Bird flu has killed a 28-year-old Cambodian man, officials said on Thursday as authorities in neighbouring Vietnam tested dozens of people in a village where a 5-year-old boy was infected with the virus.

Keo Saran is Asia’s 48th bird flu victim and Cambodia’s second after a 25-year-old woman, who lived in the same southern province of Kampot, died in a Vietnamese hospital in late January.

“The bird flu virus killed him,” said Dr. Heng Taykry, the director of the Calmette hospital where the man died on Tuesday.

Keo Saran appeared to have been infected after eating dead chickens, the doctor said. Tests on seven relatives of the dead man have so far proved negative for the virus.

The virus, which produces a high fever, coughing and acute pneumonia, has killed about 70 percent of the people known to have been infected, but it does not pass easily from birds to humans.

But experts fear it will eventually combine with a variety of human flu to become a highly contagious virus capable of killing millions of people worldwide.

In hardest-hit Vietnam, where 34 Vietnamese have died, health inspectors found 37 people with fever in Chau Hoa commune in the central province of Quang Binh, where the 5-year-old boy tested positive for bird flu nearly 2 weeks ago.

“We don’t see anyone in serious condition and nobody shows clinical symptoms that need medical intervention,” said senior provincial health official Truong Dinh Dinh, disputing state media reports that up to 200 people had flu-like symptoms.

He said samples taken from residents, chickens, flies and the water supply would be tested for bird flu.

ON ALERT

Officials have been on alert in the province since the boy tested positive. He is now in stable condition in hospital.

His 13-year-old sister died on March 9 after eating chicken, but doctors did not take tissue samples to test for bird flu.

Dinh said a 16-month-old boy from Chau Hoa was in hospital with suspected bird flu, while five other villagers are under supervision, including the aunt of the 13-year-old girl who died.

The woman had a slight fever after tending to her niece, Dinh said, but she appeared to be getting better.

Authorities are also searching for a 41-year-old man from Chau Hoa who walked out of a hospital on Wednesday where he and other suspected bird flu cases were held for observation.

“The patient is in the group of bird flu suspects so we have informed local authorities to monitor his case,” Bui Duc Phu, deputy director of the Hue Central Hospital told Reuters.

On Wednesday, Hong Kong Health Minister York Chow said he was concerned about the reports from central Vietnam and the city may issue a travel warning if the cases turned out to be bird flu.

The virus made the first known jump from bird to human in Hong Kong in 1997, where it killed six people.

It has shown no signs of waning since late 2003, recurring across large parts of Asia several times and killing 34 Vietnamese, 12 Thais and two Cambodians despite the slaughter of millions of poultry.

However, the World Health Organization says it has seen no evidence so far to suggest the virus is changing into a form that could be transmitted easily from one human to another.