Ringworm Information for Healthcare Professionals

Sources

Tinea (commonly called “ringworm”) spreads easily between people and animals. Tinea can also spread from one part of the body to another (for example, a patient with tinea pedis can go on to develop tinea cruris). Humans and animals can also be non-symptomatic carriers and can spread tinea to others. Transmission also occurs via fomites; infection can spread through shared towels, clothing, bedding, etc., as well as hard surfaces (particularly in moist areas) such as shower stalls, locker room floors, pool areas, etc.

Diagnosis

Physical examination

A thorough history and physical examination is often sufficient to diagnose tinea. The classic lesion is an erythematous, raised, scaly ring with central clearing. Multiple lesions may be present. The severity of the infection can range from mild, scaly lesions, to erythematous, exudative lesions characteristic of superimposed bacterial infections.

Microscopy

Potassium hydroxide (KOH) stain a commonly-used method for diagnosing tinea because it is inexpensive, easy to perform, and has high sensitivity.¹ Scrapings from the lesion(s) are placed in a drop of KOH and examined under a microscope for the presence of fungal hyphae.

Ultraviolet light (Wood’s lamp)

Normally, ultraviolet light is not useful in the diagnosis of tinea with the exception of two species – Microsporum canis and audouinii. Although both species fluoresce blue-green under a Wood’s lamp, both species are uncommon causes of tinea infections. A Wood’s lamp may be useful to differentiate between erythrasma caused by Corynebacterium minutissimum (which fluoresces coal-red) from tinea cruris, which is non-fluorescent.²

Culture

Fungal culture can be performed as a confirmatory test if results from a KOH stain are inconclusive. Hair and/or scrapings extracted from affected areas are placed on Sabouraud’s medium. Fungal culture is more specific than KOH stain, but it can take up to three weeks to become positive.^3,4

Treatment

Tinea pedis: Athlete’s foot can usually be treated with over-the-counter topical antifungal products; terbinafine appears to be most effective, but other agents can also be used.⁵ Chronic or extensive tinea pedis may require treatment with oral antifungal agents such as terbinafine, itraconazole, or fluconazole.⁶ In addition, chronic tinea pedis may require adjunctive therapy such as foot powder or talcum powder to prevent skin maceration.

Tinea capitis: Treatment with systemic antifungal medication is required, as topical antifungal products are ineffective for treatment of tinea capitis. Many experts consider griseofulvin to be the drug of choice.⁶ Terbinafine is also FDA-approved for the treatment of tinea capitis in patients four years of age and older. Itraconazole and fluconazole have been shown to be safe and effective, but are not FDA-approved for this indication.⁶ Selenium sulfide shampoos can be used as adjunctive therapy.^6–8

Tinea corporis/cruris: Tinea corporis and tinea cruris can usually be treated with over-the-counter antifungal products.⁶ Patients who have tinea cruris should be advised to keep the groin area clean and dry and to wear cotton underwear. Persons who have extensive or recurrent infections may require systemic antifungal therapy.⁶