In vitro diagnosis of farmers' IgE-mediated allergy by Phadiatop and three new multiallergen RAST analyses.

Identification of persons with atopic allergy in a population is difficult if the pattern of sensitizing allergens is unique. Three new multiallergen tests, Professional Allergy Mixes (PAX) 1-3 (Pharmacia Diagnostics, Uppsala, Sweden), have recently been introduced to screen IgE-mediated allergy among farmers. PAX 1 contains animal danders and feathers, PAX 2 mites and insects, and PAX 3 pollens and molds. The value of these new tests for the determination of IgE-mediated allergy among farmers was compared with that of Phadiatop, a test for general atopy. Of 440 farmers, 91 were positive to Phadiatop and 97 to any of PAX 1-3. None of the farmers were positive in all tests. Only 70/97 sera positive in RAST to PAX 1-3 had a positive Phadiatop, whereas of 91 sera positive in Phadiatop, 70 had specific IgE antibodies to PAX 1-3. The value of using either Phadiatop or PAX 1-3 is limited (sensitivity 74-79%), but, together, these four tests will detect almost all (95.9%) farmers with IgE-mediated sensitization and all (100%) with symptoms. We have also shown that the grain weevil Sitophilus granarius and the botfly Gasterophilus intestinalis are important sources of allergens in rural environments.