Avian influenza (bird flu)

Notification requirement for avian influenza

Avian influenza in humans is an 'urgent' notifiable condition in Victoria.

Medical practitioners and pathology services must notify any suspected or confirmed cases immediately to the Department of Health by calling 1300 651 160 (24/7) and connecting to the relevant Local Public Health Unit. Pathology services must follow up with written notification within 5 days.

This is a Victorian statutory requirement.

Primary school and children's services exclusion for avian influenza

Cases should be excluded until no longer infectious, as advised by the Local Public Health Unit.

Infectious agent of avian influenza

Avian influenza is caused by strains of influenza A virus, which are subtyped by the antigenicity of their haemagglutinin (H) and neuraminidase (N) surface proteins.

In animal health, strains of avian influenza virus are generally classified into 2 categories based on the severity of disease in birds:

• low pathogenicity avian influenza (LPAI), which typically causes no or mild disease
• highly pathogenicity avian influenza (HPAI), which can cause severe disease and death.

These categories do not correlate with the severity of disease in humans. Both LPAI and HPAI strains may cause severe disease in humans.

Public health significance and occurrence of avian influenza

There are multiple strains of avian influenza virus that have been detected in birds, including wild birds and poultry. Certain strains can also affect other animal species, including wild and domestic (such as livestock or pet) mammals. Migratory birds have a role in the spread of virus across geographical areas and animal populations.

While human infections are rare, they usually occur in people with close contact with sick birds and livestock. Person-to person transmission is extremely rare and has only been reported with prolonged close contact while caring for an infected person. Avian influenza poses a risk to human health due to its potential to cause severe disease and outbreaks or possible pandemics if strains mutate and adapt to spread easily from person-to-person.

Since 2021, a variant of the H5N1 strain of avian influenza virus, named clade 2.3.4.4b, has been spreading rapidly across the world. It has been causing widescale outbreaks in wild birds, poultry, and mammals (including livestock such as cows). A number of human infections have been detected in animal workers. While this variant has not been found in Australia yet, state and national animal and health authorities are closely monitoring the situation and preparing for potential onshore detections.

Other strains of avian influenza have been detected in Australia and have led to a number of small outbreaks on poultry farms. These outbreaks caused less severe disease in birds and resulted in a small number of mild infections in people who had close contact with sick birds. For example, several H7 subtype avian influenza outbreaks were reported between 2023 and 2025 in poultry farms across Victoria, New South Wales and Australian Capital Territory. These outbreaks were contained through culling and other biosecurity measures in collaboration with affected sites and animal and human health authorities.

Identification of avian influenza

Not everyone with flu-like symptoms need to be tested for or notified as having suspected avian influenza. A suspected case requires both epidemiological and clinical evidence.

Potential exposures

Epidemiological evidence may include any of the following potential exposures to avian influenza:

• close contact with wild birds or poultry, their remains, respiratory secretions, faeces or other bodily fluids, and contaminated environments (in an area with suspected or confirmed avian influenza infections)
• consumption of raw or undercooked poultry meat, eggs or other animal products (that were produced from an area with suspected or confirmed avian influenza)
• close contact with other animals confirmed to be infected with avian influenza (for example, livestock such as cows or pigs, and pets such cats)
• close contact with a probable or confirmed human case of avian influenza (such as caring for, speaking with, or touching the infected person)
• handling samples suspected of confirmed of containing avian influenza virus in a laboratory or other setting.

Potential exposure may occur during travel to countries or areas with avian influenza outbreaks, or in settings which have close contact with poultry, wild birds or animals.

Clinical features

Human infection with avian influenza is rare. Symptoms can vary from being asymptomatic or mild, to severe.

Symptoms may include one or a combination of flu-like symptoms such as:

• fever
• chills
• cough
• sore throat
• coryza
• conjunctivitis
• fatigue
• muscle aches and pains
• headache
• shortness of breath.

Less common symptoms may include diarrhoea, nausea and vomiting.

Severe disease can result in pneumonia, neurological changes (such as seizures), encephalitis, sepsis and multi-organ failure, which can potentially lead to death.

Diagnosis

All suspected human cases of avian influenza should be tested urgently and discussed with the relevant Local Public Health Unit. They can provide advice on testing and coordinate with the laboratory.

Polymerase chain reaction (PCR) testing is the recommended confirmatory test for avian influenza. Samples are usually taken as a nose and throat swab. If there are conjunctival symptoms, a conjunctival swab should be collected.

Samples should be collected while wearing appropriate personal protective equipment (PPE) and in a negative pressure room if available. For the management of a suspected human case of avian influenza, this includes gloves, gown, protective eyewear and a P2 or N95 respirator as well as airborne and contact transmission-based precautions.

Swabs should be sent directly to the Victorian Infectious Diseases Reference Laboratory (VIDRL) for urgent testing with relevant clinical details, suspected diagnosis and risk factors recorded on the request form.

Incubation period of avian influenza

The incubation period for avian influenza varies from one to 10 days depending on the strain.

Reservoir of avian influenza virus

Wild birds are the natural host and reservoir for avian influenza viruses. The virus can spill over from wild birds to domestic birds or other animal populations via direct contact with infected wild birds or indirectly via feed or water contaminated with virus by wild birds.

Mode of transmission of avian influenza virus

Infected birds and other animals shed the virus in respiratory secretions (such as saliva or nasal fluids), faeces and other body fluids.

Transmission mainly occurs through:

• inhaling infectious respiratory droplet or contaminated fomites (such as dust)
• close contact with infected birds or other animals, their respiratory secretions, faeces and other body fluids or contaminated objects and surfaces.

The virus usually does not spread easily from birds or other animals to humans. Human cases are rare and mainly occur in people who have close or prolonged contact with infected birds or other animals, their body fluids or contaminated environments.

Person-to-person transmission of avian influenza is extremely rare and has occurred in some instances with close prolonged contact with an infected person while giving care.

There is no evidence that people can become infected with avian influenza by eating fully-cooked meat or eggs (even from areas with an avian influenza outbreak).

Period of communicability of avian influenza

The exact infectious period for avian influenza in humans is not clearly defined and may vary depending on the strain.

For public health purposes, an infected person is generally considered infectious from one day before symptom onset to 7 days after symptom onset, or until acute symptoms resolve – whichever is longer. This may be re-evaluated based on available evidence.

Susceptibility and resistance to avian influenza virus

Seasonal influenza vaccination does not specifically protect against avian influenza. However, it protects against possible co-infection with strains of avian and human influenza viruses. This reduces the risk of genetic re-assortment and potential pandemics from avian strains that have become more virulent or transmissible to humans.

Therefore, seasonal influenza vaccination is recommended for all individuals working with poultry and/or responding to avian influenza outbreaks, at least 2 weeks prior to exposure.

Control measures for avian influenza

Preventive measures

Most people are not at risk of avian influenza. In general, people should avoid contact with sick or dead animals if possible. Anyone who finds multiple sick or dead birds or animals should avoid contact, record what they see and report this to the Department of Energy, Environment and Climate Action or Emergency Animal Disease Hotline on 1800 675 888.

People travelling to countries or areas affected by avian influenza outbreaks can reduce their risk further by:

• avoiding poultry farms and live bird 'wet' markets
• avoiding contact with wild or domesticated birds
• washing hands thoroughly after handling birds and uncooked poultry products such as meat or eggs
• washing all kitchen utensils and cleaning cooking surfaces used to prepare raw poultry
• ensuring poultry, meat or other products are cooked thoroughly before eating
• not consuming raw, unpasteurised milk or milk products.

People are also advised to check for any notices or recommendations prior to travel on the Australian Government Smartraveller.

People working in settings with close contact with potentially infected birds or other animals are advised to follow appropriate occupational health and safety practices and infection prevention and control measures. This includes good hygiene practices and use of appropriate PPE including:

• P2/N95 respiratory masks
• goggles
• gloves
• protective clothing.

Workers are also advised to get the seasonal flu vaccine each year.

See Agriculture Victoria's Avian Influenza factsheet for more information.

For information on the latest outbreaks of avian influenza in animals, see:

• World Organisation for Animal Health Situation reports
• World Organisation for Animal Health Events management.

For information on the latest outbreaks of Avian influenza in humans, see:

• World Health Organization Situation reports.

Control of human cases

Treatment is the responsibility of the treating medical practitioner in consultation with an infectious diseases specialist.

Influenza antiviral treatment is recommended as soon as possible for suspected, probable or confirmed cases of human infection, even if more than 48 hours has elapsed since symptom onset and regardless of disease severity.

Cases should be isolated until they are no longer infectious as advised by the relevant Local Public Health Unit.

Hospitalised cases should be cared for under airborne and contact precautions and in a negative pressure room if available.

The Department of Health and Local Public Health Units investigate all human cases of avian influenza to:

• confirm the diagnosis
• find a possible source of infection
• identify other potential human cases
• identify and provide advice to susceptible contacts
• prevent onward transmission in the community.

See Bird flu on the Better Health Channel for more information on avian influenza, including advice on self-isolation and transmission prevention measures.

Control of human contacts

The Local Public Health Unit undertakes contact tracing to identify and assess people who may have been exposed to avian influenza.

Contacts are usually provided education and requested to monitor for symptoms of avian influenza for a defined period as determined by the Local Public Health Unit.

Some contacts who are at higher risk of developing avian influenza may be recommended to receive influenza antiviral medication as post-exposure prophylaxis.

If contacts become symptomatic, they are advised to stay home and report their illness to the Local Public Health Unit. They can help facilitate testing.

Further information on avian influenza including symptoms and testing are outlined on the Better Health Channel.

Control of environment

Avian influenza is a notifiable exotic disease in birds and any suspected or confirmed cases are required to be notified immediately by owners, vets or laboratories to Agriculture Victoria on the Emergency Animal Disease Hotline.

Anyone who finds multiple sick or dead birds or animals should avoid contact, record what they see (by taking a photo or video of the animals and your location) and report this to the Department of Energy, Environment and Climate Action or Emergency Animal Disease Hotline by calling 1800 675 888 (24/7).

To stay up to date with the avian influenza outbreaks in birds in Victoria, see Agriculture Victoria.

For information on outbreaks within Australia, see the Australian Outbreak website.

For information on international outbreaks, see Food and Agriculture Organization.

Outbreak measures for avian influenza

If human cases are suspected in Victoria, the Local Public Health Unit and the Department of Health work with the patient, treating doctors, and the laboratory to confirm the diagnosis. Cases are isolated from others to prevent further transmission.

Close contacts of cases are counselled about the risk of infection and monitored by the Local Public Health Unit. If they develop symptoms, they are also advised to self-isolate and be tested for avian influenza.

In Victoria, avian influenza outbreaks in poultry farms or similar settings are investigated and managed by Agriculture Victoria, with support from the Department of Health and Local Public Health Units. People who have been exposed to infected birds during an outbreak are assessed and provided advice by the relevant the Local Public Health Unit.