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A 35-year-old man with fever and diarrhea visited our hospital because of white string-like fecal excretion. Based on a morphological examination of the excreted object, a Diphyllobothrium infection was suspected. Additionally, Gram staining of a fecal sample revealed Campylobacter infection. After the intraduodenal administration of meglumine/diatrizoate sodium, the tapeworm was excreted. A polymerase chain reaction-based DNA sequence analysis demonstrated that the tapeworm excreted in this case was Diphyllobothrium nihonkaiensis. This report presents a rare case of coinfection with Diphyllobothrium nihonkaiensis and Campylobacter jejuni. Therefore, it is important to consider the coexistence of other intestinal infections when diagnosing parasitic infections in patients with fever.

Diphyllobothrium spp. is a parasite with global distribution. Diphyllobothriasis is the human infestation by this parasite. Symptoms usually occur a few weeks after infection and include nausea, diarrhea, and abdominal pain; less frequently, prolonged or severe infections can lead to anemia. The endoscopic finding of the tapeworm is an incidental finding. The inflammation associated with diphyllobothriasis can be considered in the differential diagnosis of ileal ulcers. We present the case of a woman in whom a tapeworm and one ileal ulcer were found, histology suggested lymphoid proliferation; however, the clonality study showed that these inflammatory changes were secondary to diphyllobothriasis.

Human diphyllobothriasis, caused by Dibothriocephalus nihonkaiensis, is prevalent globally, especially in regions where raw fish is consumed. Recent molecular diagnostic techniques have made species identification of tapeworm parasites and the determination of genetic variations among parasite populations possible. However, only a few studies done over a decade ago, have reported on the genetic variation among D. nihonkaiensis in Japan. The present study employed PCR-based mitochondrial DNA analysis to specifically detect D. nihonkaiensis from archived clinical samples, and to determine any genetic variation that may exist among the Japanese broad tapeworms from patients of Kanagawa Prefecture, Japan. Target genes were amplified from DNA extracted from the ethanol- or formaldehyde-fixed samples by PCR. Further sequencing and comparative phylogenetic analyses based on mitochondrial COI and ND1 sequences were also performed. In our results, all PCR-amplified and sequenced samples were identified as D. nihonkaiensis. Analysis of COI sequences revealed two haplotype lineages. However, clustering of almost all COI (and ND1) sample sequences into one of the two haplotype clades, together with reference sequences from different countries worldwide, revealed a common haplotype among D. nihonkaiensis samples in our study. Our results suggest a possible presence of a dominant D. nihonkaiensis haplotype, with a global distribution circulating in Japan. Results from this study have the potential to improve the management of clinical cases and establish robust control measures to reduce the burden of human diphyllobothriasis in Japan., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023. Published by Elsevier B.V.)

Diphyllobothrium, also known as the "Broad Tapeworm" or "Fish Tapeworm," is a genus of Cestoda acquired through the consumption of undercooked fish. Although infection by a Diphyllobothrium spp. in the United States is rare, it remains an important global zoonosis, with an estimated burden of approximately 20 million people worldwide. A seldom on the Primary Care Physician's differential diagnosis in the United States, Diphyllobothrium spp. should be considered more readily when treating operational service members as they are exposed to endemic regions more frequently than the civilian population. This case presents one such service member diagnosed with Diphyllobothrium while aboard a U.S. naval vessel at sea, illustrating the importance of military medical providers considering Tapeworm infection even when risk factors seem remote. Diagnostic considerations, practical limitations of the Ova and Parasite (O&P) exam, particulars of specimen collection and handling, and recommendations for empiric treatment in the operational setting will be reviewed., (Published by Oxford University Press on behalf of the Association of Military Surgeons of the United States 2020. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

Diphyllobothriasis is a parasitic fish-borne disease caused by tapeworms of the genus Dibothriocephalus (=Diphyllobothrium). The majority of reported cases are attributed to D. latum, based on morphological identification of eggs or proglottids. However, numerous reports in recent years suggested that other Dibothriocephalus species could be involved in human infections, mainly after consumption of salmonid fish. Among these, D. nihonkaiense has been predominantly reported from Eastern Asia and probably underestimated in the rest of the world. We report here a clinical case of D. nihonkaiense in a French patient (without history of travel abroad) after consumption of salmon. Suspected on morphological characteristics, the final identification of D. nihonkaiense was performed using molecular methods by sequencing nad1, cox1, and 5.8S rRNA (containing ITS1 and 2) genes sequences. The patient was successfully treated by a single dose of praziquantel. Reports of diphyllobothriasis due to D. nihonkaiense are rare outside Asia, but worldwide demand of seafood could lead to the globalization of cases and reflect the need to monitor the distribution of Dibothriocephalus species. Thus, clinical parasitologists should be aware of this risk and able to raise the possibility of infections by non-endemic Dibothriocephalus species in order to use the proper molecular tools.

Background: Diphyllobothriosis is an intestinal cestodosis caused by tapeworms of the family Diphyllobothriidae. In France, endemic cases are limited to south-east and due to Dibothriocephalus latus. In this paper, we investigate a series of seven cases of diphyllobothriosis in the non-endemic French region of Brittany. All have been diagnosed between 2016 and 2018 at the University Hospital of Rennes., Methods: Parasites were identified by their morphological features and by phylogenetic analysis of the cox1 gene. Phylogenetic tree was built using maximum likelihood criterion under the GTR+G+I model and 2000 bootstrap replicates. A form was sent to all patients to collect data concerning clinical signs and possible sources of infection., Results: All cases were due to Dibothriocephalus nihonkaiensis, a species strictly distributed in the North Pacific. Epidemiological investigation showed that the parasite was probably acquired in France, after consumption of Japanese food containing raw salmon. All patients presented with at least abdominal pain and fatigue except for one patient who had no symptoms., Conclusions: To our knowledge, this case series is the most important cohort of allochthonous diphyllobothriosis described in Europe. This sudden emergence raises concern about foodborne infections, highlighting (i) risky food habits in absence of adequate sanitary control; and (ii) the breaking of the rule of geographical restriction due to globalization and worldwide trades.

Background: Diphyllobothriasis is estimated to afflict 10-20 million people worldwide; however, this is the first case reported in a United States military aviator. Among the largest parasites of humans, the "fish tapeworm" grows from 2-15 m in length, can live >20 yr in the intestines, and is contracted through consumption of uncooked, unfrozen freshwater or anadromous fish species., Case Report: A 32-yr-old male F-22 pilot presented with mild stomach cramping, bloating, nausea, and intermittent loose stools. Symptoms were relieved with bismuth subsalicylate until several days later when the patient, during otherwise normal bowel movements, extracted multiple broken segments of tapeworm. Although physically asymptomatic, he was psychologically disturbed. Based on the large number of ova with characteristic shape, size, color, and operculum, coupled with the flattened body, yellowish coloration, and rectangular proglottids with centrally located "rosette" uteri, he was diagnosed with diphyllobothriasis (likely D. latum or D. nihonkaiense). Successful treatment with a single oral dose of praziquantel (>10 mg · kg-1) was confirmed by negative stool examination over 60 d posttreatment. He likely contracted the parasite from ingesting salmon sushi or sashimi while previously stationed in Japan., Discussion: Despite only mild physical symptoms, the pilot's psychological distress and distraction from knowing about the meters-long tapeworm was significant. Prompt treatment was paramount to resumption of military operations. Aviators should be educated and encouraged to eat only well-cooked or previously frozen fish, especially when indulging in cultural cuisine.Kasteler SD. Diphyllobothriasis in a U.S. military aviator. Aerosp Med Hum Perform. 2018; 89(5):473-477.

We first constructed and characterized the complete mitochondrial genome (mitogenome) sequence of Diphyllobothrium stemmacephalum, the type species of genus Diphyllobothrium, using next generation sequencing (NGS). The mitogenome of D. stemmacephalum was 13,716bp, including 12 protein-coding genes, 22 tRNA genes, 2 rRNA genes and 2 longer intergenic non-coding regions, and has features common to mitogenomes of other cestodes. Although it has been accepted that tRNA for serine (trnS2 (UCN) ) in Platyhelminthes lacks a D arm, the trnS2 (UCN) of D. stemmacephalum was predicted to have a paired D arm as in Diplogonoporus balaenopterae. The non-coding region 2 contained eight tandem repeat units (34nucleotides/unit). This study also corroborated that D. stemmacephalum is phylogenetically more closely related to Dip. balaenopterae than to Diphyllobothrium latum and Diphyllobothrium nihonkaiense. As demonstrated here, mitogenome sequence data obtained using NGS is useful for gaining a better understanding of the systematics, phylogeny and taxonomic revisions involving valuable specimens preserved in museums, universities or research institutes for which sequence data are not yet available, and also for making diagnoses based on clinical samples., (Copyright © 2017 Elsevier B.V. All rights reserved.)

We described 4 human infection cases of zoonotic fish-tapeworm, Diphyllobothrium nihonkaiense , identified with morphological and molecular characters and briefly reviewed Chinese cases in consideration of it as an emerging parasitic disease in China. The scolex and mature and gravid proglottids of some cases were seen, a rosette-shaped uterus was observed in the middle of the mature and gravid proglottids, and the diphyllobothriid eggs were yellowish-brown in color and displayed a small knob or abopercular protuberance on the opposite end of a lid-like opening. The average size of the eggs was recorded as 62-67 × 42-45 μm. The parasitic materials gathered from 4 human cases were morphologically identified as belonging to the genera Diphyllobothrium and Adenocephalus . The phylogenetic analysis based on the nucleotide sequences of cytochrome c oxidase subunit 1 gene of the etiologic agents confirmed that the 4 cases were D. nihonkaiense infection. The finding of 4 additional D. nihonkaiense cases suggests that D. nihonkaiense might be a major causative species of human diphyllobothriasis in China. A combined morphological and molecular analysis is the main method to confirm D. nihonkaiense infection.

Parasitic infections are generally diagnosed by professionals trained to recognize the morphological characteristics of the eggs in microscopic images of fecal smears. However, this laboratory diagnosis requires medical specialists which are lacking in many of the areas where these infections are most prevalent. In response to this public health issue, we developed a software based on pattern recognition analysis from microscopi digital images of fecal smears, capable of automatically recognizing and diagnosing common human intestinal parasites. To this end, we selected 229, 124, 217, and 229 objects from microscopic images of fecal smears positive for Taenia sp., Trichuris trichiura, Diphyllobothrium latum, and Fasciola hepatica, respectively. Representative photographs were selected by a parasitologist. We then implemented our algorithm in the open source program SCILAB. The algorithm processes the image by first converting to gray-scale, then applies a fourteen step filtering process, and produces a skeletonized and tri-colored image. The features extracted fall into two general categories: geometric characteristics and brightness descriptions. Individual characteristics were quantified and evaluated with a logistic regression to model their ability to correctly identify each parasite separately. Subsequently, all algorithms were evaluated for false positive cross reactivity with the other parasites studied, excepting Taenia sp. which shares very few morphological characteristics with the others. The principal result showed that our algorithm reached sensitivities between 99.10%-100% and specificities between 98.13%- 98.38% to detect each parasite separately. We did not find any cross-positivity in the algorithms for the three parasites evaluated. In conclusion, the results demonstrated the capacity of our computer algorithm to automatically recognize and diagnose Taenia sp., Trichuris trichiura, Diphyllobothrium latum, and Fasciola hepatica with a high sensitivity and specificity.

Background: Tapeworms of the order Diphyllobothriidea are parasites of tetrapods and several species may infect man and cause neglected human disease called diphyllobothriosis. Identification of human-infecting diphyllobothriid cestodes is difficult because of their morphological uniformity, which concerns also their eggs in stool samples., Methods: In the present study, we analysed by far the largest dataset of more than 2,000 eggs of 8 species of diphyllobothriid cestodes that may infect humans, including the most frequent human parasites Diphyllobothrium latum, D. nihonkaiense and Adenocephalus pacificus (syn. Diphyllobothrium pacificum). Size (length, width and length/width ratio) and the surface of the egg shell from naturally and experimentally infected hosts were studied using light and scanning electron microscopy., Results: A high degree of intraspecific and host-related size variability has been detected, but combination of morphometrical and ultrastructural data made it possible to distinguish all of the studied species, including otherwise quite similar eggs of the 3 most common species infecting man, i.e. D. latum, D. nihonkaiense and D. dendriticum. The surface of all marine species is covered by numerous deep pits with species-specific density, whereas the surface of freshwater species is smooth or with isolated shallow hollows or wrinkles.

Most of the diphyllobothriid tapeworms isolated from human samples in the Republic of Korea (= Korea) have been identified as Diphyllobothrium nihonkaiense by genetic analysis. This paper reports confirmation of D. nihonkaiense infections in 4 additional human samples obtained between 1995 and 2014, which were analyzed at the Department of Parasitology, Hallym University College of Medicine, Korea. Analysis of the mitochondrial cytochrome c oxidase 1 (cox1) gene revealed a 98.5-99.5% similarity with a reference D. nihonkaiense sequence in GenBank. The present report adds 4 cases of D. nihonkaiense infections to the literature, indicating that the dominant diphyllobothriid tapeworm species in Korea is D. nihonkaiense but not D. latum.

Diphyllobothrium latum and Diphyllobothrium nihonkaiense are morphologically similar to each other, and only genetic method can differentiate clearly between the 2 species. A strobila of diphyllobothriid tapeworm discharged from a 7-year-old boy was analyzed to identify the species by mitochondrial cytochrome c oxidase subunit 1 (cox1) gene sequencing. He and his family (total 4 persons) ate slices of 3 kinds of raw fish 16 days before visiting our outpatient clinic. All family members complained of abdominal pain and watery diarrhea. They all expelled tapeworm strobilae in their stools. They were treated with a single oral dose of praziquantel and then complained of no more symptoms. The cox1 gene sequencing of the strobila from the boy revealed 99.9% (687/688 bp) similarity with D. nihonkaiense and only 93.2% (641/688 bp) similarity with D. latum. Thus, we assigned this tapeworm as D. nihonkaiense. This is the first report of D. nihonkaiense infection in a family in Korea, and this report includes the 8th pediatric case in Korea. The current report is meaningful because D. nihonkaiense infection within a family is rare.

Until 2012, a total of 48 cases of diphyllobothriasis had been reported in Korea, all of which were morphologically identified as Diphyllobothrium latum. However, some of these specimens were analyzed by nucleotide sequencing of the mitochondrial cox1 gene, which showed that all were D. nihonkaiense, not D. latum. After that, 3 further cases of diphyllobothriasis were confirmed as D. nihonkaiense. In the present study, 3 new cases of D. nihonkaiense were detected from 2011 through 2013. The hosts were infected through consumption of salmonid fishes, such as the trout or salmon, and 2 of them experienced severe diarrhea prior to proglottid passage. All of the tapeworms were confirmed to be D. nihonkaiense by genetic identification. This proved again that most diphyllobothriasis in Korea have been caused by D. nihonkaiense.

Diphyllobothrium latum and Diphyllobothrium nihonkaiense are the 2 reported main causes of human diphyllobothriasis in the Republic of Korea. However, the differentiation of these 2 species based on morphologic features alone is difficult. The authors used nucleotide sequencing of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene to diagnose Diphyllobothrium spp. Two patients visited the emergency room at Kyungpook National University Hospital on 3 April and 12 April 2013, respectively, with fragments of parasites found while defecating. The parasites were identified as Diphyllobothrium spp. based on morphologic characteristics, and subsequent cox1 gene sequencing showed 99.9% similarity (1,478/1,480 bp) with D. nihonkaiense. Our findings support the hypothesis that D. nihonkaiense is a dominant species in Korea.

We document a case of locally acquired "broad- or fish-tapeworm" infection caused by Diphyllobothrium latum in a 27-year-old Spanish man, confirmed by molecular analysis (COI gene). The patient had naturally expelled a worm of 110 cm in length, but the physical examination did not yield any remarkable findings, and the patient did not suffer from any particular symptoms. Laboratory test results were normal except for a remarkable increase in the red blood cell count, and an evident decrease in the mean corpuscular volume and mean corpuscular hemoglobin. Vitamin B12 and folic acid values were in the normal range without signs of anemia. It was suggested that these anomalies in erythrocyte formation might not be related to the parasite, and analysis of the patient's anamnestic data revealed that the infection could only have been caused by the ingestion of imported fish, although no light could be shed on the specific source of infection. From a public health viewpoint, this human case of fish-borne zoonosis is exemplary, suggesting that not only is control of fish and fish product quality essential, but also increased awareness of the general population with regard to changes in culinary habits.

The cause of diphyllobothriosis in 5 persons in Harbin and Shanghai, China, during 2008-2011, initially attributed to the tapeworm Diphyllobothrium latum, was confirmed as D. nihonkaiense by using molecular analysis of expelled proglottids. The use of morphologic characteristics alone to identify this organism was inadequate and led to misidentification of the species.

Following a first clinical case of infection by Diphyllobothrium dendriticum in Switzerland in 2006, we report a second case in the country. The species was identified by molecular methods. In the Swiss, French and Italian subalpine regions, human diphyllobothriasis has seen a comeback since the late 1980's, and Diphyllobothrium latum is usually considered the causative agent of the disease. In addition, several locally acquired and imported clinical infections due to allochthonous Diphyllobothrium species have been documented in the last years. Due to the colonisation potential of these parasites and their probably underestimated presence in the human population, there is a need for discriminating them at the medical laboratory level. Because the morphological characters are very similar among the different taxa, a correct identification requires the use of molecular methods. Molecular identification would improve diagnosis and help monitor the distribution of Diphyllobothrium species in Europe.

Diphyllobothrium latum infections in 4 young Korean men detected from 2008 to 2012 are presented. Three were diagnosed based on spontaneously discharged strobila of the adult worm in their feces, and 1 case was diagnosed by finding the worm at colonoscopy examination in a local clinic. The morphologic characteristics of the gravid proglottid and eggs were consistent with D. latum. All patients were treated with praziquantel 15 mg/kg, and follow-up stool examinations were done at 2 months after the medication. The main clinical complaints were intermittent gastrointestinal troubles such as indigestion, abdominal distension, and spontaneous discharge of tapeworm's segments in their feces. The most probable source of infection was the flesh of salmon or trout according to a patient's past history. These are the 45th to 48th recorded cases diagnosed by the adult worm in the Republic of Korea since 1971.

Diphyllobothriosis is an intestinal parasitosis caused by cestodes infection of the genus Diphyllobothrium. In Argentina, the Andean Patagonia is considered an endemic area for this parasitosis. Diphyllobothrium latum infection has not been previously reported in the province of Mendoza, Argentina. We are now reporting then the first case. Diphyllobothriosis was confirmed by examination of morphologic characteristics of the eggs eliminated in the patients' feces. These results suggest the requirement of a more specific training of health workers in the diagnosis and treatment of non endemic parasitosis. We want to emphasize the need of health workers' education on diagnosis and treatment of endemic and non-endemic parasitosis.

The efficiency of the direct candling technique on fillets (candling 1) was compared with examination of cuts 4 mm thick or less (candling 2) and glass plate compression for the detection of plerocercoids of Diphyllobothrium spp. in muscles of rainbow trout, Oncorhynchus mykiss. Application of the three procedures gave the following results (percentage of infected fish/percentage of isolated plerocercoids): candling 1: 40.9/22, candling 2: 29.5/18.8, glass plate compression: 29.5/59.2, and combination of candling 1 and 2: 70.5/40.8. The combination of the three techniques yielded 100% sensitivity: 44 infected fish were detected of 77 trout examined. When different regions of the musculature were compared using the three techniques, a high density of plerocercoids and the highest percentage of infection (90.9%; 40 infected trout) were detected in the ventral musculature. Candling 1, candling 2 and glass plate compression on the ventral musculature gave the following case numbers and percentages, respectively, for the total of 44 cases: 9 (20.5%), 9 (20.5%), and 22 (50%).

We present the case of a patient who was referred to our hospital after she reported having passed a long, whitish object per rectum. Accordingly, capsule endoscopy was performed using the PillCam(®) SB video capsule. A tapeworm of the species Diphyllobothrium nihonkaiense was detected; it appeared to be freely floating and unfolded in the jejunum and sometimes tangled or irregularly folded in the ileum. The stretching of the strobila by strong peristalsis in the ileum may have resulted in the separation of the caudal portion of the strobila, which descended into the colon and was eventually passed per rectum., (© 2011 The Japanese Society of Internal Medicine)

Identification of Diphyllobothrium species has been carried out based on their morphology, especially sexual organs. In addition to these criteria, PCR-based identification methods have been developed recently. A 20 year-old Japanese living in Kochi Prefecture passed tapeworm. He was successfully treated with single dose of gastrografin. We examined the morphologic features of the proglottids and eggs using histology and scanning electron microscope. We also analyzed mitochondrial cytochrome c oxidase subunit 1 (cox1) gene of the proglottids. The causative tapeworm species was identified as D. nihonkaiense based on the results of morphologic features and genetic analysis. We discussed the advantage of PCR-based identification methods of Diphyllobothrium species using cox1 sequence in the clinical laboratory.

The specific identification of broad tapeworms (genus Diphyllobothrium) infecting humans is very difficult to perform by morphological observation. Molecular analysis by PCR and sequencing represents the only reliable tool to date to identify these parasites to the species level. Due to the recent spread of human diphyllobothriosis in several countries, a correct diagnosis has become crucial to better understand the distribution and the life cycle of human-infecting species as well as to prevent the introduction of parasites to disease-free water systems. Nevertheless, PCR and sequencing, although highly precise, are too complicated, long, and expensive to be employed in medical laboratories for routine diagnostics. In the present study we optimized a cheap and rapid molecular test for the differential identification of the most common Diphyllobothrium species infecting humans (D. latum, D. dendriticum, D. nihonkaiense, and D. pacificum), based on a multiplex PCR with the cytochrome c oxidase subunit 1 gene of mitochondrial DNA.

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.

An anomalous tapeworm with abnormal segmentation was obtained from a 6-year-old boy in Japan. The tapeworm consisted of proglottids with slanted anterior and posterior margins of proglottids and 4-6 sets of reproductive organs arranged between the margins. The morphology of the tapeworm did not correspond to any of the described cestodes. However, molecular identification based on nuclear and mitochondrial genes clearly showed the tapeworm was Diphyllobothrium nihonkaiense.

Between 1997-2006, 3,523 intestinal cestode infections were registered in Poland. Among them 2,748 were caused by Taenia saginata, 41 by T. solium, 533 by Taenia species, 20 by Hymenolepis nana, 5 by Hymenolepis diminuta, 11 by Diphyllobothrium latum, 3 by Dipylidium caninum. Moreover, 350 cases of cystic echinococcosis and 8 cases of cysticercosis were also registered. The obtained results confirmed decreasing frequency of intestinal cestodoses in Poland.

Global increases in salmon consumption and changes in fish-eating habits have meant that Diphyllobothrium infections now occur in regions where they were previously absent. In the present paper, a case of diphyllobothriasis through the likely ingestion of raw salmon in New Zealand in a Japanese patient is reported. The causative tapeworm species was identified as Diphyllobothrium nihonkaiense based on mitochondrial DNA analysis of proglottid expelled from the patient.