Mold

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• Mold spores are far more numerous than pollens in outdoor air. However, since they are much smaller, the total volume of mold spores is approximately equal to that of grass pollens (see ref. 1 for review).
   
• Spore numbers and types change with the time of day, weather, season and geographical location, and may be affected by local sources of spores (see ref. 1 for review).
   
• The importance of molds in causing seasonal allergy is probably underestimated because of the difficulties in standardizing the relevant allergens in the diagnosis, and in the sampling methods to define the relation between disease and exposure (see ref. 1 for review).
   
• The importance of mold genera for sensitization varies greatly between patient groups from different geographic areas (2).
   
• Multiple sensitivities are common (2, 3, 4) and seem to be caused by sensitization to many mold species rather than by cross-reactivity (2) and be related to the abundance of the mold spores in the environment (3).
   
• Sensitization to molds occurs mostly in patients with a high potential for being sensitized to common inhaled allergens, especially house-dust mite and animals (5).
   
• Cladosporium and Alternaria are believed to be the most numerous outdoor mold spores and Aspergillus and Penicillium spp the most numerous indoor mold spores. In winter, when there is less ventilation and especially if the house is damp, outdoor spore types, e.g. Cladosporium and Alternaria increase indoors (see ref. 1 for review).
   
• In a population of 18-73 year old adults (n=1512), the prevalence of specific IgE to molds was 0.2% compared with a prevalence of 3.2% for house-dust mite sensitization (6). 
   
• A restricted RAST-panel of molds (Alternaria, Cladosporium, Aspergillus, Penicillium Candida, and Mucor) detected over 90% of all mold-sensitized asthmatic children in relation to an extending panel with 10 more mold species (Aureobasidium, Botrytis, Curvularia, Epicoccum, Fusarium, Helminthosporium, Phoma, Rhizopus, Stemphylium and Trichoderma) (4).
   
• The most frequent sensitization in asthmatic children to molds (a panel of 16 species) was Cladosporium (28%), Candida (28%) and Helminthosporium (26%). A remarkable degree of simultaneous reactivity to almost all molds tested was observed (4).
   
• The overall incidence of mold allergy in atopic patients in a Midwestern allergy practice was 44%
   
• (Alternaria>Helminthosporium>Aspergillus>Candida>Curvularia) (7).
   
• The prevalence of sensitization to Alternaria varies from 1.8% to 29.3% in different parts of Italy in a population with respiratory symptoms (8).
   
• The frequency of positive RAST for mold allergens was higher in patients with atopic dermatitis and the severity of asthma increased more in mold-allergic individuals compared with atopic individuals without mold sensitization (9).
   
• An association between Cladosporium spore count and weekly asthma symptom scores has been shown (10).
   
• Alternaria is the major allergen associated with the development of asthma in children raised in a semi-arid environment (11).
   
• In one study, positive RAST to molds had a high specificity for patients clinically evaluated as positive for mold-allergic asthma (12).
   
• There is a higher risk of bronchial hyperreactivity in patients sensitized to molds than in those reactive to grasses (13). 
   
• In homes of subjects with asthma-related symptoms, significantly higher levels of bacteria, molds and house-dust mites were found than in homes of subjects with no asthma-related symptoms (14).

References:

1. Lacey J. Fungi and actinomycetes as allergens. In: Kay AB, editor, Allergy and allergic diseases. Oxford: Blackwell Science Ltd. 1997:858-87.
2. Karlsson-Borgå Å, Jonsson P, Rolfsen W. Specific IgE antibodies to 16 widespread mold genera in patients with suspected mold allergy. Ann Allergy 1989;63(6 Pt 1):521-6.
3. Malling HJ, Agrell B, Croner S, Dreborg S, Foucard T, Kjellman M et al. Diagnosis and immunotherapy of mold allergy. I. Screening for mold allergy. Allergy 1985;40:108-14.
4. Koivikko A, Viander M, Lanner Å. Use of the extended Phadebas RAST panel in diagnosis of mold allergy in asthmatic children. Allergy 1991;46:85-91.
5. Iversen M, Dahl R. Characteristics of mold allergy. J Investig Allergol Clin Immunol 1995;5:205-8.
6. Omenaas E, Bakke P, Elsayed S, Hanoa R, Gulsvik A. Total and specific IgE levels in adults: relationship to sex, age and environmental factors. Clin Exp Allergy 1994;24:530.
7. Corey JP, Kaiseruddin S, Gungor A. Prevalence of mold-specific immunoglobulins in a Midwestern allergy practice. Otolaryngol Head Neck Surg 1997;117:516-20.
8. Corsico R, Cinti B, Feliziani V, Gallesio MT, Liccardi G, Loreti A et al. Prevalence of sensitization to Alternaria in allergic patients in Italy. Ann Allergy Asthma Immunol 1998;80:71-6.
9. Iguchi H, Ueda M, Sakamoto T, Yamada M, Torii S. (Study of the frequency and clinical significance of positive RAST for mold allergen in asthmatic patients). Arerugi 1990;39:1388-96.
10. Malling HJ. Diagnosis and immunotherapy of mold allergy. IV. Relation between asthma symptoms, spore counts and diagnostic tests. Allergy 1986;41:342-50.
11. Halonen M, Stern DA, Wright AL, Taussig LM, Martinez FD. Alternaria as a major allergen for asthma in children raised in a desert environment. Am J Respir Crit Care Med 1997;155:1356-61.
12. Malling HJ, Dreborg S, Weeke B. Diagnosis and immunotherapy of mold allergy. III. Diagnosis of Cladosporium allergy by means of symptom score, bronchial provocation test, skin prick test, RAST, CRIE and histamine release. Allergy 1986;4:57-67.
13. Cookson WO, De Klerk NH, Ryan GR, James AL, Musk AW. Relative risks of bronchial hyper-responsiveness associated with skin-prick test response to common antigens in young adults. Clin Exp Allergy 1991;21:473-9.
14. Björnsson E, Norback D, Janson C, Widström J, Palmgren U, Ström G, Boman G. Asthmatic symptoms and indoor levels of micro-organisms and house dust mites. Clin Exp Allergy 1995;25:423-31.

• References