My six-year-old girl lost a patch of hair about 2.6 inches across six months ago. The doctor said she had ringworm. I treated her with an antifungal cream and it did not go away. They sent me to a dermatologist, who did a culture and that came back Microsporum canis. He gave her Lamisil. It got extremely worse. She has a third of the left front part of her head covered in it. How serious is this, and what is the best way to get this under control?

Christina

Ringworm is a fungal infection of the skin. It can be caused by a variety of dermatophyte (skin fungi) species. Depending on the species, some of these infections spread person-to-person, while others can be acquired from animals. Microsporum canis is the most common dermatophyte arising from animals, specifically dogs and cats.

Ringworm can affect any area of skin, typically appearing as a round scaling area with a raised edge, with a variable amount of redness. In some cases, the patient's main complaints are itching and the appearance of the lesion itself. In scalp ringworm, however, hair loss in the affected areas is the symptom that most distresses the patient and/or the patient's parents. Ringworm involving the scalp, called tinea capitis, is seen almost exclusively in children. When it is caused by dermatophyte species that spread by person-to-person contact, it can be very contagious. Although this infection usually resolves without treatment, this does not occur until puberty -- clearly too long to wait in most cases. With treatment, however, the lesion completely disappears over time, and the hair grows back completely.

Ringworm in areas other than the scalp is treated with topical antifungal creams, which are available in a variety of formulations that are safe and very effective. Ringworm in the scalp, however, usually requires oral medications. There are several oral agents that can cure this infection. Griseofulvin (Fulvicin), which has been the standard treatment for this scalp ringworm, is given daily for four to six weeks or longer. This drug can cause some side effects, but it is usually well tolerated. Two newer drugs, itraconazole (Sporanox) and terbinafine (Lamisil), which are often used for nail fungal infections, are also effective. They are sometimes used in children, but the ideal dosage regimen is not known.

What you should do is ask your daughter's physician whether griseofulvin is a good choice in her case. I think that it is more accepted than Lamisil for the treatment of scalp ringworm in children, and it should be effective. Sometimes an over-the-counter or prescription antifungal shampoo is given in addition to the oral drug to resolve the infection more quickly.