Airborne Fungal Diseases
Molds reproduce by releasing spores into the air. The main route of entry of mold spores is through respiration of dust particles contaminated with the fungi. The ubiquitous presence of fungi in both indoor and outdoor environments is a potential health threat that is poorly understood and almost ignored in community medicine.
Many species of fungi around the home grow on food and other organic materials such as damp paper, textiles and wood. Fungi produce allergens, enzymatic proteins, toxins and volatile organic compounds that cause respiratory disease. Various strains of airborne molds have been implicated as the cause of asthma and hypersensitivity pneumonitis. Chronic nose and sinus inflammation have been linked to airborne fungi. Shin et al, for example, demonstrated immune responses to Alternaria by finding elevated levels of IL-5 and IL-13.
Green et al suggested that 100 genera of fungal conidia are currently recognized as sources of allergens, but the real number of fungal allergens is much greater: different components of fungal growth such as fungal hyphae and fragmented conidia are airborne and may become allergenic. Most wild species are not detected by standard culture techniques. In addition, inhaled spores of pathogenic fungi grow in the lung and other organs, establishing chronic and sometimes lethal infections that are difficult to diagnose. There is an overlap of allergic hypersensitivity diseases with infection caused by the fungi that infect by spore inhalation.
Fungi produce toxins that are released into the air. Bünger et al studied five toxigenic airborne moulds of the genera Aspergillus and Penicillium collected at composting plants: sterigmatocystin, fumagillin, verruculogen, penitrem A, and roquefortine C. All five extracts caused toxic effects to cultured cells. They suggested that mycotoxins may be involved in producing the lung diseases from the inhalation of organic dust. Panaccione and Coyle reported finding ergot alkaloids associated with Aspergillus fumigatus. Ergot molds produce an array of potent chemicals. The hallucinogen, LSD, was derived from ergot alkaloids.
Kodama and McGee found sixteen types of indoor airborne fungi. The main species belong to the families: Aspergillus, Penicillium, Cladosporium, Mucor, Stachybotrys, Absidia, Alternaria, Fusarium and Cryptostroma. The greatest health risks are Candida, Aspergillus, Histoplasma and Penicillium. The two most prevalent fungal infections in hospitals are caused by Candida and Aspergillus species. These organisms can occur naturally in the exterior environment and enter as spores or active fungi attached to dust particles.
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