Computer illustration of fruiting bodies (conidiophores) and hyphae of the fungus Aspergillus fumigatus. A. fumigatus is a widely distributed saprophyte which grows on household dust, soil, and decaying vegetable matter, including stale food, hay and grain. Humans and animals constantly inhale numerous conidia of this fungus. A. fumigatus can cause a number of disorders in people with compromised immune function or other lung diseases, including allergy and the serious lung disease aspergillosis. This fungus can also spread to the brain, kidneys, liver and skin.