Ringworm is an infection of the skin, hair, or nails that is caused by various kinds of fungi. Ringworm tends to infect moist areas of the body, such as the groin and the regions between the toes and under the arms. The affected area usually becomes inflamed because of sensitivity to the fungus or because of infection by another organism. Although ringworm may be irritating, it is never serious because it affects only the outermost layers of the skin.
The most contagious form of the disorder is ringworm of the scalp, which occurs primarily in children. It causes itching, and the hair may break off or fall out, giving the scalp a patchy appearance. To treat ringworm of the scalp, the hair is shaved off. Sometimes a mercury ointment is applied to the infected area. The sores must be kept clean and dry, and often the child is isolated to prevent the infection from spreading to other children.
On the limbs, trunk, and face, ringworm causes raised circular patches, which heal in the centers as the patches widen. In the groin or armpit the patches often take the shape of butterfly wings. Ringworm of the beard usually occurs on only one side of the face and is often highly irritated by shaving. Ringworm may also affect the nail, causing a painless thickening and overgrowth.
To determine if ringworm is present, a physician scrapes off portions of the infected areas and cultures them on a gelatin-like substance. If a fungus is present, a characteristic type of growth will be evident. Ringworm of the scalp is usually diagnosed by examining the hair under an ultraviolet light. If the condition is present, the hair will glow with a bright-green color.
Ringworm infections are often difficult to clear up. Keeping the infected area clean and dry helps prevent growth and spread of fungus. Scraping of overgrown skin or nail tissue may be helpful, and various anti-fungus medications may be applied.