Noriyuki Sato

Anisakidae and anisakidosis.

During the 1950s, Ishikura noticed in the fishing town of Iwanai, Hokkaido, an intestinal disease that frequently occurred in winter with clinical and histopathologic characteristics different from those of ordinary ileitis terminalis. He reported eight such cases, which occurred within a 2-month period in 1955, as acute ileitis terminalis showing peculiar pathologic features (1). By 1959, thirty cases of this disease had been reported (2). Ishikura, Kikuchi, and their coworkers considered the lesion peculiar because this regional enteritis (or terminal ileitis) caused severe allergic tissue reaction with extensive eosinophilic infiltration. On histologic examination, cross sections of a nematode-like worm were sometimes found, and the specimens were sent to parasitologists for identification. The parasitologists regarded these structures as roundworm larvae, not realizing that they were Anisakis larvae. Meanwhile Otsuru et al. (3), based on a description by Beaver (4), warned that visceral larva migrans might occur in Japan.