Live poultry feeding and trading network and the transmission of avian influenza A(H5N6) virus in a large city in China, 2014-2015
Authors: Zhang Rusheng , Lei Zhao , Liu Chan , Zhu Yuanzhao , Chen Jingfang , Yao Dong , Ou Xinhua , Ye Wen , Huang Zheng , Luo Li , Sun Biancheng , Chen Tianmu 
Published: October 2020

To understand clearly the mechanism of H5N6 transmission, the role of a live poultry feeding and trading network should be explored deeply. However, there is little data to show the network in an area. In this study, we performed a field epidemiological investigation to collect the numbers of farms, wholesale markets, and live poultry retail markets, and the numbers of purchased (from where) and sold (to where) live birds in Changsha City, China in 2014. We also collected samples from the network in the city from January 2014 to March 2015, including the LPMs visited by the patient known to be infected with A(H5N6) virus, and sequenced the genomes of 10 A(H5N6) viral strains isolated from these environmental samples, to determine the source of virus that infected the patient reported in Changsha. Additionally, we collected and analyzed A(H5N6) virus genome sequence isolated from humans, poultry, and LPMs registered in National Center for Biotechnology Information (NCBI; NIH, Bethesda, MD, USA) 14, to determine the source of other human infections with A(H5N6) virus reported in China. Changsha City in China has a large live poultry feeding and trading network (LPFTN) which had 665 farms, 5 wholesale markets, and 223 live poultry retail markets in 2014. The network covered nine provinces and purchased and sold more than 150000 live birds every day. About 840 environmental samples collected from the LPFTN network from January 2014 to March 2015. About 8.45% (71/840) environmental samples were shown to be positive for N6 and 10 full genome sequences of H5N6 virus were analyzed. We performed phylogenetic analyses and virus characterization, which demonstrated that the H5N6 viral strains isolated from Chinese patients were closely related to those isolated from the poultry and environmental samples obtained from the LPFTN network. This indicates that the network with a large volume of live poultry provides a platform for the transmission of H5N6, and provides an infectious pool which makes the people in high risk.

Importance

Avian influenza A(H5N6) virus is an emerging threat to public health. With several human cases reported in recent years, it has become a dominant avian influenza virus (AIV) subtype in China. Live poultry feeding and trading network (LPFTN) contributes to the presence of novel AIV. By a field epidemiological investigation in the complex LPFTN in Changsha, we demonstrated that the H5N6 viral strains isolated from Chinese patients were closely related to those isolated from the poultry and environmental samples obtained from the network, suggesting the LPFTN with a large volume of live poultry provides a platform for the transmission of H5N6 and creates an infectious pool which makes people in high risk. Considering the wide circulation and dynamic reassortment of this highly pathogenic avian influenza H5N6 virus, it should be carefully monitored in poultry and humans due to the pandemic potential.