A case of anaphylaxis caused by landlocked ayu fish, koayu fish, from Lake Biwa

Abstract

A 28-year-old man was transferred to our emergency room for dyspnea and wheals on the entire body. He had eaten landlocked ayu fish (Plecoglossus altivelis) the so-called “koayu fish”, from Lake Biwa, and had immediately experienced a stomachache. Wheals and dyspnea developed one hour later and were successfully treated with intravenous corticosteroids. The patient was examined for koayu fish and related allergens by skin prick and allergen-specific immunoglobulin E (IgE) (ImmunoCAP®) tests. Positive skin prick results were obtained for Lake Biwa koayu fish (raw and heated) as well as for standard skin test allergens (prepared by Torii pharmaceuticals) including shrimp, crab, and squid. Negative prick test results were observed for regular ayu fish and other fish such as horse mackerel, sardine, salmon, mackerel, codfish, and tuna. Allergen-specific IgE tests (ImmunoCAP®) showed positivity for shrimp, crab, ticks, moths, and mosquitoes, while ImmunoCAP® tests were negative for the allergen components rGad c 1 (pollackparvalbumin) and rPen a 1 (shrimp tropomyosin). Moreover, enzyme-linked immunosorbent assay (ELISA) tests were negative for mackerel parvalbumin and collagen. We considered this case to be of anaphylaxis caused by koayu fish from Lake Biwa and speculated that a novel koayu-specific antigen might have been the cause of the condition.