ringworm or tinea (tĭnˈēə) [key], superficial eruption of the skin caused by a fungus, chiefly Microsporum, Trichophyton, or Epidermophyton. Any area of the skin may be affected, including the scalp and nails, but the most common site is the feet. That disorder is often called athlete's foot in the belief that the infection is contracted during the use of communal shower facilities. Actually, fungi are present on the bodies of most persons, but some individuals are more resistant to fungus invasion than others. Moreover, a prolonged moist, airless condition caused by excessive perspiration may subject a formerly resistant person to fungus invasion. Ringworm infection causes dry, scaly patches or blisterlike elevations, usually with burning or itching. Griseofulvin, a modified form of penicillin, is effective against scalp infection but is ineffective against foot fungi. In mild cases of athlete's foot, often the only treatment is to keep the feet scrupulously dry. In more persistent cases local antifungal ointments, sprays, or soaks are recommended.