[Analysis on avian influenza virus contamination in poultry related environment in Shaanxi Province, 2020-2024]

Objective: To analyze the contamination of avian influenza virus (AIV) in poultry related environment in Shaanxi Province, and provide reference for the improvement of local avian influenza prevention and control. Methods: The relevant environments in 10 prefecture-level cities in Shaanxi from 2020 to 2024 (including urban and rural live poultry markets, large-scale poultry breeding farms, areas with small-scale poultry breeding houses, and slaughter houses and processing plants, etc.), were selected as surveillance points. External environmental samples such as poultry manure, surface swabs of poultry cages, poultry drinking water, and swabs of chopping boards were collected monthly. The subtypes of AIV were detected by real-time fluorescence quantitative RT-PCR, and finally descriptive analysis was conducted according to the surveillance time, area, site and sample type. Statistical analysis was performed by using software SPSS 25.0. Results: The annual average positive rate of AIV in poultry related environments was 3.54% (466/13 152) in Shaanxi from 2020 to 2024. Exhibiting two distinct positive rate peaks, with slight variation with years. AIV was mainly detected in the Loess Plateau area in northern Shaanxi (8.10%, 221/2 728) and the Qinba Mountain area in southern Shaanxi (3.34%, 121/3 622). The surveillance sites with relatively high positive rates included urban and rural live poultry markets (7.50%, 219/2 920) and poultry slaughtering and processing houses (7.19%, 32/445). The sample types with relatively high positive rates included swabs of chopping boards (10.95%, 81/740) and poultry cleaning wastewater (7.39%, 37/501), the differences were significant (P<0.001). In the positive samples, H9N2 virus was detected in all years, indicating that it was the most common subtype (81.76%, 381/466). Conclusions: From 2020 to 2024, the contamination of H9N2 AIV existed widely in poultry related environments in Shaanxi. The urban and rural live poultry markets and poultry slaughtering and processing houses in the Loess Plateau area in northern Shaanxi and the southern Qinba Mountain area in southern Shaanxi were the key places for the prevention and control avian influenza. It is necessary to strengthen the surveillance for the contamination of AIV in the poultry related environments. In the areas with high incidences, active and effective intervention measures should be taken in the places at high risk to reduce the risk of avian influenza outbreaks in humans and poultry.