Intestinal anisakiasis. A case diagnosed by morphologic and immunologic methods.

The diagnosis of the fourth reported case of intestinal anisakiasis in the United States was based on the morphologic characteristics of the worm in histologic sections of resected ileum. Detection of antibodies to the worm by a radioallergosorbent test (RAST), enzyme-linked immunosorbent assay (ELISA), and an immunofluorescent antibody assay (IFA) support the diagnosis. IgE antibodies in patient serum reacted specifically to larval Anisakis antigens but not to larval Ascaris antigens in the RAST. IgG and IgM antibodies to larval Anisakis antigen could be detected by ELISA up to six months after infection. IFA findings demonstrated that patient serum recognized the excretory-secretory products produced by the worm and showed their presence in vivo. These products appear to originate from the excretory pore and dorsal esophageal gland of the larval parasite.