March 21, 2007

Drug-resistant bird flu strain found in Thailand

Scientists have found that a strain of the H5N1 bird flu virus circulating in Thailand is resistant to the flu drug amantadine.

Amantadine is one of two drugs recommended by the World Health Organization for treatment against bird flu inoutbreaks, the other being Tamiflu. The organisation recommends a dual therapy of both drugs in outbreaks.

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, making it more dangerous if treatment workers do not identify the strain people are infected with. 

Yong and his researchers said the strain has been circulating in Thailand, Cambodia and Vietnam since 2004.

It is not known how effective a dual Tamiflu-amantadine therapy may be as Thailand has not tried administering such a treatment.

There are two H5N1 strains circulating in Thailand, one in the north-east and the other in the central part of the country.

Yong identified the strain in the north-east province of Nakhon Phanom as the Fujian-like strain, which an international group of virologists said may start another wave of H5N1 outbreaks in poultry in Southeast Asia and Eurasia.

The strain was also in the Chinese provinces of Anhui and Zhejiang, and Laos, Yong said.

The more strains there are, the more different they will be and it would be harder for scientists or aid workers to determine the efficacy of the vaccines they use, he said.