What is ringworm?

Causes and Symptoms

Ringworm is a skin


disease characterized by itching and redness. Despite its name, it is caused by a fungal infection
, not a worm. The skin in areas affected with ringworm often contains round lesions that are colored red, have scaly borders, and contain normal-appearing skin in their centers. Alternatively, the lesions can simply be scaly, red patches with no clearly defined shape. Typically, these lesions are relatively small, approximately 1 inch in their largest dimension. Complications of ringworm include spread to the scalp, hair, or nails of the fingers or toes.

The lesions of ringworm are caused by species of fungi that are members of the genus
Trichophyton. The most common pathogen is Trichophyton rubrum. Ringworm appears on exposed areas of the body, often on the face and arms. Cats are the most common means of transmitting the Trichophyton pathogen from one person to another.

Examination of scrapings from skin lesions is used to diagnose ringworm. Species of Trichophyton can be tentatively identified by their microscopic structure. Culturing material from a skin lesion provides a definitive diagnosis.

Treatment and Therapy

The treatment of ringworm involves both the patient and any carriers. The patient can be treated effectively with any of several creams applied to the skin that are available without a prescription. Their use should be continued for one to two weeks after the skin lesions have cleared. Other drugs are available but require a physician’s prescription. They are used for more extensive lesions or when fingernails or toenails are involved. Body ringworm usually responds within four weeks of treatment. The carrier should be identified and treated. Avoiding contact with infected household pets or clothing that has been worn by an infected person can prevent ringworm.

Perspective and Prospects

Tinea species cause infections in other parts of the body: tinea capitis on the scalp, tinea pedis on the feet, and tinea cruris in the groin region. Ringworm must be differentiated from several other diseases that also cause round skin lesions: psoriasis, syphilis, pityriasis rosea, and systemic
lupus erythematosus. The lesions of psoriasis usually appear on the elbow, knees, and scalp. Syphilis lesions usually appear on the mucous membranes of the genitals or on the palms of the hands or soles of the feet. Although pityriasis rosea often begins with a single round lesion, many more usually follow. The classic skin lesion of lupus is butterfly-shaped and covers the nose and cheeks. The presence of a cat or other domestic pet is often an important element in establishing a diagnosis of ringworm.

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