaths.
Those most at risk are wildlife carers, although authorities are watching out for other groups such as poultry workers should the virus spread.
Allen Cheng writes:
Bird flu is circulating among birds on the Australian mainland. So with the confirmed number of detections growing, you may be wondering about the risk of birds infecting humans.
So far in 2026, no humans in Australia have been diagnosed with the currently circulating strain. And evidence from overseas indicates that in the rare situation this would occur, illness would generally be mild.
But not everyone with flu-like symptoms gets tested. And even if they did, a general flu test cannot distinguish between bird flu and seasonal flu.
So how would we know if a human caught bird flu from an infected bird?
Bird flu (or avian influenza) refers to strains of flu viruses that mainly affect birds. The current strain of concern is known as H5N1.
Since 2020, a sub-strain of H5N1, known as 2.3.4.4b, has been circulating around the world. This has resulted in the deaths of millions of birds (including poultry).
It has also crossed into other species, including dairy cows in the United States, and marine mammals. Distressingly, mass mortality events – where many animals die suddenly – have been reported.
In June, the first cases of H5N1 influenza were reported in Australia, first in migratory birds, then in local wild birds. Now, the government does not report case numbers, just events, where one or more birds may be involved.
There has been at least one mass mortality event reported in Australia [Note from editor: see updated details here as more events have been reported since this article was written].
Low risk for most
So with more bird flu now circulating in Australia, can we expect more humans to be infected?
Since 2003, the World Health Organization (WHO) has reported 1,000 cases of H5N1 bird flu in humans globally, with 479 deaths. This year, it has reported seven cases of H5N1 bird flu in humans (in Cambodia, Bangladesh and India) with two deaths.
The sub-strain currently circulating globally, including Australia – 2.3.4.4b – seems to generally cause mild disease in humans. However, there have been a few cases of more severe 2.3.4.4b disease (including two deaths in the United States).
To date, there have been no human cases of 2.3.4.4b in Australia. But there was one case of a related H5N1 strain, 2.3.2.1a, in a child who returned from overseas travel.
Even with more 2.3.4.4b circulating in recent weeks, the Australian Centre for Disease Control still assesses the risk to humans as low.
While humans can catch the virus from close contact with infected birds, the virus does not currently spread between humans. This means the risk of a significant human pandemic – which would need widespread transmission between humans – is currently low.
Experience in other countries suggests most human infection results from close contact with infected animals.
In Australia, the highest risk groups currently are wildlife carers, including veterinary staff and those managing sick or dead birds. But public health authorities are watching for other groups who may become at risk should the outbreak spread, such as poultry workers.
Symptoms are typically mild, with a runny nose, cough and fever, and sometimes nausea and diarrhoea. Conjunctivitis (“pink eye”) is one symptom associated with bird flu that we don’t often see in seasonal flu.
However, more serious disease can develop. In other countries, this has generally been associated with infections due to H5N1 strains other than 2.3.4.4b.
Is there a test?
Standard flu tests should detect bird flu too. But they don’t distinguish between seasonal flu and bird flu.
Detecting bird flu relies on doctors letting the lab know they suspect bird flu (for example, if a patient has had contact with birds that may be infected).
So if you have flu-like symptoms and are in one of the groups more likely to be exposed to bird flu, tell your doctor so they can order the specific test for bird flu. It’s best to phone ahead, and present for testing wearing a mask.
People with confirmed bird flu should be monitored and follow the directions of their local public health unit. Authorities will also assess whether others may have been exposed and infected.
Some people may be offered the preventive antiviral medicine oseltamivir to reduce their risk of becoming infected or to treat an infection.
There is also surveillance for bird flu in humans. This means actively looking out for signals without relying on individuals coming forward for testing.
For instance, the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne tests a selection of isolates (samples) routinely sent from other laboratories.
Other ways to look out for humans infected with bird flu include surveillance systems based in selected hospitals and general practices.
Precautions
If you work with birds, advice is available about the right type of personal protective equipment to use to minimise your risk of infection. Washing your hands is also important.
A regular seasonal flu vaccine is recommended for people at risk. This is not to protect against bird flu but to prevent people becoming sick with both seasonal and bird flu viruses at the same time.
Author details:
Allen Cheng is Professor of Infectious Diseases, Monash University. He receives funding from the Australian Centre for Disease Control for respiratory virus surveillance. He is a member of the Communicable Diseases Network of Australia and the National Respiratory Infections Surveillance Committee advising on surveillance and response to influenza. This article was first published in The Conversation.
If you notice sick or dead birds, or other animals, you should: avoid touching them; record your location and what you see (take photos or video, if possible); report this to the 24-hour Emergency Animal Disease Hotline on 1800 675 888.
Also read at The Conversation: Australia has long relied on volunteers and wildlife carers. As bird flu spreads, they will need support
See Croakey’s archive of articles on avian influenza
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