Congenital syphilis

Congenital syphilis is caused by the spirochete Treponema pallidum, which can cross the placenta during pregnancy or be acquired via contact with a maternal lesion at delivery ^[1]. It is the fetal and neonatal consequence of untreated or inadequately treated maternal syphilis, with no dedicated diagnostic test available—all live or stillborn infants of women with syphilis should be examined for clinical and serological evidence of infection ^[3]. As a congenital manifestation of a sexually transmitted bacterial infection, it shares the preventable and curable profile of syphilis when timely intervention occurs ^[4][3].

Clinical manifestations at birth range widely from asymptomatic infection to stillbirth or neonatal death ^[1]. Reported features in affected newborns include low birth weight, rash, hepatosplenomegaly, osteolytic bone lesions, pseudoparalysis, and central nervous system infection, as well as long-term disabilities ^[1].

Congenital syphilis incidence is increasing globally, with an estimated 700,000 to 1.5 million cases reported annually between 2016 and 2023 ^[1]. In the United States, 2,677 cases were reported in 2021 despite widespread availability of penicillin, and from 2019 to 2023 U.S. congenital syphilis cases rose by 106% ^[1][2]. Up to 40% of fetuses exposed in utero are stillborn or die during infancy, underscoring the disease burden at the population level ^[2].

Transmission occurs from an infected mother to her fetus via transplacental passage of T. pallidum during pregnancy or, less commonly, through contact with a maternal lesion at the time of delivery ^[1][2]. Mother-to-child transmission of syphilis is usually devastating to the fetus in cases not detected or treated sufficiently early in pregnancy ^[4][3].

Prevention of congenital syphilis is multifaceted: routine antenatal screening, timely treatment of perinatal syphilis with penicillin, partner tracing and treatment, and health education programs emphasizing safe sex practices and strategies to curb illicit drug use are all essential components ^[1]. Congenital syphilis can only be prevented by diagnosing and treating the mother with penicillin ^[4].

1. 1 Sankaran D et al. Congenital Syphilis-An Illustrative Review. Children (Basel). 2023 Jul 29. PMID: 37628309. doi: 10.3390/children10081310. PubMed: https://pubmed.ncbi.nlm.nih.gov/37628309/
2. 2 Chevalier FJ et al. Syphilis: A Review. JAMA. 2025 Dec 2. PMID: 41100079. doi: 10.1001/jama.2025.17362. PubMed: https://pubmed.ncbi.nlm.nih.gov/41100079/
3. 3 World Health Organization. Syphilis -- Global [Internet]. cited 3 Sept 2026. Available from: https://www.who.int/health-topics/syphilis
4. 4 World Health Organization. Syphilis [Internet]. cited 3 Sept 2026. Available from: https://www.who.int/news-room/fact-sheets/detail/syphilis