A woman in Hanoi has become the fourth recorded bird flu patient this year, the health ministry's Preventive Health and Environment Department reported on Friday.
The 25-year-old, whose name wasn't revealed, from Soc Son District fell sick last Friday with fever, cough, sore throat, headache and respiratory difficulties.
She was examined at the local Bac Thang Long Hospital, where she was diagnosed as having pneumonia and given antibiotics with antiviral drugs.
When she failed to recover, she was admitted to the Bach Mai Hospital in the capital city five days later in critical condition. She continues to be treated there.
Tests done by the National Institute of Hygiene and Epidemiology later showed she was infected by the influenza A (H5N1) virus. Nguyen Tran Hien, head of the institute, said poultry had been found sick and dead around her house since earlier this month.
It was the first H5N1-positive case to be recorded in Vietnam's capital over the past 14 months, he said.
Since 2003, 115 people have been infected by H5N1 in Vietnam with 58 fatalities. The last death was recorded last month. Last year Vietnam reported five avian flu patients, all of whom died.