A man with unsuspected marine eosinophilic gastritis

A 49-year-old man with a history of hypertension and type 2 diabetes mellitus was referred for an internal medicine consultation because of worsening heartburn for the past 3 months. The patient regularly ate pickled anchovies (raw anchovies in vinegar sauce). His overall health was good, and fi ndings from physical examination were unexceptional. Laboratory results showed peripheral eosinophilia (1·7 × 103 cells per μL, normal 0·5 × 103 cells per μL) but were otherwise unremarkable. Upper gastrointestinal endoscopy showed characteristic fi ndings of gastro-oesophageal refl ux disease and Barrett’s oesophagus (confi rmed by pathological study); an isolated, thickened gastric fold (which was biopsied; fi gure); and no macroscopic evidence of erythema, oedema, erosive gastritis, ulcerations, tumour-like nodules, or worms. Nevertheless, histological assessment showed a striking eosinophilic infl ammatory infi ltrate and a sectioned larva of the nematode Anisakis simplex embedded in the gastric mucosa (fi gure). Additionally, serum IgE specifi c for A simplex was increased. We gave the patient omeprazole to treat his gastro-oesophageal refl ux disease and specifi c preventive recommendations to avoid ingestion of potentially contaminated seafood (eg, by freezing or suitably heating fi sh) and decrease the risk of anaphylaxis due to A simplex. 10 months after the diagnosis of anisakidosis was made, his blood eosinophil count was within normal limits, and both gastroscopy and examination of gastric biopsy samples showed no abnormalities. Anisakidosis, a disease caused by any member of the family Anisakidae that occurs worldwide, usually results from consumption of raw or undercooked marine fi sh or squid contaminated with the larvae of A simplex or Pseudoterranova decipiens. Although symptomatic gastrooesophageal, intestinal, ectopic, and allergic diseases are the most common clinical presentations in human beings, this case shows that symptomless eosinophilic gastritis with secondary eosinophilia can also develop. In view of the popularity of raw seafood consumption, clinicians should keep anisakidosis high on their list of diff erential diagnoses for a wide range of disorders, especially in patients known to have these dietary habits. Lancet Infect Dis 2015; 15: 248