Introduction: Infection with the parasite Anisakis simplex is common in Japan and northern European countries. The number of reported cases in Spain has increased since the first description in 1991. The aim of the present study was to evaluate the incidence, clinical patterns, histopathological lesions, treatment, and outcome of Anisakis simplex infection in our environment.
Material and method: Cases of gastrointestinal anisakiasis diagnosed in our center from December 1999 to January 2002 were studied. Only patients with detection of the parasite in oral endoscopy or the surgical specimen and those with elevated levels of specific IgE to Anisakis simplex, a clinical picture compatible with anisakiasis, or a history of raw fish intake were included. Epidemiological, clinical and laboratory data, as well as diagnostic, histopathologic and therapeutic features, and outcome in these patients were recorded.
Results: Twenty-five cases of gastrointestinal anisakiasis were diagnosed during the study period, representing an incidence of 3.87 cases per 100 000 inhabitants/year. All the patients had ingested raw anchovies. Two groups were observed. The first group was composed of 10 patients with a gastric form of the infection, in which the main symptom was epigastralgia (90%). Oral endoscopy was performed in all patients and the parasite was detected in five (50%). The second group was composed of 15 patients with intestinal involvement in which the main manifestations were symptoms mimicking appendicitis (80%). The most frequent finding of laparotomy and/or imaging tests (abdominal ultrasonography, intestinal transit, abdominal CAT) was terminal ileitis (80%). Seven patients underwent surgery: intestinal resection was performed in four with detection of Anisakis simplex in three. Eosinophilic infiltration was found in all surgical specimens. Treatment was symptomatic in most of the patients and outcome was favorable in all.
Conclusions: Infection with Anisakis simplex should be investigated in patients with abdominal pain after intake of raw fish, ileitis of unclear origin, or eosinophilic gastroenteritis.