What you should know about H5 bird flu
Australia remains the only continent free from H5 bird flu, specifically high pathogenicity avian influenza H5N1 clade 2.3.4.4b, a strain causing global concern. This strain, in particular, has spread rapidly between continents and is associated with the movement of wild birds.
In July 2023, the Australian Government commissioned an expert assessment of the level of risk from H5 bird flu to wild birds in Australia. It summarised the risk of incursions and establishment of H5 bird flu in wild birds to be 'high'. An abridged version of the High Pathogenicity Avian Influenza (HPAI) clade 2.3.4.4b incursion risk assessment for Australia is available on Wildlife Health Australia’s website.
Outbreaks of H5 bird flu overseas have led to extensive losses of poultry, and mass mortalities of wild birds and mammals, particularly marine mammals (seals, sea lions and dolphins) and mammals that prey or scavenge on birds.
Based on the level of impact in other countries, it is expected that an outbreak in Australia would have severe impacts on our wildlife and poultry industry.
While preparedness for H5 bird flu has been a focus, the dynamic global situation requires ongoing monitoring and vigilance.
If you see any unusual signs of disease, behaviour, or unexplained death in your poultry or kept birds, immediately call your local veterinarian or the Emergency Animal Disease (EAD) Hotline 1800 675 888.
What is H5 bird flu?
Avian influenza, or bird flu, is an infectious disease of poultry (and other birds) and occurs worldwide. H5 bird flu is different to other forms of avian influenza in that it circulates in wildlife in a highly infectious form causing disease and deaths not just in birds but also in other wildlife, particularly mammals. Overseas it has caused a large number of deaths in many different wild bird species, as well as wild mammals, including marine mammals such as sea lions.
Chickens, ducks, geese, turkeys, guinea fowl, quail, pheasants, emus and ostriches are included in the more than 400 species that are susceptible to H5 bird flu. Many species of wild birds, including waterfowl and seabirds, can also carry the virus.
Mammals, especially carnivores and marine mammals, are known to be susceptible to H5 bird flu. It is thought they become infected by consuming infected birds. Infection of marine mammals is thought to occur via close contact with, or ingestion of, infected birds or contact with marine environments contaminated with virus from infected birds.
Livestock and domestic pets can also be susceptible.
How H5 bird flu spreads
H5 bird flu is a viral disease that spreads rapidly between birds. Virus is found in saliva and faeces as well as the tissues and fluids (blood) of infected animals and in eggs. It can persist in the environment for extended periods under favourable environmental conditions.
The virus is mostly spread by wild birds after having direct contact with domestic poultry or birds, or by contaminating their food, water or bedding. It can also spread through movements of eggs, birds, people, vehicles and clothing, footwear, aerosols, water and feed. The virus can also be spread by the wind in poultry-intensive areas.
In severe cases of poultry (chickens, ducks and turkeys) involving sudden death, symptoms may not be seen. Mortalities occur as early as 24 hours after the first signs of the disease and frequently within 48 hours. Mortality rates of nearly 100% have been reported for severe and acute cases. In other cases, more diverse visible signs occur, and mortalities can be delayed for as long as a week.
Biosecurity measures such as movement restrictions and disinfection practices will be essential to minimise the spread of the virus.
Signs of H5 bird flu
Signs of infection in birds can include:
- Sudden death without clinical signs
- Lethargy or reluctance to walk, eat or drink
- Droopy appearance or ruffled feathers
- Purple discolouration or bruising of the wattles, combs and legs
- Respiratory signs such as panting, nasal discharge, coughing or sneezing
- Swelling around the head and neck, incoordination, inability to walk or stand
- Watery or green diarrhoea
- Incoordination, head tremors, twisted necks, or head held upside down
- Tremors, spasms, seizures, circling
- Inability to stand or fly, decreased response to stimuli
- Rapid horizontal eye movements
- Unusual vocalisations
- Emaciation
- Swelling of the head
- Eye cloudiness or change in eye colour of birds.
- Sudden decrease in egg production
Infected wild mammals may show a wide range of symptoms, including:
- incoordination and tremors
- seizures
- difficulty breathing
- nasal discharge
- drooling
- sudden death, including the potential for mass mortality events.
Some species may not show any signs of disease or show only very mild signs. In some cases, birds and animals may die suddenly without displaying any clinical signs, or be found dead.
Avian influenza can only be confirmed through laboratory testing of samples collected by a veterinarian or government animal health officer.
Preparation and response
There is no way to prevent H5 bird flu entering Australia because the most likely pathway for transmission is through the migratory movements of wild birds. Unfortunately this also means complete eradication will not be possible. The Australian Government is working with state and territory governments, animal and wildlife health organisations, industry groups and the non-government sector to prepare for the arrival of H5 bird flu.
As the lead agency for animal and plant biosecurity, we are leading cross-agency collaboration with the Department for Environment and Water, SA Health and other partner agencies to prepare.
Australia has well-established national response arrangements in place to respond to emergency animal diseases, including bird flu.
If Australia experiences an H5 bird flu incursion, there will be a rapid and coordinated national response led by the Australian Department of Agriculture, Fisheries and Forestry, with state and territory governments leading response activities within their borders. You can read more about national response arrangements at outbreak.gov.au.
Early detection is essential to reduce the potential impact of this disease.
If you suspect poultry or other kept birds are showing signs of H5 bird flu, call your veterinarian or the Emergency Animal Disease (EAD) Hotline.
If you see sick or dead wildlife (including marine mammals and wild birds):
- Avoid contact with them and keep pets away – don’t touch them.
- Record the date, time, location, species (type of bird or animal), and how many.
- Report your observations to the Emergency Animal Disease Hotline.