Cities across China have undertaken mass bird culls and suspended the trade in live poultry to minimize human contact with birds, as the number of cases of the H7N9 strain of bird flu rises daily.

Shanghai, the city in which the first cases were discovered on March 31 and which has seen 31 confirmed cases and 11 deaths, has instigated the largest H7N9-related cull so far on the Chinese mainland.

By Monday, more than 110,000 birds - including chickens, quail, pigeon, ducks and geese - had been slaughtered in the city. Meanwhile, three wholesale centers and 461 live poultry sales outlets were closed, and the trade in live poultry and wild birds has been suspended since April 6.