The “other” shrimp allergy

Published Online: November 7, 2015

Allergic reactions to shrimp typically begin minutes following ingestion, and include symptoms such as hives, swelling of the lips, tongue and throat, wheezing, vomiting, and, possibly, anaphylactic shock. Patients with this classical form of shrimp allergy have positive skin test reactions and possess IgE antibodies to shrimp proteins. In a recent issue of The Journal of Allergy and Clinical Immunology: In Practice, Gleich et al report that classical shrimp allergy is only part of the story.

The investigators were conducting a study to evaluate immune responses against purified shrimp allergens, and 38 patients with reported allergy to shrimp participated. These patients had responded to a series of advertisements posted by the University of Utah. A history and physical examination was performed, the patients underwent skin testing and a blood specimen was obtained.

Most of the patients (79%) gave histories of immediate reactions to eating shrimp, typical of classical allergic reactions. Surprisingly, however, 21% described a different type of adverse response to shrimp.  They were able to eat shrimp, initially enjoying the meal. Later, usually after 1-2 hours, they became ill with nausea, vomiting, abdominal pain and diarrhea that lasted for hours and, in some patients, as long as two days. The reaction was reproduced each time they ate shrimp. In contrast to classical shrimp allergy, they did not react on allergy skin testing and did not possess IgE antibodies to shrimp extracts. In addition to shrimp, these patients described the same non-classical reactions to crab, scallop, mussel, abalone and lobster.

These findings indicate that a surprisingly large subset of patients with “shrimp allergy” may suffer from a heretofore unappreciated reaction or “other allergy” that differs strikingly from classical shrimp allergy. The symptoms these patients reported resemble those of infants with food protein-induced enterocolitis syndrome (FPIES). FPIES is usually triggered, in infants and children, by milk, soy, oat or rice and the mechanism for the reaction is not fully understood. The occurrence of these FPIES-like reactions in adults may provide an investigative window to probe the mechanisms of FPIES in children.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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