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

Based on online information concerning the live bird trade, we propose three transmission networks (Figures 4B, 4C, and 4D ). Because the topological map has no direction, we propose a direction of transmission based on the time order, that is, when the city was infected. Figure 4B suggests that Beijing was most likely infected by live birds that carry the virus from Chuzhou (Anhui Province) or Yancheng (Jiangsu Province). Epidemiological data support the hypothesis that the two cities were infected on March 9 and April 8, respectively, and both were infected earlier than Beijing (April 11) ( Figure 4B ). Figure 4C shows that Chuzhou was possibly infected by live birds that carry the virus from Hangzhou (Zhejiang Province) or Shanghai. Epidemiological data also show that Chuzhou was infected later than Hangzhou and Shanghai. The genome sequences of the virus strain isolated from patients in Chuzhou were highly homologous to those isolated from a patient and a chicken from Hangzhou, as well as to one of two isolates from patients in Shanghai. 1,2 Figure 4D shows that Nanchang City (Jiangxi Province) and Fuzhou City (Fujian Province) were most likely infected by the virus from live birds traded from Shanghai. Both cities were infected later than Shanghai.