Experts warn of more risks

Live poultry market bans by governments are effective in controlling the mass spread of the virus by blocking the primary source of H7N9 virus infection as well as close contact between poultry and humans, said Li Lanjuan of the Chinese Academy of Engineering.

Li, China's leading researcher on bird flu and a member of the H7N9 prevention and control group, called for more thorough measures to block the infection source.

The Hangzhou government also banned the flying of carrier pigeons and all other bird-related activities in scenic spots and zoos, said a circular on Thursday.

"These prevention measures are helpful to control the epidemic transmission by limiting close contact between poultry and humans, " said Li.

Li's team recently identified a new partial variation in the virus, demonstrating its capacity to adapt to its environment.

"It has increased the risk of human-to-human transmission and made treatment harder," said Dr Liang Weifeng of the medical college at Zhejiang University and a member of the team.

Experts also warned of rising infection risks during the upcoming festival family reunion, as Chinese traditionally prepare and eat poultry products as main dishes.

They suggested citizens choose slaughtered poultry products for their upcoming festival feasts, and warned farmers to stop free ranging of poultry to reduce infection risks.