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

What is Yaws Fever?

Yaws fever is a systemic manifestation of yaws, a chronic skin‑and‑bone infection caused by the bacterium Treponema pallidum subspecies pertenue. The disease is endemic in warm, humid tropical regions, especially in parts of Africa, South‑East Asia, the Pacific islands and some remote Central‑American communities.

Yaws primarily affects skin and underlying connective tissue. When the infection spreads beyond the skin, it can provoke a low‑grade fever, malaise, and lymphadenopathy. The fever is usually intermittent and may be the first clue that a seemingly simple skin lesion is part of a deeper infection.

Unlike syphilis, yaws is not sexually transmitted; it spreads through direct skin‑to‑skin contact with infectious lesions, often among children playing barefoot or with minor scratches.

Sources: WHO “Yaws – Fact Sheet”, CDC “Treponemal Infections”, Mayo Clinic “Yaws”.

Common Causes

Yaws fever itself is not a disease but a symptom of the underlying infection. The fever can also be triggered by other conditions that cause systemic inflammation or secondary infection of yaws lesions. The most common causes include:

• Primary yaws infection – the initial stage with a painless papule (the “mother ulcer”) that later ulcerates.
• Secondary (late) yaws – disseminated skin lesions, bone pain, and fever after the primary lesion heals.
• Secondary bacterial infection of yaws ulcers (e.g., Staphylococcus aureus, Streptococcus pyogenes).
• Co‑infection with other treponemal diseases such as endemic syphilis (bejel) or pinta.
• Malaria – common in the same endemic regions and can cause fever that overlaps with yaws.
• Viral exanthems (e.g., dengue, chikungunya) that may coexist in tropical settings.
• Hookworm or other parasitic infections that cause anemia and fever.
• Tuberculosis – especially extrapulmonary forms that can produce fever and lymph node swelling.
• Rheumatic fever – an immune reaction that may mimic yaws‑related fever.
• Non‑infectious inflammatory conditions such as lupus erythematosus, which can produce fever and skin lesions.

Associated Symptoms

The fever usually appears together with a constellation of skin and musculoskeletal signs. Typical accompanying symptoms are:

• Skin lesions – a painless, raised papule that evolves into a beefy‑red ulcer with raised, rolled edges.
• Bone pain – especially in the tibia, femur, or skull; may mimic growing‑pain in children.
• Swollen, non‑tender lymph nodes – especially in the neck, axillae, or groin.
• Joint swelling or arthralgia – more common in late-stage disease.
• Fatigue, malaise, and loss of appetite.
• Weight loss – usually gradual.
• Secondary infection signs – increased redness, pus, or foul odor from ulcer.
• Hepatosplenomegaly – enlarged liver or spleen in advanced disease.

When to See a Doctor

Because yaws can progress to debilitating skin and bone disease, early medical evaluation is essential. Seek professional care if you notice any of the following:

• Fever >38 °C (100.4 °F) lasting more than 48 hours.
• A skin ulcer that does not heal within 2 weeks or that recurs after initial healing.
• Severe bone pain or swelling around joints.
• Signs of secondary bacterial infection (increased redness, warmth, pus).
• Persistent swelling of lymph nodes.
• New rash or lesions developing after the initial ulcer.
• Any fever in a pregnant woman or immunocompromised person (e.g., HIV, diabetes).

Diagnosis

Diagnosis combines clinical assessment with laboratory testing. The steps typically include:

1. Clinical examination

• Inspection of characteristic “mother ulcer” and any secondary lesions.
• Palpation of bones and joints for tenderness or swelling.
• Evaluation of lymph node size and tenderness.

2. Laboratory tests

• Serologic testing – rapid plasma reagin (RPR) or Venereal Disease Research Laboratory (VDRL) test, followed by confirmatory treponemal test (e.g., TPPA, FTA‑ABS). Positive non‑treponemal titers with a compatible clinical picture support yaws.
• Dark‑field microscopy – direct visualization of spirochetes from lesion exudate, though rarely available in low‑resource settings.
• Polymerase chain reaction (PCR) – increasingly used to differentiate subspecies of T. pallidum.
• Complete blood count (CBC) – may show mild anemia or leukocytosis if secondary bacterial infection is present.
• Chest X‑ray or bone imaging (X‑ray, MRI) – indicated if osteitis or late skeletal disease is suspected.

3. Differential diagnosis

Physicians rule out other ulcerative skin diseases (e.g., leishmaniasis, cutaneous leprosy), bacterial infections, and other treponemal diseases.

Treatment Options

Effective treatment hinges on early antibiotic therapy. The World Health Organization (WHO) recommends a single oral dose of azithromycin, which is as effective as injectable benzathine penicillin and far easier to administer in remote settings.

Antibiotic regimens

• Azithromycin 30 mg/kg (max 2 g) orally, single dose – WHO first‑line therapy.
• If azithromycin is unavailable or contraindicated, benzathine penicillin G 2.4 MU IM (single dose) is the alternative.
• For patients with secondary bacterial infection of lesions: add oral amoxicillin 500 mg three times daily for 7–10 days or appropriate coverage based on culture.

Supportive (home) care

• Keep ulcers clean – gentle washing with soap and water, followed by sterile gauze dressing.
• Apply topical antiseptic (e.g., povidone‑iodine) if secondary infection is suspected.
• Maintain hydration and adequate nutrition to support immune recovery.
• Analgesics such as acetaminophen or ibuprofen for fever and bone pain (avoid NSAIDs in severe liver disease).
• Educate family members about avoiding direct contact with open lesions.

Follow‑up

Repeat serologic testing (RPR/VDRL) at 6 months and 12 months to ensure a four‑fold decline in titer, indicating cure. Persistent or rising titers may signal treatment failure or reinfection.

Prevention Tips

Because yaws spreads through skin contact, community‑level interventions are crucial.

• Mass drug administration (MDA) – periodic azithromycin distribution to entire at‑risk populations has dramatically reduced incidence in several African countries.
• Early detection – train community health workers to recognize primary ulcers and refer promptly.
• Personal hygiene – regular washing of hands and feet, especially after playing outdoors.
• Protective footwear – wearing shoes reduces skin abrasions that serve as entry points.
• Separate clothing and bedding – wash and avoid sharing items with persons who have active lesions.
• Environmental health – improve sanitation and reduce open‑air defecation, which can harbor other infections that compound yaws.
• Vaccination research – ongoing trials of a treponemal vaccine; keep informed of developments through WHO updates.

Emergency Warning Signs

If any of the following occur, seek emergency medical care immediately (e.g., go to the nearest hospital or call emergency services):

• High fever >40 °C (104 °F) lasting more than 24 hours.
• Rapidly spreading redness, swelling, or severe pain around an ulcer (sign of necrotizing infection).
• Sudden onset of difficulty breathing, chest pain, or severe headache.
• Confusion, seizures, or loss of consciousness.
• Signs of severe dehydration (dry mouth, scant urine, dizziness).
• Severe joint swelling that limits movement, suggesting septic arthritis.

---

Yaws fever is a treatable but potentially disabling condition if left unchecked. Early recognition, appropriate antibiotic therapy, and community prevention strategies are the cornerstones of control. When in doubt, always consult a health professional—timely care saves tissue, bone, and lives.

References: World Health Organization. Yaws Fact Sheet, 2023; Centers for Disease Control and Prevention. Treponemal Infections, 2022; Mayo Clinic. Yaws, 2024; Cleveland Clinic. Skin Ulcers, 2023; National Institutes of Health. Treponema pallidum review, 2022.