The World Health Organisation (WHO) said on Friday the bird flu virus that has killed seven people in Vietnam since December might already be in neighbouring countries.

“These other countries like Cambodia, Laos, Myanmar do not have the infrastructure or capacity at this stage to do the kind of surveillance that is necessary,” Peter Cordingley, spokesman for the Western Pacific region, told Reuters on Friday.

“There may have been human cases that weren’t spotted and reported,” he said by telephone from Manila.

Asked about China, he said: “The Chinese government is taking this very seriously and has put a lot of measures in place ... Only time will tell us if it’s been enough.”

Vietnamese state media reported on Friday that a 47-year-old man had died of the H5N1 virus, bringing to seven the number of Vietnamese killed in the latest wave of outbreaks which have spread the virus across much of the country.

The death of Nguyen Huu Viet from the virus, which has also infected his younger brother, has raised concerns about possible human-to-human transmission of the disease.

Shigeru Omi, WHO director for the Western Pacific Region, said in a telephone interview from Geneva late on Thursday that the outbreak confirmed the virus was entrenched in the region as Vietnam had been making large efforts to control it.

“If we leave it like this for long, the virus might find an efficient way for human-to-human transmission, instead of sporadic transmission as we’ve seen so far,” he warned.

What WHO fears most is that the virus will mutate into a strain capable of sweeping through a human population without immunity, killing millions worldwide.

REASONS TO WORRY

“We think there is very good reason to worry that it will happen,” added Cordingley. “Potential for it to mutate and then effectively spread between humans increases each time it makes that jump (from chickens to humans).”

The WHO warned on Thursday that the bird flu virus now endemic in Asia appears to be evolving in ways that increasingly favour the start of a deadly human influenza outbreak.

It has become “hardier”, surviving several days longer in the environment, and evidence also suggested that it is expanding its range of mammal hosts, including captive tigers and experimentally infected domestic cats, it added.

Asked what WHO recommends to prevent further spread, Cordingley said: “All countries that are at risk have to raise the surveillance of the poultry to the highest possible level.”

“If there is an outbreak in poultry - it doesn’t matter how small - they immediately identify it, kill all infected poultry and establish sanitary zones around the affected farms.”

So far, only Vietnam has reported human cases in the third wave of the outbreak since early 2004, while Thailand confirmed a single chicken at an isolated farm being infected this week.

But Cordingley said there were no reasons to believe they would not see a similar situation this year to one year ago, when nine countries were infected with H5N1 in their poultry.

WHO suspects migratory birds and domestic ducks are playing a role in spreading the virus, though they show no symptoms.

Cordingley added a Thai study showed some of its human cases in 2004 were in areas with no known outbreaks in chickens.

He said vaccinations of poultry could be useful if combined with other measures, but there was a limit.

“Do the governments really have the capacity to go around every farm and stick a needle into chicken?” he asked.