Human case of avian influenza (bird flu) detected in returned traveller to Victoria

What is the issue?

A case of avian influenza A (H5N1) infection, also known as “bird flu”, has been reported in Victoria. This is the first human case of H5N1 avian influenza in Australia. The case occurred in a child, who acquired the infection in India and was unwell in March 2024. The avian influenza virus was detected through further testing of positive influenza samples that takes place to detect novel or concerning flu virus strains, as part of Victoria’s enhanced surveillance system. Contact tracing has not identified any further cases of avian influenza connected to this case.

There are lots of different subtypes (strains) of avian influenza. Most of them don’t infect humans. Some subtypes, including H5N1, are more likely to cause disease and death in poultry. These are known as highly pathogenic avian influenza (HPAI) viruses. Significant outbreaks of HPAI viruses are being reported in poultry and non-poultry birds and mammals overseas. The United States of America is currently experiencing outbreaks of HPAI (H5N1) in dairy cows, with one recent human case in a dairy worker. Whilst the Victorian case is HPAI (H5N1), it is not the same as the strains that have caused these outbreaks in the United States of America.

The Department of Health is supporting Agriculture Victoria in responding to an outbreak of avian influenza among birds at a poultry farm in regional Victorian. Testing has confirmed this outbreak is not related to this human case.

Transmission to humans is very rare, with a small number of human cases of H5N1 reported globally, resulting in death in a number of cases. This is the first confirmed human case of highly pathogenic avian influenza in Australia, and the first time the H5N1 strain has been detected in a person or animal in Australia.

The seasonal flu vaccine doesn't protect against avian influenza. However, it can help prevent the mixing of highly pathogenic avian influenza with seasonal influenza, which can lead to new mutated viruses that could spread rapidly. This highlights the importance of seasonal influenza vaccination, particularly for poultry workers and those travelling to areas with outbreaks, to reduce the risk of new human pandemic viruses emerging.

Who is at risk?

The transmission of avian influenza from birds or animals to humans is very rare. Most people are not at risk, unless they have contact with infected birds or animals, or their secretions, while in affected areas of the world. Rarely, avian influenza infection in humans can pass to another person with prolonged contact. However, there is no evidence that the H5N1 strains of avian influenza circulating globally can be spread easily from human to human. In this case, contact tracing has identified that there is no evidence of onwards spread to people.

Symptoms and transmission

The symptoms of H5N1 infection may include fever, cough, headache, aching muscles and respiratory symptoms. Other early symptoms may include conjunctivitis and gastrointestinal symptoms. The infection may progress quickly to severe respiratory illness and neurological changes.

Avian influenza is spread by close contact with an infected bird (dead or alive), e.g. handling infected birds, touching droppings or bedding, or killing/preparing infected poultry for cooking. You can't catch avian influenza through eating fully cooked poultry or eggs, even in areas with an outbreak of avian influenza.

Recommendations

For the public

• People travelling to areas affected by avian influenza should:
  • avoid poultry farms and live bird “wet” markets
  • avoid contact with wild or domesticated birds
  • wash their hands thoroughly after handling birds and uncooked poultry products such as meat or eggs
  • ensure that poultry or poultry products are cooked thoroughly before eating
• Immunisation against seasonal influenza is recommended for everyone aged ≥6 months and over. Speak to your immunisation provider to see if you are eligible for a free flu vaccine. Otherwise, you can purchase the flu vaccine from your immunisation provider. In Victoria the most common way people access the flu vaccine is from their doctor (GP) or a pharmacist immuniser (a service fee may apply). Some local council immunisation services also provide the flu vaccine as do some hospitals, maternity services and community health services.
• As a reminder, poultry workers, people who handle poultry, and people involved in culling during an outbreak of avian influenza are recommended to receive annual seasonal influenza vaccine.
• If you have returned from a country affected by avian influenza and feel unwell, it is important to seek medical advice. Although the risk of becoming infected with avian influenza is very low, it is important when making an appointment with your healthcare provider to tell them about any possible exposures to avian influenza.

For health professionals

• Consider the possibility of avian influenza infection in people presenting with compatible symptoms and epidemiological risk factors, such as travel to an area where avian influenza is transmitting, and recent contact with poultry.
• Ensure diagnostic samples (e.g., nasopharyngeal swabs or aspirates) are taken for influenza PCR and sent for further typing in returned travellers presenting with influenza-like-illnesses who have epidemiological risk factors for avian influenza.
• Provide education and advice about the risk of avian influenza in travellers (including people returning to their country of birth, or visiting friends and family), and advise precautionary measures, such as avoiding contact with wild or domesticated birds to prevent the risk of infection and avoid consuming uncooked poultry.
• Annual influenza vaccination is the most important way to prevent influenza and its complications. Influenza vaccination is recommended for all people aged ≥6 months. Influenza vaccination can be given on the same day as COVID-19 vaccines and other vaccines.
• Encourage annual seasonal influenza vaccination in people who are at risk of being exposed to avian influenza, including poultry workers and those in regular contact with poultry.