Ringworm (tinea) is a fungal skin infection caused by several different fungi and generally classified by its location on the body.
• The fungi that cause ringworm infections tend to spread in moist areas of the skin.
• Symptoms include rashes, scaling, and itching.
• Doctors usually examine the affected area and view a skin sample under a microscope or in a culture.
• Antifungal drugs applied directly to the affected areas or taken by mouth usually cure the infection.
Despite its name, ringworm infection does not involve worms. The name arose because of the ring-shaped skin patches created by the infection. Symptoms vary depending on the location of the infection. Doctors can frequently identify a ringworm infection by its appearance. Most often, there is little or no inflammation and the infected areas are mildly itchy with a scaling, slightly raised border. These patches can come and go intermittently. Areas of the body that are most commonly affected include the head, skin, and nails (infections called tinea unguium and onychomycosis—see Nail Disorders: Onychomycosis). Treatment varies by site but always involves topical or oral antifungal drugs.
Athelete's foot (tinea pedis) is a fungal infection of the feet.
Did You Know...?
• Ringworm infection is caused by fungi, not by worms.
Tinea pedis is a common fungal infection that usually appears during warm weather. The infection may spread from person to person in communal showers and bathrooms or in other moist areas where infected people walk barefoot. People who wear tight shoes are also at risk. The infection is usually caused by Trichophyton or Epidermophyton. These fungi most commonly grow in the warm, moist areas between the toes. The fungus can produce mild scaling with or without redness and itching. The scaling may involve a small area or the entire sole of the foot. Sometimes scaling is severe, with breakdown and painful cracking (fissuring) of the skin. Fluid-filled blisters can also form. Because the fungus may cause the skin to crack, athlete's foot can lead to bacterial infection (see Bacterial Skin Infections: Introduction), especially in older people and in people with inadequate blood flow to the feet.
Diagnosis is usually obvious to doctors based on their clinical examination and review of risk factors.
The safest treatment is using topical antifungal drugs, but recurrence is common and treatment must often be prolonged. Oral antifungal drugs such as itraconazole and terbinafine are usually most effective but may have side effects. Use of a topical antifungal at the same time may reduce recurrences.
Reducing moisture on the feet and in footwear helps prevent recurrences. Wearing open-toe shoes or shoes that “breathe” and frequently changing socks are important, especially during warm weather. Spaces between toes should be thoroughly towel-dried after bathing. Applying antifungal powders (eg, miconazole, gentian violet, Burow's solution (5% aluminum subacetate) soaks, or 20 to 25% aluminum chloride hexahydrate powder helps keep the feet dry.
Jock itch (tinea cruris) is a fungal infection of the groin.
Tinea cruris is much more common in men than in women and develops most frequently in warm weather. The infection begins in the skinfolds of the genital area and can spread to the upper inner thighs. Usually the scrotum is not involved (unlike in yeast infection). The rash has a scaly, pink border. Jock itch can be quite itchy and may be painful. A susceptible person may have repeated infections. Flare-ups occur more often during the summer.
The diagnosis is usually obvious to doctors based on a physical examination. Treatment involves antifungal cream or lotion. Oral antifungal drugs may be needed in people who have inflammatory or widespread infections or infections that do not heal with use of topical drugs.
Scalp ringworm (tinea capitis) is a fungal infection of the scalp.
Tinea capitis is primarily caused by Trichophyton. Scalp ringworm is highly contagious and is common among children (see Problems in Infants and Very Young Children: Rashes). It may produce a pink scaly rash that may be somewhat itchy, or it may produce a patch of hair loss without a rash. Less commonly, it can cause a painful, inflamed, swollen patch on the scalp that sometimes oozes pus (a kerion). A kerion is caused by an allergic reaction to the fungus and may result in scarring hair loss.
Tinea capitis is diagnosed by physical examination and by the doctor examining a sample of hair or scale from the scalp under a microscope. The sample is prepared with a special solution that helps identify the type of fungus causing the infection.
In children, treatment involves an antifungal drug called griseofulvin taken orally for 6 to 8 weeks. An antifungal cream should be applied to the scalp to prevent spread, especially to other children, until the tinea capitis is cured. Selenium sulfide 2.5% shampoo should also be used at least twice a week. Children may attend school during treatment.
In adults, treatment is with the oral antifungal drug terbinafine
or itraconazole. How long treatment is needed depends on the drug used. For severely inflamed areas and for a kerion, doctors may prescribe a short course of prednisone to lessen symptoms and perhaps reduce the chance of scarring.
Body ringworm (tinea corporis) is a fungal infection of the face, trunk, arms, and legs.
Tinea corporis may be caused by Trichophyton, Microsporum, or Epidermophyton. The infection generally produces round patches with pink scaly borders and clear areas in the center. Sometimes the rash is itchy. Body ringworm can develop anywhere on the skin and can spread rapidly to other parts of the body or to other people with whom there is close bodily contact. Diagnosis is usually by physical examination.
Topical Antifungal Drugs
• Nystatin (Candida only)
• Selenium sulfide (shampoo for tinea versicolor)
Tinea corporis is treated with a topical antifungal cream, lotion, or gel applied twice a day and continued for 7 to 10 days after the rash completely disappears. If the cream is discontinued too soon, the infection may not be eradicated, and the rash will return. Several days may pass before antifungal creams reduce symptoms. Corticosteroid creams are often used to help relieve itching for the first few days. Low-dose hydrocortisone is available over the counter. More potent corticosteroids require a prescription and may be used in addition to an antifungal cream. If the ringworm infection oozes, a bacterial infection also may have developed. Such an infection may require treatment with antibiotics, either applied to the skin or taken by mouth.
Extensive and resistant infections can occur in people infected with Trichophyton rubrum and in people with debilitating systemic (body-wide) diseases. For such people, the most effective therapy is an oral drug, such as itraconazole or terbinafine, for 2 to 3 wk.
Beard ringworm (tinea barbae) is a fungal infection of the beard area most often caused by Trichophyton mentagrophytes or T. verrucosum.
Tinea barbae usually involves superficial circular patches, but deeper infection may occur. An inflammatory kerion may also develop, which can result in scarring hair loss. Tinea barbae is rare. Most skin infections in the beard area are caused by bacteria, not fungi. Doctors diagnose the infection by examining a sample of skin under a microscope.
Treatment is with an antifungal drug, such as griseofulvin, terbinafine, or itraconazole, taken by mouth. If the area is severely inflamed, doctors may add a short course of prednisone to lessen symptoms and perhaps reduce the chance of scarring.
Resource: Merck Manual Home Edition