Dermatophytoses are fungal infections of the skin and nails caused by several different fungi and classified by the location on the body. Dermatophyte infections are also called ringworm or tinea.
Dermatophytes are molds (fungi) that need the protein keratin for nutrition. Keratin is the structural material that makes up the outer layer of human skin. It is also the main structural material of hair and nails. To survive, dermatophytes must live on skin, hair, or nails (a nail infection is called tinea unguium or onychomycosis—see see Onychomycosis). Infection may occur almost anywhere on the skin, including the feet (see see Athlete's Foot), groin (see see Jock Itch), scalp (see see Scalp Ringworm), body (see see Body Ringworm), and beard area (see see Beard Ringworm).
Dermatophyte infections in humans are caused by Epidermophyton,Microsporum, and Trichophyton. These organisms may inhabit a person permanently and never cause an infection. When they do cause an infection (resulting in ringworm or tinea), it is often because the affected area's blood supply is poor or because the person's immune system is suppressed (for example, by diabetes, cancer, or HIV infection). Unlike candidiasis, these fungal infections cannot infect internal organs or blood.
Dermatophyte infections are sometimes called ringworm or tinea. Despite the name, a ringworm infection does not involve worms. The name arose because of the ring-shaped skin patches created by the infection. Symptoms vary depending on the location of the infection. Most often, there is little or no inflammation and the infected areas are mildly itchy with a scaling, slightly raised border. These patches can come and go intermittently. Occasionally, inflammation is more severe and suddenly causes large and small fluid-filled spots to appear (usually on the foot) or an inflamed, swollen patch on the scalp that sometimes oozes pus (kerion—see Kerion).
Doctors can frequently identify a ringworm infection by its appearance. To confirm the diagnosis, doctors take skin scrapings and view them under a microscope. Doctors do a culture (the process of growing an organism in a laboratory for identification) only if the person has a scalp or nail infection.
Treatment varies by site but always involves antifungal drugs that are applied to the affected area (topical) or are taken by mouth.
Last full review/revision June 2013 by Denise M Aaron, MD