Anisakis simplex (Rudolphi, 1809
) Baylis, 1920
incidence in areas where raw fish is eaten (e.g., Japan, Pacific coast of South
America, the Netherlands).
Marine mammals such as cetaceans (whales,
dolphins) and pinnipeds (seals, sea lions, walruses) are
the definitive (primary host for
A. simplex; fish are an intermediate
Hosts include: Balaenoptera acutirostrata (Lacepede, 1804), B.
borealis (Lesson, 1828), B. musculus (Linnaeus, 1758);
Delphinapterus leucas (Pallas, 1776); Delphinus delphis (Linnaeus,
1758); Eumetopias jubatus (Schreber, 1776); Hyperoodon rostratus
(Van Beneden and Gervais, 1880); Lagenorhynchus albirostris (Gray,
1846), L. obscurus (Gray, 1828); Mesoplodon bidens (Sowerby,
1804); Monodon monoceros (Linnaeus, 1758); Phocaena phocaena
(Linnaeus, 1758); Pseudoreca crassidens (Owen, 1846); Platanista
gangetica (Lebeck, 1801); Globicephala melaena (Traill, 1809);
Orcinus orca (Linnaeus, 1758); Stenella coeruleoalba (Meyen,
1833); Halichoerus grypus (Fabricius, 1791); Phoca vitulina
in humans is caused by the accidental ingestion of
juveniles of A. simplex
in raw or undercooked fish.
Adults are embedded in
clusters in the intestinal mucosa of marine mammals.
Eggs are passed in the
feces of the mammals
In the water, first-stage juveniles
develop in the eggs and molt to the second-stage
The juveniles hatch from the eggs in the second stage and are free-swimming in
The juveniles are ingested by crustaceans
and develop to third-stage juveniles that are infective to fish and squid
when they ingest crustaceans
In the fish or squid hosts, the juveniles migrate from
the intestine to the tissues in the peritoneal cavity and grow up to 3 cm in
length. Upon the host's death, juveniles migrate
to the muscle tissues and, through predation
by other fish, are transferred to other fish hosts.
Third-stage juveniles persist in fish and squid
maintain and are infective to marine mammals
(and humans) when their hosts are consumed
When ingested by mammalian hosts, juveniles molt twice
and develop into adult worms. The adult females produce eggs that are shed
by marine mammals
Humans become infected by eating raw or undercooked infected marine fish
After ingestion, the anisakid juveniles penetrate the
gastric and intestinal mucosa, causing the symptoms of anisakiasis.
Anisakiasis in humans is expressed as
violent abdominal pain, nausea, and vomiting
within hours after ingesting Anisakis juveniles.
Occasionally the juveniles are coughed up;
if they pass into the bowel, a severe eosinophilic granulomatous response
may also occur 1 to 2 weeks following infection, with
symptoms mimicking Crohn's disease.
Diagnosis is by
gastroscopic examination or by histopathologic examination of
Preferred treatment is
surgical or endoscopic removal. Drugs are available.
adequate cooking of fish (60 C) or freezing (-20 C
for seven days or -35 C for 15 hours) before ingestion will kill anisakid