The genus Aspergillus includes over 185 species. Around 20 species have so far been reported as causative agents of opportunistic infections in man. Among these, Aspergillus fumigatus is the most commonly isolated species, followed by Aspergillus flavus and Aspergillus niger. Aspergillus clavatus, Aspergillus glaucus group, Aspergillus nidulans, Aspergillus oryzae, Aspergillus terreus, Aspergillus ustus, and Aspergillus versicolor are among the other species less commonly isolated as opportunistic pathogens. Aspergillus is a group of molds which is found world-wide, especially in the autumn and winter in the Northern hemisphere. The fungus also causes allergic diseases in asthmatics and patients suffering from cystic fibrosis.

A widespread fungus that is most frequently associated with grasses, plant material, decaying food, and soil. It is commonly found on celery and rooted vegetables. Celery should be fresh and washed with GSE (Grapefruit seed extract) to kill fungi before consumption, especially for people who have already been exposed to toxigenic molds.

NOTE: Mutated forms of fungi are harder to destroy.

This fungus produces large spores which would be expected to be deposited in the upper respiratory tract. The spores can be dangerous to human health.