Ringworm, also called tinea, is a skin infection caused by fungi, microscopic organisms that are similar to yeast and molds. It does not have any relation to worms, but is called "ringworm" because the infection can produce ring-shaped patches on the skin that have red, wormlike edges.
Although ringworm can affect almost any area of the body, it favors places that are warm, dark and moist, such as skin in the groin area, the spaces between the toes and the deep skin folds of obese people. People can catch ringworm in several different ways, including:
Direct skin-to-skin contact with an infected person
Playing with, or caring for, an infected pet or farm animal
Using an infected person's clothing, shoes or personal grooming items such as combs, brushes or towels
Sharing an infected child's toys, especially stuffed toys
Touching a contaminated surface — Some common high-risk surfaces include floors in bathrooms, showers and locker rooms; shower stalls; gym mats; and pool decks, especially at school or community pools. In general, any surface that is used by many different people can carry ringworm, especially if the surface is also wet or damp. Even contaminated carpets and couches can spread the infection.
Depending on its specific location, tinea may be known by a more common name, such as athlete's foot or jock itch. The various types of ringworm include:
Ringworm of the scalp — This infection, also known as tinea capitis, causes patches of hair loss on the scalp. It is especially common among children aged 3 to 9, particularly children who live in crowded conditions in urban areas. Scalp ringworm spreads on contaminated combs, brushes, hats and pillows, and it may occur in epidemics in schools and day-care centers.
Barber's itch (ringworm of the beard) — This fungal infection affects bearded areas of the face and neck in adult men.
Ringworm of the body — Ringworm of the body, also known as tinea corporis, involves the non-hairy skin of the face, trunk, arms or legs. Of all types of ringworm, tinea corporis is the one that most often produces the classic, ring-shaped patches with wormlike borders. Ringworm of the body occurs in people of all ages and races, with women affected as often as men.
Jock itch (ringworm of the groin) — This infection, also known as tinea cruris, typically causes itchy, scaly, red patches of skin on the groin area. It most often affects teenage and adult men, especially those who are obese, or who wear tight-fitting underwear. It is the most common type of tinea.
Athlete's foot (ringworm of the foot) — Athlete's foot, also known as tinea pedis, is the second most common form of tinea. In some people, fungus also attacks the toenails. People often get athlete's foot by walking barefoot on contaminated floors, especially in gyms and locker rooms.
Doctors estimate that at least 20% of all people will develop tinea at some time during life. People who are more likely to get a fungal skin infection include:
People who live in hot, humid climates
Athletes, especially swimmers
Children in day care
People who work with animals
Obese people with deep, moist skin folds
Anyone whose immune defenses are weakened by illness (HIV, organ transplant, some cancers) or by medications.