Diphyllobothriid Cestodes Research Articles

Cestodiasis in 2 Puerto Rican crested anoles.

Two adult male Puerto Rican crested anoles (Anolis cristatellus cristatellus) housed in a research facility were presented with debilitation and were euthanized. On autopsy, anole 1 had a large cystic white structure in the left pelvic limb, which protruded through the ruptured epidermis, and a large, poorly demarcated swelling in the right caudal abdomen. Anole 2 had masses in the mid-dorsum, caudal dorsum, left pelvic limb, and tail. These masses contained variably sized cestode larvae, which ruptured into the coelomic cavity. Evaluation of the larvae revealed a thickened and wrinkled anterior end, with a cleft-like invagination, consistent with either a plerocercoid sparganum or a tetrathyridium. Histologically, several cestode larvae were contained in the body wall of both anoles. These were up to 650 μm in diameter, with a thin tegument and a spongy parenchyma. The spongy parenchyma contained numerous, up to 30 μm diameter, sharply demarcated, basophilic-to-black structures (calcareous corpuscles). There was pneumonia and hepatitis in anole 2, suggestive of potential secondary infection subsequent to immunosuppression. Molecular amplification of the cytochrome C oxidase subunit 1 revealed 100% homology for the COX1 gene of the diphyllobothriid tapeworm Spirometra erinaceieuropaei, also known as Spirometra mansoni.

Highly resolved genome assembly and comparative transcriptome profiling reveal genes related to developmental stages of tapeworm Ligula intestinalis.

Ligula intestinalis (Cestoda: Diphyllobothriidae) is an emerging model organism for studies on parasite population biology and host-parasite interactions. However, a well-resolved genome and catalogue of its gene content has not been previously developed. Here, we present the first genome assembly of L. intestinalis, based on Oxford Nanopore Technologies, Illumina and Omni-C sequencing methodologies. We use transcriptome profiling to compare plerocercoid larvae and adult worms and identify differentially expressed genes (DEGs) associated with these life stages. The genome assembly is 775.3 mega (M)bp in size, with scaffold N50 value of 118 Mbp and encodes 27 256 predicted protein-coding sequences. Over 60% of the genome consists of repetitive sequences. Synteny analyses showed that the 10 largest scaffolds representing 75% of the genome display high correspondence to full chromosomes of cyclophyllidean tapeworms. Mapping RNA-seq data to the new reference genome, we identified 3922 differentially expressed genes in adults compared with plerocercoids. Gene ontology analyses revealed over-represented genes involved in reproductive development of the adult stage (e.g. sperm production) and significantly enriched DEGs associated with immune evasion of plerocercoids in their fish host. This study provides the first insights into the molecular biology of L. intestinalis and provides the most highly contiguous assembly to date of a diphyllobothriid tapeworm useful for population and comparative genomic investigations of parasitic flatworms.

A young parasite in an old fish host: A new genus for proteocephalid tapeworms (Cestoda) of bowfin (Amia calva) (Holostei: Amiiformes), and a revised list of its cestodes.

A new genus, Laruella n. gen., is proposed for the proteocephalid cestode L. perplexa (La Rue, 1911) n. comb. (syn. Proteocephalus perplexus La Rue, 1911), a parasite of a ‘living fossil’, the bowfin (Amia calva), in North America. The new genus is differentiated from other proteocephalid genera by having a massive four-lobed scolex without an apical organ and bearing suckers possessing tear-shaped sphincters on their inner rim, vitelline follicles forming L-shaped lateral fields, with the vitellarium turned inwards (medially) ventrally alongside the posterior margin of the ovary, a ring-like vaginal sphincter situated at a considerable distance from the genital atrium, and ellipsoid eggs resembling those of bothriocephalid and diphyllobothriid tapeworms, except for the absence of an operculum. Phylogenetic relationships of the new genus are not resolved, but it belongs to the so-called Neotropical clade of the Proteocephalidae, which is composed mainly of Neotropical tapeworms of siluriforms and other teleosts, but also Nearctic and Palaearctic species of Ophiotaenia La Rue, 1911 from snakes and amphibians. A morphologically similar species, Proteocephalus ambloplitis (Leidy, 1887) from bass (Micropterus spp.) in North America, is provisionally retained in Proteocephalus Weinland, 1858 because its relationships to L. perplexa are not yet clear. The former species differs from L. perplexa by the presence of a large apical organ, large, elongate vaginal sphincter situated near the genital atrium, vitelline follicles limited to lateral longitudinal fields, strongly coiled vas deferens within the cirrus sac, and a convoluted vaginal canal anterior to the ovarian isthmus. Laruella perplexa reportedly has a s broad spectrum of hosts but most are likely postcyclic or accidental hosts. A list of cestode parasites reported from bowfin is provided; it includes eight species and three taxa not identified to the species level. However, only three adult cestodes, L. perplexa and two species of Haplobothrium Cooper, 1914, are typical tapeworm parasites of bowfin, but previous molecular studies indicate possible existence of a putative new species in bowfin.

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

BackgroundThe 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).MethodsZalophus 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.ResultsA 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.ConclusionsDiphyllobothrium 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.Graphical

Population genetic structure of diphyllobothriid tapeworms (Cestoda: Diphyllobothriidea) parasitising fish in the Baikal Rift Zone.

Tapeworms of the genus Dibothriocephalus are widely distributed throughout the world, and some are agents of human diphyllobothriasis, one of the most important fish-borne zoonoses caused by a cestode parasite. Until now, the population genetic structure of diphyllobothriid tapeworms in the Baikal Rift Zone (BRZ) has remained unexplored. The major aim of this study was to analyse the population genetic structure of D. dendriticus and D. ditremus parasitising fish in the BRZ based on internal transcribed spacer 1 (ITS1) and mitochondrial gene cytochrome oxidase subunit I (cox1) sequences. We found that both species had complex population genetic structures. Each species formed 2 clades (D. dendriticus: Clade 1 & 2; D. ditremus Clade A & B) that differed in genetic diversity. D. dendriticus haplotypes in Clade 1 formed a star-like sub-network with a main haplotype, whereas the haplotypes in Clade 2 formed a diffuse network. We assumed that the complex population genetic structure of D. dendriticus was a consequence of populations evolving under different palaeoecological conditions during the Last Glacial Maximum. In contrast to D. dendriticus, both clades in the D. ditremus samples formed a diffuse network. Our findings revealed hypothetical pathways in the formation of the population genetic structure of diphyllobothriids in the BRZ. On one hand, isolation by distance played an important role; on the other hand, lake recolonisation from refugia and a genetic bottleneck after the end of the Last Glacial Maximum had a possible influence.

Neglected rare human parasitic infections: Part I: Sparganosis Wael M Lotfy

Some neglected parasitic larvae and worms may cause rare human infections. They are mostly zoonotic species. Sparganosisis is the infection with a plerocercoid larva of an animal diphyllobothriid cestode. The valid species incriminated in causing human sparganosis are Spirometra erinaceieuropaei, Spirometra decipiens, Spirometra mansonoides, Spirometra theileri, and the aberrant Sparganum proliferum. Other species reported to infect human in the literature are probably nonspecific. Coenuriasisis the infection with a metacestode of Taenia species, mainly T. multiceps or T. serialis. Acanthocephaliasis, on the other hand, is the infection with acanthocephalan worms. Man was reported to be infected with at least nine acanthocephalan species, among them, Macracanthorhynchus hirudinaceus and Moniliformis moniliformis are the most common species. Hirudiniasisis is the human attack by leeches. They are temporary parasites because they attack victims only when they are hungry and drop off when they are engorged. Among all species of leeches, only true leeches especially jawed leeches are known to attack humans. These species are either freshwater or land dwellers. This review summarizes current knowledge of the public health significance of human affections by these parasites, and the recommended methods of prevention and control.

A century of taxonomic uncertainty: re-description of two species of tapeworms (Diphyllobothriidea) from Arctic seals

Diphyllobothriid tapeworms are well-known parasites of mammals including humans. Most species are known for centuries, but the validity of many species and their classification are still poorly understood. Based on new collections and re-observation of museum material, we focus on widely distributed taxa infecting several species of seals (Phocinae) in Arctic and sub-Arctic waters. The existence of two morphologically similar diphyllobothriid species, Diphyllobothrium lanceolatum and Diphyllobothrium schistochilos, is revealed through detailed analyses of morphological and morphometric data as well as supported by genetic data published recently. Both species show a striking similarity in their body shape, which historically resulted in numerous misidentifications and erroneous records in the literature. Despite previous attempts to unequivocally recognize the species identity of these congeners, D. lanceolatum can be differentiated from D. schistochilos by the presence of a triangular scolex with a posterior velum, a rapid maturation of the strobila and the pointed or slightly rounded appearance of the last proglottid. In addition to the re-descriptions of both species, we provide novel information on their host spectrum and biogeographic distribution.

Comparative mitochondrial genomics among Spirometra (Cestoda: Diphyllobothriidae) and the molecular phylogeny of related tapeworms

The larva of Spirometra erinaceieuropaei can parasitize humans, causing a serious parasitic zoonosis known as sparganosis. Although it is medically important, our knowledge about the phylogenetic position of S. erinaceieuropaei and its evolutionary history is fragmentary. In this study, complete mitochondrial (mt) genomes of 4 geographically distinct isolates of S. erinaceieuropaei spargana collected from 4 frog hosts (Hylarana guentheri, Rana nigromaculata, R. rugulosa, R. temporaria) were characterized using an Illumina sequencing platform. In addition, all available mt genomes of Cestoda in GenBank were included to reconstruct the phylogeny and to explore the evolutionary history of these tapeworms. The genome features of S. erinaceieuropaei contained 12 protein-coding genes (PCGs), 22 transfer RNA genes, 2 ribosomal RNA genes and 2 non-coding regions. Nucleotide sequences of mtDNA from different frog hosts were similar. Three genes, cox1, cytb and nad4, had high levels of nucleotide diversity. Phylogenetic analyses supported the sibling relationship between Bothriocephalidae and Diphyllobothriidae. Molecular dating analysis indicated that the divergence between Diphyllobothrium and Diplogonoporus started in the late Miocene. The mt genomes of S. erinaceieuropaei will serve as a useful dataset for studying the genetics and systematics of the species of Spirometra genus in particular and diphyllobothriid tapeworms in general.

Using the small subunit of nuclear ribosomal DNA to reveal the phylogenetic position of the plerocercoid larvae of Spirometra tapeworms

Although medically important, the systematics of Spirometra and the taxonomic position of S. erinaceieuropaei remain unclear. In this study, the 18S rDNA gene of S. erinaceieuropaei sparganum from naturally infected frogs caught in 14 geographical locations of China was sequenced. In addition, all available 18S sequences of the family Diphyllobothriidae in the Genbank database were included to reconstruct the phylogeny of diphyllobothriid tapeworms. The secondary structure model of the 18S rDNA was also predicated to further explore the sequence variation. Phylogenetic analyses were performed using maximum parsimony (MP), maximum likelihood (ML) and Bayesian inference (BI) methods. The intraspecific divergences of 18S rDNA in Chinese sparganum isolates ranged from 0.0 to 0.4%. Regions of V2, V4 and V7 were the most variable regions in the secondary structure of 18S rDNA. With the exception of genera Duthiersia and Probothriocephalus, other genera (i.e., Adenocephalus, Diphyllobothrium, Diplogonoporus, Duthiersia, Schistocephalus and Spirometra) selected in the Diphyllobothriidae shared similar topologies of V2, V4 and V7 structures. The topology of generated phylogenetic trees revealed close relationships among Adenocephalus, Digramma, Diphyllobothrium, Diplogonoporus, Ligula, Sparganum and Spirometra. The exact phylogenetic position of Spirometra species should be further analyzed with more sampling and more useful molecular markers.

Molecular identification of Spirometra spp. (Cestoda: Diphyllobothriidae) in some wild animals from Brazil

Species of the genus Spirometra are diphyllobothriid tapeworms with complex life cycles and are involved in human sparganosis, a neglected disease that affects individuals worldwide. Although some species were reported in wild felids and human cases of sparganosis were described in Brazil, the biology and taxonomy of these parasites are poorly understood. In the present study, samples of diphyllobothriids (eggs and/or proglottids) obtained from the stools of wild carnivores (Leopardus pardalis and Lycalopex vetulus) and plerocercoid larvae found in a snake (Crotalus durissus) from Brazil were analysed by amplifying a fragment of the gene cytochrome c oxidase subunit 1 (cox 1). The DNA sequences obtained here for the first time from the Spirometra spp. from Brazil were used to evaluate the phylogenetic relationships with other species. Molecular data identified two species in the Brazilian samples (evolutionary divergence of 17.8–19.2%). The species were identified as Spirometra sp. 1, found in Le. pardalis, and Spirometra sp. 2 found in Ly. vetulus and C. durissus, and they differed from Asian isolates of Spirometra erinaceieuropaei (17.5–20.2% and 12.2–15.6%, respectively), a species previously considered to be distributed worldwide. Moreover, Spirometra sp. 1 is genetically distinct from Sparganum proliferum from Venezuela (19.6–20.4%), while Spirometra sp. 2 is more closely related with the Venezuelan species (6.1–7.0%). Sequences of Spirometra sp. 2 revealed that it is conspecific with the Argentinean isolate of Spirometra found in Lycalopex gymnocercus (1.9–2.2%). Taxonomic and phylogenetic aspects related to New World species of Spirometra are briefly discussed.

Eggs as a Suitable Tool for Species Diagnosis of Causative Agents of Human Diphyllobothriosis (Cestoda).

BackgroundTapeworms 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.MethodsIn 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.ResultsA 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.

Characterisation of the relationship between Spirometra erinaceieuropaei and Diphyllobothrium species using complete cytb and cox1 genes

Spirometra erinaceieuropaei is an important diphyllobothriid cestode whose larval plerocercoid (sparganum) can parasitise humans, causing sparganosis. In China, sparganosis is an important foodborne parasitic zoonosis and poses a serious threat to human health. However, our knowledge of the taxonomic classification of S. erinaceieuropaei and its relationship with other diphyllobothriid cestodes, such as Diphyllobothrium, remains fragmentary. In this study, we determined the complete sequences of cytochrome b (cytb) and cytochrome c oxidase subunit I (cox1) genes from 61 isolates of S. erinaceieuropaei collected from 11 geographical locations in eastern China and compared them to the sequences of Diphyllobothrium species from the GenBank database. Then, we evaluated the genetic variation of S. erinaceieuropaei and the phylogenetic relationship between S. erinaceieuropaei and Diphyllobothrium. Both negative Tajima’s D and Fu’s FS values of neutrality tests and unimodal curve of mismatch distribution analyses supported demographic population expansion. Bayesian skyline plot (BSP) analyses indicated that a population expansion occurred in the Pleistocene. Phylogenetic analysis based on cytb, cox1, and cytb+cox1 under all three methods tested (neighbour-joining, maximum parsimony, and maximum likelihood) suggested that the S. erinaceieuropaei isolates from eastern China and the genus Diphyllobothrium are separate monophyletic groups. Furthermore, the uncorrelated log-normal relaxed molecular-clock model suggested that divergence between Spirometra and Diphyllobothrium began in the late Miocene.

High morphological plasticity and global geographical distribution of the Pacific broad tapeworm Adenocephalus pacificus (syn. Diphyllobothrium pacificum): Molecular and morphological survey

The most important causative agent of human diphyllobothriosis in South America, Diphyllobothrium pacificum, is transferred to the original genus Adenocephalus Nybelin, 1931; revised and redescribed on the basis of the evaluation of an extensive material collected mainly from northern fur seal, Callorhinus ursinus, from St. Paul Island, Alaska. Detailed analysis of morphological and morphometrical data shows a high variability in most of the characteristics traditionally used in diagnosis of diphyllobothriid tapeworms. Phylogenetic analyses based on newly characterised sequences of mitochondrial cytochrome c oxidase subunit 1 and nuclear large subunit ribosomal RNA genes consistently reveal Adenocephalus pacificus as a sister lineage to the clade formed of the remaining Diphyllobothrium species and other genera (Digramma, Diplogonoporus, Ligula). Despite the generally similar morphology, A. pacificus can be differentiated from the closely related taxa in the presence of transverse papilla-like tegumental protuberances distributed anteriorly, separated by narrow semicircular grooves on the ventral surface of proglottids between their anterior margin and the anterior edge of the male gonopore, and relatively small eggs. A. pacificus displays a relatively low host specificity (found in 9 of 16 otariids, and in accidental hosts such as man, dog and jackal, the latter representing a new host) and a uniquely wide geographical distribution on both hemispheres. In addition, suitability of morphological criteria used in diagnostics of diphyllobothriid cestodes is discussed.

Diphyllobothrium nihonkaiense: wide egg size variation in 32 molecularly confirmed adult specimens from Korea.

The eggs of Diphyllobothrium nihonkaiense were reported to be smaller than those of the classical Diphyllobothrium latum in general. However, verification using a large number of adult tapeworms is required. We assessed the egg size variation in 32 adult specimens of D. nihonkaiense recovered from Korean patients in 1975-2014. The diagnosis of individual specimens was based on analysis of the mitochondrial cytochrome c oxidase 1 gene sequence. Uterine eggs (n = 10) were obtained from each specimen, and their length and width were measured by micrometry. The results indicated that the egg size of D. nihonkaiense (total number of eggs measured, 320) was widely variable according to individual specimens, 54-76 μm long (mean 64) and 35-58 μm wide (mean 45), with a length-width ratio of 1.32-1.70 (mean 1.46). The worm showing the smallest egg size had a length range of 54-62 μm, whereas the one showing the largest egg size had a length range of 68-76 μm. The two ranges did not overlap, and a similar pattern was observed for the egg width. Mapping of each egg size (n = 320) showed a wide variation in length and width. The widely variable egg size of D. nihonkaiense cannot be used for specific diagnosis of diphyllobothriid tapeworm infections in human patients.

The first report of sparganosis (Spirometra sp.) in Eurasian badger (Meles meles)

Spirometra sp. is a diphyllobothriid cestode which reproduces mainly in cat-like carnivores and canids. Several animal species that are not definitive hosts function as paratenic hosts, in which plerocercoids migrate to other tissues causing sparganosis. In this paper we describe the first case of sparganosis (Spirometra sp.) in Eurasian badger (Meles meles). It was found in an adult female Eurasian badger killed on the road in the Białowieża Primeval Forest (north-eastern Poland) in April 2013. At necropsy, 128 complete and 40 fragments of plerocercoids (spargana) were found and were located subcutaneously, mainly on the hind legs and along the spine. The average length of spargana was 87±38mm. No adult Spirometra sp. tapeworms were found in the animal intestine, indicating that the investigated badger was a paratenic host for Spirometra sp. Analysis of 18S rRNA gene sequences combined with morphological examination confirmed affiliation of the concerned plerocercoids to genus Spirometra.

Morphologic and Genetic Identification of Diphyllobothrium nihonkaiense in Korea

Diphyllobothrium nihonkaiense was first described by Yamane in 1986 but the taxonomical features have been obscure due to lack of critical morphologic criteria in its larval and adult stages. In Korea, this tapeworm had long been known as Diphyllobothrium latum. In this study, we observed 62 specimens collected from Korean residents and analyzed them by morphological features and nucleotide sequences of mitochondrial cox1 gene as well as the ITS1 region. Adult tapeworms were examined after carmine or trichrome stain. Longitudinal sections of the gravid proglottids showed an obtuse angle of about 150 degree between the cirrus sac and seminal vesicle. This angle is known as a major differential point compared with that of D. latum. Nucleotide sequence differences between D. latum and the specimens from Koreans represented 17.3% in mitochondrial DNA cox1 gene. Sequence divergence of ITS1 among 4 Korean isolates was 0.3% and similarity was 99.7% with D. nihonkaiense and D. klebanovskii. All of the Korean specimens analyzed in this study were identified as being D. nihonkaiense (n = 62). We propose its Korean name as "Dong-hae-gin-chon-chung" which means 'long tapeworm of the East Sea' for this newly analyzed diphyllobothriid tapeworm in Korea.

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.

Commentary

Spirometra erinaceieuropaei is an important diphyllobothriid cestode whose larval plerocercoid (sparganum) can parasitise humans, causing sparganosis. In China, sparganosis is an important foodborne parasitic zoonosis and poses a serious threat to human health. However, our knowledge of the taxonomic classification of S. erinaceieuropaei and its relationship with other diphyllobothriid cestodes, such as Diphyllobothrium, remains fragmentary. In this study, we determined the complete sequences of cytochrome b (cytb) and cytochrome c oxidase subunit I (cox1) genes from 61 isolates of S. erinaceieuropaei collected from 11 geographical locations in eastern China and compared them to the sequences of Diphyllobothrium species from the GenBank database. Then, we evaluated the genetic variation of S. erinaceieuropaei and the phylogenetic relationship between S. erinaceieuropaei and Diphyllobothrium. Both negative Tajima’s D and Fu’s FS values of neutrality tests and unimodal curve of mismatch distribution analyses supported demographic population expansion. Bayesian skyline plot (BSP) analyses indicated that a population expansion occurred in the Pleistocene. Phylogenetic analysis based on cytb, cox1, and cytb + cox1 under all three methods tested (neighbour-joining, maximum parsimony, and maximum likelihood) suggested that the S. erinaceieuropaei isolates from eastern China and the genus Diphyllobothrium are separate monophyletic groups. Furthermore, the uncorrelated log-normal relaxed molecular-clock model suggested that divergence between Spirometra and Diphyllobothrium began in the late Miocene.

Gastrointestinal Helminths in the Hawaiian Monk Seal (<I>Monachus schauinslandi</I>): Associations with Body Size, Hematology, and Serum Chemistry

Gastrointestinal helminth parasites are found commonly in the Hawaiian monk seal (Monachus schauinslandi), the most endangered seal in the United States and one of the world’s most endangered pinnipeds. We studied potential associations between gastrointestinal helminth infections and body size, and hematologic and serum chemistry variables in a sample of 282 monk seals captured between 1998 and 2002 as part of a population health assessment. Based on the presence of eggs in feces, the highest prevalence of infection (78%) was for cestodes belonging to a complex of several Diphyllobothrium spp. Infections with the nematode Contracaecum turgidum were found in 29% of samples tested. Eggs of the acanthocephalan Corynosoma rauschi were found in 4% of seals examined; and the feces of four weanling seals on the French Frigate Shoals contained eggs of the recently described trematode, Heterophyopsis hawaiiensis. We used a general linear model and analysis of variance techniques with adjustment for subpopulation and age to determine whether infections with Diphyllobothrium spp. or C. turgidum were associated with changes in hematologic or serum chemistry variables and found little evidence of an effect when we compared infected with negative seals or seals in the highest quartile of egg counts with negative seals. We also conducted analyses of associations between infection and morphometric values in adjusted, age-stratified data. Infection with Diphyllobothrium spp. was associated with a decrease in axillary girth and an increase in dorsal standard length/axillary girth ratio in seals less than 2 y of age, with the effects most pronounced in seals less than 1 y of age. After adjustment for Diphyllobothrium spp., C. turgidum infection was not associated with morphometric parameters. Co-infection with Diphyllobothrium spp. and C. turgidum was not associated with differences in body size greater than those found with diphyllobothriid tapeworm infection alone. These findings suggest that intervention strategies to reduce the prevalence of tapeworm infections in immature Hawaiian monk seals should be considered as a conservation measure for this highly endangered marine mammal.

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.