Abstract
Colonic anisakiasis is rare because most cases of anisakiasis occur in the stomach. An accurate diagnosis is sometimes difficult because of the rarity and symptom nonspecificity. We should consider the possibility of colonic anisakiasis when examining patients who have a history of consuming raw fish.
Keywords: anisakiasis, endoscopy, parasitology, seafood
Colonic anisakiasis is rare because most cases of anisakiasis occur in the stomach. An accurate diagnosis is sometimes difficult because of the rarity and symptom nonspecificity. We should consider the possibility of colonic anisakiasis when examining patients who have a history of consuming raw fish.
1. INTRODUCTION
A 63‐year‐old man presented to our hospital for further examination of slight abdominal discomfort and a positive fecal occult blood test at his annual health check‐up. We proceeded to perform a colonoscopy, which revealed an approximately 20‐mm grayish‐white worm penetrating the mucosa of the sigmoid colon (Figure 1). The larva was removed using biopsy forceps, and the parasitological evaluation revealed that it was Anisakis simplex (Figures 2 and 3). We were informed that the patient had consumed slices of raw squid seven days prior to the examination. Anisakiasis is a human parasitic infection of the gastrointestinal tract caused by the consumption of raw seafood containing Anisakis simplex. In Japan, gastric anisakiasis is relatively common because of the tradition of consuming raw fish. Furthermore, the number of anisakiasis cases may reportedly increase throughout the world as the Japanese style of eating raw fish becomes more popular. 1 Among them, colonic anisakiasis is rare and most of them have been reported in the right side of the colon. 2 Although the present case is extremely rare since the parasite was found in the sigmoid colon, we should consider the possibility of colonic anisakiasis in patients who have a history of consuming raw fish.
FIGURE 1.
Colonoscopy reveals a grayish‐white worm penetrating the mucosa of the sigmoid colon
FIGURE 2.
Through the neighboring mucosa was slightly edematous, the larva was removed using biopsy forceps
FIGURE 3.
Parasitological evaluation reveals the presence of Anisakis simplex with a diameter of 20 mm
CONFLICT OF INTEREST
The authors state that they have no conflict of interest.
AUTHOR CONTRIBUTION
HN and KT: drafted the manuscript. RM, AS, YH, and YK: were involved in the patient's care. SK: supervised the study.
ETHICAL APPROVAL
This study does not require any ethical committee approval.
CONSENT
Written informed consent was obtained from the patient to publish this report in accordance with the journal's patient consent policy.
ACKNOWLEDGEMENT
All authors would like to thank the patient and his family for allowing this case study.
Nakamura H, Takanashi K, Morita R, et al. A case of anisakiasis in the sigmoid colon. Clin Case Rep. 2022;10:e05445. doi: 10.1002/ccr3.5445
Funding information
None
DATA AVAILABILITY STATEMENT
Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.
REFERENCES
- 1. Matsuura H, Jinno H. Colonic anisakiasis. Am J Med. 2018;131(5):e203. [DOI] [PubMed] [Google Scholar]
- 2. Mineta S, Shimanuki K, Sugiura A, et al. Chronic anisakiasis of the ascending colon associated with carcinoma. J Nippon Med Sch. 2006;73(3):169‐174. [DOI] [PubMed] [Google Scholar]
Associated Data
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Data Availability Statement
Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.