Survey on negative impact of chironomid midges (Diptera) on bronchial asthmatic patients in a hyper-eutrophic lake area in Japan.

Chironomid midges have been revealed to be a hazardous inhalant antigen of bronchial asthma. To determine the awareness of the negative impact of chironomid midges (Chironomus plumosus and Propsilocerus akamusi) among patients, a questionnaire survey of 118 patients in the Lake Suwa area and in the Matsumoto area was conducted from early September to mid-November of 1993. The life style was almost the same among the asthmatic patients in the Lake Suwa area and in the Matsumoto area, but the reactions to the nuisance differed significantly from each other. Although "Flight density" was higher in the Lake Suwa area (p < 0.01) than that in the Matsumoto area, 25.5% of the patients in the Lake Suwa area and 9.1% of those in the Matsumoto area answered "Endurable" (p < 0.01). Further follow-up studies including prick tests, intradermal tests and provocation tests should be conducted for patients who complained a strong allergic reaction.