Temporal changes in prevalence and viral load of avian influenza virus at live poultry markets in Guangzhou, Guangdong, China, 2015-2018
Kit Ling Cheng1, Eric HY Lau1, Wen Su1, Wei Ling Shen2, Zhi Feng Zhong2, Xun Ming Ji2, Jie Zhou1, Malik Peiris1, Jie Wu2, Hui-Ling Yen1
1School of Public Health, LKS Faculty of Medicine, The University of Hong Kong; 2Guangdong Provincial Center for Disease Control and Prevention
Annual epidemics of human infections with avian influenza virus (AIV) such as H5N1 and H7N9 particularly arise in winters through exposing to infected poultries at live poultry markets (LPMs). It is not clear if the increased human infection risk correlates with the prevalence or viral load of zoonotic avian influenza viruses at live poultry markets. We performed a 28-month longitudinal study to monitor avian influenza virus prevalence and viral load at retail and wholesale LMPs in Guangzhou. From Dec. 2015-Mar. 2018, chicken oropharyngeal and cloacal swabs, environmental swabs and air samples were collected twice per month at one wholesale and one retail market. Viral RNA was extracted to detect influenza A virus M gene and the H5, H7, and H9 hemagglutinin genes by qRT-PCR. The epidemic curves of H5N1 human infections correlated with the H5 positive rate detected from the poultry and environmental swabs at both the wholesale and the retail markets by Spearman rank correlation test. In contrast, human H7N9 infection risk was only associated with H7 positive rate detected in the environmental swabs from the retail market. The H5, H7, and H9 viruses exhibited different temporal patterns. Overall, our result support that human infection risk is associated with H5 and H7 detection rate at the live poultry markets.