Silent geographical spread of the H7N9 virus by online knowledge analysis of the live bird trade with a distributed focused crawler

Chen, Chen; Lu, Shan; Du, Pengcheng; Wang, Haiyin; Yu, Weiwen; Song, Huawen; Xu, Jianguo

The transmission networks based on live bird trade information are also shown in this study. The major links between infected cities were taken from the relationship map of cities ( Figure 4A ). Figure 4A shows that 8 of the 11 first-wave cities had the most frequent links to the live bird trade, indicating that these cities, namely, Shanghai, Hangzhou, Chuzhou, Yangzhou, Nanjing, Huzhou, Zhenjiang, and Wuxi, had more important functions than the others. Among them, five firstwave cities, namely, Shanghai, Hangzhou, Yangzhou, Nanjing, and Huzhou could have important functions in spreading the second wave of infection ( Figure 4A ). One link was found for Suqian City in Jiangsu Province. Thus, the geographic spread of H7N9 virus in China was likely driven by live birds traded from the first-wave cities.