Southeast Asian bird flu experts met in Thailand Wednesday to work out how to prevent a second wave of the virus, which has already killed millions of chickens and 24 people, from continuing its march across the region.

In the absence of any major breakthroughs over the last six months, such as easy-to-use animal vaccines, experts say better surveillance and faster detection of outbreaks of the virulent H5N1 strain remains the main containment strategy.

A rash of cases in Thailand, Vietnam, China and Indonesia this month have shown the virus, which first erupted in Hong Kong in 1997, was never going to disappear quickly after sweeping across much of Asia earlier this year.

Underlining the severity of the problem, Vietnamese state media said Wednesday bird flu had spread to the north despite earlier assurances outbreaks in the south had been contained.

Bird flu’s re-emergence has also rekindled fears the H5N1 virus could lie dormant in domestic or wild birds for months before mutating and jumping to humans to unleash a global pandemic of a type of flu that kills people.

“Though these outbreaks so far appear to only affect poultry populations, they nonetheless increase the chances of virus transmission to humans, as well as the possible emergence of a new influenza virus strain capable of causing a global pandemic,” said Mary Elizabeth Miranda of the World Health Organization.

The WHO and its counterparts, the Food and Agriculture Organization (FAO) and the OIE animal health body, have been rushing to develop effective H5N1 treatments and vaccinations.

However, none is yet commercially available, and in their absence, old-fashioned techniques such as identifying sick animals and then culling them are the only defenses, meeting organizers said.

“There is decisively nothing new,” said Hans Wagner of the FAO in Bangkok, admitting the fight against bird flu would be long and drawn out.

At the three-day meeting, Thailand - a major poultry exporter and one of more advanced countries in the region - offered to act as a regional center for bird flu detection and diagnosis to ensure standardized reporting of outbreaks

Previously, impoverished countries such as Cambodia were sending tissue samples to Paris or London for H5N1 analysis, delaying culling or other containment measures.

“We need to have unified rules and regulations in containing the outbreak, including monitoring, reporting and testing,” said Yukol Limlaemthong of the Thai Agriculture Ministry.

Mass vaccination of domestic birds is a possible future means of tackling the virus, although the jury is still out on whether it would ever be practical across Southeast Asia.

It has worked in Hong Kong, but there are doubts it would be effective in a sprawling and poorly regulated archipelago such as Indonesia, whose response to its latest outbreak has nevertheless been to administer 300 million shots of vaccine.

Joseph Domenech of the FAO in Rome said that while bird vaccines are administered by injection, mass inoculation campaigns are practically impossible.

There was also increasing evidence to suggest the virus has established itself among wild bird populations, rendering such campaigns less effective, Domenech said.

“Wildlife and waterbirds such as ducks are of central importance in understanding how the virus is maintained and disseminated,” he said.