Observation on the morphology of Anisakis simplex pathogenic to sea perch by scanning electron microscopy

Anisakis simplex is a zoonotic parasite infecting sea fishes and mammals and also a causative agent of a human disease called anisakiosis.We had found larvae of A.simplex from the diseased sea perch Lateolabrax japonicus from fish farm in Zhejiang province,in which 20-30 larvae of A.simplex were isolated per fish with a detection rate of 100%(11/11).They were mainly located in liver,stomach and intestinal walls and mesentery of the sampled sea perch.In the severely infected fishes,gastric perforation,hemorrhage on the gastric wall and the presence of white nodules in liver.As demonstrated on the observation by light and electron microscopy,the adult worms appeared to be long and round cylinder-shaped and smaller at both end of the worm body.Their front end was blunt with one prominent boring tooth and 4 projections,while their tail was short and round with distinct mucron,cuticle with transverse striations and irregular wrinkles near the tail.