Gastroallergic anisakiasis: Borderline between food allergy and parasitic disease - Clinical and allergologic evaluation of 20 patients with confirmed acute parasitism by Anisakis simplex

Background: Human subjects can be parasitized by Anisakis simplex by eating raw or undercooked fish, Gastric anisakiasis is probably the most frequent clinical entity presenting with severe epigastric pain, vomiting, and diar rhea. In gastroallergic anisakiasis hypersensitivity symptoms predominate. Objective: We sought to describe clinical features, laboratory data, and ga stroscopic findings in gastroallergic anisakiasis. Methods: We selected 40 patients presenting to the emergency department wit h an acute allergic reaction, and if we suspected acute parasitism by A sim plex, a fiberoptic gastroscopy was performed. In 20 patients we could detec t one or more nematodes; these patients are referred to as group A. Those i n whom no worm could be found are referred to as group B (n = 20). A detail ed history, clinical features, gastroscopic findings, laboratory data, and skin prick test responses were compared. Results: Long-time intervals of up to 26 hours between fish intake and onse t of hypersensitivity symptoms were found (group A, 5.4 +/- 6.3 hours; grou p B, 5.3 +/- 2.6 hours). Patients in groups A and B did not differ with res pect to allergic symptoms (urticaria, angioedema, erythema, bronchospasm, a nd anaphylaxis) or the mainly light abdominal symptoms (upper abdominal pai n, nausea, vomiting, and diarrhea). No significant differences were found w ith respect to age, time interval between fish intake and onset of symptoms , white fell and eosinophil counts, specific IgE levels against A simplex, or total IgE levels. Conclusions: The peculiar sometimes long-time interval between fish intake and onset of allergic symptoms render the diagnosis difficult. An early gas troscopy can confirm the diagnosis and prevent complications. We suggest th at gastroallergic anisakiasis be considered a distinct clinical entity in w hich the predominant symptoms are hypersensitivity symptoms and in which th e correct diagnosis is not only important in the management of the acute re action but also in the prevention of further allergic episodes.