A five-year-old came into the office recently for a small, slightly itchy red patch on her arm. Upon inspecting it, I saw that it was circular, raised at the edges, with a somewhat scaly middle. I informed the mother that her daughter had ringworm. She gazed at the lesion, confused, and asked a perfectly reasonable question, “But, doctor...where’s the worm???”
Despite the suggestive name, ringworm is not caused by worms. It is, in fact, caused by a fungal infection of the skin. Ringworm of the body, or tinea corporis, involves the non-hairy skin of the body, and appears as a circular, slightly red lesion with a raised bumpy border. It may have no associated symptoms, or may be slightly itchy. There may be a single lesion or multiple lesions scattered about the body. It is usually fairly straightforward to diagnose if it has the characteristic appearance. But, occasionally it may be confusing if the child has been scratching a great deal.
The fungi that cause tinea corporis are common and all around us. They are transmitted by direct contact with infected people, animals or even contaminated objects. This condition can be diagnosed clinically or with laboratory help by looking at skin scrapings under the microscope, or attempting to culture the fungus. The treatment is with an anti-fungal cream. Usually the child will look better within two weeks of treatment. But four weeks is usually needed to fully clear the infection. For severe cases or those that don’t respond to anti-fungal creams, oral medications can be used as well. This situation is uncommon, however, as the vast majority of cases will respond to topical therapy. Children with tinea corporis do not need to be excluded from school. It is spread by direct contact. Thus, consideration needs to be taken for activities that involve direct contact with affected areas, such as wrestling.
Fungi can also cause other common skin infections. The rash of tinea pedis or athlete’s foot usually involves the areas between the toes. One can see a scaly or bumpy red rash and it can be very itchy. It is common in adolescents and adults but is uncommon in children. What looks like tinea pedis in children may instead be a type of eczema or shoe sensitivity. It may be a reaction to the frequent wet/dry cycle the foot often experiences as it oscillates between the environment of a sweaty shoe and the open air. Tinea pedis is usually diagnosed by the clinical appearance. Lab tests such as those used for tinea corpros can be used in clinically confusing cases.
One of the more frustrating fungal infections to treat is that of the scalp or tinea capitis. It can present in a number of ways. There can be patchy areas of scaling with hair loss or patchy areas of hair loss only with “black dots” representing broken hairs. There can also be soft, tender swellings of the scalp that occur from a hypersensitivity reaction to the fungus. Sometimes this disorder can be confused with other causes of hair loss as well seborrheic dermatitis (also known as “cradle cap” in babies).
The type of fungus varies, depending on the geographic area. In this country most cases are caused by a fungus called Trichophyton tonsurans. The infection spreads person-to-person. Although the fungus can live on objects such as combs and brushes, their role in spread is unclear. This condition is most common in children between the ages of three and nine years, and is more common in black children.
There are a number of tests that can be used to establish the diagnosis that involve testing scrapings from the scalp and broken hairs. Some kinds of fungus, excluding tonsurans, will fluoresce under a special light called a Woods lamp.
Topical anti-fungal creams are not helpful in treating tinea capitis. Children must receive oral anti-fungal medication, usually from four-to-six weeks. During that time, they may need blood testing to ensure that they are not having any adverse reaction to the medication. In order to limit the spread of the infection, parents can also use a selenium sulfide shampoo, such as Selsun Blue, while awaiting full resolution. Children being treated for tinea capitis can return to school as long as they are using such a shampoo to limit spread. Hair brushes and combs should not be shared.
As for the five-year-old patient, her mother was quite relieved to find out her child just had a simple fungal infection of the skin. She was happy to learn that there was no worm in ringworm.