A 26-year-old Vietnamese male nurse who tended a patient with bird flu has caught the virus that has killed 47 people in Asia, a health official said on Monday.

It was not yet clear if the nurse caught the H5N1 bird flu virus from the patient or by other means, said Tran Khac Vien, head of a district health care centre in the northern province of Thai Binh, 110 km (70 miles) southeast of Hanoi.

“He looked after and had contact with a H5N1 patient,” Vien told Reuters.

“We have been informed that he was infected by bird flu but there might be other reasons that could cause the infection. We have not made any conclusion yet.”

Vien said the nurse was in a Hanoi hospital with a high fever, a symptom of the H5N1 strain that infected his patient, a 21-year-old man from Thai Binh who caught the virus last month after drinking raw duck blood, a local delicacy.

The nurse had provided bed care to the man, whose 14-year-old sister was also infected after coming into contact with sick poultry.

The Thai Binh siblings have raised public concerns about the possibility of human-to-human transmission of the virus that first erupted in Asia in late 2003, believed to have been brought by migrating birds.

Health Minister Tran Thi Trung Chien said last week, prior to the nurse’s case, that all bird flu cases in Thai Binh were related to slaughtering or eating poultry. There was no evidence of human-to-human transmission of the virus, which has killed 13 Vietnamese since the latest outbreaks in December 2004.