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

We used the context-based connection (CC) and information-based connection (IC) to evaluate the activity of live poultry trade at two levels, provincial and city, respectively. CC data are connections directly observed from web knowledge collected by a crowd-powered extension system in our center. The key words and 367 city names were distributed in the discussion forum. The searchers were required to obtain all traces with the city name and live poultry trade or its synonyms. The search results were returned, collected, and combined. All queries were required to provide the source websites or internet protocol address (IP address) when they supplied connection information between cities. This information was individually validated to ensure accuracy. Our script-on-text comparison removed repeated queries and filtered ambiguous web sites. The co-occurrence of city names in one page was estimated to have trading links by comparing scripts in automatic manuscripts. All the connections between these cities were double-checked manually. A total of 315 queries and 591 CCs associated with 211 cities were included in our study.