Some of the dermatophyte species can also produce perforating organs in the hair shaft. The dermatophytes present in the soil start invading the hair and produce colonies using hair as the substrate, showing their affinity for the hair.

The ability of the dermatophytes to grow on the hair can easily be demonstrated by the hair bait technique, which involves placing the sterile (acetone treated and dried) hair in a Petriplate containing soil. The dermatophytes causing trichomycosis may be anthropophilic (human), zoophilic (animal) or geophilic (soil). Trichomycosis of the animals, although not described here, is also important because of the spread of infection to human and other animals and because the infected hide could be one of the causes for considerable economic loss in leather industries. Finally, hair infection has been suggested to be the portal of entry for deep mycosis due to dermatophytes. There may be infection of the siblings and schoolmates in residential schools, especially with tinea capitis, and endemicity of the infection in Chennai has also been reported. Vellus hair infection in sites other than the scalp may also give rise to recurrent episodes of infection and may maintain chronicity.

The antigens of these fungi can induce severe inflammation, which may disable the persons. Human trichomycoses cause great concern due to the cosmetic problem of loss of hair. This field of trichology is gaining importance because of the following facts. Trichomycoses by definition are diseases of the hair caused by fungi.

Causes translucent nails