Athlete's foot, also calle Tinea Pedis, is a parasitic fungal infection of the epidermis of the human foot. The term "athlete's foot" refers to the disease and not the organism (fungus) that causes it. Several different fungi, called dermatophytes, can cause tinea pedis. Moreover, a fungus species that causes athlete's foot can also cause, for example, jock itch (tinea cruris). It is typically caused by a mould (but in some cases a yeast) that grows on the surface of the skin and then into the living skin tissue itself, causing the infection. It usually occurs between the toes, but in severely lasting cases may appear as an extensive "moccasin" pattern on the bottom and sides of the foot. The malady more commonly affects males than females. Tinea pedis is estimated to be the second most common skin disease in the United States, after acne. Up to 15% of the U.S. population may have tinea pedis.