A map to identify the different strains of bird-flu virus in each locality will be completed by the end of this month, Deputy Minister of Agriculture and Rural Development Diep Kinh Tan has said.

Tan also said that after the map is completed, appropriate vaccines to combat each strain will be imported and sent to the appropriate districts. However, until this is done, only a single type of vaccine will be used - mainly in the South.

Nguyen Huu Duong, director of Hai Duong Province 's Agriculture and Rural Development Department, said failure to identify and treat the exact strain of virus is one of the main reasons for its rapid transmission in the province.

He said more than 15,000 domestic fowls in the province have already been killed to try and control the disease, but it keeps spreading.

Tan said high humidity and the cold weather are sapping the resistance of poultry to fight infection.

According to localities, there are not enough animal-health workers to control the transportation of infected fowls from infected to uninfected areas.

Hoang Van Nam, head of the Animal Health Department, said more than 52,000 infected birds have been culled in 12 cities and provinces so far this year.

He said if localities fail to take tough measures, the disease will keep spreading.

At the beginning of the week, the ministry announced that 50 million doses of vaccine will be imported, despite the fact that it is for a strain of virus prevalent only in southern localities.-VNA