Yaws skin ulcer - Symptoms, Causes, Treatment & Prevention

📅 Updated: June 2026 ⏱️ 6 min read ✅ Medically reviewed
```html Yaws Skin Ulcer – Comprehensive Medical Guide

Yaws Skin Ulcer – Comprehensive Medical Guide

Overview

Yaws is a chronic, contagious skin disease caused by the bacterium Treponema pallidum pertenue. It belongs to the same family of spirochetes that cause syphilis, but it is transmitted exclusively through skin‑to‑skin contact, not sexual contact. The disease is endemic in warm, humid tropical regions, primarily affecting children aged 2–15 years who live in remote, poverty‑stricken villages.

According to the World Health Organization (WHO), there were an estimated 2.5 million cases of active yaws worldwide in 2022, with the majority of cases concentrated in West Africa, Southeast Asia, and the Pacific Islands. Active case‑finding programs have reduced prevalence in many countries, but pockets of infection remain, especially in areas lacking adequate health‑care access.

Symptoms

Yaws progresses through three clinical stages. The first stage (primary) produces the classic skin ulcer; later stages cause widespread skin lesions and bone involvement.

Primary (Initial) Stage

  • Mother‑wort (Papule): A painless, raised bump that appears 2–4 weeks after exposure.
  • Chancre (Ulcer): The papule ruptures, forming a well‑defined, “ raspberry‑like” ulcer with a raised, thickened border. The base is thin and may ooze serous fluid but is usually painless.
  • Location: Commonly on the legs, arms, or buttocks; may be solitary or multiple.
  • Healing: Ulcers often heal spontaneously within 3–6 weeks, leaving a scar.

Secondary (Disseminated) Stage

  • Multiple lesions: New, smaller papillomatous or ulcerative lesions appear on the trunk, face, and extremities.
  • Bone pain: Painful swelling of long bones (especially the tibia and radius) may develop weeks to months after the primary ulcer.
  • Systemic symptoms: Low‑grade fever, malaise, and lymphadenopathy can accompany the skin lesions.

Late (Tertiary) Stage

  • Hyperkeratotic plaques: Thickened, wart‑like lesions that may ulcerate.
  • Bone deformities: Chronic osteitis can cause permanent deformities, especially in the legs (e.g., “sabre‑shin”).
  • Neurologic involvement: Rare, but can include peripheral neuropathy.

Causes and Risk Factors

Yaws is caused by Treponema pallidum pertenue, a spirochete that thrives in warm, moist environments. Transmission occurs when the bacterium from an infected ulcer contacts broken skin or mucous membranes of another person.

Key Risk Factors

  • Geography: Living in or traveling to endemic rural areas of Africa, Oceania, and Southeast Asia.
  • Age: Children 2–15 years old account for ~90 % of cases because they play barefoot and have frequent skin abrasions.
  • Poor sanitation & crowding: Lack of clean water, inadequate footwear, and close‑quarter living increase exposure.
  • Limited health‑care access: Delayed diagnosis allows the disease to spread unchecked.
  • Immunocompromised state: Though not a primary factor, HIV infection can worsen disease course.

Diagnosis

Correct diagnosis relies on clinical recognition and laboratory confirmation.

Clinical Evaluation

  • History of exposure in an endemic area.
  • Characteristic painless ulcer with raised edges.
  • Presence of secondary lesions or bone pain.

Laboratory Tests

  • Serologic testing:
    • Non‑treponemal tests (RPR, VDRL) are usually positive in active disease.
    • Treponemal tests (FTA‑ABS, TPPA) confirm infection but cannot differentiate yaws from syphilis.
  • Polymerase chain reaction (PCR): Detects T. pallidum pertenue DNA from ulcer exudate; increasingly used in research settings.
  • Dark‑field microscopy: Direct visualization of spirochetes from ulcer fluid; requires skilled personnel.
  • Radiography: X‑ray of affected bones if osteitis is suspected; shows cortical thinning or periosteal reaction.

In resource‑limited settings, a diagnosis is often made clinically and treated empirically, as recommended by WHO guidelines.

Treatment Options

Yaws is highly curable with a single dose of oral antibiotics. Early treatment prevents progression to later stages.

First‑line Antibiotics

  • Azithromycin 30 mg/kg (max 2 g) orally, single dose – WHO’s preferred regimen since 2012 due to excellent efficacy and ease of administration.
  • Benzathine penicillin G 50,000 IU/kg (max 2.4 million IU) intramuscularly, single dose – Alternative for patients who cannot receive azithromycin (e.g., allergy, contraindication).

Alternative Regimens

  • Oral amoxicillin 50 mg/kg/day divided TID for 10 days (used where azithromycin resistance is suspected).
  • Re‑treatment after 3 months if serology remains positive or new lesions develop.

Adjunctive Care

  • Wound care: Gentle cleaning with saline, application of non‑adherent dressings, and keeping the ulcer moist to promote healing.
  • Pain management: Acetaminophen or ibuprofen for bone pain.
  • Nutrition: Adequate protein and vitamin C support skin repair.

Living with Yaws Skin Ulcer

Even after treatment, ulcers may take weeks to heal. The following practical tips help manage daily life and reduce transmission.

  • Wound hygiene: Wash hands before and after touching the ulcer; use clean gloves if dressing the wound.
  • Footwear: Encourage children to wear closed shoes to protect skin from cuts and reduce exposure.
  • Avoid scratching: Keep nails trimmed; apply a barrier ointment (e.g., petroleum jelly) if itching occurs.
  • School attendance: Children can attend school once the ulcer is covered with a sterile dressing; inform teachers to avoid close skin contact.
  • Community support: Join local health‑education programs that provide antibiotics and follow‑up visits.
  • Follow‑up serology: Repeat RPR/VDRL at 6 and 12 months to ensure treatment success.

Prevention

Because yaws spreads through direct skin contact, prevention focuses on hygiene, education, and mass‑drug administration (MDA) in endemic regions.

Individual‑Level Measures

  • Wear shoes and clothing that cover skin breaks.
  • Promptly clean any cuts or abrasions with soap and clean water.
  • Avoid sharing personal items (e.g., towels) with someone who has an active ulcer.

Community‑Level Strategies

  • Mass drug administration: WHO recommends azithromycin MDA (30 mg/kg) for all children 1–15 years in endemic villages, repeated annually for at least 3 years.
  • Health education: Teach parents and teachers to recognize early lesions and seek care.
  • Surveillance: Active case‑finding teams conduct quarterly skin examinations in high‑risk areas.
  • Improved sanitation: Access to clean water and latrines reduces skin trauma and secondary infections.

Complications

If left untreated, yaws can cause serious, sometimes disabling, sequelae.

  • Chronic osteitis: Painful bone inflammation leading to fractures or permanent deformities (e.g., sabre‑shin, pigeon‑toed gait).
  • Severe skin scarring: Disfiguring plaques that may affect self‑image and social interactions.
  • Secondary bacterial infection: Ulcers can become colonized with Staphylococcus or Streptococcus species, leading to cellulitis or abscess formation.
  • Functional impairment: Joint involvement may limit mobility, especially in children during growth years.
  • Rare neurologic involvement: Peripheral neuropathy or, exceptionally, meningitis.

When to Seek Emergency Care

Immediate medical attention is required if you notice any of the following:
  • Rapidly spreading or extremely painful ulcer with foul discharge.
  • High fever (>38.5 °C / 101.3 °F) lasting more than 48 hours.
  • Signs of systemic infection: rapid heart rate, low blood pressure, confusion.
  • Severe bone pain with swelling, inability to bear weight, or visible deformity.
  • Allergic reaction after taking azithromycin or penicillin (hives, swelling of face/throat, difficulty breathing).

Call emergency services or go to the nearest health‑facility right away.

References

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⚠️ Medical Disclaimer

Important: The information provided on this page is for general informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

If you think you may have a medical emergency, call your doctor, go to the emergency department, or call 911 immediately.

📚 Medical References