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Published on August 23, 2007

DCD director general Dr Thawat Suntrajarn said the agency had closely monitored changes in the virus and found the genomic sequence of the H5N1 virus had still not altered into a dangerous pandemic strain.

"The results from laboratory testing have found there has been a small change of amino acids within the bird flu virus, but this alteration has still not developed into the mutation stage," Thawat said.

Dr Paijit Warachit, director-general of the Department of Medical Science, confirmed the strain had not shown any significant mutation - particularly the Hemagglutinin antigen of H5N1, which could indicate mutation was underway.

"We have seen some changes, but nothing significant, particularly the position of the Hemagglutinin antigen in the H5N1 virus, which has not altered." Paijit said.

The avian influenza virus contains two types of antigen - Hemagglutinin (H) and Neuraminidase (N) - which constitute the main structure of the virus. Most scientists and health experts are worried the virus could change its H antigen and then develop into a highly pathogenic or low pathogenic avian influenza virus.

Dr Prasert Thongchareon, a senior World Health Organisation medical adviser, expressed concern about an internal change in the virus at the amino acid level that could develop into a dangerous strain.

"Even if there was a small change in the virus, this would bring it closer to mutation," Prasert said.

The Public Health Ministry and World Health Organisation experts recently collaborated on an investigation into bird flu deaths in Thailand.

Their report suggested that even though deaths from the virus in Thailand were not caused by the mutated strain, people could still be infected by droplet transmission if they stayed too close to a patient, Thawat said.

He said no bird flu deaths had been reported this year. From 2003 to 2007, 25 patients were infected with avian influenza resulting in four deaths.

Meanwhile, the DCD will continue to closely monitor the prevalence of the disease and possible mutation of the virus.

Pongphon Sarnsamak

The Nation