A 58-year-old Vietnamese man has been infected with the H5N1 bird flu virus, state media reported on Tuesday, the country’s second human case in a month.

The man, from the northern province of Thanh Hoa, was hospitalised in Hanoi last Friday and tests confirmed he has the virus, which has killed 52 people in Asia since 2003, the Vietnam News quoted a doctor as saying.

Doctors at the same hospital are treating a 52-year-old man from the northern province of Vinh Phuc who has been confirmed infected by bird flu after being admitted last Thursday.

Both men were in stable condition, the doctor said.

Vietnam’s last human H5N1 case was in early April, and no new outbreaks among poultry have been reported for nearly a month.

The virus has killed 36 people in Vietnam, 12 in Thailand and four in Cambodia since the disease swept across much of the region starting in late 2003.

It has proved difficult to eradicate despite the slaughter of tens of millions of poultry. Animal health experts say H5N1 is endemic in the region and will take years to stamp out.

The World Health Organization fears the virus could mutate into a form that can pass easily among humans and trigger a global pandemic that could kill millions.