Re-Emergence of the Great Mimicker: Congenital Syphilis in a Low Prevalence Setting.

BACKGROUND: Congenital syphilis remains a significant cause of adverse birth outcomes despite effective screening and treatment. Data on its epidemiology in Saudi Arabia are limited. This study aims to describe the incidence, clinical characteristics, and outcomes of congenital syphilis at a tertiary pediatric center in Riyadh, Saudi Arabia, and to identify gaps in antenatal care and prevention. METHODS: We conducted a retrospective chart review of all infants diagnosed with congenital syphilis (aged 0-24 months) and pregnant women with positive syphilis serology who presented to our center between January 2021 and December 2025. Cases were classified as highly probable, possible, less likely, or unlikely based on Center for Disease Control (CDC) and European criteria. Incidence rates were calculated per 1000 live births. RESULTS: Over the five-year study period, there were 11,722 live births and 12 cases of probable or possible congenital syphilis, yielding an incidence rate of 1 per 1000 live births. An additional two cases were classified as less likely due to successful prevention of mother-to-child transmission. The majority of cases (n = 7) were attributed to inadequate maternal treatment. Three cases of abortion and intrauterine fetal demise were identified, probably due to untreated maternal syphilis. Most infants were asymptomatic at birth; however, one patient presented with hepatosplenomegaly, cytopenia, and cholestasis, while two had abnormal long bone findings. No cases of neurosyphilis were identified. Five infants were born to mothers with suspected false-positive serology but were managed as possible cases due to incomplete follow-up. Favorable neurodevelopmental outcomes were observed in all patients who completed follow-up (n = 5). CONCLUSIONS: We report congenital syphilis incidence rates that align with the global upward trend. We also identified multiple missed opportunities for screening and early treatment-findings that can inform future guidelines and enhance awareness among healthcare providers and the public.