新築家屋, 一般家屋での室内塵ダニ類の季節変動について

Abstract

Surveys of house dust mites were carried out during a period from December 1974 to January 1976 in two households in the suburbs of Tokyo, one in a newly buit concrete apartment house, and another in a nine year old wooden Japanese style house. Both had the rice straw mats (tatami) as the floor material. The mites were isolated from dust collected with a vacuum sweeper at monthly intervals. The dust samples were sieved first with a 9 mesh and a 200 mesh sieve, and fine dust on the 200 mesh was collected and weighed; 0.5g of the fine dust was transferred to a 100ml beaker, sstirred in 50ml of Darling's solution (mixture of equal amount of glycerine and saturated sodium chloride solution in water) for 10min, and was centrifuged for 5 min at 300 r.p.m. The supernatant containing mites were filtered with a Buchner filter, and the mites on the filter papers were collected with a needle under a stereomicroscope. The recovery rate of mites from house dust with this centrifugation and floatation method was estimated to be about 80% of the total mites contained in the original materials. The house dust collected from the new straw mat surface in December 1974 before the apartment house was inhabited contained large numbers of Tyrophagus putrescentiae and Glycyphagus destructor and also small numbers of Tydeus sp. and Tarsonemts sp. These mite species are considered to be breeding in the straw materials. On the other hand, mites of the family Pyroglyphidae, especially Dermatophagoides farinae and D. pteronyssinus began to appear from about one month after the family moved in the house, reached a peak in July at the end of the rainy season and in the beginning of summer. The increase in the predatory mites of the family Cheyletidae and of Mesostigmata occurred after this in September or October. The total number of mites isolated from 14 dust samples collected at monthly intervals from the old Japanese style house was 17,142 and more than twice larger than that of the new apartment house. The most abundant was Dermatophagoides pteronyssinus (48.0%), followed by D. farinae (33.8%) : The seasonal density of the seven groups of mites was shown in a table; the peak density of Dermatophagoides was seen also in July.