A 1918 Spanish flu outbreak killed between 40 million to 50 million people from rapid human-to-human transmission.

Officials have repeatedly expressed concern that the H5N1 strain of avian influenza that has swept through poultry populations in many parts of Asia since 2003 and jumped to humans, killing at least 60 people, could mutate to become contagious among people.

So far, most of the infections have been traced to direct contact with sick fowl.

Pushing for a Globall Strategy

"If the [H5N1] virus mutates to allow easier human-to-human transmission, it could end in an influenza pandemic," said Paula Dobriansky, undersecretary for democracy and global affairs at the US State Department.

"There are also consequences for economic growth as well as regional and global security.... It could kill millions."

Dobriansky and Health Secretary Michael Leavitt are touring Southeast Asia after President Bush last month established the "International Partnership on Avian and Pandemic Influenza." Washington is pushing for a global strategy against H5N1 and other types of influenza.

Accompanied by World Health Organization director-general Dr. Lee Jong-wook, Dobriansky met Singapore health officials and visited the country's regional infectious diseases research lab.

"At the time of SARS ... the economic impact was worth billions of dollars," said Lee, referring to a 2003 outbreak of severe acute respiratory syndrome that killed 774 people worldwide. "You can imagine if we leave this global pandemic of influenza unchecked what would be the tremendous social, economic and political consequences."

National Pandemic Plans

A 1918 Spanish flu outbreak killed between 40 million to 50 million people from rapid human-to-human transmission.

Only 30 countries have national pandemic plans, while others are scrambling to develop them, Lee said. Anyway, plans are "clearly not enough" to battle such outbreaks as countries need to test and hold exercises to ensure readiness, he added.

The WHO has reached an agreement with a Swiss pharmaceutical company to stockpile at least 30 million capsules of the antiviral drug Tamiflu -- enough for 3 million people -- and to distribute the medicine in the event of an outbreak, he said.

The problem, Lee added, was getting it to countries who do not have the means to pay for the drug -- which could be used to prevent the illness.

"Right now, every country that can afford to buy the drug is stockpiling it for its own use," said Lee, but added that sharing the drugs was a "topic to be discussed."

Dobriansky said US officials have recently toured Cambodia, Laos, Vietnam, China and Indonesia -- where people have died from bird flu, while $25 million has been allocated to identify "capacity-building needs" in those countries.

"It's not about detecting the virus at its source or culling stock and compensating farmers. It's also about have a capacity that is built from within," she said.

Both Lee and Dobriansky will meet Malaysian officials later Wednesday.