Bird flu, or avian flu, is an infectious type of influenza that spreads among birds. In rare cases, it can affect humans.
There are many different strains of bird flu virus, most of which don't infect humans. However, two particular strains have caused serious concern in recent years:
Although these viruses don't infect people easily and aren't usually transmitted from human to human, several people have been infected around the world, leading to a number of deaths.
Other bird flu viruses – particularly H7N7 and H9N2, and more recently H6N1, H10N8 and H5N6 – have also infected people, but these have been very rare or only rarely caused severe illness.
Bird flu affects many species of birds, including chickens, ducks, turkeys and geese. It can be passed between commercial, wild and pet birds. Birds don't always get sick from infection, so seemingly healthy birds may still pose a risk to people who come into contact with them.
Like other types of flu, bird flu symptoms often include:
These symptoms can come on suddenly. The time from infection to the start of symptoms (incubation period) is usually three to five days, although in some cases it can be up to seven days.
Within days of symptoms appearing, potentially fatal complications such as pneumonia , acute respiratory distress syndrome and multiple organ failure may develop. Prompt treatment with antiviral medication may help prevent complications and reduce the risk of death.
People with suspected symptoms of bird flu (avian flu) will be advised to stay at home, or will be cared for in hospital in isolation from other patients.
The main recommendations are:
In many countries, certain antiviral medications have been stockpiled for use in the event of an outbreak. These medications work by stopping the virus multiplying in your body.
Oseltamivir (Tamiflu), Zanamivir (Relenza) and Peramivir (Rapivab) help reduce the severity of the condition, prevent complications and improve the chances of survival.
For regular flu, these medications are most effective if given within 48 hours of symptoms developing, but it's not clear if this is the case for bird flu. Nevertheless, they should be given as soon as possible to people suspected or proven to be infected, even if it's more than 48 hours after symptoms started.
These medications may also be given as a preventative measure to people who could have been exposed to bird flu viruses – for example, other household members, healthcare workers, or people who have had close contact with infected birds.
In these cases, the course of medication should begin as soon as possible after exposure to the virus and continue for 7 to 10 days after the last known exposure.
Complications such as bacterial pneumonia may develop in some people and can be treated with regular antibiotics.
People who are severely affected may need to be given extra oxygen to help them breathe – for example, through a ventilator (a machine that assists with breathing).
You should contact your doctors or call local emergency services immediately if you experience these symptoms and you've visited an area affected by bird flu in the last two weeks.
An initial assessment can be made over the phone, at a doctor's surgery, at home, or in a side room at a hospital.
Bird flu is diagnosed based on your symptoms and the likelihood that you've been exposed to an infected bird. The doctor will ask you whether you've:
If bird flu is suspected, the following tests will be carried out to establish whether you have the infection:
If the laboratory tests and chest X-ray results are normal, it's unlikely you have bird flu.
Bird flu is spread through direct contact with infected birds (dead or alive), an infected bird's droppings, or secretions from their eyes or respiratory tract.
Close and prolonged contact with an infected bird is generally required for the infection to spread to humans. For example:
Another possible source of bird flu can be live markets, where birds are sold in crowded and sometimes unsanitary conditions. Avoid visiting these markets if you're travelling in countries that have had an outbreak of bird flu.
Bird flu isn't transmitted through cooked food. Poultry and eggs are safe to eat in areas that have experienced outbreaks of bird flu.
There are a number of things you can do to reduce your risk when you visit areas where outbreaks have been reported, such as:
There are no restrictions on travel to countries that have been or are currently affected by bird flu.
Read more about preventing bird flu .
The World Health Organization (WHO) confirmed that by May 2015, 840 people had been infected with the H5N1 virus worldwide and 447 had died. Indonesia, Egypt and Vietnam experienced most cases and fatalities.
Since March 2013, there have been reports of people being infected with the H7N9 virus, mostly in the southeastern part of mainland China. By May 2015, there had been 665 confirmed cases and 229 deaths. Most cases were among middle-aged to elderly men. A small number of cases were reported in travellers from Hong Kong, Taiwan, Malaysia and Canada.
For both viruses, there have been some reports of limited human to human transmission, usually as a result of very close contact between family members.
People who have had bird flu generally developed the virus after coming into close and prolonged contact with infected birds. Millions of birds have been killed during outbreaks to prevent the disease spreading and being passed on to people.
As the bird flu (avian flu) virus is carried by birds, it's very difficult to prevent it spreading. However, there are some general measures you can take to reduce your risk of catching a viral infection.
To reduce your risk of catching and passing on viral infections, such as flu, always ensure you:
You can feed wild birds and ducks, but it's important to wash your hands thoroughly afterwards. Don't go near sick or dead birds. Keep away from bird droppings if possible and wash your hands thoroughly if you accidentally touch any.
If you come across between one and four dead birds, Defra advises leaving them alone or disposing of them carefully. See the Defra website for guidelines on disposing of dead birds.
In general, you don't need to change the way you look after your pets. If you have a dog that sometimes catches wild birds, try to avoid areas where this is likely to happen. In theory, the H5N1 bird flu strain can be passed on to other animals, but it's very unlikely.
If you have a pet bird, you should avoid letting it have any contact with wild birds or wild bird droppings.
If you're travelling in a country that's had an outbreak of bird flu, don't go to live animal markets or poultry farms.
Don't go near bird droppings or dead birds, and don't bring live birds or poultry products back to the UK with you, including feathers.
The NHS has plans in place to manage a potential outbreak of bird flu in the UK, although such an outbreak is considered highly unlikely.
Bird flu isn't transmitted through cooked food. It's safe to eat poultry and eggs in areas that have had outbreaks of bird flu.
As a precaution, always ensure good hygiene standards when preparing and cooking meat. For example:
Read more about bird flu and food.
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.