GENEVA (AP) -- The world still faces a substantial threat of a flu pandemic and countries need to speed up preparations for a global outbreak, health experts said Tuesday.

"We can't delude ourselves. The threat of a pandemic influenza has not diminished," said Keiji Fukuda, coordinator for the World Health Organization's Global Influenza Program.

Fukuda spoke to a meeting of around 150 health experts from governments, WHO and other agencies to update WHO's pandemic influenza preparedness plan.

Scientists fear that the H5N1 strain of bird flu virus -- which began ravaging Asian poultry stocks in late 2003 -- could mutate into a form that spreads easily among humans, potentially sparking a pandemic that kills millions. So far, most human cases have been linked to contact with infected birds.

Fukuda said more than 150 countries had some kind of national preparedness plans but some of them were merely a piece of paper acknowledging the risk.

He said it was crucial that all levels of society were involved in the preparations and that everyone knows where to go for information.

"If somebody is sick in the family for example and it's difficult to get to hospital, they need to know what sort of advice might be available," Fukuda told The Associated Press.

WHO says 382 people have come down with bird flu since 2003, and that 241 of them have died. Indonesia, with 108 of the deaths, is seen by experts as a potential hotspot for a pandemic.

WHO is updating its 2005 preparedness plan to include progress in research on flu viruses, stronger international cooperation and experience with human cases of bird flu.

"Our understanding of the virus, the effects on people, the epidemiology how viruses move around the world, is much greater than it was a few years ago and this continues," Fukuda said.

Stockpiles of antivirals have been built since 2005, he said. WHO has stockpiled a total of 5 million antiviral treatment courses ready to be handed out if a pandemic breaks out.

He said the development of a possible pandemic vaccine have made significant strides.

"A few years ago it would not have been possible to talk about pandemic vaccines," he said. "All of a sudden we have new things to work with."

Experience and research over the last few years have led experts to believe that it is possible to stop a pandemic influenza right at the beginning of the outbreak, said Fukuda, adding that they recognized it will be difficult.

Fukuda said WHO will take into account the revised International Health Regulations in updating its pandemic preparedness plan, which is expected to be published by the end of the year.

Max Hardiman from WHO's secretariat for the health regulations said the agreement, which took effect in 2007, should help the world to know about a pandemic outbreak as soon as possible.

The health regulations oblige countries to report new disease threats with global public health significance, such as new flu subtypes. They also allow the WHO to act on credible information sources, rather than being reliant strictly on official government channels.

Hardiman said measures to contain a pandemic should avoid unnecessary travel restrictions.

Under the health regulations countries are putting in place measures to curb the spread of a pandemic, he said. These include assuring access to medical centers, control of airports and other points of entry and preparations to isolate sick people and quarantine contacts.

"One day we will face a pandemic but we don't know when," Fukuda said.

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