A 10-year-old boy from southern Kampot province has been confirmed positive for the H5N1 virus, bringing the number of the cases to 24 so far this year, the World Health Organization and the Cambodian Health Ministry said in a joint statement Friday.

The boy was confirmed positive for human H5N1 avian influenza on Thursday after he was admitted to the Kantha Bopha Hospital in Phnom Penh with fever, cough, sore throat, a distended abdomen and dyspnea.

"The boy has been treated with Tamiflu. Currently, his condition is critical," the statement said.

"Investigations in his village found that a month before the 10- year-old boy's illness, about 30 chickens had died suddenly in the village, and the boy helped carry dead chickens for his brother who was preparing a meal from them," it said.

Only 12 out of the 24 cases this year survived.

Health Minister Mam Bunheng said bird flu remains a serious threat to the health of all Cambodians and children seem to be most vulnerable and are at high risk.

"Once again, I'd like to appeal to parents and guardians to keep children away from sick or dead poultry and make sure children wash their hands with soap and water after any contact with poultry," he said.

H5N1 influenza is a flu that usually spreads between sick poultry, but it can sometimes spread from poultry to humans, according to the World Health Organization.

Cambodia sees the worst outbreak of the virus this year since it was first identified in 2004. To date, the country has reported 45 human cases of the virus, killing 31 people.