Syphilis epidemiology in Jordan: prevalence, incidence, and seroreversion from 15 years of laboratory-based data

Syphilis is a health priority targeted for elimination by 2030, yet its global epidemiology remains insufficiently characterized. The study analyzed data from 25,630 adults aged ≥ 15 years who underwent syphilis testing in Jordan at Biolab Diagnostic Laboratories during 2010–2025. Cross-sectional and retrospective cohort analyses were used to estimate prevalence, temporal trends, patterns of rapid plasma reagin (RPR) and Treponema pallidum pallidum hemagglutination assay (TPHA) reactivity, associated risk factors, and incidence rate. Syphilis prevalence (ever RPR- or TPHA-reactive) was 0.9% (95% CI: 0.8–1.0%) overall and only 0.08% (95% CI: 0.05–0.10%) among those tested for visa-related medical screening. RPR reactivity was 0.5% (95% CI: 0.4–0.6%), and among RPR-reactive individuals, 79.2% (95% CI: 65.0–89.5%) were TPHA-reactive within 30 days. Outpatient or walk-in visits, doctor referrals, and laboratory referrals showed substantially higher reactivity than visa-related medical screening, whereas sex, governorate, insurance status, and testing year showed no significant associations. Cumulative syphilis incidence was 0.18% (95% CI: 0.04–0.72%) after two years of follow-up, with an incidence rate of 0.92 per 1,000 person-years (95% CI: 0.23–3.68). Syphilis prevalence and incidence in Jordan are relatively low, but with no evidence of decline over 15 years, indicating limited progress toward elimination targets.