UN guidelines say separating wild birds from domestic fowl is essential. But on small holdings in Asia, where free-range chickens often sleep in the same room as their owners, this is next to impossible.

United Nations health experts warned at a medical conference in Kuala Lumpur that the situation is critical. If a global pandemic is to be averted, eight stricken Asian countries need $100m (pounds 57m) over the next two years -- 10 times the funds pledged by the West -- for research and vaccination of poultry.

'Spanish Flu' Killed 25 Million

Some 25 million people died during the 1918-19 outbreak of "Spanish Flu," believed to be a mutant strain of avian influenza which infected half the world's population at the time and cost more lives than the First World War.

"The virus has behaved in ways that suggests it remains as unstable, unpredictable and versatile as ever," said Shigeru Omi of the World Health Organization (WHO). "We need to be on constant alert."

Because wild fowl can be carriers of bird flu without showing symptoms, veterinarians predict that gulls and geese are likely to introduce the deadly H5N1 virus to India and Pakistan during their imminent annual migration south.

With unregulated poultry farms and countless bazaars where fowl are sold live, then taken home by customers on crowded public transport, this is a recipe for disaster.

In the remote Chinese province of Qinghai, where nearly 6,000 wild geese died last month, three million doses of bird flu vaccine have been distributed. Chinese officials enforced quarantines after detecting the outbreak, but international health authorities demand more transparency from the Chinese government about how they deal with suspected bird flu.

Culling wild birds is frowned upon, and the UN guidelines say separating wild birds from domestic fowl is essential.

Endemic in Vietnam

On small holdings in Asia, where free-range chickens often sleep in the same room as their owners, this is next to impossible. Vietnam, where the majority of human deaths have occurred, admits that bird flu has become endemic, and is about to undertake widescale vaccination of domestic ducks.

Seven new human cases were reported in Vietnam last month, and both Cambodia and Indonesia diagnosed new human cases. Thailand, after recording a dozen human deaths in 2003-04, has had no new cases.

China was criticized for allowing poultry farmers to misuse the human antiviral drug amantadine to protect domestic poultry at risk. Medical experts demanded statistics and cautioned that this practice could develop influenza strains that are resistant to the only known medical treatment for people who have contracted bird flu.

The disease, if untreated in people, causes acute respiratory distress and organ failure within days.

No Human-to-Human Transmission

Joseph Domenech, the Food and Agriculture Organization's chief veterinary officer, stressed the need to include pigs in surveillance plans when an outbreak occurs in poultry. Sick hogs can be a mixing vessel for avian and human influenzas.

But, he added, it was too early for "mass killing of pigs, which are a crucial part of farmers' livelihoods and of food security in Asia."

The focus of the three-day meeting in Kuala Lumpur is how to protect laborers at farms and markets, and to prepare physicians and vets for an epidemic.

The WHO is searching for a strategy to keep the virus from leaping from animals to humans, and mutating into a more infectious hybrid.

"The virus has yet to develop efficient human-to-human transmission and there is still time for action," said a joint statement by the three UN groups organizing the three-day conference in Malaysia: the Food and Agriculture Organization, the WHO and the World Organization for Animal Health known by its French acronym OIE.