What are the natural causes of fungus?

Fungal diseases are most often caused by a person breathing in or otherwise coming into contact with a fungus that is prevalent in the environment. According to the Centers for Disease Control, there are 1.5 million types of fungi in the world and 300 of those can make people sick.

Fungi live everywhere, in the soil, on plants and trees and even on human skin. Common diseases caused by a fungus are ringworm, fungal eye infections, candidiasis and histoplasmosis.

Fungi cause problems because they thrive in warm, moist environments and may enter the body through tiny cuts on the skin or when breathed in, according to the Mayo Clinic.