A 35-year-old woman has become Vietnam’s fifth fatality in two weeks from the bird flu virus, which is spreading again through the country’s poultry farms, mainly in the south.

The woman, who was transferred from Tra Vinh province and tested positive for the H5N1 poultry virus, died on Jan. 12 in a Ho Chi Minh City hospital, the state-run Labour newspaper said on Friday.

She had suffered from high fever and respiratory difficulties two weeks ago after eating a chicken infected in renewed outbreaks that struck in early December and refreshed fears the virus could mutate into one which could cause a pandemic.

Vietnamese officials said they suspected another death would soon be blamed on the virus.

One of Vietnam’s laboratories designated for bird flu tests was also looking into whether bird flu was the cause of death of another patient, who died on Thursday in a Mekong Delta province.

The World Health Organization said H5N1 was “a particular frightening virus” as more than 70 percent - 25 people - of human cases identified in Vietnam had died.

“If strong measures are not in place, the influenza H5N1 epidemic can spread to an unmeasurable extent,” Hans Troedsson, Vietnam representative of the U.N. health agency, was quoted by state media as saying at a health conference on Thursday.

“If this virus is capable of jumping from human to human, the risk is that two to seven million people could die,” the Labour newspaper quoted him as saying.

There has been one firm case, in Thailand where 12 people have died of bird flu, where experts are fairly sure the virus was passed from person to person.

But there is no evidence yet that the H5N1 virus has mutated into a form which could cause a pandemic. To do that, it would have to get into an animal, probably a pig, which can also host human flu viruses.

INFECTED WHILE SWIMMING

So far most bird flu victims have eaten or lived with sick chickens. But the Labour newspaper quoted officials as saying a 9-year-old boy who died from bird flu on Jan. 4 caught it by swimming in water used for the disposal of infected poultry.

The Agriculture Ministry’s animal health department said on Friday that the bird flu had recurred just outside Hanoi, killing 600 chickens and ducks at two farms in Long Bien district on Thursday.

Health workers slaughtered the remaining 400 chickens and ducks and disinfected the farms, it said. Hanoi, home to around 3 million people, has now become the second place in Vietnam’s north to face a recurrence of bird flu.

The ministry said 10 new outbreaks were detected on Thursday in four Mekong Delta provinces and Hanoi, resulting in the slaughter and death of more than 22,000 chickens, ducks and birds.

The disease has devastated the poultry industry in a number of countries as millions of birds were slaughtered to halt the virus. Malaysia, however, has declared itself free of the disease and Thailand has had no new cases since November.

WHO said on its Web site at http://www.who.int said the Dec. 26 Indian Ocean tsunami may have raised the risk of an influenza pandemic, even though the giant wave did not hit the areas where the poultry virus has been rampant.

“Any activity that spreads avian influenza increases the possibility of the emergence of a pandemic virus,” the statement said, calling for tight controls on poultry movement into the areas hit by the tsunami and on food relief activities.

By Thursday, nearly 180,000 poultry had been slaughtered or died from bird flu in Vietnam since it recurred. Last year, the epidemic wiped out 17 percent of Vietnam’s poultry stock of 250 million.