Avian influenza virus dynamics in poultry and the environment: an eight-year longitudinal study in the southwestern Poyang Lake region of China

Surveillance of the Avian influenza virus serves as the first line of defense, encompassing monitoring of both animals and environment. These approaches vary across countries due to differences in epidemiology and public health policies. We conducted an eight-year active surveillance program in the Poyang Lake region, a critical wintering site along the East Asian-Australasian Flyway, to investigate the correlation between poultry and environmental samples. From February 2017 to June 2024, 7570 poultry and environmental samples were collected and tested in Nanchang, the largest city in the Poyang Lake region, revealing an overall avian influenza positivity rate of 40.1 %. In 2017, the poultry and environmental positivity rates were 16.9 % and 15.5 %, respectively. By 2024, these rates had risen to 69.4 % and 77.7 %, respectively, with significant and consistent annual increases observed in both environmental and poultry samples. Specifically, in poultry surveillance, chickens (54.2 %) showed higher overall AIV positivity rates compared to ducks (30.6 %), and oropharyngeal swabs (45.5 %) demonstrated greater sensitivity than cloacal swabs (22.3 %). Analysis of environmental samples revealed that, compared with smear samples (39.0 %) and fecal samples (30.9 %), sewage samples (46.5 %) exhibit superior sensitivity. Correlation and wavelet coherence analyses revealed a significant relationship between environmental and poultry samples. In scenarios where poultry sampling is unavailable, environmental surveillance can complement and potentially serve as an alternative to poultry surveillance.