It is often difficult or impossible to identify the source of a particular person's skin fungus. The fungi may spread from person to person (anthropophilic), from animal to person (zoophilic), or from the soil to a person (geophilic). When ring worm is on the feet it's called athletes foot, if it's in the groin area it's called jock itch. It's contagious and while it usually is spread by skin to skin, or skin to soil contact it can also be spread by contact with personal items used by infected people, like, towels, combs, hats, brushes, bed lines can spread the infection. (Ring worm isn't really worms, it's a fungus that can live in the soil, on the skin of animals and people. It forms a crusty itchy circle that resembles the shape of a worm.)