Use of national pneumonia surveillance to describe influenza A(H7N9) virus epidemiology, China, 2004-2013

Nijuan Xiang, Fiona Havers, Tao Chen, Ying Song, Wenxiao Tu, Leilei Li, Yang Cao, Bo Liu, Lei Zhou, Ling Meng, Zhiheng Hong, Rui Wang, Yan Niu, Jianyi Yao, Kaiju Liao, Lianmei Jin, Yanping Zhang, Qun Li, Marc-Alain Widdowson, Zijian Feng

Research output: Contribution to journalA1: Web of Science-articlepeer-review


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.

Original languageEnglish
JournalEmerging Infectious Diseases
Issue number11
Pages (from-to)1784-1790
Number of pages7
Publication statusPublished - 2013


  • Adolescent
  • Adult
  • Aged
  • Animals
  • Child
  • Child, Preschool
  • China/epidemiology
  • Disease Outbreaks
  • Female
  • Humans
  • Infant
  • Influenza A Virus, H7N9 Subtype
  • Influenza, Human/epidemiology
  • Male
  • Middle Aged
  • Pneumonia/epidemiology
  • Public Health Surveillance
  • Young Adult


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