Host- and pathogen-dependent susceptibility and predisposition to dermatophytosis

Dermatophytes are a highly specialized group of keratinophilic and keratinolytic filamentous fungi causing a ringworm disease called dermatophytosis or superficial mycoses. Although dermatophyte infections do not threaten the host's life, they lower its quality in humans by causing discomfort related to cosmetic problems and through their epidemiological significance, whereas in farm animals they are responsible for economic losses and constitute a source of the spread of spores. Evidence from countless observational studies that have been conducted over the last 90 years indicates that dermatophytes infect humans of every age, race, gender and socioeconomic status with strikingly high rates, as well as both farmed and wild animals in various health conditions and with various epidemiological statuses. However, the prevalence of superficial fungal infections is highly variable, since it depends on several parameters associated with the infected individual and the dermatophyte, their mutual interactions, and epidemiological and geographical factors. The curious disparity in dermatophyte infection patterns has prompted many investigators to search for a link between the host, the host's predispositions and susceptibility to the disease, and the dermatophyte species and virulence. Thus, the question arises as to whether, in addition to the generally recognized factors predisposing hosts to diseases, there are some other predispositions to dermatophyte infections in a species-specific host. In this review, we describe recent findings about the mechanism of dermatophyte infections, focusing on the adaptation of the fungi to the host and conditions predisposing each side to the disease.