Transmission Risk of Avian Influenza Virus along Poultry Supply Chains in Guangdong, China.

•Increasing circulation of avian influenza viruses along poultry supply chain.•Higher circulation of avian influenza viruses translates to higher human infection risk.•Strengthening control at each level of the poultry supply chain is needed.•One health strategy is crucial to control transmission of avian influenza viruses.