JAPANESE SUISHI
SUSHI AND ANISAKIASIS



INTRODUCTION

Since 1972, Japan and some other countries such as the USA have seen a sudden increase in
cases of anisakiasis (infection with Anisakis sp.) and codworm an isakiasis (infection with the
codworm, Pseudoterranova [= Phocanema] decipiens). Larval stages of these nematodes occur
in the muscles of a variety of fish and squid, and ingestion of raw and undercooked fish or squid is
the prime route of human infection. Thus the Japanese style of eating sashimi (sliced raw fish fillet)
and the increasing popularity of sushi bars where such dishes are served, has often been
suggested as contributing to the spread of anisakid infections. [3]

ANISAKIASIS

Anisakiasis is a zoonotic disease caused by the ingestion of larval nematodes (belonging to the
subfamily Anisakinae) in raw seafood dishes such as sushi, sashimi, ceviche, and pickled herring.
Symptoms of anisakiasis include abdominal pain, nausea, vomiting, and diarrhea.
Because symptoms are vague, this disease is often misdiagnosed as appendicitis, acute
abdomen, stomach ulcers, or ileitis. Endoscopic examination with biopsy forceps has facilitated
the diagnosis of gastric anisakiasis. Worms can be removed and identified, and a definitive
diagnosis can be made. Patients generally recover with no further evidence of disease.
Worms can become invasive, however, and migrate beyond the stomach, penetrating the
intestine, omentum, liver, pancreas, and probably the lung. Surgery is often necessary for
treatment of invasive anisakiasis. [2]

CASES REPORTED

CASE I A case of gastric anisakiasis in a 45-yr-old Asian woman who had eaten fresh, raw
salmon was reported. This happened in the United States a few years ago [1,4]

CASE II In 1991, Hiramoto JT, John A. Burns School of Medicine, Hawaii reported a few cases
occurring in individuals who had consumed a large amount of raw squid sushi at a restaurant in
Hawaii. The diagnosis of anisakiasis could be made after the parasite was identified by X-ray. [5]

CASE III Schuster R Santa Barbara Cottage Hospital, California reported a 25-year-old healthy
woman with no prior history of surgery presented to the emergency room with bowel obstruction.
They found a mass in the right lower quadrant.

She had eaten seviche, a raw fish appetizer, 2 days earlier and sashimi 3 weeks before
admission. She was taken to the operating room for an exploratory laparotomy and was found to
have an obstruction, the 2-cm mass in the mesentery, and diffuse mesenteric adenopathy. She
had an ileocolectomy. Pathology showed a degenerating fish worm, anisakiasis. She also had a
serologic test for immunoglobulin E specific to anisakiasis and it was highly positive. [Health info:
Check www.zhion.com]

CASE IV / REPORT IV Most human infections have been reported from Japan and The
Netherlands and involve the stomach. Invasion of the gastric or intestinal wall one to 5 days after
eating raw fish may be characterized by the abrupt onset of abdominal pain, nausea and/or
vomiting, diarrhea, or an ileus. For transient anisakiasis, supportive measures and reassurance
are all that is needed. If the larvae have invaded the intestine or the stomach wall diagnosis
and cure occur with endoscopic or surgical removal if evidence of obstruction or perforation
is found.  [7]

CASE V Sasaki T et al,  Fukuoka University, Japan reported a case of small bowel obstruction
caused by enteric anisakiasis in a 59-year-old Japanese man. This man presented an abdominal
pain a few hours after eating sliced, raw fish. Because of signs of an intestinal obstruction, a
laparotomy was performed. Focal thickening and stenosis of the ileocecal region were seen
about 100 cm from the end of the ileum and the lesion was excised.

They found a moving anisakis thrusting its head into the mucosa of the excised small intestine.
Histopathological examination revealed the infiltration of eosinophils in all layers of the intestinal
wall and severe edema. Enteric anisakiasis is very rare, and its diagnosis is usually only made
after laparotomy. Note: Zhion is the author for this article. Nevertheless, when signs of acute
abdomen develop after the ingestion of raw fish, such as sushi or sashimi, the possibility of enteric
anisakiasis should be borne in mind. [8]

CASE VI Takabe K et al  Yokohama City University Hospital, Japan reported a case of
strangulating small bowel obstruction in a 60-yr-old Japanese woman caused by anisakidosis
(previously known as anisakiasis). [9]

CASE VII Muraoka A and co-workers Suma Red Cross Hospital, Kobe, Japan.have reviewed 28
patients with acute gastric anisakiasis during the last 10 years from November 1984 to October
1994. This disease has rarely been detected in persons over 60 years of age and in
patients with gastric surgery. Therefore it is postulated that gastric acid secretion influences the
activities of anisakis larvae. An alkaline gastric pH could interfere with the toxicity of anisakis
larvae. [10]

With the growing popularity of "sushi" bars and the increasing numbers of Americans developing a
taste for raw fish, this condition may become more prevalent in the future.

REFERENCES

[1] Hsiu JG Gastric anisakiasis: report of a case with clinical, endoscopic, and histological findings. Am J Gastroenterol. 1986
Dec;81(12):1185-7.[2] Rushovich AM et al Omental anisakiasis: a rare mimic of acute appendicitis. Am J Clin Pathol. 1983 Oct;80(4):517-20.  
[3] Oshima T Anisakiasis - is the sushi bar guilty? Parasitol Today. 1987 Feb;3(2):44-8. [4] Sakanari JA Anisakiasis Clin Microbiol Rev. 1989
Jul;2(3):278-84 [5] Anisakiasis in Hawaii: a radiological diagnosis. Hawaii Med J. 1991 Jun;50(6):202-3.[6] Recent topics on hepatitis E virus:
emerging, zoonotic, and animal-to-human transmission in Japan Uirusu. 2004 Dec;54(2):243-8. [7] Anisakiasis of the colon presenting as bowel
obstruction Am Surg. 2003 Apr;69(4):350-2. [8] Small bowel obstruction caused by anisakiasis of the small intestine: report of a case. Surg
Today. 2003;33(2):123-5. [9] Anisakidosis: a cause of intestinal obstruction from eating sushi. Am J Gastroenterol. 1998 Jul;93(7):1172-3. [10]
Acute gastric anisakiasis: 28 cases during the last 10 years. Dig Dis Sci. 1996 Dec;41(12):2362-5.
McKerrow JH Anisakiasis: revenge of the sushi parasite. N Engl J Med. 1988 Nov 3;319(18):1228-9.
Wittner M Eustrongylidiasis--a parasitic infection acquired by eating sushi. N Engl J Med. 1989 Apr 27;320(17):1124-6.
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