Syphilis
Systemic infection caused by *Treponema pallidum*, presenting in stages (primary, secondary, latent, tertiary) and with neurosyphilis or ocular involvement. Penicillin remains definitive treatment; serological follow-up is essential.
Key Facts
Key points
- Primary: painless chancre; secondary: rash (often palmar/plantar), mucous patches, condylomata lata.
- Latent: positive serology without clinical signs; early latent (<2 years) vs late latent.
- Neurosyphilis: meningitis, stroke, general paresis, tabes dorsalis — LP if suspected.
- Treatment early syphilis: benzathine benzylpenicillin G 2.4 million units IM stat (split doses if needed per local policy).
- Penicillin allergy: doxycycline 100 mg BD 14 days (early) — avoid in pregnancy; seek specialist advice.
- Jarisch–Herxheimer reaction: fever within 24 h of therapy — counsel patients.
Overview
Epidemiology
Resurgence in UK MSM populations; HIV co-infection affects presentation and management.
Pathogenesis
Haematogenous dissemination follows primary inoculation; treponemes cross placenta (congenital syphilis) — antenatal screening is critical.
Clinical Presentation
Stages
- Primary: single ulcer with rubbery lymphadenopathy.
- Secondary: diffuse rash, alopecia, hepatitis, ocular involvement.
- Tertiary: gummas, cardiovascular syphilis, neurosyphilis.
Congenital
Hepatosplenomegaly, rash, snuffles, bone changes — neonatal emergency.
Differential Diagnosis
| Mimic | Notes |
|---|---|
| HSV ulcer | Painful grouped vesicles/ulcers |
| Chancroid | Painful ulcer, uncommon UK |
| Pityriasis rosea | Herald patch, collarette scale |
Diagnosis / Investigation
Serology
- EIA/CLIA screen; TPPA/TPHA confirmatory; RPR/VDRL titre for activity and follow-up.
CSF
- If neurological/ocular signs: CSF VDRL, cell count, protein.
Management
Early syphilis (primary/secondary/early latent)
- Benzathine benzylpenicillin 2.4 MU IM once (some centres give weekly doses for late latent — follow BASHH).
Late latent / unknown duration
- Benzathine benzylpenicillin 2.4 MU IM weekly for 3 weeks (per guideline).
Neurosyphilis
- Benzylpenicillin IV 1.8–2.4 g 4-hourly for 14 days (or ceftriaxone alternative in penicillin allergy — specialist).
Pregnancy
- Penicillin is mandatory; desensitisation if allergy — do not use doxycycline.
Prognosis
Excellent if treated early; neurosyphilis and cardiovascular syphilis can cause permanent deficits if missed. Serological titres should decline after therapy.
Other Relevant Information
Follow-up
Repeat RPR/VDRL at 3, 6, 12 months; HIV co-testing at diagnosis.