Bird flu virus strain in Vietnam has mutated, becoming more dangerous, local newspaper Pioneer reported Wednesday.

    However, the mutation is not big enough for the virus to transmit among humans, the paper quoted Vietnamese Minister of Agriculture and Rural Development Cao Duc Phat as saying at a meeting of the country´s Anti-bird flu Central Steering Committee on Tuesday.

    The vaccination among poultry is still effective in preventing the disease due to the high compatibly between the vaccine and the virus, he said.

    Vietnam is encountering high risk of bird flu reoccurrence late this year, when cold weather condition is more favorable for the development of viruses, he said.

    The minister has asked local relevant agencies to focus on intensifying disease surveillance, monitoring of poultry raising, transporting and trading, and vaccination among fowls nationwide.

    Vietnam has detected seven bird flu patients from the five northern provinces of Vinh Phuc, Thai Nguyen, Thanh Hoa, Ha Nam and Ha Tay since May 10, of whom four died, according to the Preventive Medicine Department under the Vietnamese Health Ministry.

    Bird flu outbreaks in Vietnam, starting in December 2003, have killed and led to the forced culling of dozens of millions of fowls in the country, according to the Department of Animal Health under the Ministry of Agriculture and Rural Development.