Pathogen

• Treponema pallidum (spirochaete)

Epidemiology

• Approx 6 million new cases /year (2018)

• Sexual contact (with sore, rash in second stage), MTCT

• Higher in FSW/MSM

Clinical

• Incubation 9-90 days

Primary

• Local infection, painless ulcer (chancre): heals without treatment 2-6 weeks

Secondary

• Dissemination, systemic illness (fever, malaise, LN, meningitis...) & rash (trunk, palms, soles, many forms, papules: condylomata lata)

Latent period

• Early (first 4 years after contact)

• Late

Tertiary

• Skin/mucosa/bone: gumma (painless punched out ulcer), periostitis

• Cardiac: aortic aneurysm, coronary artery stenosis

• Nervous system: general paresis, tabes dorsalis (spinal cord degeneration)

Diagnosis

• Visual bacteria: dark field microscopy of fresh tissue fluid

• Nucleic acid detection

• Antibody detection/serology: main method

  • Screen for active disease with sensitive non-treponemal test e.g. Rapid Plasma Reagin (RPR) or VDRL

  • Confirm with specific treponemal (T.pallidum antigen) test e.g. THPA, TPPA or FTA (stay positive for life)

Management

• Penicillin (benzathine)

Pregnancy

• Penicillin stat dose (also treat infant if >28/40)

Prevention

• Screen in pregnancy