Fungi infect human skin on its most superficial layer(Stratum corneum)as well as nails and hair.Spread is usually from animals and humans and rarely from soil.Superficial infections affect only 1-2 mm of the superficial skin layer but the deep ones may go down to invade deeper tissues.
Dermatophytosis are much more common in clinical practice.The three common genera are Trichphyton,Epidermophyton and Microsporum,each is further sub devided into species.They digest and live on keratin(a skin protein).Tinea infections have characteristic features depending on the site of infection,hence they are classified according to the part of the body involved,rather than the species or genera.Stating from the top scalp(capitis)beard(barbae)face(faciei)body(corporis)groin(cruris)hands(manum)feet (pedis)and nains(unguium).