The Nematodes that Cause Anisakiasis

Abstract

Anisakine nematodes responsible for human anisakiasis have been recognized in fish hosts for over a decade. They are larval stages, relatively simple in form, and lack many morphological features used for identification of the adults (e.g., cephalic structures, spicules, etc.). However, these immature helminths can be sorted into larval types on the basis of the anterior digestive tract formation and the position of the excretory pore. Problems in identfying larvae, even as to type, are often encountered in tissue sections that may not show those anterior regions containing features of the digestive system which are diagnostic for type sorting. Hence, it is necessary to reconsider the diagnostic value of lateral chords, muscle cells, etc., that are visible in all cross-sections. Fish which are eaten by the human consumer also contain larval stages of other roundworms (nematodes) than those responsible for human anisakiasis, as well as numerous species of adult nematodes.