A 14-year-old girl in Vietnam (search) has become the third person in a week to contract deadly bird flu (search) in the same northern province, health officials said Monday, prompting concerns over a larger outbreak.

The bird flu has killed 46 people in Vietnam, Thailand and Cambodia since it surfaced in mass outbreaks on Asian poultry farms (search) in 2003, then spread rapidly last year among poultry across a wide swath of the region, devastating the industry.

Since bird flu re-emerged in Vietnam nine weeks ago, 14 people have died.

The girl from Thai Binh province, the most recent person to come down with the disease, tested positive for the H5N1 virus (search), said Nguyen Duc Hien, director of the tropical disease unit at Hanoi's Bach Mai. Her 21-year-old brother is in critical condition in the same hospital with the disease; he was diagnosed Friday.

Provincial officials have said the two had eaten chicken at a friend's house during Lunar New Year festivities earlier this month. The family did not raise poultry, but there were bird flu outbreaks in their neighborhood.

"We are very worried about the bird flu," said Pham Van Diu, director of the Thai Binh's Preventive Medicine Center. "Thai Binh is an agriculture province with many farmer families involved in backyard poultry farming. It's therefore very difficult to deal with. The war on bird flu is very complicated."

In Thai Binh province three human cases have been discovered in the last week, including a 69-year-old man who died on Wednesday.

The man had eaten chicken with his family during the Lunar New Year, health officials said. None of his family have reported symptoms.

Another suspected case in the province — that of a 36 year-old man — is currently being tested.

Last week, health experts and representatives from 28 nations convened in Ho Chi Minh City to discuss how to battle the deadly virus in Asia.

Experts said the H5N1 virus is now entrenched in the region and international efforts should concentrate on containing the disease, minimizing the risk of transmission from poultry to people.

Health experts have warned that the longer the virus remains in the environment, the greater the chance it will mutate into a form that can be passed easily among humans.

Monday's Tuoi Tre (Youth) newspaper reported that the State Bank of Vietnam has ordered commercial banks to suspend credit for farmers who want to raise waterfowl.

Earlier this month, the government had imposed a ban on breeding birds such as ducks and geese until June 30.

Health experts have said ducks, which can carry the H5N1 virus without showing any symptoms, are major culprits in spreading bird flu.