Der Fang des Tages: Scombrotoxin und Anisakis simplex als Ursache allergieähnlicher Krankheitsbilder

Abstract

Introduction: By the changing attitude of eating habits, increasing import of exotic food into industrialized countries and growing worldwide tourism, also in temperate climate zones, patients with diseases elicited by marine parasites or toxins may be observed. From an epidemiological point of view the most common and important diseases are scombroid or histamine fish poisoning, anisakiasis and ciguatera. Whereas the former two may be also encountered in northern countries, ciguatera intoxications are only observed from tropical sea fish. In all three allergy-like symptoms may occur, they represent, therefore, an important differential diagnosis from IgE-mediated allergic reactions to fish and seafood allergens. Methods/patients: We present five typical cases of scombroid poisoning and a case of anisakidosis, and discuss the characteristics, elicitors, diagnostic criteria and differential diagnosis of these disorders. Results and discussion: Scombroid poisoning is an intoxication from biogene amines that are formed due to inadequate storing and insufficient freezing after the catch. Particularly the odor- and tasteless histamine, possibly together with other substances or cofactors, may induce acute allergy-like symptoms such as flush, pruritus, urticaria and gastrointestinal symptoms. The reaction is self-limiting, it lasts a few hours and it usually results in complete recovery. Anisakidosis or anisakiasis is caused by the fish parasite Anisakis simplex. The acute parasitic infestation of the accidental human host by live parasites results in acute severe abdominal pain, caused by an eosinophilic inflammation in the gastrointestinal wall, which subsides within a few hours after the death of the worm. In sensitized individuals exposure to undercooked fish infested by anisakis elicits allergic symptoms ranging from urticaria, angioedema to dyspnoe and life-threatening anaphylactic shock. Some authors have reported a combination of parasitic and allergic reaction called gastroallergic anisakiasis. Ciguatoxins are lipid-soluble toxins known as ciguatoxins accumulated in the muscles of carnivorous subtropical and tropical fish. Ciguatoxins arise from biotransformation in the fish from gambier-toxins produced by Gambierdiscus toxicus, a marine dinoflagellate that lives on macroalgae in corals. The toxins and their metabolites are concentrated in the food chain when carnivorous fish prey on smaller herbivorous fish. More than 400 species offish can be vectors of ciguatoxins. Symptoms include gastrointestinal, neurological and cardiovascular disturbances, in severe cases paralysis, coma and death may occur. Symptoms subside typically in few days but may persist for months or years, or recur periodically. In the differential diagnosis toxins from seafood such as saxatoxin and brevitoxin have to be considered. Conclusions: In patients with suspected allergic symptoms after the consumption of fish or seafood, the differential diagnosis should include disorders from marine toxins or parasites, which may elicit allergy-like symptoms and signs. This permits an exact diagnosis, therapy and adequate preventive measures.