Active surveillance of avian influenza in the southwestern Poyang Lake area, China: Analyzing changes in wholesale and frozen fresh retail markets post-policy implementation.

This study aims to conduct active surveillance of avian influenza in the southwestern Poyang Lake area of China and to analyze the changes in avian influenza prevalence in wholesale poultry markets and frozen fresh retail markets following the implementation of policies regulating frozen fresh poultry products. The type A avian influenza virus nucleic acids were detected using real-time reverse transcription polymerase chain reaction (real-time RT-PCR), and a triplex real-time RT-PCR assay kit specific for H5/H7/H9 RNA was utilized on the influenza A-positive samples to differentiate among the avian influenza virus subtypes. From October 2020 to June 2024, the positivity rate of the live poultry wholesale market was 59.2 %. The positivity rate of frozen fresh retail markets was 45.4 %. In August 2023, the H9 subtype had the highest positivity rate in both markets. However, after that, the rate of untyped positives began to rise, particularly in the live poultry wholesale market where the positivity rate of the H5 subtype also showed an increasing trend. Implementing a frozen fresh poultry products policy has effectively reduced the avian influenza positivity rate in frozen fresh retail markets over the first two years. However, the positivity rate showed a rebound trend in the last two years. The live poultry wholesale market may be the source of the spread of avian influenza in frozen fresh retail markets, so managing the live poultry wholesale market and surveillance avian influenza should be strengthened. Recent surveillance indicates a significant uptick in the positivity rates of the H5 subtype and untyped strains of avian influenza, underscoring the importance of continued vigilance and strengthened prevention and control measures.