Anisakis larval type I in fresh salmon.

Larval ascarid nematodes recently discovered in fresh salmon were identified as Anisakis larval Type I, this roundworm is the etiologic agent of anisakiasis, a parasitic disease characterized by eosinophilic granulomas affecting the human gastrointestinal tract. Infection may occur following ingestion of raw or poorly cooked fish. Patients generally present with an acute abdominal syndrome mimicking a wide variety of clinical conditions, thus creating a diagnostic dilemma. Unselected samples of fresh salmon tested by the University of Michigan Clinical Microbiology Laboratory and School of Public Health were all infected, the mean worm burden calculated as 79.3 larvae per kilogram of fish. The significance of this infection and the implications for morbidity in the United States are discussed.