Eleven people who had direct contact with chicken infected with H5N2 avian influenza virus are in quarantine on Monday in north China's Hebei Province, according to local government.

So far none have shown any symptoms nor been confirmed as infected with the virus, said the Nanshi district government of Baoding City in Hebei.

On Sunday, areas within 3 km of a poultry farm where an H5N2 outbreak occurred last week were sealed off.

On Dec 17, 4,000 chickens at the farm were killed after they showed symptoms avian flu, according to the Ministry of Agriculture. The National Avian Influenza Reference Laboratory on Saturday confirmed the epidemic was H5N2 after testing samples collected at the farm.

Local authorities have sealed off and sterilized the infected area, and a total of 125,700 chickens have now been culled and safely disposed of.

The 11 isolated people, including the farm owner and his wife, remain quarantined on the farm. Their daily necessities are delivered to them by epidemic prevention workers, said Zhang Wenguang, head of the district agriculture bureau. He said their body temperature and other indicators are monitored on a daily basis.

Disinfection checkpoints have been set up on all access routes to the farm.

Bird flu, or avian influenza, is a contagious disease of animal origin caused by viruses that normally only infect birds and, less commonly, pigs. It can be fatal to humans.

From Dec 15 to 19, four new human cases of H7N9 bird flu were confirmed in south China's Guangdong Province.

East China's Jiangxi Province also confirmed a human case of H10N8, a new strain of bird flu, last Wednesday.