Thai Binh and Bac Ninh provinces are the newest ones to be hit by the H5N1 strain of bird flu, making 17 of the country's 64 cities and provinces infected in the last month.
Vietnam has been battling the H5N1 virus since it emerged across poultry farms in late 2003. At least 67 people have died in the region from bird flu, with about two thirds of those deaths in Vietnam.
The country has taken increasingly tough measures against bird flu as the winter months approach, when the virus is most likely to spread.
In northern Bac Ninh province, tests results released Friday on samples taken from a flock of chickens at a commercial farm were positive for bird flu, said Nguyen Van Lung, director of the provincial animal health department.
Thai Binh provincial animal health director Dang Duc Rieu said 40 chickens had fallen ill and died early in the week. The entire flock of 100 birds was culled the same day. Tests results Friday showed they had bird flu, he said.
Provincial animal health officials said all poultry in the town was destroyed Friday afternoon. Thirteen of the 17 affected provinces are in the northern region, while two are in central Vietnam and two in the southern Mekong Delta.
In related developments:
Thursday, Vietnam's Prime Minister Phan Van Khai approved another $82.6 million for the fight against bird flu in Vietnam, as the government announced plans for its first large-scale emergency drill later this month.
China on Friday also reported two new outbreaks of bird flu among its vast poultry flocks, even as it released dozens of farmers and villagers from medical observation with clean bills of health, the government said.
The latest poultry outbreaks were hundreds of miles apart in the northern province of Shanxi and the far northwestern region of Xinjiang, the official Xinhua News Agency said. All poultry on nearby farms have been killed as a precaution, it said.
China has now reported 15 outbreaks of bird flu in poultry nationwide since Oct. 19 and has promised tough control measures to prevent human infections.
It confirmed itsof bird flu on Wednesday, a woman who died and a boy who recovered. The boy's sister, who died, is a suspected case.
The dozens of people who had contact with the three patients showed no signs of the disease and have been released from medical care, Xinhua said.
In the eastern province of Anhui, 22 farmers who had close contact with the 24-year-old woman "were all OK," Wu Fuqing, an Anhui official, was quoted as saying by Xinhua.
In Hunan province in central China, "no abnormal signs" were detected in 152 villagers who came in contact with the 9-year-old boy or his 12-year-old sister, who died of the same symptoms, Xinhua said. She is considered a suspected case because her body was cremated and there weren't adequate samples for testing.
Additionally, 908 people who came down with fever are recovering, said Ai Ronggui, deputy director of the health bureau in Xiangtan, the county in Hunan where the outbreak occurred.
At least 67 people in Asia have died since 2003, when the virulent H5N1 strain of bird flu became entrenched in poultry populations.