dermatophytoses

Dermatophytoses, also known as tinea or ringworm infections, are common fungal infections caused by keratinophilic dermatophytes of the genera Trichophyton, Microsporum, and Epidermophyton. These organisms invade keratinized tissues—skin, hair, and nails—producing pruritus and often annular, scaling lesions. Infections are typically named by site: tinea capitis (scalp), tinea corporis (body), tinea faciei (face), tinea pedis (foot), tinea cruris (groin), and tinea unguium (nails).

Transmission occurs by direct contact with an infected person or animal or via contaminated objects and surfaces. Risk factors include warm, moist environments, occlusive footwear, participation in contact sports, diabetes or immunosuppression, and seasonal or geographic factors. Dermatophytoses are generally superficial, confined to the stratum corneum, with the fungus requiring keratin for growth.

Diagnosis is clinical and supported by microscopy of skin scrapings or nail clippings treated with potassium hydroxide to reveal hyphae. Fungal culture can identify the species but is slower. Wood's lamp examination may reveal fluorescence for some Microsporum species, but it is not definitive.

Treatment is guided by site and extent. Localized skin infections typically respond to topical antifungals (azoles such as clotrimazole or miconazole; allylamines such as terbinafine) for several weeks after clinical resolution. Widespread disease, tinea capitis, or onychomycosis often requires systemic therapy, with terbinafine or itraconazole as common first-line options. Treatment duration varies by site and agent.

Prevention focuses on keeping skin dry, avoiding sharing personal items, wearing breathable footwear, and addressing animal contacts when zoonosis is suspected. Recurrence is common after stopping therapy, underscoring adherence to prescribed courses.