The man died Wednesday at the National Institute for Infectious and Tropical Disease in Hanoi after battling with the disease for two weeks, said Vu Van Can, deputy director of the health department in Ninh Binh province, where the man was from.

Can said the man, who tested positive for bird flu, had become ill after slaughtering and eating ducks his family raised in Ninh Binh, which is some 100 kilometers (60 miles) south of Hanoi.

Last week, a 23-year-old woman from the northern province of Quang Ninh died of bird flu, in Vietnam's first bird flu death in 2009. Bird flu has killed 54 people in Vietnam, including five last year, since it began rampaging through Asian poultry stocks in late 2003.

So far this year, bird flu outbreaks among poultry have spread to 13 provinces nationwide, killing or forcing the cull of more than 50,000 birds, according to the Department of Animal Health.

The H5N1 strain has killed at least 255 people worldwide since 2003, most through contact with sick birds, according to the WHO. Vietnam's latest death was not included in the WHO's toll.

Scientists are monitoring the virus because of its potential to mutate into a new human influenza virus, which could infect millions.