Epidemiological characteristics of human brucellosis in Yunnan, 2022

Objective To understand the epidemiological characteristics and incidence trend of human brucellosis in Yunnan province in 2022 and provide evidence for the improvement of prevention and control measures against the disease.

Methods The incidence data of human brucellosis in Yunnan in 2022 were extracted from China Information System for Disease Control and Prevention for a descriptive epidemiological analysis on the epidemiological characteristics of the human brucellosis cases.

Results In 2022, a total of 1 039 confirmed and clinically diagnosed cases of human brucellosis were reported in Yunnan, with an incidence rate of 2.22/100 000. The cases were reported all the year round, with the majority occurring between March and November. The disease was reported in 13 prefectures, with high case numbers and incidence rates being reported in Qujing, Kunming, and Honghe. Approximately 81.62% of the cases (848/1 039) were aged 30–69 years, with a mean age of 48 years. The male-to-female ratio of the cases was 2.15∶1. The cases in farmers accounted for 84.02% (873/1039) of the reported cases. In the screening of 4 538 individuals at high risk, 206 serum samples were tested positive (4.54%). The differences in brucellosis sero-prevalence among key populations across counties were significant( χ²=1630.91, P＜0.05). A total of 132 Brucella strains were isolated from clinical blood samples, including 125 strains of B. melitensis biovar 3 and 7 strains of B. melitensis biovar 1.

Conclusion In 2022, the cases and the incidence rate of human brucellosis in Yunnan province showed continuous upward trends. Most cases were middle-aged and elderly male farmers in Qujing, Kunming, Honghe, and other areas, the incidence was higher during summer-autumn. B. melitensis was identified as the predominant pathogen. It is suggested to conduct targeted health education and behavioral interventions in periods and areas with high incidence of human brucellosis to improve self-protection in residents and reduce the transmission risk of human brucellosis.