Thai bird flu strain found to be resistant to drug

By Tan Ee Lyn

HONG KONG (Reuters) - Scientists have found that a strain of the H5N1 bird flu virus circulating in Thailand is resistant to the flu drug amantadine, and they called for rigorous study of H5N1 strains to better treat human victims.

While the World Health Organization has long recommended that Tamiflu be used as the first line of defense against H5N1, it said last May that a "dual therapy" combining amantadine and Tamiflu may be considered in case of an outbreak.

Yong Poovorawan, a medical professor at Chulalongkorn University in Bangkok, said an H5N1 strain in the central part of Thailand had become resistant to amantadine, casting more doubt over its use to fight the disease .

"It would be very dangerous if we don't know the sensitivity or resistance of the strain to amantadine and we use amantadine (to treat people infected with this strain of H5N1)," Yong said.

He urged more rigorous surveillance and study.

"If you follow any new strain you will know the genetic changes, you analyze its molecular structure, make experiments to see which drug it is sensitive to and find out which is the best antiviral for any given strain," he said.

"It's like a jigsaw, we have to find the pieces and see the big picture."

Yong and his researchers came to the latest conclusion after studying the molecular structure of the strain, which has been circulating in Thailand, Cambodia and Vietnam since 2004.