Common occurrence in Toyama of bronchial asthma induced by chironomid midges.

A total of 119 asthmatic children were investigated by prick tests for the hypersensitivity against chironomid antigens. The percentages of cases who showed positive prick tests to the antigens of the adults of Polypedilum kyotoense, Chironomus yoshimatsui and Tokunagayusurika akamusi, that of the larvae of Tokunagayusurika akamusi and of Dermatophagoides farinae were 23.5%, 17.6%, 7.6%, 16.0% and 94.2%, respectively. The correlations among the wheal size in prick test, the threshold dilution in the intradermal test, the RAST score, and the result of the provocation test were significant. The specific IgE antibodies against two additional midge species were measured with the Phadezyme RAST test in a total of 27 asthmatic cases who were positive to either of the 3 adult midge antigens previously tested. RAST was positive in 59.3% with Chironomus plumosus and 100% with Tanytarusus oyamai. In the RAST inhibition tests, the Polypedilum kyotoense antigen causing allergic reaction was shown to be quite independent from Dermatophagoides farinae. These results suggest that the extracts of chironomid midges have strong allergenicity, and are one of the important inhalant antigens causing asthma in Toyama.