<prompt> The major cause of us isM. canisE. floccosumT. rubrumT. schoenlenii  <response>: Favus is a chronic infection caused most commonly by T schoenleinii and usually affecting the scalp. Most common organism associated with us is Trichophyton schoenlenii. E. floccosum- cause Tinea unguium nail beds M. canis- cause ECTOTHRIXinfection of hair T. rubrum- cause Tinea cruris groin area 