November 17, 2005

Vietnamese scientists report new bird flu strains

Vietnamese scientists have reported new strains of bird flu in the country's poultry, namely the H3 and H4 subtypes. State media said the exact strains were the H3N4 and H4N5.

According to scientists, the H3 and H4 subtypes could kill birds but were generally less virulent and spread more slowly than the H5 subtype.

H5N1 bird flu has already claimed 64 human lives in Asia since late 2003, including 42 in Vietnam.

Dong Manh Ha, director of Ho Chi Minh City's Regional Animal Health Center, said samples sent to a World Organisation for Animal Health (OIE) laboratory in Australia would be further studied.

Meanwhile, a Hong Kong infectious disease expert warned that if such less virulent strains were allowed to spread in poultry, people who were exposed to those birds at close range would be at risk.

In addition, there were concerns those subtypes might mix and exchange genetic material with the H5N1 strain, thus becoming more pathogenic.