Occupational Allergy to Aquarium Fish Food

Background: Chironomids seem to be the main cause of occupational allergy to aquarium fi sh food. Objective: The aim of this study was to investigate the pattern of occupational sensitization to 3 different arthropod species used as components of aquarium fi sh food. Methods: The study sample comprised 8 workers from a fi sh food packing department. The control group comprised 40 atopic patients (20 of whom were allergic to mites). We performed prick tests with extracts of red midge larva (Chironomus thummi), freshwater shrimp (Gammarus species), earthworm (Tubifex species), and other arthropod species and a battery of common inhalant allergens. We measured peak expiratory fl ow rate (PEFR) and specifi c immunoglobulin (Ig) E and performed a methacholine challenge test, nasal challenge test, and immunoblotting. Cross-reactivity analyses were completed using immunoblotting and CAP inhibition. Results: Prick test results were positive to red midge larvae in 7 patients (87.5%), Gammarus in 5 (62.5%), Tubifex in 3 (37.5%), and mites in 6 (75%). In the mite-allergic controls, 30% had positive prick test results to red midge larvae. PEFR decreased 20% during the packing process in all patients, and in 1 patient it indicated a dual asthmatic response. Methacholine challenge test results were positive in all participants. Nasal challenge tests were performed in 4 patients, and the results were positive. Specifi c IgE to red midge larvae was detected in 62.5%, Gammarus in 50%, and Tubifex in 16%. Bands of approximately 14-15 kDa and 31 kDa were observed in Gammarus and red midge larvae extracts. Cross-reactivity assays demonstrated that Gammarus totally inhibited red midge larvae, while Tubifex did so partially. Dermatophagoides pteronyssinus showed very low inhibitory capacity. Conclusions: Aquarium fi sh food arthropods are potent allergens with an elevated prevalence of sensitization and variable degree of crossreactivity. This is the fi rst report of occupational allergy to Tubifex. More data are necessary to identify and characterize the responsible allergens.