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

avian influenza | poultry trade | phylogeography | community-structured transmission H 5N1 highly pathogenic avian influenza A virus (HP AIV) was first identified in 1996 (1) . In the following two decades, it has circulated among various bird species and spread to more than 60 countries (2) . Domestic poultry are thought to play an important role in the transmission and spread of H5N1 HP AIV and the virus's ability to occasionally infect humans means it poses a significant public health risk (3, 4) . Human infection with H5N1 HP AIV results in an estimated fatality rate of 50 to 60% (5) , and most cases are linked directly or indirectly to exposure to live poultry (4) . Maintenance of the virus in domestic poultry hosts has enabled further virus evolution and the emergence of novel influenza viruses of avian origin. H5N1 HP AIV emerged in part from the adaptation of low-pathogenicity AIVs from waterfowl to domestic poultry hosts (6) . More recently, two novel reassortant H5 AIV subtypes, H5N6 and H5N8, have emerged in Asia (7, 8) ; the latter subtype subsequently spread to Europe, North America, and Africa, causing outbreaks in local poultry (9) . However, the mechanisms by which these viruses disseminate and cause repeated large-scale waves of infection in domestic poultry remain unclear.