Bird flu (avian influenza)

Bird flu, also known as avian influenza, is an infectious disease of birds caused by several different strains of the bird flu virus. It spreads between both wild and domesticated birds and very rarely spreads from birds to humans. Human cases usually involve people in close contact with infected poultry or other birds.

Types of bird flu#

There are different strains of bird flu. Some are more likely to cause death and disease in birds (highly pathogenic) and some are less likely to do so (low pathogenic). Highly pathogenic strains have caused outbreaks in wild birds, in domesticated poultry and in mammals in many parts of the world. Outbreaks have occurred among commercial flocks in a number of countries, and in many cases these have been contained and eradicated.

How is bird flu spread?#

Wild birds are believed to be the main carriers of bird flu viruses. They do not usually show symptoms, although highly pathogenic strains have caused illness and death in some wild birds. Migratory birds carrying the virus could potentially spread it to the countries they travel to.

Bird flu viruses often kill domesticated birds such as chickens and turkeys. Symptoms in sick birds vary by species but can include diarrhoea, breathing difficulties and death. A sick bird sheds the virus in its feathers, mucous, saliva and faeces.

There is no clear evidence that bird flu can pass from one person to another, and no evidence that the highly pathogenic strains currently circulating (for example H5N1) spread easily between humans. Person-to-person spread may have happened in rare cases, such as when someone has been caring for a sick family member.

Who is at risk?#

Most people are not at risk. The main risk is to people who come into contact with infected birds or their secretions in affected areas, and possibly to those caring for an infected person. People with close contact with sick birds, such as poultry workers, are most at risk.

Infection can happen when the virus gets into a person’s eyes, nose or mouth, or is inhaled. For example, a person might handle a sick bird, contaminate their hands with bird droppings, forget to wash their hands before eating, and then swallow the virus.

You cannot catch avian influenza by eating fully cooked poultry or eggs, even in areas where there is a bird flu outbreak.

How is it prevented?#

Be aware of the risk if you are travelling to, or living in, a place where outbreaks are occurring in birds or humans. If you are travelling to an affected area, you should:

• avoid poultry farms and live bird (“wet”) markets
• avoid contact with wild or domesticated birds
• wash your hands thoroughly after handling birds or uncooked poultry products such as meat or eggs
• make sure poultry and poultry products are cooked thoroughly before eating

The seasonal flu vaccine does not protect against avian influenza. However, it can help prevent seasonal flu and bird flu viruses mixing, which reduces the chance of new mutated viruses that could spread quickly, so seasonal influenza vaccination is strongly recommended.

People working with infected birds must use personal protective equipment (including a P2 or N95 respirator/mask, goggles, gloves and protective clothing), follow infection control procedures, and may need antiviral medication.

What are the symptoms?#

When people are infected with bird flu, the most common outcome is no symptoms or only mild ones, such as red, sore eyes (conjunctivitis) or mild respiratory symptoms. However, some strains can cause symptoms like severe human flu: fever, cough, tiredness, muscle aches, sore throat, shortness of breath, runny nose and headache. Pneumonia, encephalitis (inflammation of the brain) and diarrhoea may also occur. Symptoms may appear between 1 and 10 days after exposure.

If you have returned from an affected area and feel unwell, seek medical advice. Although the risk of infection is very low, tell your healthcare provider about any possible exposure when you make an appointment. Wear a mask and call ahead so you can be kept apart from others.

How is it diagnosed and treated?#

In humans, bird flu is usually diagnosed by testing swabs taken from the nose and throat. Several antiviral medications used to treat human flu are also effective against bird flu. These can be used to treat someone who develops symptoms after possible exposure, or to prevent illness in someone who has been in close contact with the virus.

Public health response#

If human cases are suspected, public health authorities work with the patient, their doctors and the laboratory to confirm the diagnosis. Cases are kept apart from others to prevent further infections, and close contacts are advised about the risk of infection. If contacts develop symptoms, they are advised to isolate and be tested. When there is an outbreak on a poultry farm, people exposed to infected birds are followed up by public health authorities and monitored for symptoms, while animal health authorities manage the outbreak among the birds. Tell your doctor if you have travelled to a place where there is bird flu.

Key points#

• Bird flu viruses typically kill domesticated birds, such as chickens and turkeys.
• Symptoms in sick birds vary by species but can include diarrhoea, breathing difficulties and death.
• People with close contact with sick birds, such as poultry workers, are most at risk of infection.
• Symptoms in people may appear between 1 and 10 days after exposure.
• If you have returned from an affected area and feel unwell, seek medical advice.

Where to get help#