By Tan Ee Lyn

HONG KONG, April 27 (Reuters) - Asia battled SARS and H5N1 bird flu in 2003 and has improved its health infrastructure but there is a wide gulf in how prepared countries in the region are to fight swine flu.

Countries around the world have moved to contain the spread of a possible pandemic after a new swine flu outbreak killed 103 people in Mexico. Twenty cases have been identified in the United States and six in Canada, with no deaths reported.

Possible cases are being checked as far afield as New Zealand.

"With SARS and H5N1, there was a lot of impetus to improve preparedness in many countries in Asia, but there is still a huge variation in preparedness," said Malik Peiris, a virologist and professor at the University of Hong Kong.

Densely populated cities in developing countries such as China or India would encounter major problems, said Guan Yi, a Chinese virologist at the University of Hong Kong who helped fight SARS and bird flu and trace their sources in the past.

"If it goes to China or India, where populations are very dense and infrastructure is not enough, there will be many problems," Guan said. "We are counting down to a pandemic."

Health experts are also worried about impoverished countries such as Laos, Cambodia and Myanmar, which have rudimentary public health systems, meaning a delay in reporting cases and risking the spread of outbreaks.

Since SARS and H5N1 swept through Asia in 2003, governments around the region have beefed up disease surveillance systems, built hospital isolation units and maintained stockpiles of Tamiflu, a drug that appears effective against the new virus.

However there are still big discrepancies between countries.

While many dead birds found in Hong Kong are routinely tested for diseases like H5N1, that would be hardly be possible in sprawling countries like China or India.

NEW LABS

Sophisticated laboratories have been set up in Hong Kong and even Indonesia, which has four such facilities. In Thailand, there are flu monitoring systems in place in the countryside, a legacy from battling H5N1.

However, experts are jittery because such facilities are scarce and there are many questions surrounding the new virus.

"Indonesia has prepared a system in case of a flu pandemic. But there is something I am not certain of, the early warning, reporting and action system," said I Gusti Ngurah Mahardika, a virologist at Udayana University in Indonesia.

"The laboratories and government research institute are of course ready, but the question is, do the rest (in the country) have the early diagnostic (systems) already?"

"I am trying to find out about the H1N1 that spread in Mexico and California, why is it new? How is it connected to swine?"

Thailand strengthened its pandemic preparedness after an initial slow response to bird flu in 2003, and health experts say it now has a "robust" surveillance system, improved laboratory facilities and better training.

Health Minister Witthaya Kaewparadai said 14 medical centres were capable of tackling an outbreak of swine flu. Another six mobile units were on standby to handle remote outbreaks.

"It will take us four hours to verify suspected cases," Witthaya said, adding Thailand had enough Tamiflu stockpiled in the country to treat 300,000 patients, and the government drug maker can produce more if necessary.

(Additional reporting by Olivia Rondonuwu and Telly Nathalia in Jakarta, Darren Schuettler in Bangkok; Editing by Nick Macfie and Dean Yates)

AlertNet news is provided by