A. fumigatus is a type of filamentous mold (ascomycete) that is found all over the world. It is saprophytic and therefore most commonly found in soil (especially compost piles) where it can recycle the Carbon and Nitrogen of deceased organic matter. The mitospores of A. fumigatus are thought to be inhaled several hundreds of times a day by the average person, usually with no consequence. It is, however, the most common species of Aspergillus to cause disease in humans: Holh and Feldmesser state that out of the 200 or so Aspergillus species, less than 20 of them cause human disease, and of those A. fumigatus is by far the most common isolate. This is partly because its spores are so ubiquitous (Gow estimated in 2005 that there were 10 conidia per cubic meter of air), but mostly because immunosuppressive treatments are more common now than ever before. This is true of treatments like chemotherapy, organ transplants, bone marrow transplants, high doses of corticosteroids (used to prevent and treat graft-versus-host disease), and
. A. fumigatus cannot be transferred from person to person or between different animal species.
Jeremy Knoble (
Emily Malkin II
Following modified from Taiwan Biodiversity National Information Network