Surveillance for avian influenza virus in poultry related environment in Changzhou, Jiangsu, 2016−2022

Objective To understand the distribution of avian influenza virus in poultry related environment in Changzhou, Jiangsu province, from 2016 to 2022, and provide scientific evidence for the prevention and control of human infection with avian influenza viruses.

Methods Quantitative real-time polymerase chain reaction was used to detect the nucleic acid of avian influenza virus, and the detection results were statistically analyzed by descriptive statistics.

Results A total of 3142 poultry related environment samples were collected from 2016 to 2022 in Changzhou, in which 493 were positive for avian influenza A virus (15.69%). The main subtype of avian influenza virus was H9 (82.76%). The proportion of avian influenza virus positive samples was higher in winter and spring. The positive rate of subtype H7 and others peaked in winter in 2016, which was positively correlated with the number of confirmed infection cases of H7 subtype avian influenza virus (Spearman, r=0.832, P=0.020). The positive rate was highest in Xinbei (26.32%) and lowest in Liyang (8.09%). There were significant differences in positive rate among different surveillance sites (χ²=123.587, P＜0.001) and environment samples (χ²=56.830, P＜0.001). Among the five kinds of surveillance sites, the positive rate was highest (20.07%) in urban and rural live poultry markets, and lowest in wild poultry habitats with no positive sample detected. In the six kinds of samples, the positive rate was highest in the surface swabs of chopping board (21.29%), and lowest in throat/anal swabs or stool samples (10.37%).

Conclusion The main subtype of avian influenza virus was H9 in poultry related environment in Changzhou during 2016−2022. It is necessary to strengthen the surveillance in urban and rural live poultry markets as key places for the prevention and control of avian influenza virus infection, especially in winter and spring.