What is bird flu?
Can humans catch it?
Can bird flu be passed from human to human?
Who is most likely to catch it?
What are the symptoms of bird flu?
Can it be treated?
How dangerous is it?
How do you protect yourself from it?
What is the situation in the UK?
What is bird flu?
Bird flu is an infectious disease found in birds. The disease was first identified in Italy more than 100 years ago. It occurs worldwide.
Until mid-December 2003 bird flu was considered a rare disease. Since 1959, only 21 outbreaks amongst birds had been reported worldwide, most of them in Europe and the Americas.
But since 2003 a severe form of bird flu – H5N1 – has affected poultry flocks and other birds in several countries in the far East, and most recently spread throughout the majority of mainland Europe. Some humans have died of the infection, which they caught from infected birds. But people are worried about the possibility of the disease passing from human to human.
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Can humans catch it?
Yes. The first human cases were found in Hong Kong in 1997.
There are three main groups of flu viruses (A, B and C). Flu B and C viruses only infect humans. Flu A viruses can cross the species barrier and infect people, birds and animals.
Among humans, flu A is the source of flu epidemics and pandemics. Bird flu is caused by a type of flu A – the infamous H5N1 virus.
Humans can catch bird flu through close contact with infected birds. Birds excrete the virus in their faeces, which dries and turns to dust. This dust is then inhaled.
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Can bird flu be passed from human to human?
Until now there is no firm evidence that H5N1 can pass easily from person to person. But if it becomes able to do so, H5N1 could then spread widely and rapidly among people. This could cause another flu pandemic.
It is possible that the bird flu virus could merge with a human flu virus and create a new virus that could be passed between humans. This could cause a flu pandemic.
Until now, though, possible instances of spread from one person directly to another have been isolated one-off occurrences.
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Who is most likely to catch it?
Young children seem especially vulnerable to the virus. Some scientists think this because they may simply be more likely to breathe in infected faeces dust. On the other hand, tens of thousands of unprotected Asian workers involved in culling chickens haven't developed the disease.
At the moment, too few people have been infected for us to know all the possible risk factors for bird flu.
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What are the symptoms of bird flu?
In birds, the viruses cause a range of symptoms from mild illness to highly contagious disease, which kills nearly every bird that catches it.
Symptoms of bird flu in people range from conjunctivitis to flu-like symptoms –fever, cough, sore throat, muscle aches and in severe cases breathing problems - which can lead to pneumonia, acute respiratory distress, viral pneumonia, and other severe and life-threatening complications.
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Can it be treated?
There is some evidence that recent H5N1 viruses can be treated by a class of antiviral drugs – like Tamiflu.
Recent cases of H5N1 in northern Vietnam have caused concern because of signs that the virus is changing. It has become less lethal and is occurring in larger clusters than past cases. Very recent studies also revealed that the virus is changing.
Tamiflu can save lives if it is given early, no more than two days after symptoms first appear. But in May 2005, the WHO reported that a patient in Vietnam had a strain of H5N1 that was resistant to Tamiflu.
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How dangerous is it?
Bird flu appears to have a high mortality rate among people who get it.
If the virus continue changes substantially, it is unlikely that existing vaccines would be effective against it. A new one would have to be developed.
Every time a bird flu virus jumps from a bird to a person, the risk of a new flu virus being produced increases. For this reason, governments are keen to prevent the spread of bird flu among birds.
As the virus can affect all parts of the body, not just the lungs, this could mean that many illness, and even deaths, thought to have been caused by something else, may have been due to the bird flu virus.
The World Health Organisation (WHO) says that bird flu could be more deadly than SARS virus.
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How do you protect yourself from it?
Vaccines are the main way of protecting humans against flu. If they are available rapidly and in sufficient quantities, they can protect against the disease. However, at the moment there is not enough vaccine.
If you are travelling to areas experiencing outbreaks of the disease in poultry, you should avoid contact with live animal markets and poultry farms. Large quantities of the virus are known to be present in the droppings from infected birds.
You should not attempt to bring any live birds or poultry products back to the UK.
Experts say bird flu is not carried in food, so eating chicken is still safe.
In the countries that have been affected by bird flu, governments have begun to cull affected birds. It is hoped that this will contain the virus.
If traveling abroad – check the Foreign Office travel advice.
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What is the situation in the UK?
EU and UK controls aim to prevent bird flu in UK poultry. Nonetheless, there is a small possibility that bird flu could be introduced to poultry through the migration of wild birds, importing of dead chickens for food, the illegal import of live birds or through someone coming into the UK who has caught the illness abroad.
The NHS would have real trouble in coping with an epidemic in the UK.
As a precaution, the UK has banned imports of live chickens from the following countries: Russia, Kazakhstan, Thailand, Cambodia, China, Hong Kong, Laos, Indonesia, Vietnam, Pakistan, Malaysia, South Africa, North Korea, Turkey and Romania.
The UK Government is expanding its stockpile of antiviral drugs. On 1 March 2005, the Health Secretary announced the purchase of 14.6 million doses of the antiviral, Tamiflu – but that is still enough to treat only a quarter of the UK population.
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Sources of information
Foreign Office: www.fco.gov.uk
World Health Organisation: www.who.int
Department of Health: www.doh.gov.uk
Health Protection Agency www.hpa.org.uk
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Page last medically reviewed: Jan '08
