Deadly disease doesn't stop in the farmyard

AVIAN flu first jumped the ‘species barrier’ from bird to human in 1997 when cases were seen in Hong Kong.

Humans catch the disease though close contact with live infected birds. Birds excrete the virus in their faeces, which dry and become pulverised, and are then inhaled.

Symptoms are similar to other types of flu - fever, malaise, sore throats and coughs. People can also develop conjunctivitis.

All 18 who were infected in the 1997 outbreak had been in close contact with live animals in markets or on farms.

There are many strains of avian flu, but it is the H5N1 strain which has been found to have a unique capacity to cause severe disease with high mortality rates in humans.

The virus can survive for long periods in the tissues and faeces of dead birds, particularly at low temperatures.

Patients can be treated with antiviral drugs and researchers are currently working to develop a vaccine.

In 1997, six out of the 18 people who were infected died. Up to 10 deaths have been linked to the virus in this latest outbreak.

In comparison, Sars has killed around 800 people worldwide and infected at least 8,400 since it first emerged in November 2002.

As yet, there have been no cases where the flu has been passed from person to person and the best way to avoid infection is not to have contact with live poultry in areas where avian flu is rife.

However, experts are so concerned because there are fears that the virus could attach itself to a human flu virus, creating a new virus which could spread between humans.

This could happen if a person was simultaneously infected with avian and human flu. The more this double infection happens, the higher the chance the disease could mutate.

As far as continuing to eat chicken is concerned, the advice is that avian flu is not a food-borne virus and so it is safe.

To contain the virus in the countries affected, millions of birds have been culled in an attempt to stop the spread of the disease among birds, which would in turn stop it being passed on to humans.

Experts say people in the UK are at "very low risk" of developing the disease.