Health officials confirmed the 22nd case of H5N1 human avian influenza this year in Cambodia on Friday – a 6-year-old girl from Battambang province’s Phnom Proek district.

The number of H5N1 cases this year is already the highest ever in Cambodia, where a total of 43 people have been reported infected.

The girl was diagnosed last month and remains in stable condition after being a administered Tamiflu – only used in severe cases – on October 24, a joint statement from the Ministry of Health and the World Health Organization said.

The Health Ministry and the Ministry of Agriculture, Forestry and Fishery’s animal health task force has deployed a rapid response team to investigate any “epidemiological linkages among the 22 cases and initiate preventive treatment as required”, the statement said.

Initial findings reveal chickens and ducks recently died in neighbouring houses and villages close to the girl’s own, but officials are yet to confirm whether she was directly in contact with sick or dead poultry.

Only three recorded cases of H5N1 – all fatal – were confirmed in 2012, WHO found.

The increasing mobility of Cambodians presents one explanation for the doubling in total cases this year, said Sonny Krishnan, spokesman for the WHO Cambodia office.

“[But] what is particularly concerning right now is that we’re seeing chickens dying in large numbers in villages,” he said yesterday.

“Normally, ducks can carry the virus for a long period of time but appear asymptomatic, so this is really not a good sign.”

Previous trends point to an increase of cases in Cambodia between November and February, Krishnan added.

The Health Ministry and WHO statement focuses on ways in which people can help prevent the spread of the virus. “The government’s message is – wash hands often with soap and water, before eating and after coming into contact with poultry; keep children away from poultry; keep children away from poultry; keep poultry away from living areas; do not eat dead or sick poultry; and all poultry eaten should be well cooked,” the statement says.