Figure 4.

Proposed transmission networks of the H7N9 virus based on live bird trade information. Cities in different infection waves are represented by red, yellow, and grey nodes. Cities where the virus was detected in birds are labeled by a blue star. (A) Topological connection structure of infected cities based on live bird trade information. Trading among first-wave cities is indicated by the yellow line. The other cities with trade information to the cities in these networks are complemented beside the cities, and connected by the gray line. The day when the city was infected was marked as day/month below the name of the city. (B) Proposed transmission network for Beijing. (C) Proposed transmission network for Chuzhou, Anhui Province. (D) Proposed transmission network for Fuzhou City, Fujian Province.