HEALTH experts are watching the spread of deadly bird flu among humans with increasing concern after doctors reported a second suspected case yesterday among medical staff treating a victim.

The World Health Organisation (WHO) has given a warning that the flu, which has killed 47 people in Asia, could mutate into a form that spreads quickly between humans and trigger a global pandemic.

Britain has stockpiled more than 14m courses of the antiviral drug Tamiflu at a cost of £200m, enough to treat a quarter of the population.

The bird flu has a mortality rate of 60-80% and the government says 50,000 people could die if it takes hold here — four times the number who die each year from influenza.

So far there have been five suspected instances of bird flu among poultry in Britain, but no human cases. Health experts have called for a ban on imports of poultry feathers from Asia.

Yesterday doctors at Bach Mai hospital in Hanoi, the Vietnamese capital, said a 41-year-old nurse had been admitted for treatment suffering classic symptoms of high fever, coughing and lung infection. Earlier it was confirmed that a 26-year-old male nurse had caught the H5N1 strain of the virus.

Both nurses had treated the same patient, a young man who is thought to have passed on the virus to other family members. He is in a critical condition.

Experts say there is a difference between a cluster of infections by a single victim and a chain of infection that jumps at random from one person to another. The Asian outbreak is so far limited to clusters. The H5N1 virus has killed 34 Vietnamese, 12 Thais and one Cambodian since 2003.

It has recurred several times despite the slaughter of millions of birds and has spread across about half of Vietnam since the latest outbreak began in the Mekong delta. The WHO has advised travellers to avoid animal markets and poultry farms in affected countries.

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