Mites living in hay: an important allergen source?

Fifty-two farmers and 21 non-farmers with symptoms related to hay contact were investigated. Skin prick tests (SPT) and RAST were performed with an extract made of barn dust (BDE) consisting of hay remnants. At microscopy, the barn dust was found to contain large amounts of dead mites, most of them identified as Lepidoglyphus destructor and Acarus siro. Twenty-one patients (9 farmers and 12 non-farmers) had positive RAST or BDE, with a good correlation to the case histories. Other allergies, especially to Dermatophagoides pteronyssinus, pollens, and animal danders were also common among patients. However, there was no correlation between positive SPT and RAST to BDE and any other allergen tested. This indicates that BDE contains distinct allergens, most likely of mite origin.