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

• Published in: Emerging infectious diseases 2013-11, Vol.19 (11), p.1784-1790
• Main Authors: Xiang, Nijuan, Havers, Fiona, Chen, Tao, Song, Ying, Tu, Wenxiao, Li, Leilei, Cao, Yang, Liu, Bo, Zhou, Lei, Meng, Ling, Hong, Zhiheng, Wang, Rui, Niu, Yan, Yao, Jianyi, Liao, Kaiju, Jin, Lianmei, Zhang, Yanping, Li, Qun, Widdowson, Marc-Alain, Feng, Zijian
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Animals; Avian influenza; Child; Child, Preschool; China - epidemiology; Development and progression; Disease Outbreaks; Epidemiology; Expedited; Female; Humans; Infant; influenza; Influenza A Virus, H7N9 Subtype; influenza A(H7N9) virus; influenza virus; Influenza, Human - epidemiology; Influenza, Human - transmission; Male; Middle Aged; Pneumonia - epidemiology; Pneumonia - etiology; pneumonia surveillance; Public Health Surveillance; viruses; Young Adult
• ISSN: 1080-6040; 1080-6059
• DOI: 10.3201/eid1911.130865

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