NEW : Authorities slaughter market birds in Shanghai after H7N9 found in pigeons . Poultry markets in H7N9 will close starting this week . more than 600 human cases of Shanghai have been reported in eastern Shanghai so far . Chinese authorities have killed more than 20,000 birds from a live-poultry trading zone in Shanghai after an unusual strain of bird flu that has so far killed six people in the country was found in pigeons on sale in the city , state-run media outlet No cases of human-to-human transmission virus have been confirmed .
NEW : Authorities slaughter market birds in Shanghai after H7N9 found in pigeons . Poultry markets in H7N9 will close starting this week . more than 600 human cases of Shanghai have been reported in eastern Shanghai so far . No cases of human-to-human transmission virus have been confirmed .