Fungal Skin Infections that infect the skin are what cause fungal or fungal infections. They are common, infectious diseases that are treatable with the right care. Fungi are microorganisms that often thrive in warm, humid climates. Because of this, many mycoses are typically contracted in public locations like swimming pools, showers, or locker rooms, which are frequently used by a large number of people and have the necessary levels of heat and humidity.