Avian influenza (bird flu)

Avian influenza, or bird flu, is a viral disease of birds found globally. In 2024, 7 properties close to Meredith were infected with H7N3 bird flu. A property near Terang was infected with a different strain called H7N9 bird flu. Agriculture Victoria instigated a response program working with industry, and the disease on all of the impacted farms was eradicated.

Avian influenza, commonly referred to as ‘bird flu’, is a highly contagious viral infection of birds. Severe cases of bird flu can lead to serious symptoms and sudden death in domestic poultry, affecting large numbers of birds. Virus strains are described as low pathogenicit (LPAI) or high pathogenicity (HPAI).

Mild avian influenza infections with low pathogenicity viruses may not produce symptoms in poultry. It can be difficult to detect in some birds. Despite this, it can still result in some deaths.

Influenza viruses are complex and grouped by 2 surface proteins, the haemagglutinin (HA) and neuraminidase (NA). For example, a virus that has an HA 3 protein and an NA 2 protein is designated as subtype H3N2. At least 16 haemagglutinins (H1 to H16), and 9 neuraminidases (N1 to N9) subtypes have been found in viruses from birds.

Some LPAI virus such as subtypes H5 and H7 can become HPAI viruses when they move from wild birds to poultry.

H5N1 is a subtype of HPAI that causes serious disease in poultry, wild birds and some species of wild mammals globally. H5N1 has not been detected in Australia to date.

Birds like chickens, ducks, geese, turkeys, guinea fowl, quail, pheasants, emus and ostriches are at high risk for avian influenza. Wild birds like waterfowl and seabirds can have the LPAI virus without getting sick.

Scientists think that all bird species can be affected by the H5 bird flu strain (currently not in Australia) and they have found it in 50 species of mammals.

Scientists consider wild birds the natural host for the virus. In Australia, some wild birds carry LPAI but usually do not show any symptoms of the disease.

Infected birds shed the avian influenza virus in saliva, nasal secretions and faeces.

Sometimes the virus spills over from wild birds into domestic bird populations and may cause disease. This can occur when wild birds interact with domestic birds. It can also happen when wild birds contaminate the food or water of domestic birds.

H7 bird flu can spread from property to property by the movement of people, poultry, clothing and equipment.

With the emergence of H5 bird flu internationally, many animal species have become infected following close contact with infected birds or contaminated environments. Consumption of infected bird carcases has resulted in the transmission of H bird flu1 to some predatory and scavenger species. H5 bird flu is not in Australia.

The most important sign to be aware of and report is sudden death.

Other signs that can be associated with bird flu can include:

• respiratory signs (noisy or rapid breathing, coughing, sneezing, increased nasal secretions)
• conjunctivitis
• swelling of the head
• purple discolouration of the comb and wattles
• rapid decrease in feed and water intake
• decreased egg production
• ruffled feathers
• depression
• closed eyes
• diarrhoea
• nervous signs (twisted neck, inability to stay upright, inability to fly, uncoordinated movement, walking or swimming in circles, partial or full paralysis).

All bird owners need to watch for any signs of bird flu in their flocks.

Avian influenza is a notifiable disease. This means that legally you must tell us if you know of or suspect the presence of avian influenza in any birds.

You can do this by immediately calling one of the following:

• VicEmergency hotlie on 1800 226 226.
• Emergency Animal Disease Hotline on 1800 675 888.

Good biosecurity practices are essential to reduce the risk of disease. Take these simple steps to minimise the risk to your animals:

• Restrict contact between pet birds, poultry and wild birds.
• Prevent access by wild birds to food and water sources for your birds.
• Keep equipment and yards or aviaries clean.
• Limit visitors to your birds.
• Bird owners should wash their hands before and after handling birds.
• Monitor your birds’ health and report sudden death in your poultry.

For more information visit:

• Biosecurity for poultry producers
• Keeping backyard poultry
• Report sick or dead wild birds or wildlife

Ongoing outbreaks of H5 bird flu globally have increased the level of risk to Australia for incursions of HPAI viruses of global concern. Occasional outbreaks of internationally notifiable high pathogenicity avian influenza (non-H5N1) and of low pathogenicity avian influenza do occur on poultry farms in Australia, such as the H7 outbreaks in 2020, 2024 and 2025.

Annual migration of wild birds has the ongoing potential to introduce new subtypes of avian influenza virus to Australian birds.

State and Commonwealth governments share the costs of managing avian influenza outbreaks with chicken meat, duck meat and egg industries. This includes both high pathogenicity and low pathogenicity H5/H7 viruses. This ensures that a rapid and effective emergency response can be immediately mounted if the disease occurs.

Owners may qualify for compensation if they need to destroy birds or property to eradicate the disease.

Procedures for responding to outbreaks generally include:

• euthanasia of infected and in-contact poultry (depopulation)
• decontamination
• strict quarantine
• movement controls to prevent the spread of infection
• tracing and surveillance to locate the extent of infection.

Vaccination might be an option in some circumstances but there is no vaccine currently available in Australia.

Between 1976 and the end of 2024, there were 13 outbreaks of HPAI on poultry farms in Australia.

The outbreaks happened in different states and years. In Victoria outbreaks occurred in 1976, 1985, 1992, 2020 and 2024. In Queensland there was an outbreak in 1994. In NSW, outbreaks happened in 1997, 2012, 2023 and 2024. The ACT saw an outbreak in 2024.

In 2024 Agriculture Victoria worked with the poultry industry and the community to control and eradicate outbreaks of avian influenza.

Surveillance of both domestic and wild birds was a key part of the response and is ongoing.

The ongoing surveillance activities mean we are confident that the virus is no longer present on the farms or in surrounding areas.

A wild bird surveillance program is in place across Australia, supported by Wildlife Health Australia.

Report an unusual sign of disease or death in wild birds.