title: Risk Factors for Influenza A(H7N9) Disease in China, a Matched Case Control Study, October 2014 to April 2015.
abstract: Background.Human infections with avian influenza A(H7N9) virus have been associated with exposure to poultry and live poultry markets (LPMs). We conducted a case-control study to identify additional and more specific risk factors.Methods.Cases were laboratory-confirmed A(H7N9) infections in persons in China reported from October 1, 2014 to April 30, 2015. Poultry workers, those with insufficient data, and those refusing participation were excluded. We matched up to 4 controls per case by sex, age, and residential community. Using conditional logistic regression, we examined associations between A(H7N9) infection and potential risk factors.Results.Eighty-five cases and 334 controls were enrolled with similar demographic characteristics. Increased risk of A(H7N9) infection was associated with the following: visiting LPMs (adjusted odds ratio [aOR], 6.3; 95% confidence interval [CI], 2.6-15.3), direct contact with live poultry in LPMs (aOR, 4.1; 95% CI, 1.1-15.6), stopping at a live poultry stall when visiting LPMs (aOR, 2.7; 95% CI, 1.1-6.9), raising backyard poultry at home (aOR, 7.7; 95% CI, 2.0-30.5), direct contact with backyard poultry (aOR, 4.9; 95% CI, 1.1-22.1), and having ≥1 chronic disease (aOR, 3.1; 95% CI, 1.5-6.5).Conclusions.Our study identified raising backyard poultry at home as a risk factor for illness with A(H7N9), suggesting the need for enhanced avian influenza surveillance in rural areas.
authors.affiliation: Public Health Emergency Center , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Public Health Emergency Center , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Ruiqi
authors.initials: R
authors.lastname: Ren
authors.affiliation: Fujian Center for Disease Control and Prevention , Fuzhou.
authors.forename: Jianming
authors.initials: J
authors.lastname: Ou
authors.affiliation: Guangdong Center for Disease Control and Prevention , Guangzhou.
authors.forename: Min
authors.initials: M
authors.lastname: Kang
authors.affiliation: Zhejiang Center for Disease Control and Prevention , Hangzhou , China.
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Wang
authors.affiliation: United States Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Fiona
authors.initials: F
authors.lastname: Havers
authors.affiliation: Jiangsu Center for Disease Control and Prevention , Nanjing.
authors.forename: Xiang
authors.initials: X
authors.lastname: Huo
authors.affiliation: Jiangxi Center for Disease Control and Prevention , Nanchang.
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Liu
authors.affiliation: Hunan Center for Disease Control and Prevention , Changsha.
authors.forename: Qianlai
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Shanghai Center for Disease Control and Prevention.
authors.forename: Yongchao
authors.initials: Y
authors.lastname: He
authors.affiliation: Public Health Emergency Center , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.affiliation: Fujian Center for Disease Control and Prevention , Fuzhou.
authors.forename: Shenggen
authors.initials: S
authors.lastname: Wu
authors.affiliation: Public Health Emergency Center , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Yali
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Public Health Emergency Center , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Haitian
authors.initials: H
authors.lastname: Sui
authors.affiliation: Chinese Field Epidemiology Training Program , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Yongjie
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Chinese Field Epidemiology Training Program , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Shaopei
authors.initials: S
authors.lastname: Tang
authors.affiliation: Chinese Field Epidemiology Training Program , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Caiyun
authors.initials: C
authors.lastname: Chang
authors.affiliation: Chinese Field Epidemiology Training Program , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Lunhui
authors.initials: L
authors.lastname: Xiang
authors.affiliation: Public Health Emergency Center , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.affiliation: Public Health Emergency Center , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Shiguang
authors.initials: S
authors.lastname: Zhao
authors.affiliation: United States Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Suizan
authors.initials: S
authors.lastname: Zhou
authors.affiliation: National Influenza Center , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Tao
authors.initials: T
authors.lastname: Chen
authors.affiliation: Public Health Emergency Center , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Nijuan
authors.initials: N
authors.lastname: Xiang
authors.affiliation: United States Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Greene
authors.affiliation: Public Health Emergency Center , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: National Influenza Center , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Yuelong
authors.initials: Y
authors.lastname: Shu
authors.affiliation: Chinese Center for Disease Control and Prevention , Beijing , China.
authors.forename: Zijian
authors.initials: Z
authors.lastname: Feng
authors.affiliation: Public Health Emergency Center , Chinese Center for Disease Control and Prevention , Beijing.
authors.forename: Qun
authors.initials: Q
authors.lastname: Li
keywords: avian influenza A(H7N9); case-control study; risk factor