The immune system is a set of chemical and cellular responses that attack disease-causing organisms and help prevent their growth. A number of factors can depress this system. A depressed immune system less effectively fights off all types of infection. Thus a fungus that normally would be controlled by the immune system may begin to grow. Environmental Factors Fungi require moisture to grow and reproduce.
Fungal infections are more prevalent in warm, moist areas of the body, such as the mouth and vagina.
Also, sweaty clothes and shoes can enhance fungus growth on the skin. Exposure to fungi is more frequent in communal areas with moisture, such as locker rooms and showers. Some people seem to have a genetic predisposition toward fungal infections. They may contract infections more easily than others exposed to the same conditions. Whether this is due to differences in immune response, skin chemistry, or other factors is not known.