Bird flu experts from around Asia were gathering in Vietnam on Tuesday to figure out how to kill off a virus one leading American expert has called the world’s biggest threat to human health.

“At the moment, we are not on top of it,” said Hans Wagner of the U.N.‘s Food and Agriculture Organization as he prepared for a two-day conference in Vietnam, the country worst hit by a virus which has killed 46 people since it arrived in Asia in late 2003.

“Definitely we have made progress, but there is much to be done,” he said in Ho Chi Minh City, home to 10 million people and close to the Mekong Delta where Vietnam’s latest outbreak began.

The H5N1 virus, which experts in Asia say thrives best in the cool season now coming to an end, spread to half Vietnam’s 64 provinces and cities, killed 13 people and forced the government to take drastic measures to contain it.

The new outbreak a year after the highly contagious virus arrived in Asia, probably brought by migrating wildfowl, has reinforced fears that it could mutate into a form which could spread through a world population with no immunity to it.

Such an influenza pandemic, like the one in 1918 which killed between 20 million and 40 million people, could be devastating.

There is yet no vaccine against the H5N1 virus.

“This is a very ominous situation for the globe,” Dr Julie Gerberding, head of the Centers for Disease Control and Prevention in the United States, said on Monday.

“I think we can all recognise a similar pattern probably occurred prior to 1918,” she said.

The virus was the “most important threat that we are facing right now”, Gerberding added.

FRUSTRATION

Governments in Asia, where tens of millions of poultry have been slaughtered in a vain bid to eliminate the virus, were hard at work on the problem, the FAO’s Wagner said.

Surveillance systems were in place, laboratories had been upgraded to do the necessary testing and warnings to the public not to touch sick chickens commonplace, he said.

“Every country is fully aware of the threat and the global threat, but the work has to be intensified,” he said.

There is yet much to be learned about the virus, which has killed more than 70 percent of the people known to have contracted it.

Nobody knows how many people may have been exposed to the virus but not become ill.

Just last week, an international team of doctors said the H5N1 virus can produce encephalitis, diarrhoea and other symptoms which do not look like the classic respiratory disease.

Meanwhile, farmers dependent on chickens in countries such as Vietnam and Thailand, which are also suffering from recurrences of the virus, are struggling to make a living.

Do Van Hoi, a 50-year-old chicken farmer in the Mekong Delta province of Long An, lost 18,000 chickens last year.

The government gave him 5,000 dong ($0.317) apiece in compensation. This year, it has doubled that. The problem is, he reckons it costs him 50,000 dong to raise a bird.

And he has had to fence in his birds with chicken wire to keep them away from wild birds and spray their compounds with disinfectant three times a day.

“I’m afraid there will be an outbreak on a nearby farm and the government will slaughter all poultry in the area,” he said with an eye on a farm 1 km (mile) away raising ducks, which, like their wild cousins, can carry the virus without showing symptoms.

“I’m frustrated. Last year, I didn’t sell a chicken. I had to slaughter them all.