Migratory birds have been found with the highly pathogenic avian influenza (HPAI) H5N1 in Australia with several cases detected in Western Australia, including metropolitan Perth, as well as in South Australia and New South Wales.
The confirmation of bird flu reaching our shores has led to increased interest in how the pathogen spreads, who is at risk, what can be done to protect our unique fauna and how could it affect the human population.
Here, clinical microbiologist Professor Tim Inglis, from The University of Western Australia’s Medical School and School of Biomedical Sciences, helps break down some of the myths and provides expert analysis of the risk from avian influenza.
What is bird flu?
We've known about avian influenza, caused by influenza A viruses, for a long time. Veterinary colleagues and human disease epidemiologists followed the strain known as H5N1, a high pathogenicity avian influenza or HPAI, as it spread in Southeast Asia decades ago.
How does it spread?
Contact with body secretions such as faeces, saliva and nasal secretions distribute the virus. Bird-to-bird spread can occur easily when there are large concentrations of birds, including points along their flyways such as shorelines or river beaches where migratory birds stop, rest and feed. Multiple bird species spend time in areas that have recently been visited by other bird species, and these locations are where contact with contaminated material, and therefore transmission, can take place.
How did it end up in Australia?
The strain found in Australia has been confirmed as a variant of the H5N1 strain and that didn’t originate here – it’s from overseas. Airborne connections between different continents are most likely to explain how the first discovered case; a migratory brown skua found in the Cape Le Grande Park area, made its way to our shores. Regrettably we are now catching up with the rest of the world where avian influenza is already established.
How is it being monitored?
There are networks of monitoring veterinary and public health laboratories around the country. Some of the laboratories are equipped to perform sophisticated genetic analysis of influenza viruses from humans. They will now be on the lookout for evidence of further spread of avian influenza, especially the current H5N1 strain.
What are the risks to bird populations?
Seabirds follow flyways; established migratory routes that link continents. The Australian Centre for Disease Control has taken a serious interest in surveillance monitoring. Of note to the wider population is the black swan population of Australia, which has been protected by geographic isolation. However, prolonged isolation means black swans have not evolved protection against avian influenza through surviving repeated waves of infection, as has happened in the rest of the world. If influenza-vulnerable species such as the black swan get bird flu, the fatality rate will be high due to their genetic susceptibility.
What are the risks to native fauna?
Geographic isolation curbed the spread of Covid in WA’s human population but for our native species isolation has left them vulnerable to new virus epidemics. We have a lot of small mammals that live in tiny little pockets of WA where the pristine ecology is relatively undisturbed and where, until recently, very little infection has been introduced. In Tasmania, the Tassie devils have just come back from the brink of extinction after devastation by devil facial tumour disease. As devils are scavengers that may feed off dead birds, exposure to HPAI could put them back at risk of extinction.
What are the risks to companion animals?
Because of their proximity to humans most companion animals are regularly exposed to human diseases. Throughout every influenza epidemic that has worked its way through the population of WA we will have generously shared germs with our pets. Fortunately, they don't seem to go down badly with influenza and have some of the genetic traits needed to deal with human infections.
What are the risks to livestock?
It could impact livestock such as cattle and poultry if they are exposed.
What happens to a person who gets bird flu?
There have been so few cases that we have little idea how different it would be from strains of human influenza. If there is a human case, the treatment would be conventional antiviral medications as approved for treating influenza. If we start seeing a lot of cases in humans, undoubtedly there will be a fast-track process to get a preventive vaccine up and running. However, there is a catch: if a human who currently has influenza handles an infected bird and gets a simultaneous infection with a second influenza virus, there is an opportunity for the two types of viruses to exchange genetic material. Cross-pollination of influenza from an avian source could give us something we really don’t want. RNA viruses have a very short replication time. We don’t want to see the highly pathogenic avian influenza, through mutation, acquire the ability to cause a highly pathogenic human influenza. We therefore need to take some precautions, backed up by data, and make rational decisions based on past experience of easily transmissible respiratory diseases to stop it from happening. I encourage everyone who hasn’t already done so to get a flu vaccine.
Can humans get it from eating eggs and meat?
It's unlikely unless farm produce is undercooked or eaten raw.
What can be done to prevent bird flu spreading?
People should stay clear of all dead birds, not just dead seabirds. Abattoir workers, vets, wildlife carers and workers need to take some additional precautions, such as wearing PPE, while handling dead birds. If we get to the stage where multiple deaths have occurred in seabird populations and wildlife is affected, a higher level of caution will be activated. There is a contingency plan and there are some so-called mock-up avian influenza vaccines available. It's speculation as to how that would be used and what the triggers for its use would be.
Any final words?
We have contingency plans and we know we're ready to step up should the need arise.