STUDIES OF BRONCHIAL-ASTHMA INDUCED BY CHIRONOMID MIDGES (DIPTERA) AROUND A HYPEREUTROPHIC LAKE IN JAPAN

There have been few reports on hypersensitivity to chironomid midges i n bronchial asthmatic patients around the area of hypereutrophic natur al lakes, which have been notorious as an environmental hazard due to the massive occurrence of adult chironomids during several periods of the year. Our study investigated IgE antibodies to chironomid midges i n bronchial asthmatic patients around the Lake Suwa area in comparison with those of the Matsumoto area (control area). A total of 123 adult patients with bronchial asthma were investigated by measurement of Ig E antibodies with extracts of three chironomid midges (Chironomus yosh imarsui, C. plumosus, and Tokunagayusurika akamusi), mite, and silkwor m. In addition, in the allergy testing, 12 common inhalant antigens we re used. Of 123 adult patients with bronchial asthma, 65 (52.8%) produ ced positive allergy tests. Thirty-three (50.8%) were positive to mite , 28 (43.1%) to silkworm, 11 (16.9%) to C. yoshimatsui, eight (12.3%) to C. plumosus, and three (4.6%) to T. akamusi. We compared our result s with the previous reports. The number of positive tests to silkworm in the Lake Suwa area was higher than in other areas. However, C. plum osus and I: akamusi showed a lower number of positive reactions. We co nsidered the lower positive number of C, plumosus and T. akamusi tests in the Lake Suwa area to be related to the advanced age of patients i n this area. The chironomids are an important cause of asthma, togethe r with mite and silkworm, in the Lake Suwa area, but affect old asthma tic patients less than asthmatic children.