Trends and age-period-cohort effect on incidence of brucellosis from 2006 to 2020 in China.

Brucellosis remains a major public health challenge in China and globally. This study analyzed long-term trends in brucellosis incidence in China from 2006 to 2020, assessed the effects of age, period, and birth cohort, and projected future incidence up to 2030. Data on brucellosis were obtained from the Data-center of China Public Health Science, and temporal trends in incidence rates were analyzed using joinpoint regression, while an age-period-cohort model evaluated the effects of age, period, and cohort. A Bayesian age-period-cohort model was applied for future projections. From 2006 to 2020, 586,371 brucellosis cases were reported, with an upward trend in age-standardized incidence rates for both males and females, showing average annual percent changes of 3.37 % and 4.61 %, respectively. The age-period-cohort model revealed that age, period, and cohort all influenced incidence, with males facing higher rates. High-risk groups were identified among those aged 50-84, particularly in the 65-69 age range, where incidence was highest and showed the most significant annual increase. Period risk initially rose then declined, while later-born cohorts had higher risks. Projections indicate a continued rise in brucellosis incidence. Targeted prevention and control measures are recommended, especially for older adults and males.