Long-term (chronic) bacterial infection that mainly affects the skin, bones, and joints


  • Development of a sore called a “mother yaw” (about 2-4 weeks after infection)
  • Bone pain
  • Scarring of the skin
  • Swelling of the bones and fingers
  • initial yaws lesion( primary stage)
  • multiple skin lesions (Secondary stage)
  • skin lesions can relapse ( Latent stage)
  • bone, joint, and soft tissue deformities (tertiary stage)
  • painless ulcer with scab
  • papillomas
  • palmar/plantar hyperkeratosis (thickening)
  • Swollen lymph node
  • A rash that forms a brown crust
  • Painful bumps or sores on the skin and on the soles of the feet
  • Facial swelling and disfiguration


  • Caused by spirochete bacterium- Treponema pertenue
  • Transmitted by skin-to-skin contact
  • Direct contact with the skin sores of infected people

Risk factors:

  • Age: young children under 15 years of age
  • Occurrence: warm, humid, tropical areas of Africa, Southeast Asia, South America
  • Poor rural populations living in overcrowded conditions-more prone
  • Break (cut) or abrasion of the skin-chances of bacterial infection
  • Poor hygiene and crowded conditions

Diagnostic tests:

  • Clinical diagnosis
  • Dark field microscopy of samples taken from early lesions (Skin)
  • Non-treponemal tests (eg RPR, VDRL)
  • Specific anti-treponemal antibody tests (eg TPHA, EIA)
  • Blood tests for syphilis ( since bacteria that cause these 2 conditions are closely related)

Differential diagnostics:

  • Acute Complications of Sarcoidosis
  • Blastomycosis
  • Dermatologic Manifestations of Leprosy
  • Impetigo
  • Leishmaniasis
  • Molluscum Contagiosum
  • Nongenital Warts
  • Pediatric Atopic Dermatitis
  • Pediatric Syphilis
  • Plaque Psoriasis
  • Rhinoscleroma
  • Scabies
  • Tuberculosis
  • Tungiasis


  • Single dose of penicillin or 3 weekly doses for later stage disease
  • Erythromycin, doxycycline, or tetracyclin(if allergic to pencillin)
  • Azithromycin

Lifestyle Management:

  • Yaws eradication (Morges strategy)- established by WHO to eradicated Yaws by 2020
  • Interrupting the transmission of the disease
  • Practicing good hygiene
  • Early diagnosis and rapid appropriate treatment
  • Health education and improvement in personal hygeine
  • No vaccines are available for the disease