Helminthes detected from wild sika deer (Cervus nippon centralis) in Kanto-Chubu region,Japan

The helminth fauna of 105 sika deer (Cervus nippon centralis) captured in Yamanashi, Kanagawa and Nagano Prefectures, Japan was investigated during 2014–2019. As a result, 12 helminthes, i.e. 3 digeneans (Ogmocotyle sikae, Dicrocoelium chinensis and D. dendriticum), 8 nematodes (Gongylonema pulchrum, Dictyocaulus sp., Pygarginema sp., Spiculopteragia houdemeri, Chabaudstrongylus ninhae, Trichuris discolor, Oesophagostomum sikae and Oes. asperum), and 1 cestode (Moniezia sp.) were detected. To our knowledge, this is the first report of Pygarginema sp., Cha. ninhae, and Oes. asperum from sika deer in Japan. Some helminthes detected in the present study can infect livestock. Considering the possibility of the spread of the helminthes to livestock through deer excrement, it is important to promote understanding the parasite fauna in wild deer.     

A possible circulation of a dominant Dibothriocephalus nihonkaiensis haplotype in Japan revealed by molecular analysis of clinical tapeworm samples

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.     

Molecular Identification of Diphyllobothrium nihonkaiense from 3 Human Cases in Heilongjiang Province with a Brief Literature Review in China

Human diphyllobothriasis is a widespread fish-borne zoonosis caused by the infection with broad tapeworms belonging to the genus Diphyllobothrium. In mainland China, so far 20 human cases of Diphyllobothrium infections have been reported, and the etiologic species were identified as D. latum and D. nihonkaiense based on morphological characteristics or molecular analysis. In the present study, proglottids of diphyllobothriid tapeworms from 3 human cases that occurred in Heilongjiang Province, China were identified as D. nihonkaiense by sequencing mitochondrial cytochrome c oxidase subunit I (cox1) and NADH dehydrogenase subunit 5 (nad5) genes. Two different cox1 gene sequences were obtained. One sequence showed 100% homology with those from humans in Japan. The remaining cox1 gene sequence and 2 different nad5 gene sequences obtained were not described previously, and might reflect endemic genetic characterizations. D. nihonkaiense might also be a major causative species of human diphyllobothriasis in China. Meanwhile, the finding of the first pediatric case of D. nihonkaiense infection in China suggests that infants infected with D. nihonkaiense should not be ignored.     

Current situation of human Taenia asiatica taeniosis in Japan

This report describes 33 confirmed cases of “Taenia asiatica” taeniosis in Tokyo, Japan, and six adjacent prefectures between 2010 and 2019. Of the 33 cases, 28 were domestic infections. Thirty patients had histories of eating raw pork and/or beef liver. It was highly suspected that the sources of infection were foreigners from T. asiatica-endemic countries who had worked on pig farms in these prefectures. We postulated that the rate of domestic infection has decreased as a result of legal regulations that have banned the serving of raw and undercooked pig and cattle viscera in restaurants in Japan. Haplotype analyses of genetic markers revealed that “T. asiatica” in Japan are the descendants of hybrids of T. asiatica and Taenia saginata that originated from the Philippines and/or Taiwan. It is critical that close attention continues to be paid to domestic recurrences and imported cases of T. asiatica taeniosis, with the goal of communicating information on risk factors for this infection to consumers, pig farmers, restaurant owners, physicians, and visitors coming to Japan.     

Studies on the specific immunodiagnosis of larval cestode infections of cattle and sheep using antigens purified by affinity chromatography in an enzyme-linked immunosorbent assay (Elisa)

Craig P.S. and Rickard M.D. 1981. Studies on the specific immunodiagnosis of larval cestode infections of cattle and sheep using antigens purified by affinity chromatography in an enzyme-linked immunosorbent assay (ELISA). International Journal for Parasitology11: 441–449. Crude somatic or cyst fluid extracts prepared from Taenia saginata, T. hydatigena or Echinococcus granulosus were partially purified by absorption against homologous and heterologous bovine or ovine antisera on immunoabsorbent affinity columns. Antigens in parasite extracts which were eluted after binding to the homologous anti-parasite antisera (bovine or ovine) coupled to CNBr-activated Sepharose were then passed sequentially through affinity columns containing heterologous anti-parasite Ig and the ‘run-through’ antigens collected. The level of cross reactions to these absorbed antigens, in an enzyme-linked immunosorbent assay (ELISA) using sera from cattle or sheep given heterologous parasite infections (including Fasciola hepatica), were significantly decreased. Absolute specificity was not achieved, and some loss in sensitivity occurred. The absorption of cross-reactive antigen(s) using affinity Chromatographie techniques may be a useful first step in the production of species-specific immunodiagnostic antigens for larval cestode infections.     

Amphibian chytridiomycosis in Japan: distribution,haplotypes and possible route of entry into Japan

A serious disease of amphibians caused by the chytrid fungus Batrachochytrium dendrobatidis was first found in Japan in December 2006 in imported pet frogs. This was the first report of chytridiomycosis in Asia. To assess the risk of pandemic chytridiomycosis to Japanese frogs, we surveyed the distribution of the fungus among captive and wild frog populations. We established a nested PCR assay that uses two pairs of PCR primers to amplify the internal transcribed spacer (ITS) region of a ribosomal RNA cassette to detect mild fungal infections from as little as 0.001 pg (1 fg) of B. dendrobatidis DNA. We collected swab samples from 265 amphibians sold at pet shops, 294 bred at institutes and 2103 collected at field sites from northern to southwestern Japan. We detected infections in native and exotic species, both in captivity and in the field. Sequencing of PCR products revealed 26 haplotypes of the B. dendrobatidis ITS region. Phylogenetic analysis showed that three of these haplotypes were specific to the Japanese giant salamander (Andrias japonicus) and appeared to have established a commensal relationship with this native amphibian. Many other haplotypes were carried by alien amphibians. The highest genetic diversity of B. dendrobatidis was found in the American bullfrog (Rana catesbeiana). Some strains of B. dendrobatidis appeared to be endemic to Japanese native amphibians, but many alien strains are being introduced into Japan via imported amphibians. To improve chytridiomycosis risk management, we must consider the risk of B. dendrobatidis changing hosts as a result of anthropogenic disturbance of the host‐specific distribution of the fungus.     

Phylogeography of ostreopsis along west Pacific coast, with special reference to a novel clade from Japan

Background

A dinoflagellate genus Ostreopsis is known as a potential producer of Palytoxin derivatives. Palytoxin is the most potent non-proteinaceous compound reported so far. There has been a growing number of reports on palytoxin-like poisonings in southern areas of Japan; however, the distribution of Ostreopsis has not been investigated so far. Morphological plasticity of Ostreopsis makes reliable microscopic identification difficult so the employment of molecular tools was desirable.

Methods/Principal Finding

In total 223 clones were examined from samples mainly collected from southern areas of Japan. The D8–D10 region of the nuclear large subunit rDNA (D8–D10) was selected as a genetic marker and phylogenetic analyses were conducted. Although most of the clones were unable to be identified, there potentially 8 putative species established during this study. Among them, Ostreopsis sp. 1–5 did not belong to any known clade, and each of them formed its own clade. The dominant species was Ostreopsis sp. 1, which accounted for more than half of the clones and which was highly toxic and only distributed along the Japanese coast. Comparisons between the D8–D10 and the Internal Transcribed Spacer (ITS) region of the nuclear rDNA, which has widely been used for phylogenetic/phylogeographic studies in Ostreopsis, revealed that the D8–D10 was less variable than the ITS, making consistent and reliable phylogenetic reconstruction possible.

Conclusions/Significance

This study unveiled a surprisingly diverse and widespread distribution of Japanese Ostreopsis. Further study will be required to better understand the phylogeography of the genus. Our results posed the urgent need for the development of the early detection/warning systems for Ostreopsis, particularly for the widely distributed and strongly toxic Ostreopsis sp. 1. The D8–D10 marker will be suitable for these purposes.     

The phylogeographic puzzle of Pseudoacanthocephalus toshimai,an amphibian acanthocephalan in northern Japan

The amphibian acanthocephalan, Pseudoacanthocephalus toshimai, was considered to be an island-endemic species in Hokkaido, Japan. However, the parasite was found from Rana ornativentris, Rana tagoi, Zhangixalus arboreus, and Bufo japonicus formosus in northern Honshu (Aomori and Iwate Prefectures), which is separated from Hokkaido by the Tsugaru Strait. The mitochondrial DNA-based phylogenetic and population genetic analyses of P. toshimai showed that the northern Honshu isolates are far distantly related to the Hokkaido isolates, and that a demographic population expansion occurred in Hokkaido during the recent geological past. The rich genetic diversity of P. toshimai in northern Honshu suggests a scenario that anuran hosts invaded Hokkaido together with P. toshimai via the land bridge of the Tsugaru Strait. However, the evolutionary history of Rana pirica, a main definitive host for P. toshimai in Hokkaido, is contradictory to the introduction scenario inferred from the parasite. The finding of several geographically mismatched isolates of P. toshimai from both northern Honshu and Hokkaido suggests a possibility that the migration of the parasite infrequently occurred between the two areas even after the land bridge disappeared. More detailed information on the evolutionary history of anurans is needed to resolve the biogeographical enigma of P. toshimai.     

Current Status and Perspectives of Cysticercosis and Taeniasis in Japan

This mini-review describes recent epidemiological trends in cysticercosis and taeniasis in Japan. Some of the topics discussed herein were presented at the first symposium on "Current perspectives of Taenia asiatica researches", that was held in Osong in Chungbuk Province, South Korea, in October 2011 and organized by Prof. K. S. Eom, Chungbuk National University School of Medicine. To better understand the trends in the occurrence of cysticercosis and taeniasis in Japan, clinical cases reported in 2005 have been updated. In addition, the current status of Taenia asiatica infections successively occurring in Japan since 2010 is also discussed.     

Geographical distribution of Polycelis (Seidlia) auriculata in Japan

Polycelis (Seidlia) auriculata is endemic to mountain districts of Japan, from the central part of Honshû to the area of the Daisetsu Mts of Hokkaidô. In northern Japan, it sometimes occurs in cold-water biotopes of lowland areas. The progenitor of P. auriculata appears to have been the oldest immigrant into northern Japan among the Japanese Polycelis species, entering through a northern route as a preglacial faunal element. P. auriculata now shows a discontinious distribution in northern Japan. By virtue of its geographical and vertical distribution, ecological niche, variation in anatomy of the copulatory apparatus, and cytodemes, this species appears to be in the process of transformation.     

An unknown species of Leucochloridium (Trematoda: Leucochloridiidae) from northern Honshu,Japan

Pulsating broodsacs of Leucochloridium sp. (Trematoda: Leucochloridiidae) were found from amber snails (Succinea lauta) in Iwate, the northern part of Honshu, Japan. A pattern with red-brown vertical stripes was characteristic of the broodsac. Very similar broodsacs were already detected from Okinawa Islands, the southern archipelago of Japan, and tentatively identified as Leucochloridium cf. passeri. A phylogenetic analysis based on DNA sequences of mitochondrial cytochrome c oxidase subunit 1 (cox1) showed that Leucochloridium sp. is different at species level from L. cf. passeri and that both species are related to Leucochloridium vogtianum from Europe. In this study the definitive identification of larval Leucochloridium sp. was impossible, but the resulting phylogeny confirmed that at least 4 species of Leucochloridium are distributed in Japan, depending on locality and climate. The DNA barcode generated in this study will be useful in detecting the adult stage of Leucochloridium sp. from birds.     

On the Fourth Diadema Species (Diadema-sp) from Japan

Four long-spined sea urchin species in the genus Diadema are known to occur around the Japanese Archipelago. Three species (D. savignyi, D. setosum, and D. paucispinum) are widely distributed in the Indo-Pacific Ocean. The fourth species was detected by DNA analysis among samples originally collected as D. savignyi or D. setosum in Japan and the Marshall Islands and tentatively designated as Diadema -sp, remaining an undescribed species. We analyzed nucleotide sequences of the cytochrome oxidase I (COI) gene in the “D. savignyi-like” samples, and found all 17 individuals collected in the mainland of Japan (Sagami Bay and Kyushu) to be Diadema-sp, but all nine in the Ryukyu Archipelago (Okinawa and Ishigaki Islands) to be D. savignyi, with large nucleotide sequence difference between them (11.0%±1.7 SE). Diadema-sp and D. savignyi shared Y-shaped blue lines of iridophores along the interambulacrals, but individuals of Diadema-sp typically exhibited a conspicuous white streak at the fork of the Y-shaped blue iridophore lines, while this feature was absent in D. savignyi. Also, the central axis of the Y-shaped blue lines of iridophores was approximately twice as long as the V-component in D. savignyi whereas it was of similar length in Diadema-sp. Two parallel lines were observed to constitute the central axis of the Y-shaped blue lines in both species, but these were considerably narrower in Diadema-sp. Despite marked morphological and genetic differences, it appears that Diadema-sp has been mis-identified as D. savignyi for more than half a century.     

Zoonotic filariasis caused by Onchocerca dewittei japonica in a resident of Hiroshima Prefecture,Honshu, Japan

A female of Onchocerca sp. was found to be the probable causative agent of a subcutaneous nodule in the left knee of a 70-year-old man in a rural area of Hiroshima Prefecture, Honshu, the main island of Japan. We compared the characteristics of the agent with the features of the four previously suspected species found in cattle and horses in various parts of the world, as well as O. lupi and O. jakutensis that were suspected or proved, respectively, in zoonotic cases in Europe. In addition, the morphologic characteristics of this parasite were compared with those of the four Onchocerca species found in wild animals in Japan. Based on such characteristics as the large triangle ridges, the considerable distance between any two adjacent ridges, and the absence of inner cuticular striae in the longitudinal sections, we found the causative agent in the present case to be identical to the female of Onchocerca dewittei japonica. All five previous cases of zoonotic onchocerciasis in Japan had been found in Oita, Kyushu, the main southern island. This human case caused by O. dewittei japonica suggests that zoonotic onchocerciasis is liable to occur in rural areas in Japan where wild boar, Simulium vectors, and humans overlap.     

Comparison between the trypanorhynchid cestode infections of Penaeus duorarum and Penaeus brasiliensis in Biscayne Bay,Florida

Penaeus brasiliensis and P. duorarum from Biscayne Bay, Florida, were both found to be infected with four species of trypanorhynchid cestode larvae: Parachristianella monomegacantha, P. heteromegacanthus, Prochristianella penaei, and Renibulbus penaeus. The two shrimp species contained the cestodes in significantly different proportions and female P. duorarum had different proportions of cestodes than males. Three linear regressions of cestode infection on host size were also significant. The incidence and intensity of infection is given for each species of shrimp and cestode. This is the first record of P. heteromegacanthus and R. penaeus infecting Penaeus duorarum and modifies earlier information of P. duorarum infections in the bay.     

A new intermediate host for Echinococcus multilocularis: The southern red-backed vole (Myodes gapperi) in urban landscape in Calgary,Canada

Human Alveolar Echinococcosis (HAE) is a potentially fatal parasitic disease caused by Echinococcus multilocularis, a cestode characterized by a sylvatic life-cycle involving several species of rodents and lagomorphs as intermediate hosts and canids as definitive hosts. Despite the wide distribution of the parasite in North America, the number of competent intermediate host species identified to date is still relatively small, and mainly includes the northern vole (Microtus oeconomus), brown lemming (Lemmus sibiricus), northern red-backed vole (Myodes rutilus), deer mouse (Peromyscus maniculatus) and meadow vole (Microtus pennsylvanicus).By monitoring the infections in rodents in the city of Calgary (Alberta, Canada), we have detected a case of severe alveolar echinococcosis in a southern red-backed vole (Myodes gapperi), a species never reported before as an intermediate host for this parasite. Observation of protoscolices in the intra-abdominal multilocular cysts indicates that M. gapperi could act as a competent intermediate host for the transmission of E. multilocularis.Since M. gapperi can be found in close proximity to, and within metropolitan areas, this species could play a role in the establishment and maintenance of the sylvatic life-cycle of E. multilocularis in urban landscapes, where the potential for zoonotic transmission is higher. The new intermediate host reported needs to be taken into account in future surveys and transmission models for this parasite.     

Antennatula katumotoi,a new euantennariaceous sooty mould,with a Hormisciomyces-like synasexual morph from central Honshu,Japan

A new species of euantennariaceous sooty mould, Antennatula katumotoi, is described and illustrated. It has a Hormisciomyces-like synasexual morph and inhabits twigs of the conifer Abies veitchii in Sugenuma (alt. ca. 1719 m), Katashina-mura, Tone-gun, Gunma Prefecture, central Honshu, Japan. The expected Euantennaria-like sexual morph linked to this genus was not seen in the specimen studied. This is the first proof that the genus Antennatula of the family Euantennariaceae also occurs in Japan. In addition, A. katumotoi also occurs with another metacapnodiaceous sooty mould that is composed of characteristic moniliform, barrel-shaped hyphae probably of a Capnobotrys-like asexual morph, but this is a minor inhabitant in the subicula.     

Molecular Identification of Echinococcus multilocularis Infection in Small Mammals from Northeast,Iran

Background

Alveolar echinococcosis is a zoonotic disease caused by the metacestode of Echinococcus multilocularis. Many species of small mammals, including arvicolid rodents or Ochotona spp., are natural intermediate hosts of the cestode. The main aim of this study was to identify natural intermediate hosts of E. multilocularis in Chenaran County, Razavi Khorasan Province, northeastern Iran, where the prevalence of infected wild and domestic carnivores is high.

Methodology/Principal Findings

A program of trapping was carried out in five villages in which this cestode was reported in carnivores. The livers of 85 small mammals were investigated for the presence of E. multilocularis infection using multiplex PCR of mitochondrial genes. Infections were identified in 30 specimens: 23 Microtus transcaspicus, three Ochotona rufescens, two Mus musculus, one Crocidura gmelini, and one Apodemus witherbyi.

Conclusions/Significance

A range of small mammals therefore act as natural intermediate hosts for the transmission of E. multilocularis in Chenaran County, and the prevalence suggested that E. multilocularis infection is endemic in this region. The existence of the life cycle of this potentially lethal cestode in the vicinity of human habitats provides a significant risk of human infection.