Vietnam confirmed on Thursday that an 18-year-old woman was killed by bird flu, and state-run media reported infection of another 35-year-old as health officials scrambled to contain the virus in the country’s south.

A doctor at Ho Chi Minh City’s Pasteur Institute said tests found that the woman, a resident in the southern province of Hau Giang but who died in nearby Can Tho city on Monday, was infected with the deadly strain known as H5N1.

This is the fourth bird flu death confirmed by Vietnamese doctors and Vietnam’s 24th to die in the past two weeks since the country was struck by renewed bird flu outbreaks that began in early December.

Health officials declined comment on a report by Thursday’s daily Liberation Saigon, which quoted health officials saying the virus also killed an 18-year-old woman from the southern province of Tien Giang after she was hospitalised the previous week.

The virus has also been found in a 35-year-old woman from the southern province of Tra Vinh. Suffering from high fever and respiratory difficulties, she was admitted to hospital on Tuesday after eating an infected chicken two weeks ago, another newspaper quoted a doctor as saying.

Doctors in Ho Chi Minh City have been treating a 15-year-old girl, sister of the 18-year-old woman who died of bird flu, as another suspected bird flu case.

They said she was hospitalised after eating infected chicken, despite warnings not to eat poultry that had died of an unknown cause.

Bird flu has killed at least 36 people across Asia and has laid waste to the poultry industry in a number of countries as thousands of birds were slaughtered to prevent further spread of the disease. Malaysia, however has declared itself free of the disease and Thailand has had no new cases since November.

The World Health Organisation has warned Vietnam it may face new bird flu cases this month as poultry is moved around the country ahead of the Lunar New Year celebrations.

The WHO is also worried the virus will mutate in human-to-human contact and cause a global pandemic that could potentially kill millions worldwide.

As of Wednesday, more than 127,000 poultry had been burned by health workers or had died of bird flu in 16 provinces and cities in Vietnam. Last year the epidemic wiped out 17 percent of Vietnam’s poultry stock of 250 million.