Syphilis is a bacterial sexually transmitted infection with distinct stages: a primary chancre, a variable secondary illness, a latent period, and possible late (tertiary) complications affecting the cardiovascular and nervous systems. Diagnosis uses serologic testing and direct detection when possible. Benzathine penicillin G is the standard treatment and the only proven therapy to prevent congenital syphilis; macrolide resistance limits alternative options. Routine screening of at-risk groups and pregnant people prevents irreversible outcomes.
What is syphilis?
Syphilis is an infection caused by the spirochete bacterium Treponema pallidum. It spreads most commonly through sexual contact and from an untreated pregnant person to their fetus (congenital syphilis).
Stages and typical symptoms
- Primary: A painless or only mildly painful ulcer called a chancre usually appears at the site of exposure. The chancre often heals on its own after a few weeks.
- Secondary: Weeks to a few months after the chancre, a systemic stage can produce a skin rash (often including the palms and soles), mucous patches, fever, and enlarged lymph nodes.
- Latent: After the secondary symptoms resolve, the infection can enter a latent phase with no symptoms. Early latent infection is within the first year after exposure; late latent is later. The infection can remain latent for years.
- Tertiary: In a minority of untreated people, years to decades after infection, late complications (tertiary syphilis) can develop. These include gummatous lesions (soft tissue granulomas), cardiovascular disease (for example, aortitis), and neurologic disease (neurosyphilis), which can cause cognitive change, motor problems, or vision and hearing loss.
Diagnosis
Clinicians usually diagnose syphilis with blood tests (non-treponemal tests such as RPR or VDRL for screening and treponemal tests for confirmation). Direct detection methods (dark-field microscopy or nucleic acid amplification tests) can identify the organism from chancre material when available.
Treatment
Injectable benzathine penicillin G remains the recommended and highly effective treatment for most stages of syphilis, including for pregnant people. People with neurosyphilis require specific parenteral regimens. Alternatives exist for those with penicillin allergy, but penicillin is the only proven therapy for preventing congenital infection; desensitization is recommended in pregnancy if needed.
Azithromycin and other macrolides have been used in the past, but macrolide resistance in Treponema pallidum has been reported and makes those drugs unreliable for routine treatment.
Pregnancy and congenital syphilis
Untreated maternal syphilis can cause miscarriage, stillbirth, neonatal death, or long-term disability in surviving infants. Early detection and penicillin treatment in pregnancy prevent most cases of congenital syphilis.
Prevention and public health
Condoms reduce - but do not eliminate - risk because chancres can appear on areas not covered by a condom. Routine screening of sexually active people at increased risk and of all pregnant people early in pregnancy (and later if risk persists) helps identify infections early and prevent complications.
Historical attributions
Historical claims that specific historical figures died of syphilis are often speculative. Modern evidence is usually insufficient to make firm retrospective diagnoses.
Key message
Syphilis is curable with timely treatment. Because early stages can be mild or unnoticed, regular testing for people at risk and prompt treatment in pregnancy are essential to prevent irreversible harm.
- Confirm the typical incubation range for primary syphilis (days to weeks; commonly ~21 days). [[CHECK]]
- Verify current global/regional trends and recent statistics for syphilis and congenital syphilis incidence to include if needed. [[CHECK]]
- Confirm recommended screening timing during pregnancy per current CDC/WHO guidance for inclusion if specifying schedules. [[CHECK]]