Syphilis: Primary, Secondary and Tertiary Stages — VDRL + TPHA Testing and Benzathine Penicillin Treatment

Syphilis is a sexually transmitted infection caused by Treponema pallidum — a spirochete that cannot be cultured in the laboratory. The disease is divided into 3 stages, with a latent period in between. If left untreated, it progresses to the Tertiary stage, which can cause complications affecting the brain and the heart and blood vessels.

Primary Syphilis — Chancre

Incubation period 9-90 days (average 3 weeks) → Chancre — a firm-edged, painless ulcer with a round shape and well-defined border, found on the genitals, lips or inside the mouth, together with painless swollen lymph nodes. It heals on its own within 3-6 weeks (but the infection is still present!)

Secondary Syphilis

6-12 weeks after infection (or 4-10 weeks after the chancre): a reddish copper-colored (Copper-colored) maculopapular rash that can appear on the palms and soles (a characteristic sign), Condyloma Lata (moist, whitish warty growths around the genitals), Mucous patches, 'Moth-eaten' alopecia, low-grade fever and enlarged lymph nodes

Testing and Treatment

Screening: VDRL/RPR (Non-treponemal) Confirm: TPHA/FTA-ABS (Treponemal — remains positive for life and can confirm infection) Primary/Secondary/Early Latent: Benzathine Penicillin G 2.4 million IU IM as a single dose Late Latent/Tertiary: 2.4 million IU IM weekly × 3 weeks Neurosyphilis: IV Penicillin for 10-14 days Penicillin allergy: Doxycycline 100 mg × 14 days Jarisch-Herxheimer reaction — fever, aches and body pains 6-12 hours after the injection, not dangerous. Inform sexual partners so they come for treatment. Reporting is required by law.

Frequently Asked Questions

Q: How is syphilis transmitted? A: Through sexual contact, from mother to child, and through blood (possible) Q: When does the blood test turn positive? A: 3-4 weeks after infection Q: Are HIV and syphilis related? A: Highly related; an HIV test should always be done as well Q: Do I need to tell my partners? A: Very necessary; partners must be treated, with follow-up for 90 days

📞 Consult about syphilis at Siam Dermatology — LINE @siamderm | Tel +66 61 448 7000

Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed July 16, 2026