Mealworm asthma: clinical and immunologic studies.

Mealworms are larvae of the Tenibrio molitor (Tm) beetle and are widely used as fishing bait. Four of five bait handlers in a warehouse who were exposed to particulates of Tm exoskeletons reported immediate-onset asthma, rhinitis, or contact urticaria while unwrapping and packaging the larvae. Positive cutaneous prick tests to Tm extract were detected in all four symptomatic workers. Specific IgE against Tm antigens of 14.6% and 22.5% were found by the RAST method in the two workers with Tm-induced asthma. Specificity of Tm-IgE binding was confirmed by RAST inhibition of 73%, 58%, and 37% by 2 X 10(-1), 2 X 10(-2) and 2 X 10(-3) dilutions of Tm antigen. No significant inhibition of Tm-IgE binding by mite and cockroach antigen or by extracts of three other larval species of the Diptera and Lepidoptera orders, to which the workers were also exposed, was detected. Bronchial provocation challenge with Tm antigen performed in the two workers with asthma exhibited an immediate fall in FEV1 of more than 20% at provocation-dose dilutions of 2 X 10(-3) and 2 X 10(-5), respectively. In the latter worker, pretreatment with disodium cromoglycate inhibited the bronchial response to 2 X 10(-4) dilution of Tm antigen. This study demonstrates that inhaled particulates from Tm exoskeletons are potent sensitizers and elicit IgE-mediated occupational asthma. Allergenic cross-reactivity between orders of insects was not observed. This occupational setting serves as a model for the prospective study of insect allergy.