Mitochondrial DNA divergence in populations of the tapeworm Diphyllobothrium nihonkaiense and its phylogenetic relationship with Diphyllobothrium klebanovskii

Diphyllobothrium nihonkaiense [Y. Yamane, H. Kamo, G. Bylund, J.P. Wilkgren. Diphyllobothrium nihonkaiense sp. nov (Cestoda: Diphyllobothriidae)- revised identification of Japanese broad tapeworm. Shimane J Med Sci 1986;10:29-48.] and Diphyllobothrium klebanovskii [I.V. Muratov, P.S. Posokhov. Causative agent of human diphyllobothriasis - Diphyllobothrium klebanovskii sp. n. Parazitologiia. 1988;22:165-170.] are two major species of human diphyllobothriasis in Japan and Far East Russia, respectively, but their taxonomical relationship remains unclear. In this study, we analysed the DNA sequences of 16 clinical isolates of D. nihonkaiense from Japanese people, 3 isolates of D. klebanovskii from a bear in Kamchatka, and 4 clinical isolates of D. klebanovskii from native Udygeyci people in Russia, as well as 4 plerocercoids from Oncorhynchus spp. 18S rDNA and internal transcribed spacer 1 (ITS1) sequences from D. nihonkaiense and D. klebanovskii showed a high level of similarity, indicating synonymy of the two species. Analyses of mitochondrial DNA (mtDNA) sequence polymorphisms in the cox1 and nad3 genes of D. nihonkaiense (D. klebanovskii) revealed two deeply divergent lineages, A and B, with genetic distances (Kimura-2 parameter) of 0.018-0.022. Furthermore, the distinct monophyletic groupings of cox1 haplotypes corresponded to the distinct monophyletic groupings of nad3 haplotypes. The two lineages were neither distinguished by morphological features nor defined by the localities of the samples. These results suggest that the two morphologically cryptic lineages have diverged and coexisted over a long period of time.     

A case of Diphyllobothrium nihonkaiense infection successfully treated by oral administration of Gastrografin

A diphyllobothriid cestode infection found in a 54-year-old male residing in Oita, Japan, was successfully treated by oral administration of Gastrografin in combination with a intramuscular injection of Vagostigmin. The strobila expelled was 6.14 m long with a scolex, and morphologically identical with Diphyllobothrium nihonkaiense except unusual ovaries of which posterior horns were confluent in each proglottid. This is the first case of treatment of cestode infection by oral administration of Gastrografin.     

Parasites of freshwater resident and anadromous Arctic charr (Salvelinus alpinus) in Greenland

Twenty-one metazoan parasite species were found in Arctic charr at three coastal sites in west Greenland, including Neascus sp. and the nematode Pseudoterranova decipiens , new records for Arctic charr. Twelve species are new records for Arctic charr in Greenland. The quantitative composition of the parasite communities varied, but the freshwater species ( Diphyllobothrium ditremwn, Eubothriutn salvelini, Proteocephalus longicollis, Crepidostotnutn farianis ) were usually numerically dominant, even in anadromous fish. The absence from Greenland of Mysidacea, Amphipoda, Ephemeroptera and Odonata excludes parasites requiring such organisms as intermediate hosts, including the cestode Cyathocephalus truncatus , nematodes of the genus Cystidicola , and freshwater acanthocephalans.     

Metazoan parasites of sticklebacks on Sable Island, Northwest Atlantic Ocean: biogeographic considerations

Three species of sticklebacks ( Apeltes quadracus, Gasterosteus aculeatus , and Pungitius pungitius ( n = 236) were collected from five ponds on Sable Island. The nematodes Pseudoterranova decipiens, Contracaecum sp., Paracuaria adunca , and Cosmucephalus obvelatus , and the cestode Diphyllobothrium ditremum parasitized three-spined sticklebacks ( G. aculeatus ) and four-spined sticklebacks ( A. quadracus ) inhabiting four brackish water ponds. All the parasites except P. decipiens infected nine-spined sticklebacks ( P. pungitius ) from a freshwater pond. In addition, the cestode Schistocephalus pungitii , the copepod Thersitina gasterostei , and the monogenean Gyrodactylus canadensis occurred in nine-spined sticklebacks from the freshwater pond. The two cestodes, the copepod, and the sealworm, P. decipiens , were the most common parasites encountered. The remaining helminths were relatively rare. Most of the parasite species were larval forms which use gulls or seals as definitive hosts. These parasites probably colonized Sable Island with their definitive hosts, whereas only two species ( T. gasterostei and G. canadensis ) successfully colonized the island ponds with their fish hosts. The low parasite species richness encountered is attributed to the impoverished nature of the host fauna of Sable island, and the difficulty of colonization as a result of the island's isolation with respect to the mainland.     

Complete mitochondrial genomes of Diplogonoporus balaenopterae and Diplogonoporus grandis (Cestoda: Diphyllobothriidae) and clarification of their taxonomic relationships

Although the diplogonadic human tapeworm, Diplogonoporus grandis, has long been considered to be a synonym of the whale tapeworm, Diplogonoporus balaenopterae, the identity of the both species at the complete mitochondrial genomes and nuclear DNA levels has been not sufficiently undertaken to date. In the present study, to clarify the taxonomic relationships between D. balaenopterae and D. grandis at the molecular level, the complete mitochondrial genomes of both species were sequenced and compared. In addition, the genetic variation in the mitochondrial cytochrome c oxidase subunit 1 gene (cox1) and the nuclear internal transcribed spacer-1 (ITS-1) region of the ribosomal RNA gene were examined. The complete mitochondrial genomes of D. balaenopterae and D. grandis consisted of 13,724 bp and 13,725 bp, respectively. These mitochondrial genomes contained 12 protein-coding, 22 transfer RNA and 2 ribosomal RNA genes and two longer non-coding regions. Except for Hymenolepis diminuta, the genomic organization in both species was essentially identical to that in other cestode genomes examined to date. However, differences were observed between Diplogonoporus and Diphyllobothrium species in abbreviated stop codons, sequences and the number of repeat units in the 2nd non-coding regions. The genetic differences observed in the mitochondrial genomes, cox1 and ITS-1 regions of both species were considered typical of intraspecific variation. In conclusion, D. balaenopterae is a taxonomically valid species and D. grandis is a junior synonym of D. balaenopterae based on the zoological nomenclature. Further, molecular-phylogenetic analysis confirmed that D. balaenopterae is more closely related to Diphyllobothrium stemmacephalum, the type-species of the genus Diphyllobothrium, and the taxonomical validity of the genera Diplogonoporus and Diphyllobothrium was also discussed.     

A new species of Onchobothriidae (Tetraphyllidea) from Chiloscyllium plagiosum (Elasmobranchii: Orectolobidae) in China

A new species of cestode, Yorkeria xiamenensis n. sp., is described from the spiral valve of Chiloscyllium plagiosum from coastal waters of Xiamen, China. It is the first record of Yorkeria in China. The new species is distinguished from all other species of Yorkeria by its possession of the following characters: the length of specimens, 15.8 mm; 63-95 proglottids; 71-85 testes per proglottid; large medial and lateral hooks in scolex; and eggs with 2 long polar filaments. The new species most closely resembles Y. parva Southwell, 1927 in the follicular vitellaria and similar ratio of lateral-to-medial hooks (1:2.15 vs. 1:2-2.5). However, Y. xiamenensis n. sp. has a longer strobila, more proglottids, a smaller ratio of pedicel to cephalic peduncle, larger hooks, more testes, and a different host.     

Intraspecific variation of Spirometra erinaceieuropaei and phylogenetic relationship between Spirometra and Diphyllobothrium inferred from mitochondrial CO1 gene sequences

Spirometra erinaceieuropaei is a diphyllobothriid cestode whose adult stage occurs mainly in cat-like carnivores, but occasionally in canids and humans. Although it is generally accepted that the distribution of S. erinaceieuropaei is cosmopolitan, it is controversial as to whether all of S. erinaceieuropaei reported are the same species. This study determined partial sequences of the CO1 gene from several isolates in Asian countries and compared them to sequence data from the GenBank/EMBL/DDBJ nucleotide sequence database. Then intraspecific variation of S. erinaceieuropaei and its phylogenetic relationship with Diphyllobothrium were evaluated. The level of nucleotide variation in the CO1 gene sequences within S. erinaceieuropaei was less than 2.6%. Although it was a little larger than that within each species of Diphyllobothrium (0.1-1.0%), it was much smaller than the interspecific variation within the genus Diphyllobothrium (6.2-14%). These facts indicate that all isolates of S. erinaceieuropaei used in this study, which were collected from Asia, Australia and New Zealand, belong to the same species. Based on CO1 gene sequences, genus Spirometra is clearly separate from the genus Diphyllobothrium. It seems that the genus Spirometra is not a synonym of the genus Diphyllobothrium. The phylogenetic relationship between S. erinaceieuropaei and Sparganum proliferum inferred from the CO1 gene clearly confirm the previous opinion that S. proliferum is a distinct species from S. erinaceieuropaei.     

Five cases of Diphyllobothrium nihonkaiense infection with discovery of plerocercoids from an infective source, Oncorhynchus masou ishikawae

Five persons from 2 families residing at Miyama Town, Mie Prefecture, Japan, ingested fresh raw fish Oncorhynchus sp. on 9 May 1999 that was caught at Owase district in Mie. They all expelled diphyllobothriid cestodes 11-37 days after ingesting the fish. The parasites were morphologically identical to Diphyllobothrium nihonkaiense Yamane et al., 1986. Five plerocercoids were detected from a portion of the fish. Nucleotide sequence of a region of the cytochrome c oxidase subunit I gene of mitochondrial DNA from an adult worm was identical with that from the plerocercoid. The fish was identified as Oncorhynchus masou ishikawae according to the nucleotide sequence of the nuclear ribosomal second internal transcribed spacer region II gene. This is the first record of D. nihonkaiense plerocercoids from O. m. ishikawae.     

Use of nuclear and mitochondrial DNA PCR and sequencing for molecular identification of Diphyllobothrium isolates potentially infective for humans

Tapeworms of the genus Diphyllobothrium (Cobold, 1858) are widely distributed all around the world and some of them are agents of human diphyllobothriasis. Approximately 50 species have been described within the Diphyllobothrium genus but only 13 are human pathogens. Species identification by using morphological criteria is very difficult. We determined the value of 18S ribosomal RNA gene, internal transcribed spacer (ITS) and cytochrome c oxidase subunit 1 gene (COI) sequences to differentiate between Diphyllobothrium isolates. Sequences from 18 isolates (larvae or adults) of D. latum, D. nihonkaiense, D. ditremum, D. dentriticum and D. stemmacephalum species were obtained. COI region sequences analysis was clearly more discriminative than those of the ITS1 and 18S rRNA and was a useful tool for identifying specimens.     

The effects of periodic eutrophication on parasitism and stock identification of Trematomus bernacchii (Pisces: Nototheniidae) in McMurdo Sound, Antarctica

McMurdo Sound, Antarctica, is suited for the study of the effects of eutrophication on diet-related parasites of Trematomus bernacchii (Boulenger, 1902) (Pisces). It has been relatively well studied, the environment is predictable, and there are significant differences in primary productivity over small distances. The differences in parasitism for 5 helminth species can be attributed to the enrichment processes in the sound. The prevalences of the acanthocephalan Echinorhynchus sp., the nematode Ascarophis nototheniae, the digenean Dinosoma sp., and the cestode Phyllobothrium sp. are significantly higher on the east side of the sound than on the west. The prevalence of the digenean Lepidepedon garrardi was significantly higher on the west side. We believe that the differences in the prevalences of infection between the east and west sides suggest that at least the benthic, adult fish do not readily move from one side of the sound to the other. We report the following (new host records are marked by asterisks): Echinorhynchus sp., Corynosoma hamanni (Acanthocephala); Phyllobothrium sp., Diphyllobothrium sp., Trypanorhyncha (Cestoidea); Clavellopsis (Copepoda); Dinosoma sp., Lepidepedon garrardi (Digenea); Pseudobenedenoides brachicola, Polyopisthocotylea (Monogenea); Contracaecum sp., Ascarophis nototheniae (Nematoda); Myxoproteus sp., Henneguya sp., Ceratomyxa sp., and Zschokkella sp. (Protozoa).     

shape Echinobothrium californiense n. sp. (Cestoda: Diphyllidea) from the thornback ray shape Platyrhinoidis triseriata (Chondrichthyes: Rajoidei) and a key to the species in the genus

Systematic Parasitology - A new cestode, Echinobothrium californiense n. sp., from the spiral intestine of Platyrhinoidis triseriata, taken in California waters is described. The new species is...     

Diphyllobothrium nihonkaiense Infections in a Family

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.     

Endoparasites in Sphenomorphus jobiensis (Sauria: Scincidae) from Papua New Guinea with description of three new species

One species of digenean, Zeylanurotrema sphenomorphi n. sp., and 2 nematode species, Meteterakis crombiei n. sp. and Physalopteroides milnensis n. sp., from the intestine of Sphenomorphus jobiensis, are described and illustrated. Zeylanurotrema sphenomorphi n. sp. represents the second species, Meteterakis crombiei n. sp. the 18th species, and Physalopteroides milnensis n. sp. the 19th species assigned to each respective genus. In addition, 1 species of cestode, Oochoristica javaensis; 7 nematode species, Abbreviata oligopapillata, Aplectana macintoshii, Aplectana zweifli, Cosmocerca zugi, Maxvachonia adamsoni, Oswaldocruzia bakeri, Parapharyngodon maplestonei; 1 species of acanthocephalan, Acanthocephalus bufonis; and 1 species of pentastome, Kiricephalus sp., were found. With the exception of Abbreviata oligopapillata, Sphenomorphus jobiensis represents a new host record for each species of endoparasite.     

Cestode zoonoses of aquatic animals

The cestode zoonoses of Diphyllobothrium, and Spirometra and Sparganosis are discussed from the point of view of their transmission and epidemiology.     

Relictolepis gen. n.--a new cestode genus (Cyclophyllidea: Hymenolepididae) from rodents of the Russian Far East and the description of R. feodorovi sp. n

A new cestode genus and species Relictolepis feodorovi gen. et sp. n. having armed scolex is described ex Clethrionomis rufocanus Sundevall, 1846 (Rodentia, Microtinae) from the Russian Far East.     

Description and phylogenetic relationships of Rodentolepis gnoskei n. sp. (Cyclophyllidea: Hymenolepididae) from a shrew Suncus varilla minor in Malawi

Rodentolepis gnoskei n. sp. is described based on specimens obtained from a lesser dwarf shrew Suncus varilla minor collected in the Nyika National Park, Malawi. The new species is one of the smallest hymenolepidids known from African shrews and is morphologically closest to two other miniature hymenolepidids from African shrews, Staphylocystis loossi and S. khalili. The new species differs from both of them by a much smaller strobila size and fewer proglottids. The rostellar hooks in the new species are more numerous and smaller in size than in S. loossi. The rostellar hooks in R. gnoskei n. sp. are almost three times shorter than hooks in S. khalili. The hook shape in both S. loossi and S. khalili is substantially different from that in the new species. Molecular phylogenetic analysis indicates that the new species is close to Rodentolepis fraterna, a parasite of rodents. The new species clearly differs from R. fraterna by the much shorter strobila, larger hooks, relatively longer cirrus sac, rate of proglottid development, the number of eggs per proglottid and parasitism in shrews. Although the new species fits the current diagnosis of Rodentolepis, its generic allocation is provisional and will likely be revised in the future because the type species of Rodentolepis, R. straminea, belongs to a different well supported clade. Thus, a new genus needs to be established for the lineage that includes R. fraterna and R. gnoskei n. sp. However, this systematic rearrangement is not recommended until Staphylocystis pistillum, the type species of Staphylocystis, is included in future phylogenetic analyses. Rodentolepis gnoskei n. sp. is the first tapeworm species reported from shrews in Malawi and the first species of cestode reported from S. varilla minor and any member of Suncus in Africa.     

Two new species of Duplicibothrium Williams & Campbell, 1978 (Tetraphyllidea: Serendipidae) from the Pacific cownose ray Rhinoptera steindachneri

Two new tetraphyllidean species, Duplicibothrium cairae n. sp. and D. paulum n. sp., are described from Pacific cownose rays Rhinoptera steindachneri collected from the Gulf of California. D. cairae n. sp. differs from the only other known species in this genus, D. minutum, in its possession of two posteriorly bifurcating longitudinal septa on each bothridium and having a greater number of loculi per bothridium, wider bothridia and a greater number of segments per worm. D. paulum n. sp. differs from the above two species in being shorter, having two continuous longitudinal septa on each bothridium, rather than posteriorly bifurcating or absent longitudinal septa, having a greater number of loculi per bothridium and having fewer segments per worm. The generic diagnosis of Duplicibothrium is amended to reflect the inclusion of the two new species. Species of Duplicibothriumappear to be restricted to host species of the genus Rhinoptera. Systematic information gained from the study of these two new species supports the monophyly of the tetraphyllidean family Serendipidae and suggests that Duplicibothrium shares a phylogenetic heritage with species in the genera Glyphobothrium and Serendip, taxa that are also parasitic in cownose rays. Evidence for a phylogenetic relationship between serendipid species and species of Dioecotaenia is discussed, as are potential molluscan hosts for cestode species in Duplicibothrium and Dioecotaenia.     

Helminths of the San Diego alligator lizard, (Gerrhonotus multicarinatus webbi) (Anguidae)

Necropsy of 96 specimens of the San Diego alligator lizard (Gerrhonotus multicarinatus webbi) from Los Angeles County, California (USA) revealed the presence of two nematodes (Physaloptera sp. and Oswaldocruzia pipiens) and a cestode (Oochoristica sp.). Both O. pipiens and Oochoristica sp. represent new host records. Prevalence of helminth infection (all species) was only 4/96 (4%) indicating the lack of a helminth community and a depauperate helminth fauna in this host.