Meaning of Anisakis
Anisakis is a genus of parasitic nematodes that have life cycles that affect fish and marine mammals. They are infectious to humans and cause anisakiasis. People who produce immunoglobulin E in response to this parasite may subsequently have an allergic reaction, including anaphylaxis, after eating fish infected with Anisakis species. The genus Anisakis was defined in 1845 by Félix Dujardin as a subgenus of the genus Ascaris Linnaeus, 1758.
Anisakis species have complex life cycles that pass through a number of hosts throughout their lives. The eggs hatch in seawater and the larvae are eaten by crustaceans, generally euphausiids. Infected crustaceans are subsequently eaten by fish or squid, and the nematodes burrow into the wall of the intestine and encyst in a protective layer, usually on the outside of visceral organs, but occasionally in the muscle or under the skin. The life cycle is completed when a marine mammal eats an infected fish, such as a whale, seal, sea lion , dolphin, and other animals such as seabirds and sharks.
Nematodes in the intestine feed, grow, mate, and release eggs into seawater in the host's feces . Since the gut of a marine mammal is functionally very similar to that of a human, Anisakis species can infect humans who eat raw or undercooked fish.
The known diversity of the genus has increased enormously in the last 20 years, with the advent of modern genetic techniques in species identification. Each final host species was found to have its own biochemically and genetically identifiable 'sibling species' to Anisakis, which is reproductively isolated. This finding has made it possible to use the proportion of different sister species in a fish as an indicator of community identity in fish populations.
Anisakis share the common characteristics of all nematodes; the body plan vermiform, round in cross section and lack of segmentation . The body cavity is reduced to a pseudocous. The mouth is located anteriorly and is surrounded by projections used for feeding and sensation, with the anus slightly displaced from the posterior. The squamous epithelium secretes a layered cuticle to protect the body from digestive juices .