What is bird flu?

Also known as avian influenza, bird flu is an infectious disease of birds caused by a variant of the standard influenza A virus.

It was first noted by veterinary scientists in the early-1900s.

Since mid-December 2003, a growing number of south east Asian countries have reported outbreaks of bird flu in chickens and ducks. The virus can spread rapidly through flocks of domestic poultry.

Infections in several species of wild birds and in pigs have also been reported.

Bird flu is unique in that it can be transmitted directly from birds to humans. There are 15 different strains of the virus. It is the H5N1 strain which is infecting humans and causing high death rates.

How does it affect humans?

Humans can catch bird flu directly through close contact with live infected birds and those who work with infected chickens are most at risk.

The virus is excreted, and people may inhale these germs as dust when the droppings dry out.

The virus cannot be passed from human to human. However, experts fear that this may change in the future as the virus develops.

This could result in the infection spreading rapidly across the globe, which was the situation during the great influenza pandemic of 1918-1919.

A completely new influenza virus subtype emerged and spread around the globe in around four to six months, killing an estimated 40—50 million people.

What are the symptoms?

In humans, symptoms include fever sore throats and coughing. People can also develop conjunctivitis. It takes three to five days to develop symptoms.

The H5N1 strain is the most deadly type of the bird flu virus with 50 per cent of victims dying.

Chickens may die without showing any symptoms but typically birds suddenly show swelling about the eyes and ear lobes.

How severe is the disease?

This appears to vary. In Hong Kong in 1997 an outbreak of the H5N1 bird flu virus affected 18 people and caused six deaths.

In the current outbreak in southeast and east Asia (caused by H5N1) human illness is very severe in most cases.

There have so far been 120 confirmed cases of bird flu in Indonesia, Vietnam, Thailand and Cambodia. Of these sixty have died. Ten countries have so far been affected, and 200 million birds have died or been culled.

Should we stop eating chicken?

No. There is no evidence that cooked poultry can infect people. You need to be in close proximity to live, infected birds to catch the current mutation of the virus.

Could bird flu affect flocks in UK?

Bird flu can affect all birds including waterfowl. There was an outbreak of H5N1 flu in wild migratory geese in western China.

Experts have expressed concern that these infected birds could migrate to the UK and pass the disease on to our chickens.

Bird flu could also be spread by the international trade of live chickens.

This is why the European Community has banned the import of live poultry and feathers from Turkey where over 1,000 cases of avian flu have been reported.

What are the current plans to deal with a possible outbreak?

Your usual annual flu vaccination will not provide any protection against avian flu. However it will reduce the chance of human and avian flu swapping DNA and developing into a deadly disease.

A new vaccine would need to be produced for this new strain of flu. However it cannot be produced until the pandemic begins as scientists need to work with the actual mutated virus.

Prototypes which offer some protection against the H5N1 strain are being developed.

However antiviral drugs, which are already available, may help limit symptoms and reduce the chances the disease will spread.

Currently the antiviral drug Tamiflu, made by Swiss-based pharmaceutical company Roche, stands the best chance of curbing pandemic bird flu.

The Government has ordered 14.6 million courses of the drug Tamiflu - enough to treat around a quarter of the UK's population.

It is effective against multiple strains of influenza and can also be used as a preventative treatment.

However the Government currently only have 2.5 million courses in stock, with about 800,000 coming in a month.

Priorities for vaccination would include key workers, such as front line NHS staff and vulnerable groups such as the elderly and those with diabetes, heart conditions, asthma and pregnant women.