Anisakis worms are parasitic roundworms living in the stomach. Anisakiasis (the disease) is acquired by
eating uncooked fish or squid infected with Anisakis simplex (the most common Anisakis species).
The parasite has a protective layer against gastric acid and survives burrowed into the gastric wall. Larval
Anisakis simplex develops into a reproducing adult only in marine mammals. In humans it cannot survive and
dies within a few weeks. But the short time that it lives, it causes stomach pain and
nausea. Larval Anisakis simplex is about 2 cm long.
The life cycle of Anisakis begins in the feces (poo) of an infected sea mammal. The
feces contain Anisakis eggs which immediately hatch in the sea water. The tiny larvae are eaten (but not
killed) by small crustaceans which are eaten by fish (or squid). The larvae penetrate the gut and encyst in muscles
or other parts of the fish. Finally a marine mammal eats the infected fish. The larvae excyst in the bowel and find
another larvae of the opposite sex to mate with. (In humans the larvae stay in the stomach never reaching adulthood
nor the small intestine.) The life cycle is completed, when a female lays eggs which exit the body in the
Freshly caught fish should be gutted as soon as possible. This prevents the Anisakis larvae from
relocating to muscle tissue (fish flesh) from the intestine. Salting does not usually kill parasites. Freezing at
-20 °C for a few days or cooking at 60 °C on the other hand will. Infected fish flesh can cause allergic
reaction even if you cook it because Anisakis leaves poisons behind.
Anisakiasis treatment is not always obligatory. Your doctor can diagnose
anisakiasis gastroscopically. Depending on the severity of the infection, it might require medical attention. The
larva(e) can be removed surgically or during endoscopic examination. A drug called albendazole might also kill
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To reveal the answer you need to click the correct option.
Can Anisakis worms develop into adults inside humans?
+ A) No
Correct. Anisakis can live as a larva for several weeks in the stomach but dies before developing into an adult.
+ B) Yes
Which of the following act as an intermediate host for Anisakis
+ A) Fish and snail
+ B) Anisakis species have no intermediate hosts
+ C) Crustaceans, fish and squid
Correct. They can carry the larval stage of Anisakis.