Aspergillus fumigatus is a fungus of the genus Aspergillus, and is one of the most common Aspergillus species to cause disease in immuno-compromised individuals.
A. fumigatus is a saprotroph (an organism that gets its energy from non-living organic matter) that is widespread in nature, typically found in soil and decaying organic matter. Colonies produce thousands of minute grey-green conidia (2–3 μm) that readily become airborne.
Its spores are ubiquitous in the atmosphere and it is estimated that everybody inhales several hundred spores each day; typically, these are quickly eliminated by the immune system in healthy individuals.
In immuno-compromised individuals the fungus is not eliminated appropriately, causing disease, commonly pulmonary aspergillosis.