A 35-year-old man died of bird flu in Cambodia Tuesday, a record eighth human fatality in one year in the country, authorities said.
Sok Touch, director of the communicable disease control department at the Ministry of Health, said he was concerned at the rising number of cases but noted that they did not seem to be connected.
"We don't have any link between these cases," he said.
"This year is unusual. We need to prevent the spread of the disease and stress to people the importance of hygiene and other measures."
All human cases of H5N1 have been infected by contact with poultry, but health professionals fear the virus could combine with another or mutate and gain the ability to pass between people.
Cambodian authorities have culled thousands of ducks and chickens in several provinces this year.
Sonny Inbaraj Krishnan, a spokesman for the World Health Organization, said health workers had enhanced surveillance for bird flu in all provinces where the disease had been detected.
The WHO said in mid-February that China and Egypt were the only other countries to have reported human cases of bird flu this year, with a total of three infections and one death between them.
Bird flu has killed 370 people around the world out of 622 infected since 2003.