Syphilis

Clinical assessment

Diagnosis suspected based on clinical findings characteristic of each stage (chancre, rash, condylomata lata, gumma, neurological/cardiovascular signs). Often requires laboratory confirmation.

Investigations

• Darkfield Microscopy: Direct visualization of spirochetes from primary chancre or secondary lesion exudate (requires specialized equipment, operator skill; sensitivity decreases after treatment starts).
• Non-treponemal Tests (VDRL, RPR): Detect antibodies against cardiolipin. Used for screening and monitoring treatment response (titers should decline after successful treatment). Can be falsely positive (viral infections, autoimmune disease, pregnancy, older age). Usually positive 4-6 weeks after infection.
• Treponemal Tests (TPHA, TPPA, FTA-ABS, EIA/CIA): Detect antibodies specific to T. pallidum. Used for confirmation of positive non-treponemal tests. Usually remain positive for life, even after treatment, so not useful for monitoring response (except some newer quantitative EIAs).
• CSF Examination (Lumbar Puncture): Indicated if neurological or ophthalmic signs/symptoms present, or in tertiary syphilis, treatment failure, or HIV co-infection with late latent syphilis or syphilis of unknown duration. Look for CSF pleocytosis, elevated protein, positive CSF-VDRL (specific but not sensitive), or reactive CSF FTA-ABS (sensitive but less specific).

Diagnostic criteria

Combination of clinical presentation and reactive serological tests (positive non-treponemal test confirmed by a positive treponemal test). CSF findings confirm neurosyphilis.

Non-pharmacological management

• Counseling regarding diagnosis, transmission, and prevention.
• Partner notification and testing/treatment (partners within last 3 months for primary, 6 months for secondary, 1 year for early latent).
• Advise abstinence until patient and partner(s) are treated.
• Offer HIV testing.
• Report case according to national guidelines.

Pharmacological treatment

• Primary, Secondary, or Early Latent Syphilis (<1 year):
• - Benzathine Penicillin G 2.4 million units IM single dose (1.2 MU in each buttock).
• - Alternative if penicillin allergic (non-pregnant): Doxycycline 100 mg PO BID for 14 days OR Tetracycline 500 mg PO QID for 14 days OR Ceftriaxone 1g IM/IV daily for 10-14 days.
• Late Latent Syphilis (>1 year or unknown duration) or Tertiary Syphilis (Cardiovascular/Gumma - Neurosyphilis excluded):
• - Benzathine Penicillin G 2.4 million units IM weekly for 3 consecutive weeks (Total 7.2 MU).
• - Alternative if penicillin allergic (non-pregnant): Doxycycline 100 mg PO BID for 28 days OR Tetracycline 500 mg PO QID for 28 days.
• Neurosyphilis (or Ocular Syphilis):
• - Aqueous Crystalline Penicillin G 18-24 million units per day, administered as 3-4 MU IV every 4 hours or continuous infusion, for 10-14 days.
• - Alternative: Procaine Penicillin G 2.4 million units IM once daily PLUS Probenecid 500 mg PO QID, both for 10-14 days.
• - Alternative (less preferred): Ceftriaxone 2 g IM/IV once daily for 10-14 days.
• - Consider follow-up Benzathine Penicillin G 2.4 MU IM weekly x 3 weeks after initial neurosyphilis treatment (per some guidelines/expert opinion).
• Pregnancy: Penicillin is the ONLY recommended treatment. Penicillin-allergic pregnant women MUST undergo desensitization and treatment with penicillin.
• Jarisch-Herxheimer Reaction: Acute febrile reaction (fever, chills, headache, myalgia, rash exacerbation) often occurring within 24 hours of starting treatment (esp. for early syphilis). Usually self-limited. Manage with antipyretics (Paracetamol). Does not require stopping treatment.

Monitoring

• Clinical assessment for resolution of signs/symptoms.
• Serological monitoring with quantitative non-treponemal tests (VDRL/RPR) at 6, 12, (and sometimes 24) months after treatment for early syphilis, and 6, 12, 18, 24 months for late latent/tertiary.
• Expect a fourfold (2-dilution) decrease in titer by 6-12 months for early syphilis, or by 12-24 months for late syphilis. Failure to decline suggests treatment failure or reinfection.
• Neurosyphilis requires repeat CSF examination at 6 months.
• Monitor HIV co-infected patients closely as serological response may be slower or atypical.