HYPERSENSITIVITY REACTION TO DUST MITE IMMUNOTHERAPY FOLLOWING SHELLFISH INGESTION

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<h3>Introduction</h3> Immediate hypersensitivity reactions are an occasional side effect of allergen immunotherapy. Patients develop severe allergic symptoms within half-hour after receiving allergen immunotherapy. Symptoms range from mild, local to severe systemic reaction. Patients with House Dust Mite (HDM) allergy can be sensitized to shrimp due to the phylogenetic similarity attributable to tropomyosin. We report a patient who developed anaphylactic symptoms from HDM immunotherapy correlated with shrimp ingestion hours prior to receiving immunotherapy. <h3>Case Description</h3> A 35 year-old male asthmatic with allergic rhinosinusitis, tested positive for Dermatophagoides farinae and D. pteronyssinus, was started on Subcutaneous Immunotherapy (SCIT) for HDM. Following routine buildup, he received appropriate maintenance dosage every three weeks for 1.5 years with excellent symptom control. However, on three occasions, he developed systemic symptoms within 30 minutes post-immunotherapy, developing acute shortness of breath, widespread urticaria, itching, and light-headedness. He was treated appropriately. Questioning revealed that the SCIT reactions coincided with days the patient had eaten shrimp earlier. Skin-testing to shellfish was mildly positive to shrimp and negative to other crustaceans. Patient was advised to avoid ingesting all crustaceans on the day of immunotherapy. Subsequent three years on immunotherapy have been without incident. <h3>Conclusion</h3> <b>:</b> Among patients receiving HDM immunotherapy, it may be prudent to avoid cross-reactive foods like shellfish due to increased likelihood of allergic reactions to synergistic allergens. This expression is also likely during sublingual immunotherapy for HDM. We suggest evaluating crustacean allergy status for all patients contemplating HDM immunotherapy, and avoiding ingestion of crustaceans the same day as treatment, to forestall potential hypersensitivity reactions.