Effects of mite allergen avoidance in children in two distant towns in Japan

Abstract

We investigated the prevalence of asthma, rhinitis, and atopic dermatitis and evaluated changes in mite allergen levels on mattresses and allergic symptoms in children after allergen avoidance in two distant regions of Japan after the Great East Japan Earthquake. We performed an International Study of Asthma and Allergies in Childhood survey of 49 school children aged 6–10years in Iwanuma in 2017 and 57 school children aged 6–10years in Oiso in 2018, and measured levels of Dermatophagoides group 1 (Der 1) in their bedding. Children in the intervention group attended an allergen avoidance seminar. In the same season the following year, we again measured Der 1 level in bedding and examined changes in allergic symptoms. Children in the non-intervention group did not attend this seminar. The prevalence of asthma, rhinitis, and atopic dermatitis and the types and ages of houses at study entry did not differ between the two towns. At first measurement, the Der 1 level in the intervention group was higher at Iwanuma than at Oiso (P<0.05). The Der 1 level in the intervention group in both towns significantly decreased after implementing allergen avoidance (P<0.01) but did not decrease in either non-intervention group. In each town, symptoms of allergic rhinitis was significantly lower (P<0.05) among children whose Der 1 level were reduced to less than 10% of initial levels. Mite allergen levels in two distant regions in Japan differed slightly. Allergen avoidance ameliorated allergic symptoms in school children.