Athlete’s foot is caused by a group of diseases known as tinea. Athlete's foot is caused by a number of different fungi, including species of Trichophyton, Epidermophyton, and Microsporum. Infection occurs after someone comes into contact with infected skin or fungus in the environment. Jock itch is caused by a fungus called Tinea cruris. Ringworm is caused by Trichophyton, Microsporum, and Epidermophyton. These fungal infections are all caused by fungi that thrive in warm, dark, moist environments and can all be found in your local locker room and gym.