Bacterial sexually transmitted infections in incarcerated populations: a systematic review and meta-analysis

Background Bacterial sexually transmitted infections (STIs) are common among people in prison, a population identified by WHO as a key group to addressing the burden of sexually transmitted and blood-borne infections worldwide. To inform elimination efforts, we aimed to estimate the global prevalence of bacterial STIs (chlamydia, gonorrhoea, and syphilis) in prisons and other closed settings. Methods We conducted a systematic review and meta-analysis by searching online databases (MEDLINE, Embase, Global Health, PsycInfo, CINAHL, the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, Global Index Medicus, the Conference Proceedings Citation Index–Science, and the Conference Proceedings Citation Index–Social Sciences & Humanities) and reference lists for studies published from Jan 1, 2000, to Aug 5, 2025. We included peer-reviewed publications (scientific articles, conference abstracts, and technical reports) that reported on the prevalence of current chlamydia, current gonorrhoea, or current or previous syphilis infections, confirmed by validated diagnostic assays, among incarcerated populations (adolescents aged 10–19 years and/or adults aged >19 years). Two reviewers (GB and BH) independently assessed studies, extracted data, and evaluated the quality of studies using an adapted version of the Joanna Briggs Institute critical appraisal tool for prevalence studies. Pooled prevalence estimates for each bacterial STI were derived with use of generalised linear mixed-effects models, stratified by age group and, within each age group, by sex. Heterogeneity was quantified based on the I 2 statistic and χ 2 test. This systematic review and meta-analysis was registered with PROSPERO, CRD42023443370. Findings The search generated 5237 records, of which 212, corresponding to 206 unique studies, met the eligibility criteria and were included. Of the 206 studies, 137 included adults only (n=425 215), 53 included adolescents only (n=342 762), and 16 included both (n=675 119). 190 (92·2%) studies were conducted in high-income or upper-middle-income countries. Across the 206 studies, data were available for 1 443 096 individuals (483 438 [33·5%] females, 901 188 [62·4%] males, and 58 470 [4·1%] sex not reported). The mean age was 33·6 years (SD 9·7) for adults and 15·6 years (1·1) for adolescents. Among female adults, the pooled prevalence of current chlamydia was 6·5% (95% CI 5·1–8·3; I 2 =97·0%, p