Vietnam is bracing for a nationwide avian influenza outbreak in March, after the virus has spread to seven provinces and killed three people, health officials said Wednesday. "If the anti-bird flu measures are not taken seriously, the human infection situation could become as bad as in 2005 and the outbreak in poultry could expand nationwide in March," said Deputy Agriculture Minister Bui Ba Bong. Fresh bird flu outbreaks were detected this week in three provinces, including Hai Duong, Nam Dinh and Tuyen Quang, according to the National Animal Health Department.

The deadly H5N1 virus has infected poultry in a total of seven provinces this year, prompting local authorities to cull 17,000 ducks and chickens, said Hoang Van Nam, deputy head of the department.

The Ministry of Agriculture and Rural Development warned Tuesday that the bird flu situation had triggered a "red alert."

In the latest outbreak, more than 640 ducks at a farm in Hai Duong province, 50 kilometers east of Hanoi, died late last week. Tests on Monday showed they were positive for the H5N1 virus, according to Dong Van Chuc, head of the province's animal health department.

"None of the poultry at the farm had been vaccinated before and we fear that the outbreak will expand to other areas, though we have disinfected the farm, culled all the remaining ducks in the farm's neighborhood and banned poultry transport from the area," Chuc said.

The three people killed by the H5N1 virus this year were from Tuyen Quang, Hai Duong and Ninh Binh provinces.

On Sunday, Agriculture Minister Cao Duc Phat sent an urgent message to provincial officials, repeating warnings against eating sick birds and asked provinces to cull all sick poultry, disinfect poultry farms, ban the transport of poultry from infected areas and continue vaccination programs.

"The possibility that bird flu in poultry will expand on a large scale and that there will be more people infected with H5N1 is very high," the message said.

The virus has infected 104 people in Vietnam and killed at least 50 since it first appeared in the country in late 2003.

H5N1 mainly affects poultry and wild fowl, but can infect humans who have close contact with sick birds. Scientists fear that if it spreads unchecked, the disease could mutate into a form that could be transmitted between humans, leading to a worldwide pandemic that could kill millions.