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.
No humans have been infected with bird flu in the UK, although plans are in place to manage any suspected cases.
A few cases of bird flu were confirmed in poultry in the UK recently. In February 2015, a low-severity H7N7 strain of bird flu was confirmed at a farm in Hampshire, but restrictions around the premises were lifted 21 days later after cleaning and disinfection.
Before that, in November 2014, H5N8 bird flu was confirmed at a duck breeding farm in Yorkshire, but the Department for Environment, Food and Rural Affairs (Defra) said the risk to public health was very low. This is because H5N8 infection was not found in humans during the recent worldwide epidemic among birds.
The last reported case of H5N1 in the UK was in early 2008.
You can read reports on recent cases of bird flu in the UK on the GOV.UK website.
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 the UK, 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 GP or call NHS 111 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 GP 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.
You can read about outbreaks of bird flu in the UK on the GOV.UK website.
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.
Bird flu is a notifiable disease in animals and you should report any suspected case to the Animal and Plant Health Agency (APHA), even if you're not sure.
Call the Department for Environment, Food and Rural Affairs (Defra) helpline on 08459 33 55 77 if you find five or more dead birds in the same place.
Read about notifiable diseases in animals on the GOV.UK website.
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.