Health Fungal diseases  About fungal diseases . Fungi are everywhere. Sometimes, they are too small to see with the naked eye. Fungi live: Outdoors, for example, in soil and on plants Indoors, on surfaces and in the air On people’s skin and inside the body There are millions of fungal species, but only a few hundred of them can make people sick. Molds, yeasts, and mushrooms are all types of fungi. Fungi can cause many different types of illnesses, including: Asthma or allergies.  Learn more about mold and how it can affect your health. Rashes or infections on the skin and nails Lung infections (pneumonia), with symptoms similar to the flu or tuberculosis Bloodstream infections Meningitis   Most common fungal diseases Fungal nail infections Common infections of the fingernails or toenails. Vaginal candidiasis Caused by the yeast  Candida , also called a “vaginal yeast infection.” Ringworm A common fungal skin infection that often looks like a circular rash. Candida  infections of the mo