July 16, 2007
 

Bird flu strain in Qinghai, China found to be dangerous variation

Research from the Institute of Prevention Veterinary Medicine in Zhejiang University, has found that the H5N1 virus strains in wild geese in July 2005, at Qinghai Lake in China, was a dangerous mutation from the usually non-pathogenic versions.

The findings were published in the Journal of General Virology.

The deadly mutation caused the deaths of thousands of wild waterfowls. The researchers classified it as a reassortant virus.

The virus was found to be different from that of H5N1 viruses deposited in GenBank and analysis showed that significant antigenic variation has occurred in the new virus.

The new Bh H5N1 virus induced systemic infections and caused 100 percent mortality in chickens and mice, and 80 percent mortality in ducks and geese. Bh H5N1 virus titers were higher in multiple organs of poultry than in mice, and caused more severe histological lesions in chickens, ducks and mice than in geese, said J.Y. Zhou and colleagues at Zhejiang University.

The study called for more monitoring to prevent the transmission of highly pathogenic bird flu from wild migratory waterbirds into domestic poultry and other mammalian hosts.