Occupational IgE-mediated allergy to Tribolium confusum (confused flour beetle)

Background: We report on IgE-mediated allergy in a worker caused by Triboli um confusum (confused flour beetle). These beetles lived in the "old" flour to which he was exposed in his work. Case report: A 35-year-old, nonatopic mechanic in a rye crispbread factory developed rhinitis, conjunctivitis, and asthmatic symptoms, as well as urti caria on his wrists, lower arms, hands, neck, and face, during the maintena nce and repair of machines contaminated by flour. This flour had been in an d on the machines for a long time, and it contained small beetles. The pati ent did not suffer any symptoms when handling fresh, clean flour. Results: Skin prick tests with standard environmental allergens, storage mi tes, enzymes, flours, and molds were negative. A prick test with flour from the machines gave a 10-mm reaction. An open application of the same flour caused urticarial whealing on the exposed skin. Prick tests with fresh flou r from the factory were negative. A prick test with minced T. confusum from the flour in the machines gave a 7-mm reaction. Histamine hydrochloride 10 mg/ml gave a 7-mm reaction. Specific serum IgE antibodies to T. confusum w ere elevated at 17.2 kU/l. Prick tests with the flour from the machines wer e negative in five control patients. Conclusions: The patient had occupational contact urticaria, rhinitis, conj unctivitis, and asthmatic symptoms from exposure to flour. His symptoms wer e caused by immediate allergy to the beetle T, confusum. Immediate allergy to this beetle has rarely been reported in connection with respiratory symp toms, but it may be more common. Contact urticaria from this source has not been reported before.