Please Read This Definition First
Cross reactivity: allergic symptoms caused by similar proteins. The source of the proteins do not have to look like one another to be alike chemically 1
. Example: Birch tree pollen - apples or bananas. Some people's immune system recognises these as the same allergen. Other examples are bird feathers and egg yolks or shrimp and mites/insects. It has been known for some time that allergens of the house dust mite (European and American) cross-react with allergens of storage mites. House dust mites have evolved to live on discarded skin scales, mould and general organic debris, while its close relative, the storage mite can be found in barns, stored grains and mouldy environments. The storage mite, living mainly on plants, moulds and micro-organisms, is a vegetarian in comparison with the skin-eating house dust mite. 2,3
In spite of their different diets both mites, just like humans, have to break down digested fats in order to absorb nutrients.4The house dust mite has evolved to digest animal fats while the storage mite digests fat from plants. Although these mites have different diets, they share the same enzymes to dissolve fats in food. Sadly, for some of us, these shared enzymes are among the allergens that cause asthma and rhinitis.5 The lesson here is important: People who are allergic to house dust mites may also be allergic to the storage mite.
Some scientists prefer to call these mites domestic mites as they can be found in our homes and work places if the conditions are right. Those allergic to mites should learn to avoid their company and the symptoms for asthma or rhinitis may improve.
Please remember - man has been living with mites for 10,000 years. They are important as scavengers and we actually need them, but we must not encourage them to breed out of control in our homes or work places.6 Domestic mites can be discouraged by limiting their food source and lowering humidity. Stored grains should be kept in sealed bags or in the freezer. Good ventilation in the office/home is a key element. Beds should be aired to allow overnight perspiration to evaporate. Don't make them in the morning - that's an order! References: 1. Ortolani C. et al. 'Diagnostic problems due to cross-reactions in food allergy' Allergy, 1998,
(Suppl 46) 53: 58-61
2. Feather IH, Warner JA, Holgate ST, Thompson PJ & Stewart GA. 'Cohabiting with domestic mites', Thorax, 1993 48:5-9
3. Warner A, Bostrom S, Moller C, Kjellman N.I.M, 'Mite fauna in homes and sensitivity to house dust mite and storage mite: Allergy, 1999, 54, 681-690
4. Nigel Plummer PhD, Dietary Fats and Fatty Acids in Human Healthcare. BioMED publications Ltd. 16 Oak Grove, Harborne, B32 2HR, England
5. Rhinitis, Management Guidelines, Third Edition, 2000, British Society for Allergy and Clinical Immunology - ENT Sub-Committee, ISBN: 1 85317-969-8
6. Colloff M, J. of Clinincal Immunoassay; 'Differences between the allergen repertoires of house-dust mites and stored-product mites',16,No.2,1993
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