Diphyllobothrium stemmacephalum (Cestoda: Diphyllobothriidae) found from a harbor porpoise in northern Japan, with comments on a geographical gap with human infection cases in southern Japan.

Even though the cetacean tapeworm Diphyllobothrium stemmacephalum occurs in both cold and warm waters, human infections and final host occurrences have been confined to temperate areas in and near Japan. We recently obtained a strobila of this cestode that was excreted from a harbor porpoise accidentally caught offshore of Hokkaido of northern Japan. Genetic analysis of 28S rDNA and cox1 genes confirmed that the cestode was D. stemmacephalum. Our finding sets the northernmost record of D. stemmacephalum in the western Pacific, suggesting that the risk of human infections by this parasite in northern Japan deserves further attention.

Diphyllobothrium sprakeri n. sp. (Cestoda: Diphyllobothriidae): a hidden broad tapeworm from sea lions off North and South America.

BACKGROUND: The systematic of several marine diphyllobothriid tapeworms of pinnipeds has been revised in recent years. However, 20 species of Diphyllobothrium from phocids and otariids are still recognized as incertae sedis. We describe a new species of Diphyllobothrium from the intestine of California sea lions Zalophus californianus (Lesson) (type-host) and South American sea lions Otaria flavescens (Shaw). METHODS: Zalophus californianus from the Pacific coast of the USA and O. flavescens from Peru and Argentina were screened for parasites. Partial fragments of the large ribosomal subunit gene (lsrDNA) and the cytochrome c oxidase subunit 1 (cox1) mitochondrial gene were amplified for 22 isolates. Properly fixed material from California sea lions was examined using light and scanning electron microscopy. RESULTS: A total of four lsrDNA and 21 cox1 sequences were generated and aligned with published sequences of other diphyllobothriid taxa. Based on cox1 sequences, four diphyllobothriid tapeworms from O. flavescens in Peru were found to be conspecific with Adenocephalus pacificus Nybelin, 1931. The other newly generated sequences fall into a well-supported clade with sequences of a putative new species previously identified as Diphyllobothrium sp. 1. from Z. californianus and O. flavescens. A new species, Diphyllobothrium sprakeri n. sp., is proposed for tapeworms of this clade. CONCLUSIONS: Diphyllobothrium sprakeri n. sp. is the first diphyllobothriid species described from Z. californianus from the Pacific coast of North America, but O. flavescens from Argentina, Chile and Peru was confirmed as an additional host. The present study molecularly confirmed the first coinfection of two diphyllobothriid species in sea lions from the Southern Hemisphere.

Endohelminths of European Perch (Perca fluviatilis) from Selected Localities in Poland with an Emphasis on Search of the Broad Fish Tapeworm Dibothriocephalus latus.

INTRODUCTION: A piscivorous fish European perch (Perca fluviatilis) is present in all types of lakes and brackish waters in Poland. Previous ichthyoparasitological surveys revealed broad spectrum of endohelminths in perch from different aquatic environments. Among them, detection of Diphyllobothrium sp. and Dibothriocephalus latus (syn. Diphyllobothrium latum) in the Pomeranian Bay is of particular interest, since D. latus is one of the causative agents of diphyllobothriasis, fish-borne parasitic zoonosis. Besides, D. latus eggs were previously detected in coprological samples of otter, wolf and lynx from the Bialowieza Primeval Forest. AIM: To conduct parasitological examinations of European perch from the Pomeranian Bay in order to detect the spectrum of its endohelminths and to provide a pilot study on helminths of perch from different water bodies in the Bialowieza Primeval Forest. Due to zoonotic character of D. latus, we have focused our attention to this tapeworm. RESULTS: The larvae of tapeworm Triaenophorus nodulosus and thorny-headed worm Acanthocephalus lucii were detected in perch from the Pomeranian Bay. In perch from different localities in the Bialowieza Primeval Forest, T. nodulosus, A. lucii and tapeworm Proteocephalus percae were detected. D. latus plerocercoids were found neither in musculature nor in peritoneal cavity and other internal organs of any of the fish examined from both studied localities in Poland. CONCLUSION: Future screening implementing morphological and molecular markers is needed in order to understand the current distribution of D. latus in Europe.

Dibothriocephalus nihonkaiensis: an emerging foodborne parasite in Brittany (France)?

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.

Case Report: Acute Generalized Exanthematous Pustulosis Caused by Praziquantel.

Praziquantel is widely used for treating parasitic infections globally, especially in countries with endemic schistosomiasis. However, severe hypersensitivity to praziquantel has rarely been reported. We report the case of a 30-year-old Japanese man who developed acute generalized exanthematous pustulosis (AGEP), which is a rare and severe cutaneous reaction usually triggered by drugs, after taking praziquantel. During medical examination, eggs of Diphyllobothrium nihonkaiense were found in his stool. He took praziquantel 600 mg for 1 day and developed skin rashes and fever the next day. Pruritic generalized maculopapular erythematous eruptions were observed over the entire body. He had elevated white blood cell count, liver enzymes, and C-reactive protein level. We prescribed acetaminophen, fexofenadine hydrochloride, loxoprofen sodium, and topical ointments including difluprednate and hydrocortisone. Over the next 3 days, he developed pinhead-sized, non-follicular pustules on his diffusely erythematous skin. Histological findings of the pustular lesion showed spongiform subcorneal pustules with perivascular inflammatory cells. Approximately 8 days after taking praziquantel, the pustules resolved with desquamation. He became afebrile on day 9 and his laboratory parameters returned to normal levels on day 16. He was diagnosed with AGEP caused by praziquantel. Physicians need to be aware that praziquantel could cause AGEP, although it is generally considered a safe drug.

Archaeoparasitological Analysis of Samples from the Cultural Layer of Nadym Gorodok dated Back to the 14th-Late 18th Centuries.

An archaeoparasitological analysis of the soil samples from Nadym Gorodok site of Western Siberia has been carried out in this study. The archaeological site was dated as the 13 to 18th century, being characterized as permafrost region ensuring good preservation of ancient parasite eggs. Parasite eggs as Opisthorchis felineus, Alaria alata, and Diphyllobothrium sp. were found in the archaeological soil samples, which made clear about the detailed aspects of Nadym Gorodok people's life. We found the Diphyllobothrium sp. eggs throughout the 14 to 18th century specimens, allowing us to presume that raw or undercooked fish might have been commonly used for the foods of Nadym Gorodok inhabitants and their dogs for at least the past 400 years. Our study on Nadym Gorodok specimens also demonstrate that there might have been migratory interactions and strong economic ties between the people and society in Western Siberia, based on archaeoparasitological results of Opisthorchis felineus in Western Siberia.

Paleoparasitology of Merovingian Corpses Buried in Stone Sarcophagi in the Saint-Martin-au-Val Church (Chartres, France).

Paleoparasitological analysis was carried on 4 Merovingian skeletons, dated from the late-5th to the late-9th centuries, and recovered in the church of Saint-Martin-au-Val in Chartres (Center region, France). The corpses were buried in stone sarcophagi, which were still sealed at the time of excavation. Parasite marker extraction was conducted on sediment samples taken from the abdominal and pelvic regions, but also on samples taken from under the head and the feet as control samples. Microscopic observation revealed the presence of 3 gastrointestinal parasites, namely the roundworm (Ascaris lumbricoides), the whipworm (Trichuris trichiura) and the fish tapeworm (genus Diphyllobothrium). This analysis contributes to a better knowledge of the health status and the lifestyle of ancient medieval populations during the Merovingian period, for which very few paleoparasitological data were available, up until now. It demonstrates the presence of the fish tapeworm for the first time during this period.

Natural selection for body shape in resource polymorphic Icelandic Arctic charr.

Resource polymorphisms exhibit remarkable intraspecific diversity and in many cases are expected to be maintained by diversifying selection. Phenotypic trade-offs can constrain morphologically intermediate individuals from effectively exploiting both alternate resources, resulting in ecological barriers to gene flow. Determining if and how phenotypic trade-offs cause fitness variation in the wild is challenging because of phenotypic and environmental correlations associated with alternative resource strategies. We investigated multiple pathways through which morphology could affect organismal performance, as measured by growth rate, and whether these effects generate diversifying selection in polymorphic Icelandic Arctic charr (Salvelinus alpinus) populations. We considered direct effects of morphology on growth and indirect effects via trophic resource use, estimated by stable isotopic signatures, and via parasitism associated with trophic resources. We sampled over 3 years in (lakes) Thingvallavatn and Vatnshlíðarvatn using the extended selection gradient path analytical approach and estimating size-dependent mortality. We found evidence for diversifying selection only in Thingvallavatn: more streamlined and terminally mouthed planktivore charr experienced greater growth, with the opposite pattern in small benthic charr. However, this effect was mediated by parasitism and nontrophic pathways, rather than trophic performance as often expected. Detection of between-morph differences in the presence (Vatnshlíðarvatn) and direction (Thingvallavatn) of size-dependent mortality, together with nontrophic effects of shape, suggests that a morphological trophic performance explanation for polymorphism is insufficient. This rare insight into selection during early diversification suggests that a complex of interacting local factors must be considered to understand how phenotype influences fitness, despite morphological variation reflecting intuitive trade-off explanations.

Epidemiology of Diphyllobothrium nihonkaiense Diphyllobothriasis, Japan, 2001-2016.

We report 958 cases of cestodiasis occurring in Japan during 2001-2016. The predominant pathogen was Diphyllobothrium nihonkaiense tapeworm (n = 825), which caused 86.1% of all cases. The other cestode species involved were Taenia spp. (10.3%), Diplogonoporus balaenopterae (3.3%), and Spirometra spp. (0.2%). We estimated D. nihonkaiense diphyllobothriasis incidence as 52 cases/year. We observed a predominance of cases during March-July, coinciding with the cherry salmon and immature chum salmon fishing season, but cases were present year-round, suggesting that other fish could be involved in transmission to humans. Because of increased salmon trade, increased tourism in Japan, and lack of awareness of the risks associated with eating raw fish, cases of D. nihonkaiense diphyllobothriasis are expected to rise. Therefore, information regarding these concerning parasitic infections and warnings of the potential risks associated with these infections must be disseminated to consumers, food producers, restaurant owners, physicians, and travelers.

Clinical characteristics and epidemiology of intestinal tapeworm infections over the last decade in Tokyo, Japan: A retrospective review.

BACKGROUND: Tapeworm (cestode) infections occur worldwide even in developed countries and globalization has further complicated the epidemiology of such infections. Nonetheless, recent epidemiological data on cestode infections are limited. Our objectives were to elucidate the clinical characteristics and epidemiology of diphyllobothriosis and taeniosis in Tokyo, Japan. METHODOLOGY/PRINCIPAL FINDINGS: We retrospectively reviewed 24 cases of human intestinal cestode infection from January 2006 to December 2015 at a tertiary referral hospital in Tokyo, Japan. The patients included were diagnosed with cestode infection based on morphological and/or molecular identification of expelled proglottids and/or eggs and treated in our hospital. Fifteen and 9 patients were diagnosed with diphyllobothriosis and taeniosis, respectively. The median patient age was 31 years (interquartile range [IQR]: 26-42 years), and 13 (54%) were male. Most of the patients (91.7%) were Japanese. All patients were successfully treated with praziquantel without recurrence. Diphyllobothriosis was caused by Diphyllobothrium nihonkaiense in all patients. Taeniosis was due to infection of Taenia saginata in 8 [88.9%] patients and T. asiatica in 1 [11.1%] patient. All patients with taeniosis were infected outside Japan, as opposed to those with diphyllobothriosis, which were domestic. The source locations of taeniosis were mostly in developing regions. The median duration of the stay of the patients with taeniosis at the respective source location was 1 month (IQR: 1-8). CONCLUSIONS/SIGNIFICANCE: The cestode infection, especially with D. nihonkaiense, has frequently occurred, even in Japanese cities, thereby implicating the probable increase in the prevalence of diphyllobothriosis among travelers, as the number of travelers is expected to increase owing to the Tokyo Olympics/Paralympics in 2020. In addition, medical practitioners should be aware of the importance of providing advice to travelers to endemic countries of taeniosis, including the potential risks of infection and preventive methods for these infections.

Diphyllobothriidea in the north area of the Andean Patagonia: Epidemiology in urban dogs, morphometrical and molecular identification, with comments on wild carnivores.

Diphyllobothriidea are the principal agents of Diphyllobothriosis, a widespread food-borne cestodosis. Accurate identification of the species in samples is therefore crucial for diagnosis and epidemiology in wild and domestic animals, and also humans. We aim to identify at specific level the causative agent, and provide an observational, descriptive, and transversal study of the epidemiology of this zoonosis in urban dogs. Also data on wild carnivores from Northwestern Patagonia are presented. Dog feces were collected in thirteen neighborhoods of varying socioeconomic status, and stools were analyzed by two concentration methods. Adult worms were collected and identified by molecular methods. The population of free-roaming dogs in each neighborhood was estimated, and surveys were conducted at all veterinary clinics registered in the Veterinary Medical College of Bariloche city. A total of 36 wild carnivores road killed or found dead in three National Parks were analyzed. Molecular and morphometric analyses of proglottids and eggs from dogs indicate they are infected with D. latum. Twenty out of 118 dog feces were positive for Diphyllobothrium, from 9 out of 13 neighborhoods, with infection values between 10% and 66%. Percentage of infection was correlated positively with the number of free roaming dogs per block, and with Unsatisfied Basic Needs (UBN %), but not with distance to nearest water body. Infection by D. latum in dogs is widely distributed throughout the city. Not all local veterinarians know the occurrence of Diphyllobothriosis in the dogs of the city, and it is evident that this zoonosis is underdiagnosed in relation to the percentage of infection found in this study. None of the analyzed wild carnivores were positive for Diphyllobothrium.

Molecular Identification of Diphyllobothrium latum from a Pediatric Case in Taiwan.

Human diphyllobothriasis is a parasitic disease caused by ingestion of larvae (plerocercoids) in raw or undercooked fish and commonly found in temperate areas. Rare cases were reported in tropical or subtropical areas especially in children. The first documented case of pediatric diphyllobothriasis in Taiwan had been reported 11 years ago. Here, we report another 8-year-old girl case who presented with a live noodle-like worm hanging down from her anus, with no other detectable symptoms. We pulled the worm out and found the strobila being 260 cm in length. Examination of gravid proglottids showed that they were wider than their lengths, containing an ovoid cirrus sac in the anterior side and the rosette-shaped uterus. Eggs extracted from the uterus were ovoid and operculated. Diphyllobothrium latum was confirmed by molecular analysis of the mitochondrial DNA cytochrome c oxidase subunit 1 (cox1) gene. The girl was treated with a single oral dose of praziquantel, and no eggs or proglottids were observed from her stool in the subsequent 3 months. The reemergence of human diphyllobothriasis in non-endemic countries is probably due to prevalent habit of eating imported raw fish from endemic areas. This pediatric case raised our concern that human diphyllobothriasis is likely underestimated because of unremarkable symptoms.

Four Human Cases of Diphyllobothrium nihonkaiense (Eucestoda: Diphyllobothriidae) in China with a Brief Review of Chinese Cases.

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.