Abstract
The house dust mite has been incriminated as a major allergen of house dust in respiratory allergic diseases. Surveys were undertaken to study the mite fauna in house dusts collected from the residence of asthmatic as well as of non-asthmatic children living in and around Tokyo. House dusts were collected by electric sweeper for a week and stored in a deepfreezer until the observation. Mites were isolated from the fine dust caught on a 200 mesh sieve by flotation and centrifugation method with Darling's solution (equal volume of glycerin and saturated sodium chloride solution). Of 24 samples collected in summer, number of mites varied greatly and the average number was 499 in 0.5g of fine dust or 133 per square meter of floor. As to the mite fauna, Pyroglyphidae constituted 85%, Tyroglyphinae 3.1%, Glycyphaginae 1.3%, Cheyletidae 2.8%, Tarsonemidae 0.7%, Mesostigmata 1.3%, and Oribatei 4.4%. Among Pyroglyphid mites, Dermatophagoides pteronyssinus constituted 36% and D. farinae 39% but no significant difference was noted statistically as to the dominancy between the two. Of 9 cases, seasonal change of mite fauna was studied. The number of mites decreased in winter but no statistical difference was found among seasons. Neither the changes in dominant species were noted. Eleven control dust samples were collected from houses without asthmatic patients but no significant difference was noted in number of mites or density per square meter from those observed in the residences of asthmatic children. Mite fauna was also similar to that in the asthmatic houses.
