Assessing the role of live poultry trade in community-structured transmission of avian influenza in China

Yang, Qiqi; Zhao, Xiang; Lemey, Philippe; Suchard, Marc A.; Bi, Yuhai; Shi, Weifeng; Liu, Di; Qi, Wenbao; Zhang, Guogang; Stenseth, Nils Chr.; Pybus, Oliver G.; Tian, Huaiyu

The emergence and transmission of avian influenza viruses (AIVs) pose a threat to public health and result in enormous economic losses. Here we discover an association between the community structure of the poultry trade network and AIV transmission in China by combining virus genomes and statistical modeling of the poultry trade. Importantly, we are able to "replicate" this finding by comparing the dynamics of three strains of AIV (H5N1, H7N9, and H5N6) that currently cocirculate in poultry in China. Given the detection of a continuous process of AIV geographic spread among poultry, our results indicate that at the national scale there are repeatable and potentially predictable patterns that can be used to shape future strategies for AIV control and prevention. diffusion of AIVs in endemic areas (16) . However, it can be difficult to infer underlying transmission processes from such data due to the uneven sampling of virus genomes through time and space, and a reliance on passive surveillance means that many virus lineages may go unsampled. The paucity of data on the poultry trade and variable virus genome sampling therefore combine to hinder our understanding of the factors that facilitate the dissemination of H5N1 and other AIV subtypes over large geographic scales, especially in countries with high volumes of poultry production and trade sectors that are not strongly regulated (17) .