Health officials warned Monday that the world is close to its next pandemic -- a powerful and highly contagious mix of avian influenza and flu virus that would likely be centered in Asia.
Authorities also warned that humans, and not animals as initially thought, would probably be the carriers.
"We are getting closer, but when it's going to happen, I don't know," said Francois Xavier-Meslin, the World Health Organization's coordinator for disease control, prevention and eradication.
"If it happens, which is not yet proven, it's going to be worse than SARS," he said at a task force meeting on bird flu led in Singapore by the Association of Southeast Asian Nations. "A full-blown flu virus, you can transmit easily to people in your family or people you work with. It's a very highly contagious disease compared to SARS."
The H5N1 bird flu virus killed 32 people in Thailand and Vietnam this year, while SARS -- Severe Acute Respiratory Syndrome -- killed 774 and infected nearly 8,000, mostly in Asia, in 2003. Both outbreaks caused widespread economic losses throughout the region.
Meslin said the proximity of high-tech farms and backyard operations, coupled with high human-to-animal contact, could spur another outbreak of avian influenza in Asia.
WHO had warned previously that bird flu mixed with a human flu virus could spread rapidly and cause as many as 7 million deaths.
"Asia is an area with very high poultry density, human density. Asia has always been a center of flu, so all these factors come together," said Hans Wagner of the Food and Agriculture Organization.
Officials, including those from Japan, China and South Korea, were discussing ways to increase bird flu surveillance and inter-agency reporting between countries.
The Association of Southeast Asian Nations, or ASEAN, comprises Malaysia, Singapore, Indonesia, the Philippines, Thailand, Vietnam, Brunei, Cambodia, Laos and Myanmar.