title: [Epidemiological characteristics of human avian influenza A (H7N9) virus infection in China].
abstract: OBJECTIVE
  To investigate the epidemiological characteristics of human infections with avian influenza A (H7N9) in China and to provide scientific evidence for the adjustment of preventive strategy and control measures.
  
  
  METHODS
  Demographic and epidemiologic information on human cases were collected from both reported data of field epidemiological investigation and the reporting system for infectious diseases.
  
  
  RESULTS
  A total of 433 cases including 163 deaths were reported in mainland China before June 4, 2014. Two obvious epidemic peaks were noticed, in March to April, 2013 and January to February, 2014. Confirmed cases emerged in 14 areas of China. Five provinces, including Zhejiang, Guangdong, Jiangsu, Shanghai, and Hunan, reported about 85% of the total cases. Median age of the confirmed cases was 58 years (range, 1-91), with 70% as males. Of the 418 cases with available data, 87% had ever exposed to live poultry or contaminated environments. 14 clusters were identified but human to human transmission could not be ruled out in 9 clusters.
  
  
  CONCLUSIONS
  Human infections with avian influenza A (H7N9) virus showed the characteristics of obvious seasonal distribution, with certain regional clusters. The majority of confirmed cases were among the elderly, with more males seen than the females. Data showed that main source of infection was live poultry and the live poultry market had played a significant role in the transmission of the virus.
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Ruiqi
authors.initials: R
authors.lastname: Ren
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Nijuan
authors.initials: N
authors.lastname: Xiang
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Public Health Emergency, Jinan City CDC.
authors.forename: Xingyi
authors.initials: X
authors.lastname: Geng
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Yali
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Institute of Prevention and Control for Communicable Disease, Tianjin CDC.
authors.forename: Chao
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Prevention and Control for Communicable Disease, Liu'an City CDC.
authors.forename: Yong
authors.initials: Y
authors.lastname: Lyu
authors.affiliation: Public Health Emergency Center of Jiangxi Provincial CDC.
authors.forename: Fuqiang
authors.initials: F
authors.lastname: Yang
authors.affiliation: Public Health Emergency Center of Xuancheng City CDC.
authors.forename: Ming
authors.initials: M
authors.lastname: Yang
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Haitian
authors.initials: H
authors.lastname: Sui
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Huang
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Meng
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Zhiheng
authors.initials: Z
authors.lastname: Hong
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Wenxiao
authors.initials: W
authors.lastname: Tu
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Leilei
authors.initials: L
authors.lastname: Li
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Ding
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Jianyi
authors.initials: J
authors.lastname: Yao
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Lianmei
authors.initials: L
authors.lastname: Jin
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Daxin
authors.initials: D
authors.lastname: Ni
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Qun
authors.initials: Q
authors.lastname: Li
authors.affiliation: Public Health Emergency Center of Chinese Center for Disease Control and Prevention (CDC), Beijing 102206, China.
authors.forename: Zijian
authors.initials: Z
authors.lastname: Feng
mesh_terms: D000223:Adaptation, Psychological; D000368:Aged; D000818:Animals; D002681:China / Q000453:epidemiology; D003710:Demography; D004787:Environmental Pollution; D005260:Female; D006801:Humans; D064766:Influenza A Virus, H7N9 Subtype; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission; D008297:Male; D008460:Meat; D011200:Poultry; D012107:Research Design