Bird flu has arrived in the Illawarra: should we be worried?

On Wednesday the 26th of August, the New South Wales Government announced the first confirmed case of the Influenza A virus subtype H5N1 (also referred to as the ‘bird flu’ or ‘avian influenza’) in the Illawarra. It was detected in a greater crested tern (species of coastal bird) near the suburb of Windang following a report made to the Emergency Animal Disease Hotline. I personally heard about this through an Instagram post, complete with comments that encapsulated the two sentiments so often seen in response to this kind of news: “it’s so over,” and “nothing ever happens.” After discussing the issue with many people in my life, I realised that none of us had a concrete idea of the actual risks the bird flu may pose to our country. This led to me going down a surprisingly complicated research rabbit hole to better understand the nature of the virus and what its spread in Australia may really mean for us. From panics about the collapse of the agricultural industry and the extinction of native species, to the fear of a deadly pandemic in humans, how worried should we really be?

Since late 2020, the highly pathogenic influenza A H5N1 subtype (specifically the 2.3.3.4b clade) has been spreading globally, resulting in the largest bird flu panzootic (pandemic affecting animals) ever recorded. The panzootic clade of the virus was first detected in Europe and rapidly spread across the globe, to Africa, Asia, the Americas, before reaching Antarctica. Mainland Australia remained without a confirmed case until June this year; believed to be due to our geographical isolation and other biogeographical features (such as Wallace’s line) which has kept our wildlife relatively separated from infected populations. Genetic testing revealed that the bird flu came to mainland Australia from Heard Island, an Australian sub-Antarctic territory.

Regardless of location, three risks tend to be prioritised as major focus areas amongst those researching the panzootic. These are the prospects of large-scale biodiversity loss, spread of the virus to agricultural animals, and the evolution of the virus to better infect humans.

As the bird flu has lurched from country to country, it has left behind a trail of harrowing ecological losses. The most notorious of these have been the mass mortality events, such as the deaths of 200,000 wild coastal birds in Peru, 24,000 South American sea lions, 10,000 cranes in Hungary, and 17,400 elephant seals in Argentina. These examples are not exhaustive, and many more similar, unprecedented events have been reported throughout the panzootic. Concerningly, the consensus amongst researchers is that due to widespread difficulties in reporting and testing, the mortality figures seen are likely to be largely underestimating actual numbers. This has significant implications for animal conservation, as species of concern risk having their already low numbers further dwindled by mass deaths. Infection may also have run on effects beyond just imminent mortalities, such as changes in breeding behaviours and food chain interactions. Australia has always been a beautifully biodiverse country; in fact, we are one of seventeen megadiverse countries. Despite this, we have widespread biodiversity loss due to human activity. The spread of avian influenza to our native bird and mammal species, especially those already in need of conservation, may have quite a large impact. Alarmingly, the spread of the virus amongst our animal populations is hard to predict, as transmission is impacted by a countless number of factors. The potential of population devastating mass mortality events in our wildlife is a real and unfortunate risk that has come with the arrival of the strain in our country.

The H5N1 bird flu has had major impacts on the agricultural industries of many countries. The most infamous example of this has been in the United States, where the virus has a novel mutation allowing it to infect cattle. This has led to 1,173 confirmed cases in dairy cow herds since March 2024. The US has also seen significant spread in their poultry, with 2,243 flocks (including both commercial and backyard flocks) confirmed to have been infected, leading to an estimated 208.33 million affected poultry since 2022. This led to major economic losses and caused the prices of products such as eggs to skyrocket significantly. The Australian animal agriculture industry contributes significantly to the economy, making up 2.1% of national employment and 5.6% of rural employment from 2024-2025. If faced with widespread infection in poultry and livestock, the losses would be extremely significant. Thankfully, the gene associated with the infection of cattle in the US is not present in the variant currently in Australia. The likelihood of a similar mutation event occurring here is reportedly extremely low. In similar good news, avian influenza has not been detected in any of our commercial poultry. With Australia’s strict biosecurity measures for agricultural animals providing a large layer of protection against transmission, the odds of mass infections are further decreased. So, while an outbreak across multiple farms would have a deeply negative impact on the livelihoods of many, the current biosecurity and H5N1 preparation and response measures in place are likely to reduce the chances of nationwide agricultural losses.

Currently, the risk the H5N1 subtype of Influenza A poses to humans is low. Since the initial detection of the 2.3.4.4b clade in Europe in late 2020, the Australian Centre of Disease Control reports that there have only been around 100 global cases confirmed in humans. These cases tend to only occur in individuals who regularly handle at risk farm animals, such as American farmers working with dairy cows. Comfortingly, only a small number of those infected developed severe symptoms, with a majority of cases presenting mildly. This, however, is not enough to completely quell the potential of the virus to cause a human pandemic. While the current genes the H5N1 virus possesses do not translate to high transmission rates or virulence in humans, the ability of the virus to rapidly evolve and change its genome does have implications for possible human infection. One notable ability the H5N1 virus has that drives its rapid genomic changes is known as ‘reassortment’. If an animal is infected with H5N1 at the same time as another influenza virus, reassortment allows the viruses to ‘swap’ genes. This is considered a pathway by which H5N1 could potentially pose a larger risk in humans, as it could obtain genes that allow it to better infect us. Additionally, the wide range of mammals the H5N1 virus has the ability to infect has the potential to provide the virus with the environment it needs to develop adaptations that could be useful in  infecting humans. Now, this all sounds absolutely terrifying, but the good news is that the odds of all of this happening and then causing widespread cases in humans is still considered low. Despite this, the non-zero risk does highlight the importance of adhering to recommended precautions, such as working to prevent spread to our domestic animal populations, avoiding direct contact with infected animals, and regular surveillance efforts.

The risks that have come with the H5N1 virus establishing itself in Australia are unsettling. Although I would love to conclude that everything will be absolutely fine and we should not be worried at all, at the very least the virus does pose a serious threat to a lot of our native and beloved animals. At the same time there is a great amount of room for optimism, especially regarding the prevention of spread into our agricultural animals and thankfully to ourselves. So, while it may be wise to worry about the fate of our animals, it is important to remember that amidst the uncertainty there are always things that are being done to prevent or lessen the impact of the worst-case scenarios we so often see described in sensationalist reporting.