Prevalence of mpox infection among men who have sex with men: a systematic review and meta-analysis.

BACKGROUND: Mpox has been twice declared as public health emergency of international concern by World Health Organization. The 2022-2024 global outbreak has been primarily driven by sexual transmission within men who have sex with men (MSM) networks, predominantly involving Clade IIb, with a subsequent surge of Clade Ib in early 2024. MSM account for a large proportion of confirmed mpox cases. This review aimed to estimate the prevalence of mpox infection among MSM populations. METHODS: We searched PubMed, Web of Science, Embase, China National Knowledge Infrastructure (CNKI) and Wanfang Data for studies published in English or Chinese from inception to 16 December 2024. Eligible studies reported mpox cases among MSM with confirmed diagnosis (laboratory or self-reported) during the outbreak period. Reviews, case reports, and studies without case numbers were excluded. American Agency for Healthcare Research and Quality and Newcastle-Ottawa Scale were adopted for quality assessment. Fixed-effects or random-effects meta-analysis was performed to estimate the pooled prevalence of mpox among MSM. Heterogeneity was measured using Cochran's Q test and I2 statistics. Meta regression analysis was performed to discover the potential source of the heterogeneity. Funnel plot, Egger's regression test and Begg's rank correlation test were conducted to evaluate the publication bias. Sensitivity analyses were performed by leave-one-out analysis and by stratified validation. RESULTS: From 1606 retrieved studies, 28 studies were eligible and included, containing a total of 46,598 MSM participants and 1274 mpox cases from 15 countries. The pooled mpox prevalence among MSM population was 2.30% [95% confidence interval (CI): 1.29-3.57%]. Meta-regression identified continent as the most significant moderator, with prevalence in South America (9.58, 95% CI: 2.71-20.01%) being significantly higher than in Asia (1.14, 95% CI: 0.56-1.90%) (P = 0.019). Sampling method also contributed to the heterogeneity, whereas no statistically significant difference was observed in mpox prevalence among high-risk MSM, asymptomatic MSM, comparing to the general MSM populations respectively. CONCLUSIONS: This study confirms a significant but highly heterogeneous burden of mpox among MSM worldwide. The findings suggest that the observed prevalence is shaped more by regional epidemiological contexts and study methodologies, which emphasizes the necessity for geographically prioritized interventions and standardizing surveillance to enable accurate risk assessment and guide resource allocation in future outbreaks.