Chlamydia trachomatis infection prevalence varies significantly across Canadian populations and anatomical sitesNew data reveals how common chlamydia is in Canada

BACKGROUND: This study aimed to systematically review and synthesize evidence on Chlamydia trachomatis prevalence in Canada, describe epidemiological patterns across populations and anatomical sites, and assess associations with prevalence. METHODS: A systematic review of Chlamydia trachomatis prevalence studies was conducted and reported according to PRISMA guidelines. Random-effects meta-analyses generated pooled mean prevalence estimates, and meta-regression analyses explored epidemiological and methodological predictors of prevalence variation. RESULTS: A total of 169 publications were included, contributing 437 prevalence measures spanning 1981-2025. The pooled mean prevalence in the general population was 4.4% (95% CI: 3.6-5.2%) for current urogenital infection and 50.3% (95% CI: 44.5-56.1%) for ever infection. Among men who have sex with men and transgender people, prevalence estimates were 1.8% (95% CI: 0.6-3.5%) for urogenital infection, 6.6% (95% CI: 3.7-10.1%) for anorectal infection and 0.7% (95% CI: 0.0-2.1%) for oropharyngeal infection. Prevalence was substantially higher among symptomatic populations, reaching 18.6% (95% CI: 9.3-30.2%) in women and 24.3% (95% CI: 13.7-36.7%) in men. Meta-regression analyses explained >40% of the observed variation in prevalence, indicating that prevalence was approximately 30% lower among individuals aged ≥25 years compared with those aged <25 years, with no significant sex differences. Prevalence declined over time at a relative rate of 3% per year. CONCLUSIONS: Chlamydia trachomatis prevalence in Canada is comparable to global levels. The ongoing persistence of infection underscores the need to enhance public health responses and expand investment in vaccine development as a cornerstone of long-term prevention and control.