Tinea capitis is a dermatophytosis of world-wide distribution. Its incidence varies from country to country according to socioeconomic conditions. Tinea capitis is still the most common dermatophytosis in many regions of Africa, and is frequently found in Asia and the US (especially among blacks and Latin American immigrants), while it is rare in several European regions. According to recent Italian epidemiological studies, its relative percentage varies from 6% (observed in Florence) to 21% (reported in Foggia and Cagliari). In Cagliari it is the most common dermatophytosis during infancy and has a relative percentage of 56%. Tinea capitis predominantly, though not exclusively, affects pre-puberal subjects, with a slight bias towards the male sex depending on the etiology. The main etiologic agents may vary according to the dermatophytic flora in the countries involved. The most important etiologic agent in Italy (and in most of Europe) is Microsporum canis, which is equally widespread in Arab countries, in urban areas in Iran, in Mexico and in Brazil. Trichophyton violaceum is the most important etiological agent in Albania, Tunisia, Pakistan and India, while Microsporum audouinii is still the most common cause of tinea capitis in many countries of the so-called black Africa. Finally Trichophyton tonsurans causes endemic centres of infection in most of the US. In recent years in France, Holland and Italy reappearance of Microsporum audouinii and Trichophyton violaceum has been reported as a result of an increased flow of immigrants from Africa. Furthermore the presence of centres of infection of Trichophyton tonsurans in England has been reported. Since the dermatophytic parasitization of hair is closely related to the condition and configuration of hair structures, the pathogenesis of tinea capitis is characterised by two distinct moments: parasitization of the epidermis and parasitization of the hair. Once on the scalp, the fungi reach the orifice of the follicle, enter it and penetrate the hair following the subcuticular route, they multiply in the cortical substance while dissociating and demolishing it. While they advance, the dermatophytes are oriented towards the bulb and extend towards the keratogenous area, which they never invade. A line of equilibrium is thus formed between two opposed, but balanced, forces: hair growth on the one hand and the invasive force of the fungus on the other. The degree and modality of parasitization vary according to the type of fungus. Demolition of the hair substance by Tricophyton schonleinii is very limited and localised, so mechanical resistance. Parasitization by other types of Tricophyton is of the endotrix type and is followed by hair rupture at the follicle opening, while Microsporum cause endotrix parasitization with hairs broken at a few millimetres from the follicle.
|Number of pages||9|
|Journal||Giornale Italiano di Dermatologia e Venereologia|
|State||Published - Jan 1 1999|
- Tinea capitis, epidemiology
- Tinea capitis, etiology
- Tinea capitis, physiopathology
ASJC Scopus subject areas