Two teenager girls in southern Vietnam have tested positive for the bird flu virus, an official said Thursday.

A 10-year-old girl from Long An province and a 13-year-old girl from Dong Thap province both tested positive for the H5N1 strain of the virus. They are in critical condition and breathing on respirators at the treating Pediatric Hospital No. 1 in southern Ho Chi Minh City, said Phan Van Tu, chief virologist at the Pasteur Institute in the city.

The 13-year-old girl's mother died from the disease on Jan. 21 after the two of them slaughtered a duck. The younger girl's families buried sick chickens and ducks at their house a month ago,said Tran Van Hien, deputy director of Long An's Preventive Medicine Center.

Since Dec. 28, 2004, the virus, which jumped to humans, has killed nine people in Vietnam, bringing the toll to 29 over the past year. So far during this outbreak, over 702,000 fowls have died or been slaughtered with outbreaks in poultry reported nationwide.

As the Lunar New Year approaches next month, the focusing time of the year for the transport of people and poultry across the country, the hospitals in the country on Saturday will begin taking swabs from patients suffering from respiratory infections to be sent for testing, according to Thursday's local newspaper.

Bird flu outbreaks ravaged poultry farms across 10 Asian countries last year, killing or forcing the slaughter of more than 100 million birds, including 43.2 million in Vietnam.