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Ringworm: you'll see rings but not worms

"Ringworm" is not caused by worms, as the name would imply. This common childhood skin disease results from infection by living microorganisms known as fungi.

The two most frequently encountered forms of "ringworm" are tinea corporis, ringworm of the body, and tinea capitis, ringworm of the scalp. Body are passed on to children from infected dogs, horses, cows and cats. Because the infection is hidden under the animal's fur, parents may not be aware that their dog or cat has ringworm until the child gets the rash. Long-haired kittens seem especially prone to the fungus, and a youngster can contract the disease simply by petting an infected kitty.

If a child gets the disease, all animals that are in contact with the child should be examined. If ringworm patches are found, the veterinarian should be consulted so that the animal can be treated and the youngster will not become reinfected.

"Ringworm of the body can also be spread when one child comes into close personal contact with another child with the disease," said St. Petersburg dermatologist Dr. Harold Seder. "This usually occurs when the skin is first damaged by moisture, which favors fungus growth, and there is some mild injury to the skin, like an abrasion, scratch or insect bite. For example, I frequently treat high school wrestlers who contract body ringworm from their opponent."

Seder pointed out that "body ringworm rarely spreads by casual contact alone." Scalp ringworm, on the other hand, is most often spread from child to child, and only a small percentage are youngsters infected by animals. The incubation period from exposure to the onset of the ringworm is not known.

Generally, body ringworm starts as a small red scaly patch that, with time, expands to become a larger and larger raised red circle. The skin in the center of the circle begins to look normal as the lesion grows, usually not more than an inch in diameter. Occasionally, many circles appear at the same time, but most often only one or two patches are present. While body ringworm may appear anywhere, it usually appears on exposed areas of the body -- the face, neck, arms or legs. The lesions may also be mildly itchy.

Ringworm of the scalp most often results from child-to-child transmission. The fungus remains alive on combs, brushes, pillows, seat backs, couches, sheets and hats for long periods of time and is easily transferred from an infected child to an unsuspecting playmate.

Scalp ringworm begins the same way as the body variety but as the rings grow, the child begins to lose hair in patches. These areas are usually round, gray and scaly, with a covering of the tiny hairs that have been broken off at the scalp surface. Occasionally, scalp ringworm can become infected with bacteria, producing a yellow crust and pus. Some children with ringworm of the scalp will develop a "kerion," which is a boggy, tender swelling of the scalp that can drain, requiring additional treatment.

Diagnosis of body or scalp ringworm is usually made by the typical appearance and location. Dermatologists confirm the condition by microscopic examination of scrapings taken from the involved area. Cultures can be performed, but it takes a long time for the results and they are therefore rarely done for diagnosis.

Since fungal infections can look like other common skin conditions, parents should consult their child's physician when ringworm is suspected. There are other round rashes that can be easily confused with body ringworm. For example, allergic skin conditions such as eczema and impetigo, a skin infection usually caused by the strep bacteria, appear in patches resembling body ringworm. Occasionally, cradle cap in infants and dandruff in older children are mistakenly diagnosed as scalp ringworm.

When parents suspect ringworm and find only one or two rings on their child, "over-the-counter" anti-fungal creams recommended by the child's physician may be all that is needed. Although improvement in the lesions can begin within two weeks of medication, it usually takes up to four weeks of persistent treatment for the ringworm to disappear completely. If superficial fungus disease develops anywhere else on the body, Dr. Seder advises not to attempt self-treatment, which often spreads the condition and makes it worse. Children with body ringworm are no longer contagious once treatment is started and do not have to miss school or day care.

Scalp ringworm should always be evaluated by a physician. These infections are frequently difficult to treat and require griseofulvin, an antifungal medication given by mouth for up to four to six weeks. Even though topical antifungal medication is not effective alone in treating scalp ringworm, shampoos used twice weekly will help prevent the spread of infection. Since scalp ringworm is very contagious, infected youngsters should be treated promptly. Although body and scalp ringworm rarely pose a serious health problem, breaks in the skin from scratching may cause secondary bacterial infections and scarring. "Once the child with scalp ringworm has started on the proper treatment, he or she can attend school without restrictions," Seder said.

"Haircuts, shaving of the head or wearing a cap during treatment is no longer necessary," added the dermatologist. It is a good idea, however, to check siblings of infected children for the disease. In addition, ribbons, combs and brushes should not be shared by family members. Hair regrowth is normal after treatment but may take six to 12 months.

Body and scalp ringworm are two common skin conditions that are generally not serious. But because they can spread from child to child and complications can occur, proper medical attention makes good sense.

This column is meant to draw attention to the issues discussed and should not be relied upon as medical advice. It is not intended to replace the advice of your child's physician. Dr. Bruce A. Epstein has practiced pediatrics in St. Petersburg since 1973. He is a member of the American Academy of Pediatrics. He is married, has three grown children and a granddaughter.