What you’ll learn to do: Identify common fungal parasites and pathogens

Fungi are everywhere. There are millions of different fungal species on Earth, but only about 300 of those are known to make people sick. Fungal diseases are often caused by fungi that are common in the environment. Fungi live outdoors in soil and on plants and trees as well as on many indoor surfaces and on human skin. Most fungi are not dangerous, but some types can be harmful to health.

Parasitism describes a symbiotic relationship in which one member of the association benefits at the expense of the other. Both parasites and pathogens harm the host; however, the pathogen causes a disease, whereas the parasite usually does not. Commensalism occurs when one member benefits without affecting the other. Fungi engage in both these types of relationships with other organisms, but as parasites are responsible for economic and environmental damage, as well as some human diseases.