What is ringworm and how is it treated?

Ringworm: Description and Treatment

Ringworm (tinea) is a fungal infection of the skin caused by dermatophytes that typically presents as a circular, red, itchy rash with central clearing and requires treatment with topical antifungal medications for localized infections or oral antifungals for extensive or hair/nail involvement. 1, 2, 3

What is Ringworm?

Ringworm, despite its name, is not caused by a worm but by fungi called dermatophytes. It is a common fungal skin infection that affects approximately 10-20% of the world population 3. The condition is also known as:

• Tinea corporis (when on the body)
• Tinea cruris ("jock itch" when in the groin)
• Tinea pedis (athlete's foot when on the feet)
• Tinea capitis (when on the scalp)

Clinical Presentation

Ringworm typically presents with the following characteristics:

• Circular or ring-shaped lesions with raised, scaly borders
• Central clearing giving the classic "ring" appearance
• Redness, itching, and sometimes burning sensation
• In some cases, vesicles or pustules may be present
• May appear as crusted rash in certain locations 4

The diagnosis can be confirmed by:

• Direct microscopic examination using potassium hydroxide (KOH) preparation to visualize fungal elements 1, 4
• Fungal culture to identify the specific dermatophyte species

Transmission

Ringworm is highly contagious and can be acquired through:

• Direct contact with infected humans
• Contact with infected animals (pets, livestock, zoo animals)
• Contact with contaminated objects or environments 2

High-risk settings include:

• Animal exhibitions
• Petting zoos
• Educational farms
• Sports with close physical contact (e.g., judo, wrestling) 2, 5

Treatment Options

For Localized Infections (Most Cases)

Topical antifungal medications are the first-line treatment for localized ringworm infections 2, 3:

• Azoles (clotrimazole 1%, miconazole, ketoconazole)

  • Apply 1-2 times daily for 2-4 weeks
  • Continue for at least 1 week after symptoms resolve

• Allylamines (terbinafine 1%, naftifine 1%)

  • Apply 1-2 times daily for 1-2 weeks
  • May require shorter treatment duration than azoles

Both medication classes have shown similar efficacy, with clinical studies demonstrating significantly higher cure rates compared to placebo 3.

For Extensive or Resistant Infections

Oral antifungal therapy is indicated for:

• Extensive skin involvement
• Hair or nail involvement
• Infections resistant to topical therapy

Options include:

• Terbinafine
• Itraconazole
• Fluconazole

Special Considerations

• Combination products containing antifungals and corticosteroids should be used with caution:
  • May provide faster symptom relief in inflamed lesions
  • Should be limited to no more than 2 weeks for tinea cruris and 4 weeks for tinea corporis/pedis
  • Should be avoided in children under 12, on facial lesions, and in immunosuppressed patients 6
  • Should be switched to pure antifungal once inflammation subsides

Prevention Measures

• Practice good hand hygiene, especially after contact with animals
• Avoid sharing personal items like towels, clothing, or hairbrushes
• Keep skin clean and dry, particularly in areas prone to infection
• Wear appropriate footwear in public showers and locker rooms
• Ensure regular veterinary care for pets 2

Treatment Duration and Follow-up

Treatment should continue until clinical resolution and for at least one additional week to prevent recurrence. If symptoms persist beyond the expected treatment period, consider:

• Re-evaluation of diagnosis
• Possible resistance to the antifungal agent
• Need for oral therapy
• Concurrent conditions affecting response to treatment

Common Pitfalls

1. Misdiagnosis: Ringworm can resemble other skin conditions like eczema, psoriasis, or contact dermatitis.
2. Inadequate treatment duration: Stopping treatment too soon can lead to recurrence.
3. Inappropriate use of corticosteroids: Long-term use of topical steroids without antifungals can worsen the infection ("tinea incognito").
4. Failure to identify and treat the source: Pets or family members may need concurrent treatment.
5. Overlooking extensive disease: Some cases require oral rather than topical therapy.

Ringworm is generally responsive to appropriate antifungal therapy, with most cases resolving completely with proper treatment and preventive measures.