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Diphyllobothrium is a member of Cestoda family, which is the largest parasite of humans. The diagnosis of diphyllobothriasis is based on the detection of eggs in the stool. Because the remainder of the scolex causes a relapse in diphyllobothriasis, the scolex must be completely discharged to cure the parasite infection. However, the scolex or forefront of the Diphyllobothrium is difficult to detect with gastroduodenoscopy and colonoscopy, because most Diphyllobothrium attach to the jejunal wall. In the present case, capsule endoscopy detected proglottids as well as forefront of the parasite at jejunum. Based on the results of capsule endoscopy, the patient underwent additional vermifuge (anthelminthic) treatment to cure the diphyllobothriasis and discharged a worm measuring 3 m in length with a scolex. Capsule endoscopy is a practical option to determine whether additional vermifuge treatment is required through the detection of the proglottids as well as a scolex or forefront of the parasite.
Diphyllobothrium is a member of the Cestoda (tapeworm) family and it is the largest parasite of humans. Among Diphyllobothrium tapeworms, more than 10 species are known to cause human infection, which is called diphyllobothriasis,1 and Diphyllobothrium nihonkaiense is the main causative species of diphyllobothriasis in Japan.2 The second intermediate hosts of D nihonkaiense are anadromous Pacific salmons such as masu salmon Oncorhynchus masou masou, pink salmon Oncorhynchus gorbuscha and chum salmon Oncorhynchus keta, and humans normally acquire the parasite by eating raw or undercooked fish.1 3
The diagnosis of diphyllobothriasis is based largely on the detection of eggs in the stool of the patients. Because the remainder of the scolex causes a relapse in diphyllobothriasis, the scolex must be completely discharged to cure the parasite infection. However, the scolex or forefront of the Diphyllobothrium is difficult to detect by gastroduodenoscopy and colonoscopy, because most Diphyllobothrium attach to the jejunal wall. The current case report describes how capsule endoscopy can directly detect live Diphyllobothrium, including the forefront of the parasite; thus, suggesting the usefulness of this examination for determining the necessity of performing vermifuge (anthelminthic) treatment.
A 23-year-old man visited our hospital due to numerous white string-like excretions. No particular abnormality was noted with the physical or blood examinations. The patient had eaten no raw salmon within the period of several months. Eggs of ovoid shape with an operculum on a narrowed pole were detected in the patient's stool. Therefore, the patient was diagnosed to have a Diphyllobothrium infection. To confirm whether the scolex of the parasite remained, capsule endoscopy was performed. The examination detected the forefront of the parasite at the upper jejunum (figure 1) and numerous proglottids from the upper to lower small intestine (figure 2). Mature proglottids were also found in the small intestine. No other abnormality was observed during the examination. Subsequently, an additional vermifuge treatment using 200 ml of gastrografin (Nihon Shering, Osaka, Japan) was performed and the patient discharged a worm measuring 3 m in length with a scolex and many proglottides after approximately 1 h. To identify the tapeworm at species level, cytochrome c oxidase subunit I (cox1) and cytochrome b (cob) genes of mitochondrial DNA (mtDNA) were analysed according to Yanagida et al.4 Both cob and cox1 sequences showed more than 99.7% identities with those of D nihonkaiense (AB522615 and AB508838, respectively). These results demonstrated the tapeworm obtained in the present case to be D nihonkaiense.
The patient was completely cured by an additional vermifuge treatment.
In the present case, capsule endoscopy contributed to the diagnosis of diphyllobothriasis infection through the direct observation of the live parasite in the small intestine. It is noteworthy that the capsule endoscopy identified numerous proglottids as well as forefront of the parasite; thus, suggesting that this examination is a practical and effective procedure for determining whether additional treatment is required to treat a Diphyllobothrium infection. Seven reported cases and the present patient with tapeworm infection detected by capsule endoscopy5–10 are summarised in table 1. Three subjects were infected by Diphyllobothrium spp, while the other five were infected by Taenia. Four subjects had histories of eating raw fish or meat. Capsule endoscopy detected a scolex or forefront of the parasite in six cases and proglottids in all eight cases. In four cases, the cause of anaemia was attributed to tapeworm infection. In the present case, capsule endoscopy was useful to confirm the remaining scolex or forefront of the parasite, which might cause a relapse of the diphyllobothrium infection and it is also a safer and more comfortable method for the patient. Based on the results of capsule endoscopy, the patient underwent additional vermifuge treatment to cure the diphyllobothriasis.
In summary, the present study demonstrates that capsule endoscopy is a feasible option to identify tapeworm infection and also to determine whether additional vermifuge treatment is required through the detection of the proglottids as well as a scolex or forefront of the parasite. Therefore, capsule endoscopy, which is a safe and less invasive procedure for observing the small intestine, may be applied to accurately diagnose parasite infections in the intestinal tract.
Competing interests None.
Patient consent Obtained.