Occurrence of mites in Norway and the rest of Scandinavia.

This paper gives a faunistic review of mites that have been recorded in the indoor environment, particularly homes, barns, and stored products, in Norway and the other Scandinavian countries. Some preliminary results are given from unpublished investigations in Norway. Seven species of pyroglyphid mites have been recorded: Dermatophagoides pteronyssinus, D. microceras, D. farinae, D. evansi, Euroglyphus maynei, Gymnoglyphus longior, and Hirstia chelidonis. D. pteronyssinus was the predominant species, followed by D. microceras in Scandinavia and D. farinae in Denmark. D. evansi was detected in poultry houses in Norway. Lepidoglyphus destructor was the predominant species in barn dust, but large populations of Acarus, Tyrophagus, Tydeus, and Tarsonemidae also occurred. In humid homes, Glycyphagus domesticus was found in high numbers. The result of quantification of mites depends on the method for examination of dust. When one proposes limits for the concentration of mites in relation to risk of allergic sensitization and provocation of symptoms, reference should be made to a well-described method for sampling and analyzing dust. The number of mites should be given per area, not only per weight unit of dust. The number of mites per area indicates the number of mites in the home. The number of mites per weight unit of dust describes the concentration of mites in the vacuum cleaner.