Anisakiasis
is caused by the accidental ingestion of larvae of the nematodes
(roundworms) Anisakis simplex and Pseudoterranova decipiens.
[
Anisakiasis caused by Anisakis simplex - Herringworm disease ;
Whaleworm disease. Anisakiasis caused by Pseudoterranova decipiens -
Codworm disease; Sealworm disease.]
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(Dr Tsutsumi)
This
parasitic infection should be considered in the differential diagnosis
of acute abdominal syndromes and eosinophilic infiltrates of the
stomach, small intestine, colon, omentum, and mesentery, especially
with a history of raw marine fish consumption.
Aniskiasis is contracted when inadequately cooked fish
containing these nematode larvae are eaten.
Popular foods containing viable larvae are pickled
herring in Scandinavian countries,
sushi or
sashimi in Japan, and cord, flounder, and tuna from the
east coast of the United States.
Nematodes causing anisakiasis have a marine mammal as the
definitive host.
In humans the larvae penetrate the wall of the throat,
stomach, intestine or colon.
Intestinal discomfort begins a few
hours after eating the fish.
Larvae are released from the muscle of
the fish, penetrate the gastric or intestinal mucosa, or become
attached in the throat without invasion of tissue.
Infection is diagnosed after
surgical intervention for intestinal obstruction or peritonitis, which
is caused by necrotizing, eosinophilic, granulomatous inflammation.
Worms in the throat or stomach are
frequently vomited or coughed up, and a common clinical presentation
is a wriggling sensation in the throat, with larvae appearing in the
mouth of an alarmed patient.
Intestinal anisakiasis clinically resembles
appendicitis, with right lower quadrant pain, nausea, and vomiting.
Continued migration to omentum or
mesentery is common.
Worms lodge in and thicken the gastric
or bowel wall.
The identification of larvae provides the diagnosis.
Infections of the small intestine, caecum, or colon are usually not
diagnosed before exploratory laparotomy.
Removal of worms relieves the symptoms.
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