Infectious syphilis

Syphilis is a sexually transmitted bacterial infection progressing through primary, secondary, latent, and tertiary stages, with the early stages constituting the infectious clinical context ^[1]. The reviewed sources describe infectious syphilis as including primary, secondary, and early latent disease ^[1].

Primary infection may present with one or more usually firm, round, and painless sores at the site of entry that typically heal within weeks ^[1]. Secondary stage disease can produce varied systemic or mucocutaneous manifestations, and signs differ by stage ^[1]. Pregnant individuals can transmit infection to the fetus, potentially causing stillbirth, preterm delivery, or low birth weight ^[1].

Syphilis is a common sexually transmitted infection, and observed notification patterns depend on screening and surveillance definitions ^[1]. Recent evidence indicates alarming increases in the incidence of congenital syphilis in many middle and higher income countries across the globe, driven by increasing infectious syphilis in women of childbearing age, which in turn stems from increasing syphilis in the general population particularly in Indigenous and marginalized populations . Potential reasons for the increase include changing sexual practices and increased travel and migration, as well as factors that limit healthcare access, particularly access to antenatal care and limited awareness and education amongst mothers and maternity services .

The infection spreads through sexual contact with infectious lesions and can be passed from a pregnant person to the fetus ^[1]. Lesions outside condom coverage may still transmit despite correct condom use ^[1].

Testing, prompt treatment, reduced sexual exposure risk, and correct condom use help limit transmission, though condom coverage is incomplete ^[1]. Pregnant individuals should be tested for syphilis at least once during pregnancy, with more frequent antenatal testing recommended even for low-risk women, and immediate treatment if positive ^[1][2]. A coordinated public-health approach with education, accessible guidelines, and prioritized antenatal care is needed to prevent congenital syphilis ^[2].

1. 1 US Centers for Disease Control and Prevention. About Syphilis | Syphilis | CDC [Internet]. cited 23 Oct 2026. Available from: https://www.cdc.gov/syphilis/about/
2. 2 Thean L et al. New trends in congenital syphilis: epidemiology, testing in pregnancy, and management. Curr Opin Infect Dis. 2022 Oct 1. PMID: 36066379. doi: 10.1097/QCO.0000000000000875. PubMed: https://pubmed.ncbi.nlm.nih.gov/36066379/
3. 3 Marra CM et al. Neurosyphilis. Continuum (Minneap Minn). 2015 Dec. PMID: 26633785. doi: 10.1212/CON.0000000000000250. PubMed: https://pubmed.ncbi.nlm.nih.gov/26633785/