Observation of growth of pupils and changes in positive rate of scratch test in the same growps of subjects in Shiraoicho, Hokkaido

Comparison of data in years of 1989, 1990, 1992, 1993, 1995 and 1996

Abstract

Changes in the positive rate of a scratch test with aging were examined in the same students who all underwent a collective physical exmination and a relevant scratch test in the years of 1989, 1990; 1992, 1993 and 1995, 1996 in Shiraoicho, Hokkaido. The subjects consisted of first graders at an elementary school in 1989, 1990 who were then in the fourth grade in 1992, 1993, and in the first yeat of junior high school in 1995, 1996. The comparison of scratch test results in the years of 1989, 1990; 1992, 1993; and 1995, 1996 in the same groups of students showed that the positive rate increased significantly. The increase in the positive rate of the scratch test as the students aged is considered to be due to the duration of the period during which the students were exposed to the allergen. Main allergen, house dust and mite, are increasing recently in Japanese houses. That increased also the duration and period of exposure to the students.