The majority of athlete’s foot cases are caused by a variety of fungi all belonging to a group called dermatophytes, which also causes jock itch and ringworm. The fungi thrive in closed, warm, moist environments and feed on keratin, a protein found in hair, nails, and skin. Rarely, athlete’s foot can be caused by non-dermatophytes, like yeast (candida).
Athlete's foot is mildly contagious. It can be spread through direct contact with the infection and by skin particles left on towels, shoes, or floors.
Walking barefoot may increase your chance of contracting athlete's foot. The risk of developing athlete's foot can also depend on your susceptibility. For example, people who have impaired immune systems or diabetes are at greater risk.