Clinical Aspects of Dermatophyte Infections

Infections caused by dermatophytes are termed dermatophytoses, tinea or ringworm. They are among the most common and widespread endemic infectious diseases (Rippon 1988; Kates et al. 1990; Odom 1993; Gupta et al. 2003). In some geographic areas or environments more than 30% of the population is affected (Rippon 1985; Noguchi et al. 1995). Therefore, dermatophytoses pose a considerable worldwide health problem. In most cases dermatophytoses in humans remain superficial infections, restricted to the skin, nails, and hair (Ogawa et al.1998). These infections often lead to skin lesions, which are uncomfortable but not lifethreatening. However, infections of deeper structures like subcutaneous soft tissue can occur under conducive conditions. The relationship between the pathogen and the human host depends very much on the species of dermatophyte involved and on the patient’s immunocompetence, general health, and living conditions. Dermatophytoses provide a fascinating model for the interaction between highly specialized fungi and host defense. Because the skin is uniquely accessible to examination with the naked eye, a trained observer can examine this fungal battlefield without additional technical devices.

In the following chapter, after a short look at the dermatophytes as medically important fungi, some of the known mechanisms involved in dermatophyte infections are discussed in order to help better understand the development and pathogenesis of dermatophyte infections. The clinical aspects of the most common and characteristic types of dermatophytoses (or forms of tinea) are covered, followed by a review of their epidemiological aspects. Finally, general principles of treatment are described.