Epidemiology of Brucellosis Among Deer in China From 1978 to 2025: A Systematic Review and Meta-Analysis.

Brucellosis is a major zoonosis affecting livestock production and public health. With the rapid expansion of sika and red deer farming in China, reports of deer brucellosis have increased. We searched CNKI, Wanfang Data, VIP, PubMed, and ScienceDirect and conducted a systematic review and meta-analysis, including 47 studies published from January 1978 to September 2025 (54,699 samples). The pooled seroprevalence was 16.3% (95% CI: 10.9-22.4), with substantial heterogeneity. Subgroup analyses suggested an overall increase after 2000 and higher estimates in major deer-farming areas of northern China. Seroprevalence tended to be higher in red deer than in sika deer, in adults than in subadults and juveniles, and in females than in males, and was also higher during summer and autumn. Method-stratified subgroup meta-regression did not detect statistically significant differences across diagnostic methods (p > 0.05); method-based comparisons should be interpreted cautiously. In light of these findings, our study suggests strengthening deer surveillance systems, further standardizing diagnostic and reporting procedures, and implementing targeted control measures tailored to regional risk levels to reduce economic losses for farmers and lower infection in deer herds as well as the potential risk of zoonotic transmission.