The role of live poultry movement and live bird market biosecurity in the epidemiology of influenza A (H7N9): A cross-sectional observational study in four eastern China provinces

Xiaoyan Zhou, Yin Li, Youming Wang, John Edwards, Fusheng Guo, Archie C.A. Clements, Baoxu Huang, Ricardo J. Soares Magalhaes

A new reassortant influenza A (H7N9) virus emerged early 2013 in eastern China. Exposure to H7N9 infected poultry at live bird markets (LBM) was implicated as the main risk factor for human infection. We aimed to identify the role of LBM biosecurity indicators and poultry movement in the affected areas. A cross-sectional survey was carried out in 24 LBMs at the beginning of H7N9 outbreak in all affected provinces. We used univariable analysis to identify the biosecurity factors associated with the H7N9 presence in LBMs and social network and spatial analysis to quantify the connectivity and geographic variation in the connectivity of poultry movements. Chicken were the predominant poultry species traded by affected LBMs. The presence of H7N9 in LBMs was significantly associated with the type of LBM and with LBMs that sold chicken to other markets. The chicken movements were significantly spatially clustered and was highest in counties from Jiangsu and Anhui provinces. LBM biosecurity and chicken movement played an important role in the emergence of H7N9. This study identified highly connected areas in eastern China which continue to report human infections highlighting candidate areas for more detailed epidemiological investigations.