Avian flu in Australia: risks, symptoms and preparedness

If you’ve gone for your weekly shop and noticed that the shelves normally housing eggs are barren, or that one of the few cartons remaining are listed for an eye-watering price, you might’ve twigged that something’s the matter.  

You’d be right – this egg shortage is the result of ongoing attempts to prevent the spread of avian flu in Australia.  

The avian flu in Australia causing this shortage is known as high pathogenicity avian influenza (HPAI) H7N8. But another subtype of avian flu, known as HPAI H5N1 clade 2.3.4.4b, has been spreading rapidly worldwide, with Australia the only continent currently free from this highly pathogenic virus.  

That doesn’t mean we’re in the clear, though. H5N1 is at our doorstep, and other less pathogenic variants of avian flu are circulating within the country, posing their own risks and having the potential to evolve into highly pathogenic strains.  

What makes the H5N1 subtype of avian flu so concerning, and how worried should we be about avian flu in Australia?  

To answer these questions and more, we spoke to Professor Marcel Klaassen, an ecologist whose research primarily focuses on bird migration and disease ecology, and Assoc. Prof. Eric Lau, a biostatistician and infectious disease epidemiologist. 

What is avian flu?  

So, first things first: what exactly is avian flu? According to the CDC, avian flu refers to influenza A viruses that primarily affect birds but can also spread to other animals – and to humans, albeit rarely.  

In terms of avian flu in Australia, we’ve only had one human case of H5N1, and the person had been infected overseas and made a full recovery.  

Another important aspect of influenza is low versus high pathogenicity. According to the World Organisation for Animal Health, low pathogenicity strains typically cause little or no clinical signs in poultry, whereas high pathogenicity strains, like H5N1, can cause severe clinical signs and high mortality rates.  

There are 18 known hemagglutinin subtypes, denoted by the H. The N denotes the neuraminidase subtypes, or the surface protein in that influenza. For example, you might be familiar with H1N1, a subtype of which a specific strain the Spanish flu epidemic of 1918, which resulted in an estimated 50 million deaths.  

What is H5N1?  

Today, the avian flu variant causing global concern is H5N1 clade 2.3.4.4b, and this strain’s lineage can be traced back to Hong Kong in 1997. Why are H5 variants of additional concern? 

‘H5N1 is an avian flu strain of concern due to its track record leading to high fatality in birds and humans, and recent reports of its expanding ability to infect several mammal species including cattle and seals,’ says Lau. 

Klaassen agrees that H5s can evolve into ‘something nasty’, adding that ‘when you have a lot of a particular virus around, there’s more chance of a spillover and that it sticks.’  

‘At some point, you’ll get a virus that can infect humans and start spreading from human to human. I don’t want to scare people, but… if you think Covid viruses can change rapidly, it’s still nothing compared to influenza viruses,’ says Klaassen.  

While Australia currently remains free of the ‘most concerning’ strains like H5N1, there are still other variants of avian flu in Australia and it’s essential to stay vigilant.  

Can humans catch avian flu?  

The short answer is yes, humans can catch avian flu. But the long answer, according to Klaassen, is that ‘there are still many steps to take before H5N1 will thrive in humans –but we’ve already made quite a few steps.’ 

If you’ve heard of the H5N1 subtype of avian flu being referred to as a pandemic, we’ll stop you right there: according to Lau, the key signal that we’re dealing with a pandemic is ‘the sustained transmission of bird flu from person to person.’ It’s also important to note that a pandemic refers to a near global epidemic amongst humans, while a panzootic refers to the same but amongst animals.  

So, for now, with the CDC confirming that there are no indicators of unusual influenza activity in people, this is not a pandemic at this stage.  

‘In-depth investigations, including contact tracing, would allow us to assess if such transmission has already occurred,’ adds Lau. ‘Another signal is the expansion of host range from birds to mammals, which has already occurred for H5N1. This indicates an increased risk of spreading to humans.’

How avian flu is transmitted  

Avian flu spreads when infected birds shed the virus through their saliva, mucus and feces. This happens most commonly on a bird-to-bird level but, while rare, human infections can happen when the virus gets into a person’s eyes, nose or mouth.  

It’s important to also consider the larger reason behind how avian flu is transmitted: unsustainable poultry production processes.  

‘When we are in high densities, we are more prone to the spread of infectious diseases, and it’s the same with livestock. If you have livestock in high densities, you are much more prone to disease,’ says Klaassen. 

In saying that, it’s important not to jump to conclusions.  

‘It doesn’t automatically mean that large farms are production facilities of livestock but also zoonotic diseases that will automatically kill us. That’s far-fetched. But you’re more prone to these issues, and you have to be more aware.’  

Fact or fiction: Can you get avian flu from eggs?  

Since it’s been so hard to get eggs at the grocery store, does that mean that you can get avian flu from eggs?  

According to Better Health, you can’t catch avian flu by eating fully cooked poultry or eggs, even in areas where there is an outbreak. The shortage of eggs on shelves isn’t because eggs are the issue, but rather because poultry farms have been culling chickens to try and control avian flu in Australia from spreading.  

‘Properly cooked poultry or eggs are safe for consumption,’ confirms Lau. ‘A related issue is the recent detection of H5N1 in cows and raw milk from infected cows in the US. While sales of raw milk are illegal in Australia, pasteurised milk has been shown to effectively inactivate avian flu viruses and is safe for consumption.’ 

It’s important to squash misconceptions as they arise, and another one on Lau’s radar is the belief that avian flu is always fatal to humans. 

‘There are many avian flu strains which lead to mild diseases with flu-like symptoms and conjunctivitis in humans,’ says Lau. ‘However, some avian flu strains have led to high fatality, such as some strains of subtypes H5N1 and H7N9, with case fatality risks of over 30%.’  

Avian flu: signs and symptoms 

According to Agriculture Victoria, symptoms in birds can include respiratory signs, conjunctivitis, swelling of the head, rapid decrease in feed and water intake, depression, diarrhoea and nervous signs, including an inability to stay upright, inability to fly, uncoordinated movement, moving in circles and partial or full paralysis and sudden death. 

The CDC states that the most common human symptom of avian flu is conjunctivitis or eye redness, with other mild symptoms including a fever, cough, sore throat, fatigue and muscle or body aches. If the disease is more severe, symptoms can include seizures, altered consciousness, shortness of breath and a high fever.  

Prevention and protection: Safeguarding against avian flu 

Now that you know what avian flu is and how it’s transmitted, it’s time to think about how we can be better protected against avian flu in Australia and globally.  

Firstly, on an individual level, Klaassen advises that you simply need to be aware.  

‘Know something about disease symptoms, and when you see something, such as a couple of individual birds stargazing or exhibiting strange behaviour, just know to report it,’ says Klaassen. 

For poultry farms and live poultry markets, Lau advises a ‘One Health’ approach. This involves preventative measures and health surveillance among poultry, workers and visitors in farms and markets, as a first line of defense.  

‘Building sustainable detection and response capacity and preparedness, along with transparent and effective dissemination and communications of the risk assessment, rationale and evidence supporting the preventative or control measures would also improve response at the population level,’ adds Lau.  

On an international level, it’s important that countries collaborate.  

‘It is crucial for countries to work together and share data to accelerate and inform prevention and response with the best understanding of avian flu host range, ability of transmitting to humans and causing severe diseases, development of rapid diagnostic tests, vaccine development and production and effective treatment,’ says Lau.  

‘We never know specifically where or when a bird flu with pandemic potential will emerge – but it is most prudent and effective to leverage global response capacity at the early phase, when it’s most controllable.’  

Is there an H5N1 vaccine?  

When we talk about vaccinating against H5N1, and the role vaccines could play in preventing avian flu in Australia, it’s really a two-pronged question: whether we can vaccinate humans, and whether we can vaccinate birds. 

There are three approved H5N1 vaccines for humans in the US, but not in Australia. However, the seasonal influenza vaccine offers some protection. 

When it comes to vaccinating animals, notably poultry, the answer is more complex. It seems like a no brainer, right? If we need to limit the spread of this virus to ensure it doesn’t mutate and spread to humans, why not start by vaccinating birds? Well, there are a few reasons not to, according to Klaassen.  

‘What you want to achieve with vaccination is that it stops the virus in its tracks. When you’re vaccinated, the virus won’t replicate, and you won’t spread the virus to other animals,’ says Klaassen. ‘But if the vaccine isn’t perfect and only prevents disease and not its spread, you can actually get more spread, and because you do not notice birds are infected, you can get so-called silent spread.’  

Unfortunately, this exact situation happened in Southeast Asia and in Egypt, before the phenomenon of silent spread was widely understood.  

With wild birds, there are the obvious logistical challenges, as well as considerations such as determining how many birds to vaccinate so a critical number of the population can survive. And when a country chooses to vaccinate its poultry, there may be trade impacts.  

‘A lot of countries don’t accept meat or livestock that has been vaccinated for certain diseases because checking for disease freedom may become trickier when they’re vaccinated,’ says Klaassen.  

Are we prepared for avian flu in Australia?  

So, the question remains: are we prepared for an outbreak of avian flu in Australia, and are we prepared for H5N1? 

As mentioned, one of the most important things that we as individuals can do to prepare is to become aware of the signs and the symptoms and ensure that the attention level on this virus doesn’t wane. While it may seem like a small step, it’s key in preparing for the eventuality of avian flu in Australia. 

On a national level, the Australian government has invested more than $100 million in avian flu preparedness, focusing on surveillance and biosecurity. And on an international level, member states of the World Health Organisation are working towards a Pandemic Prevention, Preparedness and Response agreement.  

These pieces all come together for a wider strategy on raising awareness and promoting a sense of vigilance, because in a world as interconnected as ours, global defence is only as strong as its weakest link.