Predominance of mite allergy over allergy to pollens and animal danders in a farming population.

The prevalence of IgE-mediated hypersensitivity to respiratory allergens, including Lepidoglyphus destructor (a storage mite) and Dermatophagoides pteronyssinus, was studied in a rural population of Gotland, a Swedish island in the Baltic Sea. A sample of 440 farmers underwent examination, comprising skin-prick tests (animal danders, pollens, moulds, house dust mite and wheat) and blood sampling for radio-allergosorbent tests (RAST) (birch, Timothy grass, dog, D. pteronyssinus, Cladosporium and L. destructor). The highest prevalence of positive skin-prick tests was noted for D. pteronyssinus (6.0%). Low prevalences of positive skin-prick tests, 0.7-2.7%, were found for pollens, animal danders and moulds. Among the tested allergens, D. pteronyssinus and L. destructor yielded the highest prevalences of positive RAST results, namely 5.2 and 6.8%, respectively. Most farmers with allergy to pollens and animal danders had symptoms both from the upper and lower airways and from the eyes. Among farmers with both asthma and rhinoconjunctivitis, the prevalence of positive RAST results for L. destructor and D. pteronyssinus were simiar. The present study clearly demonstrates that mites are by far the most important allergens in the farming population on Gotland, whereas otherwise common allergens such as pollen and animal danders are clearly less significant.