Sensitization to storage mites and other work-related and common allergens among Finnish dairy farmers.

Skin-tests with the prick technique were made on 121 dairy farmers with allergic rhinitis and/or asthma (symptomatic subjects), 64 dairy farmers without respiratory symptoms (asymptomatic subjects), and 26 non-farming controls. The antigen panel consisted of the storage mites Acarus siro, Lepidoglyphus destructor, and Tyrophagus putrescentiae, as well as other work-related allergens (cereal grains, animal epithelia, fungi and yeasts), and common allergens (house dust mite, pollens). Mean areas of weals formed by individual allergens were adjusted by analysis of covariance for age, sex, and atopic background (past or present atopic dermatitis including infantile eczema). Adjusted mean weal areas for almost all allergens, except pollens and few other allergens, were significantly larger in farmers than in non-farming controls. In contrast, only skin reactions to cow dander, to a non-dialyzed crude preparation of fodder yeast Candida utilis, and to Candida albicans distinguished symptomatic subjects from asymptomatic ones. Stepwise discriminant analysis, in which reactions to all allergens as well as age, sex, and atopy were taken into account simultaneously, revealed that reactions to a dialysed preparation of fodder yeast best distinguished symptomatic farmers from asymptomatic ones. C. utilis and C. albicans may be cross-reactive. The results imply that skin tests alone are of limited value in the search for work-related causes of rhinitis or asthma among dairy farmers. Our study confirms the importance of cow dander as an occupational allergen in dairy farming. Fodder yeast seems to be another important occupational sensitizer.