A non-autonomous dynamic model-based study on influencing factors of seasonal brucellosis transmission and control strategies in Zhejiang Province, P. R. China

Brucellosis incidence in China has risen steadily, posing severe prevention and control challenges. Given the national “north decline, south rise” epidemiological pattern, southern epidemic dynamics are increasingly critical and require in-depth study. Focusing on Zhejiang Province, this study constructed a non-autonomous periodic dynamic model of the environment–sheep–mutton–human transmission chain, aiming to clarify regional brucellosis periodic epidemic patterns, identify core risk factors and optimize control strategies. Theoretically, we explored the model’s global dynamical behaviors (disease extinction, uniform persistence, disease-free periodic solution and endemic periodic solution) and defined the effective reproduction number as a quantitative metric. Integrating 2020–2025 multi-source quarterly data, including human brucellosis cases, livestock industry statistics and meteorological data in Zhejiang, numerical analysis revealed significant periodicity in local brucellosis. Sheep increment is the core risk factor, with susceptible-infectious sheep/contaminated mutton contact as secondary drivers. Surveillance gaps in breeding, consumption and disinfection links may trigger large-scale epidemics. Lag correlation analysis confirmed statistically significant correlations between human brucellosis cases and the following variables: lag 0 (sheep slaughter, temperature, self-produced mutton, permanent population); lag −1 (sheep increment, infected mutton); lag 1 (environmental pathogen load, sheep cases). This study demonstrates that strengthening routine testing throughout the entire circulation chain of sheep and mutton, enhancing disinfection measures and improving public protection awareness are crucial for reducing the regional incidence of brucellosis. The research provides theoretical support and practical basis for brucellosis prevention and control in southern China.