Yaws

Definition

  • Chronic non venereal treponemal infection of skin, bone and cartilage

Aetiology

  • Treponema pallidum subspecies pertenue
  • Spread by direct skin contact with lesion exudate

Epidemiology

  • Warm humid tropical regions in poor rural communities
  • Mostly children under 15 years
  • Targeted by a WHO eradication program

Clinical Features

  • Primary mother yaw, a painless papilloma at the inoculation site, often on the leg
  • Secondary yaws with multiple skin lesions and painful palmar and plantar hyperkeratosis
  • Osteoperiostitis of long bones, forearm and fingers
  • Dactylitis with polydactylitis of the hands
  • Sabre tibia from periosteal new bone, similar to congenital syphilis
  • Goundou, hypertrophic osteitis of the nasal processes of the maxilla
  • Gangosa, destructive ulceration of the nose and palate in tertiary disease
  • No cardiovascular or neurological involvement, unlike syphilis

Investigations

Yaws, skin lesion of yaws
Skin lesion of yaws. Image by , Wikimedia Commons, Public domain.
  • Treponemal and non treponemal serology, which cannot distinguish yaws from syphilis
  • PCR of lesion swab confirms subspecies
  • X-ray shows periosteal reaction, cortical thickening and lytic lesions

Differential Diagnosis

Management

  • Single oral dose of azithromycin, now first line
  • Single IM dose of benzathine penicillin as an alternative
  • Treat contacts
  • Established bony deformity may need corrective osteotomy

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.