A woman in China has died of the H10N8 strain of bird flu, the first ever reported human case of the virus, the World Health Organization said on Wednesday.

The 73-year-old woman died from the virus on Dec. 6, six days after contracting the disease, the WHO said in a statement.

The person who contracted bird flu visited a live bird market four days before becoming ill, but the specific source of the infection is not known, the WHO said. (Associated Press)

The virus has been detected in birds since 1965 in at least seven countries including China, the WHO said.

The specific source of the woman's infection was not known, the WHO said, although both wild birds and poultry were known to carry the virus and the patient had visited a live bird market four days before becoming ill.

The woman who died in Nanchang, the capital of landlocked southeastern province of Jiangxi, had an underlying medical condition, according to the WHO. Family members and other people she contacted had no symptoms and no other similar cases were detected in the area, it said.

There is currently no evidence of human-to-human transmission of the new H10N8 virus, say the authorities.

China is at the beginning of its traditional flu season, and has long had a problem with bird flu.

The H7N9 strain of bird flu emerged this year in China and has infected at least 139 people in China, Taiwan and Hong Kong, killing 45 of them.

Experts say there is no evidence of any easy or sustained human-to-human transmission of H7N9.

But a scientific analysis of probable transmission of the H7N9 virus from person to person, published in August, gave the strongest indication yet that it can at times jump between people and so could potentially cause a human pandemic.

Chinese authorities were investigating the case of H10N8 and had stepped up surveillance measures to detect and control infections, said the WHO.