Syphilis

梅毒

Evidence-backed information EN 6/7 applicable sections · ZH 6/7 applicable sections Updated Oct 23, 2026

Syphilis is a curable bacterial sexually transmitted infection caused by Treponema pallidum that produces substantial morbidity and mortality worldwide ^[1]^[2]^[3]. Global estimates indicate millions of new adult infections each year, with rising case trends reported in some regions such as the United States ^[1]^[4]. The infection is preventable through safer sex practices and can be transmitted from mother to child with severe consequences if untreated ^[2]^[3].

Read the full clinical and epidemiological profile 7

Definition

Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum subspecies pallidum, a gram-negative spirochete ^[1]^[4]. It is a preventable and curable bacterial disease that may remain asymptomatic or progress through distinct stages if untreated ^[2]^[3].

Clinical features

The manifestation varies by stage: primary disease typically shows a firm, painless, non-itchy chancre, often a single genital ulcer, while secondary disease produces a diffuse rash involving palms and soles with possible mucosal sores ^[1]^[4]. Latent infection is asymptomatic and may persist for years, whereas tertiary disease can involve gummas, neurological complications, or cardiac involvement ^[1]. Congenital infection may be initially silent but can later produce deformities such as saddle nose or saber shin if not treated ^[1].

Epidemiology

In 2012 approximately 0.5% of adults were infected with syphilis and 6 million new cases occurred, while 2015 saw about 107,000 deaths globally, a decline from 202,000 in 1990 ^[1]. An estimated 8 million adults aged 18–49 acquired the infection in 2022, and U.S. cases rose 61% from 2019 to 2023 with congenital cases up 106% ^[4]. The disease affects 700,000 to 1.6 million pregnancies annually and contributes to roughly 20% of perinatal deaths in sub-Saharan Africa ^[1].

Transmission

Syphilis spreads mainly through sexual contact with infectious lesions during oral, vaginal, or anal sex, and can also pass from mother to fetus via the placenta or during birth ^[1]^[2]^[4]. Transmission through blood transfusion is possible, and condom use reduces but does not eliminate risk since lesions may occur on uncovered areas ^[2]^[3].

Prevention

Correct and consistent use of condoms during sex is the best available method to reduce sexual transmission, though contact with uncovered body sites remains a risk ^[2]. Pregnant women should be tested at the first prenatal visit and treated promptly, as only penicillin prevents congenital syphilis ^[2]. Persons at higher risk should be screened at least annually, and those diagnosed should notify sexual partners to interrupt further spread ^[2].

Surveillance note

GlobalID source-data note: Korea's historical surveillance contains separate primary, secondary, tertiary, and latent syphilis series as well as a broader syphilis series. The stage-specific rows are subdivisions, so a broad total must not be summed with its stage components; comparisons across the 2024 definition transition require the source period and label.

References

1 Wikipedia contributors. Syphilis - Wikipedia [Internet]. Wikipedia. cited 23 Oct 2026. Available from: https://en.wikipedia.org/wiki/Syphilis
2 World Health Organization. Syphilis [Internet]. cited 23 Oct 2026. Available from: https://www.who.int/news-room/fact-sheets/detail/syphilis
3 World Health Organization. Syphilis -- Global [Internet]. cited 23 Oct 2026. Available from: https://www.who.int/health-topics/syphilis
4 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/