Yaws Lesion - Causes, Treatment & When to See a Doctor

```html

What is Yaws Lesion?

Yaws is a chronic, contagious skin disease caused by the bacterium Trepomonas pallidum subspecies pertenue. The disease is endemic in warm‑climate, rural tropical regions of Africa, Asia, the Pacific Islands, and parts of South America. A “yaws lesion” refers to the characteristic skin or bone manifestation that appears during the active stages of infection. The first skin manifestation is usually a painless, raised swelling (called a "mother‑node") that quickly ruptures to form a moist, ulcer‑like crater with a yellow‑gray base and a raised, thickened border. Over time, secondary lesions may appear on the limbs, trunk, or face, and untreated disease can progress to painful bone and joint involvement (known as “late yaws”).

Because yaws is spread by direct skin‑to‑skin contact rather than by insects or sexual transmission, it is considered a disease of poverty, limited hygiene, and close‑knitted community living.

Sources: World Health Organization (WHO) – Fact Sheet; CDC – Yaws

Common Causes

While a true “yaws lesion” is caused only by infection with T. pallidum pertenue, several other conditions can produce similar skin ulcers or plaques and must be distinguished during evaluation. Below are 8–10 common differential diagnoses:

• Treponemal infections other than yaws – e.g., syphilis (caused by T. pallidum pallidum) can produce chancres that look similar.
• Buruli ulcer (Mycobacterium ulcerans) – a necrotizing skin infection that begins as a painless nodule and evolves into a large ulcer.
• Leishmaniasis (cutaneous) – caused by Leishmania parasites transmitted by sand flies; lesions are often ulcerated with raised borders.
• Mycobacterial skin infections (atypical mycobacteria) – e.g., Mycobacterium marinum or M. scrofulaceum can mimic yaws ulcers.
• Cutaneous tuberculosis (lupus vulgaris) – slowly progressive plaques that may ulcerate.
• Fungal infections – such as sporotrichosis or chromoblastomycosis, which can produce ulcerating nodules.
• Granuloma inguinale (donovanosis) – a bacterial infection with beefy‑red granulomatous ulcers.
• Chronic ulcerative wounds – due to poor circulation, diabetes, or trauma.
• Autoimmune skin diseases – e.g., pyoderma gangrenosum can present with rapidly expanding ulcers.
• Viral infections – such as herpes simplex virus causing painful vesicles that may ulcerate.

Associated Symptoms

Yaws lesions rarely cause severe systemic illness in the early stage, but patients often report the following accompanying features:

• Low‑grade fever (often < 38 °C)
• Generalized fatigue or malaise
• Swollen lymph nodes near the lesion site
• Multiple secondary skin lesions that appear weeks to months after the primary “mother‑node”
• Itching or mild burning sensation around the ulcer
• Joint pain or swelling (late stage, due to osteitis)
• Bone pain, especially in the long bones of the arms and legs (late yaws)

Because the lesions are painless, children often continue normal activities, which facilitates transmission.

When to See a Doctor

Prompt medical evaluation is essential to confirm yaws and to rule out other serious infections. Seek care if you notice:

• Any new skin ulcer or nodule that does not heal within 2–3 weeks, especially after a minor injury.
• Multiple lesions appearing on the arms, legs, or face.
• Fever or swollen lymph nodes together with a skin ulcer.
• Joint or bone pain after a skin lesion appears.
• Recent travel or residence in a yaws‑endemic region, or close contact with someone who has a similar lesion.

Children and pregnant women should be evaluated promptly, as they are at higher risk for complications.

Diagnosis

Accurate diagnosis relies on a combination of clinical assessment, laboratory testing, and occasionally imaging. The typical diagnostic workflow includes:

1. Clinical Examination

• Inspection of the lesion’s size, shape, colour, and border.
• Assessment for additional lesions, lymphadenopathy, or musculoskeletal tenderness.

2. Laboratory Tests

• Serologic testing – Non‑treponemal tests (VDRL, RPR) are usually positive in active disease; treponemal tests (FTA‑ABS, TPPA) help confirm the specific organism.
• Dark‑field microscopy – Direct visualization of spirochetes from lesion exudate is the gold standard but requires expertise and is rarely available in low‑resource settings.
• PCR (polymerase chain reaction) – Detects T. pallidum pertenue DNA from swabs; increasingly used in research and reference labs.
• Rapid diagnostic tests (RDTs) – Point‑of‑care treponemal tests are useful in field settings, though they cannot differentiate yaws from syphilis.

3. Imaging (Late Yaws)

• Radiographs of affected bones may reveal periosteal reaction, osteolysis, or deformities.
• Bone scintigraphy or MRI can be employed when joint involvement is suspected.

4. Differential Exclusion

Because several tropical skin diseases mimic yaws, clinicians often perform additional tests (e.g., acid‑fast staining for mycobacteria, fungal cultures) to exclude alternatives.

Sources: CDC – Diagnosis; WHO – Yaws guideline 2018

Treatment Options

Yaws is highly curable with a short course of antibiotics. Treatment recommendations are based on WHO’s 2018 eradication strategy and updated CDC guidance.

1. First‑Line Antibiotic Therapy

• Azithromycin 30 mg/kg (maximum 2 g) as a single oral dose – WHO‑endorsed for both primary and secondary yaws. It is safe for children and pregnant women.
• Benzathine penicillin G 1.2 million units IM – Preferred when azithromycin is unavailable or in cases of suspected macrolide resistance.

2. Alternative Regimens (if resistance or contraindications)

• Oral erythromycin 30–50 mg/kg/day divided qid for 10 days.
• Doxycycline 100 mg PO bid for 10 days (not for children <8 y or pregnant women).

3. Management of Late (Bone) Yaws

• Repeated azithromycin dosing (e.g., monthly for 3 months) or a 10‑day course of oral penicillin.
• Physical therapy and orthopedic evaluation for severe deformities.

4. Supportive Care & Home Measures

• Keep lesions clean with mild soap and water; apply sterile gauze to prevent secondary bacterial infection.
• Use analgesics such as acetaminophen or ibuprofen for discomfort.
• Encourage good nutrition to support immune recovery.
• Isolate affected children from close contact until 24 hours after antibiotic administration.

5. Follow‑Up

Re‑examine the patient 4–6 weeks after treatment to confirm lesion healing and repeat serology (VDRL/RPR) to ensure a four‑fold decline in titre, indicating cure.

Sources: WHO – Yaws Eradication Strategy 2012–2020; CDC – Treatment

Prevention Tips

Because yaws spreads via direct skin contact, community‑level strategies are most effective:

• Mass drug administration (MDA) – Single‑dose azithromycin given to all children aged 1–15 years in endemic villages has dramatically reduced prevalence.
• Personal hygiene – Regular hand washing, keeping skin cuts clean, and avoiding sharing towels or clothing.
• Protective clothing – Wearing long sleeves and pants while playing outdoors can reduce skin abrasions that serve as entry points.
• Early case detection – Training community health workers to recognize and report lesions.
• Vaccination research – Though no licensed vaccine exists, experimental candidates are under investigation; stay informed about clinical trials if you live in an endemic area.
• Environmental improvements – Access to clean water and adequate sanitation lowers overall skin infection rates.

Emergency Warning Signs

```