Syfilis

Syfilis is a sexually transmitted infection caused by the bacterium Treponema pallidum, a spirochete. It is transmitted primarily through sexual contact, including vaginal, anal, and oral sex, and can also be passed from an infected mother to the fetus (congenital syphilis). The infection progresses through stages: primary, secondary, latent, and tertiary.

The primary stage is marked by a painless ulcer, the chancre, at the site of inoculation. The chancre typically appears a few weeks after exposure and heals within 3–6 weeks. The secondary stage may occur weeks later and can include a diffuse rash, mucous membrane lesions, fever, lymphadenopathy, and wart-like condylomata lata. Latent syphilis has no symptoms; early latent denotes infection within the first year, while late latent occurs after more than a year. Without treatment, infection can advance to tertiary syphilis years after exposure, causing gumma lesions, cardiovascular disease such as aortitis, and neurosyphilis, which can present as meningitis, sensory ataxia, or psychiatric symptoms.

Diagnosis relies on serologic testing. Non-treponemal tests (RPR, VDRL) are used for screening and monitoring response to therapy, while treponemal tests (TPPA, FTA-ABS) are more specific and usually remain positive for life. Dark-field examination of lesion material can detect spirochetes in early lesions.

Treatment is with antibiotics, most commonly benzathine penicillin G. Alternatives include doxycycline or ceftriaxone in certain contexts, and penicillin remains the preferred therapy for pregnant women to prevent congenital syphilis. Prevention focuses on condom use, regular screening (especially during pregnancy), and partner notification and treatment.