Avian influenza (bird flu)

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 all birds.

Mild avian flu from low pathogenic viruses may not have symptoms in poultry. It can be difficult to detect in some birds. Despite this, it can still result in some deaths.

Bird flu viruses are complex and grouped by 2 surface proteins, the haemagglutinin (HA) and neuraminidase (NA). For example, a virus that has HA 3 protein and 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. No one has detected it in birds 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 HPAI H5N1, 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.

With the emergence of HPAI H5N1 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 H5N1 to some predatory and scavenger species.

Symptoms associated with avian influenza can include:

• sudden death
• 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 avian influenza 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:

• Agriculture Victoria on 136 186 (Monday–Friday, 8 am – 6 pm)
• Emergency Animal Disease Hotline on 1800 675 888.

Good biosecurity practices are essential to reduce the risk of disease. For more information visit:

• Biosecurity for poultry producers
• Keeping backyard poultry

Ongoing outbreaks of H5N1 globally have increased the level of risk to Australia for incursions of HPAI viruses of global concern. Occasional outbreaks of internationally notifiable highly pathogenic avian influenza (non-H5N1) and of low pathogenicity avian influenza have occurred on poultry farms in Australia.

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 highly pathogenic and low pathogenic H5/H7 virus. 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 2021, there were 9 outbreaks of HPAI on poultry farms in Australia.

The outbreaks happened in different states and years. In Victoria outbreaks occurred in 1976, 1985, 1992 and 2020. In Queensland there was an outbreak in 1994. In NSW, outbreaks happened in 1997, 2012 and 2013.

In 2020 and early 2021 Agriculture Victoria worked with the poultry industry and the community to control and eradicate outbreaks of avian influenza.

There were 3 different strains of avian influenza, across 3 local government areas during this incident:

• 3 egg farms with highly pathogenic H7N7 avian influenza
• 2 turkey farms with low pathogenic H5N2 avian influenza
• 1 emu farm diagnosed with low pathogenic H7N6 avian influenza.

Proof of freedom of the disease was declared internationally on 26 February 2021.

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.