Background
Avian influenza virus (AIV) H9N2 have a major role in the emergence of influenza pandemic. We assessed the risk of AIV H9N2 to the human population and public health.

Methods
The hemagglutination inhibition method was used to screen for hemagglutinin antibodies. Microneutralization tests were performed to confirm neutralizing antibodies against the AIV H9N2 subtype. Real-time PCR was conducted to detect the H9 subtype in environmental samples. GraphPad Prism software was used for mapping, and STATA software was used for statistical analysis.

Findings
The nationwide seroprevalence among these populations was 0.76%. Seroprevalence was compared across regions, genders, and occupational exposure sites. The seroprevalence rates for males and females showed no significant difference. Significant differences were found across regions and occupational exposure environments (p < 0.05). The south and southwest regions had the highest seroprevalence rates at 1.58%, 1.38%. The highest seroprevalence was observed in individuals exposed to live poultry market (1.51%). Significant regional differences in H9 nucleic acid positive rates (NAPR) were found (p < 0.05), with the southwest and central regions showing the highest rates at 25.99% and 24.35%. H9 NAPR in live poultry markets (LPMs), farms, and slaughterhouses varied significantly by region (p < 0.05).

Interpretations
Poultry-related environments have become a key factor in AIV H9N2 infection among occupational populations. Exposure to LPM showed the highest seroprevalence among occupational groups. The distribution characteristics of H9N2 across different poultry environments increased the risk of infection in occupationally exposed populations.