Overview / History

Avian influenza H5N2 is a subtype of the influenza A virus, which belongs to the Orthomyxoviridae family. Both "low pathogenic" and "high pathogenic" strains occur.

This strain has caused large outbreaks in domesticated poultry and is frequently associated with significant economic losses. The first suspected bird-to-human infections with H5N2 occurred in 2006 among poultry farm workers in Japan. In June 2024, the WHO reported the first laboratory-confirmed case of H5N2 in a Human in Mexico.

Mode of spread

Animals

Transmission

Much remains unknown about this virus and its ability to infect humans. Transmission is presumed to be through direct contact with infected birds. So far, there is no evidence of H5N2 transmission from person-to-person. However, the virus can undergo genetic changes that could make it easier to spread between people.

Symptoms

Human infection with H5N2 is rare and symptoms may be absent.

Diagnosis

Highly specialised testing of respiratory samples is required to diagnose H5N2.

Treatment

Laboratory data on the H5N2 flu virus shows it may be treatable with the antiviral medications Tamiflu and Relenza. However as there have been so few human cases, it is unclear how effective treatment may be.

Vaccination

There is no human vaccine available but veterinary vaccines have been used in poultry.

Prevention

You should avoid contact with birds and other animals, and their environment.

• Do not go to live animal markets, poultry farms or pig farms.
• Do not handle any birds, even if they appear well. Prevent children from doing so.
• Avoid touching any surfaces that may be contaminated by bird droppings.
• Do not swim in any body of water that is used by birds.

Always maintain high levels of personal hygiene.

• Frequent hand washing is very important. Wash hands before and after food preparation and before eating.
• Thoroughly cook all poultry and poultry products, including eggs.

Consider having an influenza vaccination. Although it will not protect you against bird flu, it reduces your risk of a "co-infection" with human influenza.

Risk to travellers

Travellers who avoid live poultry markets and direct contact with birds are at very low risk.

Further Reading

Ogata et. al. "Human H5N2 Avian Influenza Infection in Japan and the Factors Associated with High H5N2-Neutralizing Antibody Titer." Journal of Epidemiology
World Organisation for Animal Health (OIE)