Oct 07, 2009 Views: 1261
Allergies and asthma
Atopy is a genetic predisposition to developing certain hypersensitivity reactions such as asthma, hay fever (allergic rhinitis), and food allergies. Allergic reactions to Aspergillus in atopic individuals can be caused by fungal spores in the air and from fungi ingested in food. Airborne spores are readily inhaled when we breathe; they also come into contact with the eyes and other exposed parts of the body. Moulds are involved in the initiation and exacerbation of lower airway diseases such as asthma, although the specific aetiology is poorly understood.
The level of spore inhalation varies enormously with local environmental conditions. Certain environments like compost heaps and barns have unusually high concentrations. Massive exposure, even among individuals who are not allergic or asthmatic, should be avoided because repeated contact with large doses of fungal spores may induce allergic alveolitis, in which a lymphocyte-directed hypersensitivity reaction occurs. Extrinsic allergic alveolitis is not limited to Aspergillus or even fungal spores, but is caused by the inhalation of antigenic dusts. These dusts are rarely if ever composed of one organic substance but tend to be a variable mixture of fungal and actinomycete spores, animal proteins and other organic matter. 'Occupational mycoses' are forms of extrinsic allergic alveolitis They are all inflammatory reactions caused by breathing high concentrations of mould spores and other antigenic organic matter. Some forms of these illdefined human diseases have been associated particularly with exposure to high concentrations of Aspergillus spores, including farmer's lung, malt worker's lung, compost lung and bird fancier's lung. Malt worker's lung, one of the best known of these, is an occupational mycosis encountered during beer manufacture correlated with inhalation of high concentrations of Aspergillus clavatus and A. fumigatus spores from contaminated barley.
Aspergillus: Molecular Biology and Genomics by Masayuki Machida and Katsuya Gomi, Caister Academic Press ISBN: 978-1-904455-53-0