HOUSE DUST MITES IN SWITZERLAND

The allergenic properties of the nine mite species prevalent in the house dust of northwestern Switzerland (Basel and surroundings) were studies. For the preparation of mite extracts, the average weight of each species was first determined and then the number per culture glass counted. Thus the extracts were prepared according to the weight of the mites. They were tested on 115 patients with ashma and/or rhinitis. Tests with patients own house dust and with a human dander/yeast mixture, which served as culture medium for the mites, were carried out simultaneously. Test results were either positive or negative for all substances in 93 patients (80 per cent). Dermatophagoides pteronyssinus, D. farinae and Euroglyphus maynei caused the most frequent and most severe reactions. The species Glycyphagus destructor, G. privatus, Chortoglyphus arcuatus, Gohieria fusca, Tyrophagus putrescentiae and Acarus siro seem to play a less important role, if any, in house dust allergies.