title: Use of national pneumonia surveillance to describe influenza A(H7N9) virus epidemiology, China, 2004-2013.
abstract: In mainland China, most avian influenza A(H7N9) cases in the spring of 2013 were reported through the pneumonia of unknown etiology (PUE) surveillance system. To understand the role of possible underreporting and surveillance bias in assessing the epidemiology of subtype H7N9 cases and the effect of live-poultry market closures, we examined all PUE cases reported from 2004 through May 3, 2013. Historically, the PUE system was underused, reporting was inconsistent, and PUE reporting was biased toward A(H7N9)-affected provinces, with sparse data from unaffected provinces; however, we found no evidence that the older ages of persons with A(H7N9) resulted from surveillance bias. The absolute number and the proportion of PUE cases confirmed to be A(H7N9) declined after live-poultry market closures (p<0.001), indicating that market closures might have positively affected outbreak control. In China, PUE surveillance needs to be improved.
authors.forename: Nijuan
authors.initials: N
authors.lastname: Xiang
authors.forename: Fiona
authors.initials: F
authors.lastname: Havers
authors.forename: Tao
authors.initials: T
authors.lastname: Chen
authors.forename: Ying
authors.initials: Y
authors.lastname: Song
authors.forename: Wenxiao
authors.initials: W
authors.lastname: Tu
authors.forename: Leilei
authors.initials: L
authors.lastname: Li
authors.forename: Yang
authors.initials: Y
authors.lastname: Cao
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.forename: Ling
authors.initials: L
authors.lastname: Meng
authors.forename: Zhiheng
authors.initials: Z
authors.lastname: Hong
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Niu
authors.forename: Jianyi
authors.initials: J
authors.lastname: Yao
authors.forename: Kaiju
authors.initials: K
authors.lastname: Liao
authors.forename: Lianmei
authors.initials: L
authors.lastname: Jin
authors.forename: Yanping
authors.initials: Y
authors.lastname: Zhang
authors.forename: Qun
authors.initials: Q
authors.lastname: Li
authors.forename: Marc-Alain
authors.initials: MA
authors.lastname: Widdowson
authors.forename: Zijian
authors.initials: Z
authors.lastname: Feng
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007223:Infant; D064766:Influenza A Virus, H7N9 Subtype; D007251:Influenza, Human / Q000453:epidemiology* / Q000635:transmission; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000453:epidemiology / Q000209:etiology; D062486:Public Health Surveillance; D055815:Young Adult
keywords: China; epidemiology; influenza; influenza A(H7N9) virus; influenza virus; pneumonia surveillance; viruses