RESUMEN
Short-term closing live poultry markets have been frequently adopted to control H7N9 epidemic.To evaluate the effect of short-term closing live poultry markets,we analyzed the data of environment surveillance of H7 by RT-PCR,and the human H7N9 cases in Zhongshan City from Feb 2014 to May 2017.RRx =The positive rate during the x-th week after closing / the positive rate of the week before closing days * 100％.Three rounds of short-term closing live poultry markets were administered.Round one:from Feb 10 to 23,2014,the neighboring cities didn't synchronize.The H7 positive rate increased since the trade recovered,and RR1 =0.40 (95％CI:0.28-0.59),RR3 =0.63 (95％CI:0.32-1.24),RR4 =0.83 (95％CI:0.48 -1.46).Two human cases were reported in May,2014.Round two:from Feb 19 to 28,2015,the neighboring cities synchronized as the province policy.The H7 positive rate maintained a level lower than 10％ since the trade recovered,and RR1 =0.15 (95％CI:0.07-0.34),RR2=0.21 (95％CI:0.10-0.41),RR3 =0.03 (95％CI:0.00-0.18),RR4 =0.10 (95％CI:0.04-0.27).No more human cases reported in that epidemic season.Round three:from Jan 8 to 21,2017,the neighboring cities didn't synchronize with Zhongshan City.The H7 positive rate had increased since the trade recovered,and RR1 =0.25 (95 ％ CI:0.09-0.68),RR3 =0.37 (95％CI:0.14-1.00),RR4 =1.07 (95％CI:0.54-2.11).Two human cases were reported in Feb,2017.Results indicated that,if the policy of closing live poultry markets was administered in single city,the environment pollution rate would rise shortly and the risk of human infection would increase once the trade recovered.However,if it was synchronously administered in all the cities in one region,the environment pollution rate could maintain at a low level and the risk of human infection would reduce enormously.