Survey of Spirometra erinaceieuropaei spargana infection in the frog Rana nigromaculata of the Hunan Province of China

Differential Mitochondrial Genome Expression of Four Hylid Frog Species under Low-Temperature Stress and Its Relationship with Amphibian Temperature Adaptation

Extreme weather poses huge challenges for animals that must adapt to wide variations in environmental temperature and, in many cases, it can lead to the local extirpation of populations or even the extinction of an entire species. Previous studies have found that one element of amphibian adaptation to environmental stress involves changes in mitochondrial gene expression at low temperatures. However, to date, comparative studies of gene expression in organisms living at extreme temperatures have focused mainly on nuclear genes. This study sequenced the complete mitochondrial genomes of five Asian hylid frog species: Dryophytes japonicus, D. immaculata, Hyla annectans, H. chinensis and H. zhaopingensis. It compared the phylogenetic relationships within the Hylidae family and explored the association between mitochondrial gene expression and evolutionary adaptations to cold stress. The present results showed that in D. immaculata, transcript levels of 12 out of 13 mitochondria genes were significantly reduced under cold exposure (p < 0.05); hence, we put forward the conjecture that D. immaculata adapts by entering a hibernation state at low temperature. In H. annectans, the transcripts of 10 genes (ND1, ND2, ND3, ND4, ND4L, ND5, ND6, COX1, COX2 and ATP8) were significantly reduced in response to cold exposure, and five mitochondrial genes in H. chinensis (ND1, ND2, ND3, ND4L and ATP6) also showed significantly reduced expression and transcript levels under cold conditions. By contrast, transcript levels of ND2 and ATP6 in H. zhaopingensis were significantly increased at low temperatures, possibly related to the narrow distribution of this species primarily at low latitudes. Indeed, H. zhaopingensis has little ability to adapt to low temperature (4 °C), or maybe to enter into hibernation, and it shows metabolic disorder in the cold. The present study demonstrates that the regulatory trend of mitochondrial gene expression in amphibians is correlated with their ability to adapt to variable climates in extreme environments. These results can predict which species are more likely to undergo extirpation or extinction with climate change and, thereby, provide new ideas for the study of species extinction in highly variable winter climates.

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.

Molecular Characterization of Spirometra erinaceieuropaei from Jungle Cat (Felis chaus) in North of Iran

PURPOSE

The aim of this study is to conduct a molecular characterization of Spirometra tapeworm from jungle cat (Felis chaus) in Guilan Province, north of Iran using DNA sequence analysis of the mitochondrial cytochrome c oxidase subunit 1 (Cox1) and 12S rDNA sequences.

METHODS

Morphological features of the adult tapeworm of Spirometra were evaluated using specific staining and light microscopy. The molecular characterization was performed using partial Cox1 and 12S rDNA regions. Genetic diversity was calculated and phylogenetic trees of the obtained sequences were constructed.

RESULTS

Morphological features were compatible with previous description of adult Spirometra erinaceieuropaei. The Cox1 sequence of the specimen showed 100% similarity with S. erinaceieuropaei sequences in GenBank from Korea, China and Iran. Also, the 12S rDNA sequence revealed 99.7% similarity with S. erinaceieuropaei isolates from China and Japan. Intra-species variation within isolates of S. erinaceieuropaei was 0-1.4% and 0-4.6% for Cox1 and 12S rDNA genes, respectively.

CONCLUSION

This is the first report of molecular characterization of S. erinaceieuropaei in jungle cat, F. chaus in Iran. Jungle cat probably plays a major role as reservoir host in maintaining of this parasite in this area with favorable climate condition. Needs for further assessment on the role of appropriate hosts, especially intermediate/paratenic hosts as well as the potential risk of human infectivity with sparganosis is emphasized.

Epidemiology, Diagnosis, and Prevention of Sparganosis in Asia

Sparganosis is a zoonotic parasitic disease caused by the larvae (spargana) of the genus Spirometra, which is widely distributed globally and threatens human health. More than 60 species of Spirometra have already been identified, and over 2000 cases have been reported. This review summarizes the prevalence of humans, frogs, snakes, and other animals with spargana. Furthermore, the infection mode, distribution, and site are summarized and analyzed. We also describe the epidemiology, molecular diagnosis, and other aspects which are of considerable significance to preventing sparganum.

Epidemiology and Genetic Diversity of Spirometra Tapeworm Isolates from Snakes in Hunan Province, China

Sparganosis, caused by the plerocercoid larvae of Spirometra tapeworms, is a public health hazard worldwide. The prevalence and genetics of sparganum from snakes remain unclear. In this study, we investigated the prevalence of sparganum infection in wild snakes in Hunan province and compared the prevalence of Spirometra tapeworms in snakes worldwide. Furthermore, the genetic diversity of collected isolates was analyzed using mitochondrial cytb and cox1 genes. The result shows that the sparganum infection rate in wild snakes (89.50%, 402/449) was higher in Hunan than in other regions. Genetic diversity analysis based on concatenated sequences revealed high genetic diversity but no distinct genetic structure among Spirometra populations. Phylogenetic analysis supported the division of European and Chinese Spirometra isolates and a single species in Chinese Spirometra isolates. The prevalence of Spirometra tapeworms in snakes is serious, and the risk of sparganosis should be further publicized.

Sparganosis (Spirometra spp.) in Asian Water Monitor (Varanus salvator): A medical implications for veterinarians, breeders, and consumers

Background and Aim

The high prevalence of sparganosis has been reported globally, especially in Asian countries where the majority of individuals consume raw meat from wild-caught reptiles. In Indonesia, similar cases regarding the high prevalence of sparganosis were recorded from wild reptiles such as snakes that utilized for culinary purposes, whereas, there are no data regarding other species such as water monitor lizard (Varanus salvator), which also provided as daily culinary with a high number of trades. Therefore, this study aims to investigate the prevalence of sparganosis in water monitor lizard (V. salvator), which is frequently utilized as culinary products in East Java Province, Indonesia.

Materials and Methods

A total of 313 living wild-caught and captive-bred Asian water monitor lizards were collected from the reptile markets and breeders. All samples were euthanized and observed for the presence of plerocercoid. Identification of the plerocercoid as larval infective stage was made using carmine staining method.

Results

The total prevalence of sparganosis was recorded at 69.64%. A total of 393 plerocercoids were collected in which divided 280 (71.24%) infecting muscles and 113 (28.75%) located in subcutaneous tissues.

Conclusion

To the best of our knowledge, this study not only recorded as the first evidence but also confirms the role of monitor lizards as sparganosis transmitters in Asia and reveals additional routes of sparganosis transmission in Indonesian reptiles. Local conservation laws should be strengthened to effectively control or ban wildlife trade in traditional markets. Moreover, public awareness regarding sparganosis as a neglected zoonotic disease should be applied to prevent disease transmission in Indonesia.

Foodborne Parasites Dominate Current Parasitic Infections in Hunan Province, China

Great progress has been made in the prevention and treatment of human parasitic diseases in China over the past six decades, but parasitic diseases are still one of the most serious public health problems in the world. The specific prevalence of parasitic diseases varies in different provinces due to their geographical environment and the dietary habits of people. In this study, a total of 4,428 patients suspected to have parasitic infection by clinicians or themselves from January 1, 2016, to December 31, 2020 were recommended to our laboratory for further testing. In total, 5,246 samples including fecal, blood, and other body fluids were detected by etiological and immunological methods. Approximately 15.20% (673/4,428) of all suspected patients were infected by at least one species of parasite, and the overall positive rate of suspected patients from Hunan Province was 15.10% (594/3,933). A total of 18 species of parasites, namely, nematodes (4 species), trematodes (5 species), cestodes (4 species), protozoa (2 species), and medical arthropods (3 species), and 3 of them were imported parasites outside of Hunan Province. There are 9 species of foodborne parasites, accounting for 89.92% (464/516) of patients infected by one species of parasite. Common parasites in Hunan Province include plerocercoid, Paragonimus westermani, Clonorchis sinensis, cysticercus, Toxoplasma gondii, and Schistosoma japonicum. In this study, we found that the incidence of soilborne nematode infections has decreased significantly. However, foodborne parasites gradually become the main parasitic infections as well as multiple infections are becoming more common. Therefore, we should not only continue the prevention and control of soil-derived nematodes but also focus on the prevention and control of foodborne parasites in the future.

Mitochondrial Genome of Spirometra theileri Compared with Other Spirometra Species

This study was carried out to provide information on the taxonomic classification and analysis of mitochondrial genomes of Spirometra theileri. One strobila of S. theileri was collected from the intestine of an African leopard (Panthera pardus) in the Maswa Game Reserve, Tanzania. The complete mtDNA sequence of S. theileri was 13,685 bp encoding 36 genes including 12 protein genes, 22 tRNAs and 2 rRNAs with absence of atp8. Divergences of 12 protein-coding genes were as follow: 14.9% between S. theileri and S. erinaceieuropaei, 14.7% between S. theileri and S. decipiens, and 14.5% between S. theileri with S. ranarum. Divergences of 12 proteins of S. theileri and S. erinaceieuropaei ranged from 2.3% in cox1 to 15.7% in nad5, while S. theileri varied from S. decipiens and S. ranarum by 1.3% in cox1 to 15.7% in nad3. Phylogenetic relationship of S. theileri with eucestodes inferred using the maximum likelihood and Bayesian inferences exhibited identical tree topologies. A clade composed of S. decipiens and S. ranarum formed a sister species to S. erinaceieuropaei, and S. theileri formed a sister species to all species in this clade. Within the diphyllobothridean clade, Dibothriocephalus, Diphyllobothrium and Spirometra formed a monophyletic group, and sister genera were well supported.

Low prevalence of spargana infection in farmed frogs in the Yangtze River Delta of China

Frogs are the main source of infection for human sparganosis. In this study, the prevalence and pathogenicity of plerocercoid larvae (sparganum) in frogs collected from the Yangtze River Delta in East China were investigated. A total of 386 frogs belonging to five species were purchased from farmers' markets across all three provincial level areas in the Yangtze River Delta region. The overall prevalence was 4.9% (19/386), and 39 spargana were detected visually, with the intensity ranging from 1 to 11. The spargana infection rate was 7.7% (11/143) in Jiangsu Province and 4.4% (8/181) in Shanghai City, while no spargana infection was detected in Zhejiang Province. In five tested frog species, only Rana nigromaculata and R. limnocharis were found to harbor spargana infection, with a prevalence of 7.7% (13/168) and 6.3% (6/95), respectively. There was no significant difference among the months of the experimental period, July to September. The spargana mostly parasitized the muscle tissues of frogs, especially in the hind legs. All the spargana were identified by molecular analysis based on cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes, and all plerocercoids were Spirometra erinaceieuropaei. Nine mice were infected orally with 1 to 3 scoleces, and 77.8% (14/18) of plerocercoids were found in mice at the 30th day post infection. No obvious clinical symptoms were observed in the mice; however, histopathological analysis showed an inflammatory cellular response in all tissues except intestinal tissue. Hematologic analysis showed an increased number of white blood cells (WBCs) at the 18th day post infection. These results indicated that R. nigromaculata and R. limnocharis are a potential source of zoonotic sparganosis in the Yangtze River Delta of China, and farmed frogs may substantially reduce zoonotic risk as compared to eating wild frogs. Our findings will provide data for frog food safety and prevention and control of sparganosis in the region.

Prevalence and molecular characterization of Spirometra erinaceieuropaei spargana in snakes in Hunan Province, China

Sparganosis is an important foodborne parasitic zoonosis; however, few reports on the prevalence of snake-infecting plerocercoids from Hunan province in China are available. Therefore, we investigated the prevalence of spargana infection in wild snakes from this region in 2018, and identified an astonishing prevalence rate of 91.7% (344/375). Spargana parasites were found in 99.1% of Zaocys dhumnades, 94.1% of Elaphe carinata and 86.7% of Elaphe taeniura. Parasites exhibited various distributions: 50% were located in muscular tissue, 32.1% in subcutaneous tissue and 17.9% in the coelomic cavity. To identify the specific status of spargana collected from wild snakes, partial mitochondrial cytochrome c oxidase subunit 1 (cox1) gene sequences were amplified, sequenced and analysed. Sequence variations for cox1 among all the examined plerocercoids ranged between 0.0 and 2.9%, with 21 variable sites identified (4.71%, 21/446). Phylogenetic analyses identified that all plerocercoids isolated from Hunan province were Spirometra erinaceieuropaei. This is the first report of S. erinaceieuropaei infection in snakes in Hunan province. The risks and harms of sparganosis should be publicized, and illegal wildlife trade should be controlled.

Large-scale survey of a neglected agent of sparganosis Spirometra erinaceieuropaei (Cestoda: Diphyllobothriidae) in wild frogs in China

Background

In China, frogs play an understudied role in the spread of human sparganosis (caused by the larval form of Spirometra). However, our knowledge about the prevalence of sparganum infection in frogs remains fragmented, and the taxonomic identification of the parasite is still controversial.

Methodology/Principal findings

The prevalence of sparganum infection in wild frogs was surveyed at 145 geographical locations from 28 of the 34 provinces/autonomous regions/municipalities in China for six years. The collected sparganum isolates from the different locations were subjected to molecular identification by a multiplex PCR assay and then were analysed with clustering analysis. In the survey, sparganum infection was found in 8 out of 13 of the collected frog species, and the most frequently infected species was Pelophylax nigromaculatus (the infection rate was up to 14.07%). Infected frogs were found in 80 of the 145 surveyed locations. The sparganum infection rates in the wild frogs in several regions of China were still high (above 10%), especially in South and Southwest China. A total of 72 spargana were selected for molecular identification, and the clustering analysis showed that sequences from the Chinese isolates were very similar to those identified as from Spirometra erinaceieuropaei. However, the taxonomy of the genus remains confused and further analysis is required.

Conclusions

Eating wild frogs is associated with considerable health risks in China. Several traditional Chinese folk remedies may increase the risk of infection. The sparganum isolates in China are most likely from S. erinaceieuropaei, but new studies, especially comprehensive morphological analyses, are needed in the future.

Human sparganosis has increased in recent years in China. Frogs play an important role in the spread of sparganosis. However, our knowledge about the prevalence of sparganum infection in frogs remains incomplete, and the taxonomic identification of sparganum is still controversial. In this study, the prevalence of sparganum infection in frogs was surveyed at 145 geographical locations in China. In addition, 72 spargana representing 72 distinct geographical isolates were selected for molecular identification. Frogs that tested positive for sparganum infection were found in 80 of the 145 surveyed locations, and the average infection rate was 10.96% (447/4078), with most of the spargana present in the thigh muscles of the infected frogs. The levels of sparganum infections in wild frogs in South and Southwest China were higher than those in the central and eastern regions. In the molecular identification analysis, all of the isolates revealed two specific bands in the multiplex PCR assay; the further clustering analysis of the sequenced PCR products showed that the Chinese isolates had a close relationship with Spirometra erinaceieuropaei.

Mitochondrial DNA Sequence Variability of Spirometra Species in Asian Countries

Mitochondrial DNA sequence variability of Spirometra erinaceieuropaei in GenBank was observed by reinvestigation of mitochondrial cox1 and cytb sequences. The DNA sequences were analyzed in this study, comprising complete DNA sequences of cox1 (n=239) and cytb (n=213) genes. The 10 complete mitochondrial DNA sequences of Spirometra species were compared with those of Korea, China and Japan. The sequences were analyzed for nucleotide composition, conserved sites, variable sites, singleton sites and parsimony-informative sites. Phylogenetic analyses was done using neighbor joining, maximum parsimony, Bayesian inference and maximum-likelihood on cox1 and cytb sequences of Spirometra species. These polymorphic sites identified 148 (cox1) and 83 (cytb) haplotypes within 239 and 213 isolates from 3 Asian countries. Phylogenetic tree topologies were presented high-level confidence values for the 2 major branches of 2 Spirometra species containing S. erinaceieuropaei and S. decipiens, and S. decipiens sub-clades including all sequences registered as S. erinaceieuropaei in cox1 and cytb genes. These results indicated that mitochondrial haplotypes of S. erinaceieuropaei and S. decipiens were found in the 3 Asian countries.

Genetic Identification of Spirometra erinaceieuropaei Spargana in Liaoning and Hubei Provinces, PR China

Spargana were collected from human and frogs in Liaoning and Hubei Provinces, China. PCR amplification and direct sequencing of A cox1 fragment was PCR-amplified from genomic DNA extracted from 7 specimens (5 from humans and 2 from frogs). The cox1 fragment (390 bp) showed 97–100% similarity to the reference sequence of S. erinaceieuropaei and 88–89% to the reference sequence of S. decipiens. There were 1–12 bases different between these worms, but no obvious genetic variation (0–3.3%) to the references. There was little difference of cox1 gene between sparganum samples of humans and frogs (1–3%). This study is the first report on S. erinaceieuropaei spargana from humans in Liaoning and Hubei Provinces.

Complete Sequence of the Mitochondrial Genome of Spirometra ranarum: Comparison with S. erinaceieuropaei and S. decipiens

This study was undertaken to determine the complete mitochondrial DNA sequence and structure of the mitochondrial genome of Spirometra ranarum, and to compare it with those of S. erinaceieuropaei and S. decipiens. The aim of this study was to provide information of the species level taxonomy of Spirometra spp. using the mitochondrial genomes of 3 Spirometra tapeworms. The S. ranarum isolate originated from Myanmar. The mitochondrial genome sequence of S. ranarum was compared with that of S. erinaceieuropaei (GenBank no. KJ599680) and S. decipiens (Gen-Bank no. KJ599679). The complete mtDNA sequence of S. ranarum comprised 13,644 bp. The S. ranarum mt genome contained 36 genes comprising 12 protein-coding genes, 22 tRNAs and 2 rRNAs. The mt genome lacked the atp8 gene, as found for other cestodes. All genes in the S. ranarum mitochondrial genome are transcribed in the same direction and arranged in the same relative position with respect to gene loci as found for S. erinaceieuropaei and S. decipiens mt genomes. The overall nucleotide sequence divergence of 12 protein-coding genes between S. ranarum and S. decipiens differed by 1.5%, and 100% sequence similarity was found in the cox2 and nad6 genes, while the DNA sequence divergence of the cox1, nad1, and nad4 genes of S. ranarum and S. decipiens was 2.2%, 2.1%, and 2.6%, respectively.

Molecular Genetic Findings of Spirometra decipiens and S. ranarum in Korea

The taxonomy of Spirometra species has been controversial despite the medical and veterinary importance. Currently, only a few Spirometra species are considered valid species in the genus Spirometra. In the present study, the distribution of Spirometra species obtained from animals in Korea were identified by molecular analysis of the mitochondrial cytochrome c oxidase I (cox1) gene. A total of 28 Spirometra species specimens were analyzed. These were all collected between 1973 and 2008 in the Republic of Korea. Mitochondrial cox1 sequences were examined for a total of 28 specimens comprising 14 S. decipiens and 14 S. ranarum. The difference in partial cox1 sequences (316 bp) between S. erinaceieuropaei (KJ599680) and S. ranarum (this study) was 9.3%, while that between S. decipiens (KJ599679) and S. ranarum (this study) was 2.2%. Genetic analyses identified 2 Spirometra species in animals such as cat, leopard cat, dog, duck and snake in Korea as S. decipiens and S. ranarum. S. decipiens and S. ranarum were present in Gyeongnam Province (P), Jeonnam P, Gangwon P, Chungbuk P, and Seoul. S. decipiens was found in tadpoles, snakes, ducks, cats, leopard cats and dogs, while S. ranarum was found in cats and dogs. The ratio of S. decipiens:S. ranarum calculated from the molecular data was 14:14 (or 1:1). These results indicate that S. decipiens and S. ranarum are sympatrically distributed in Korea.

Genetic and Morphologic Identification of Spirometra ranarum in Myanmar

In the present study, we identified a Spirometra species of Myanmar origin (plerocercoid) by molecular analysis using mitochondrial cox1 and nad1 genes, as well as by morphological observations of an adult tapeworm. Spargana specimens were collected from a paddy-field in Taik Kyi Township Tarkwa Village, Yangon, Myanmar in December 2017. A total of 5 spargana were obtained from 20 frogs Hoplobatrachus rugulosus; syn: Rana rugulosa (Wiegmann, 1834) or R. tigrina (Steindachner, 1867). The plerocercoids were used for experimental infection of a dog. After 4 weeks of infection, an adult tapeworm was recovered from the intestine of the dog. Morphologically, the distinct features of Spirometra sp. (Myanmar origin) relative to S. erinaceieuropaei and S. decipiens include a uterine morphology comprising posterior uterine coils that larger than the terminal uterine ball and coiling of the uteri diagonally (swirling) rather than spirally. The cox1 sequences (1,566 bp) of the Myanmar-origin Spirometra species showed 97.9% similarity to a reference sequence of S. decipiens (GenBank no. KJ599679) and 90.5% similarity to a reference sequence of S. erinaceieuropaei (GenBank no. KJ599680). Phylogenetic tree topologies were identical and presented high confidence level of values for the 3 major branches of the 3 Spirometra species in cox1 and nad1 genes. These results indicated that Myanmar-origin Spirometra species coincided with those of S. ranarum and may be considered as a valid species.

Differential Diagnosis of Human Sparganosis Using Multiplex PCR

Human sparganosis was diagnosed by morphological and genetic analyses in Korea. The complete mitochondrial genomes of Spirometra erinaceieuropaei and S. decipiens isolated in Korea have been recorded. Present study was performed to provide information to diagnose the etiologic agent of sparganosis by multiplex PCR using mitochondrial genome sequences of S. erinaceieuropaei and S. decipiens. In an effort to examine the differential diagnosis of spirometrid tapeworms, multiplex PCR assays were performed on plerocercoid larvae of S. erinaceieuropaei and S. decipiens. The PCR products obtained using species-specific primers were positively detected in all PCR assays on mixture of S. erinaceieuropaei and S. decipiens DNA. S. erinaceieuropaei-specific bands (239 bp and 401 bp) were obtained from all PCR assays using a mixture of S. erinaceieuropaei-specific primers (Se/Sd-1800F and Se-2018R; Se/Sd-7955F and Se-8356R) and S. erinaceieuropaei template DNA. S. decipiens-specific bands (540 bp and 644 bp) were also detected in all PCR assays containing mixtures of S. decipiens-specific primers (Se/Sd-1800F and Sd-2317R; Se/Sd-7955F and Sd-8567R) and S. decipiens template DNA. Sequence analyses on these species-specific bands revealed 100% sequence identity with homologous regions of the mtDNA sequences of S. erinaceieuropaei and S. decipiens. The multiplex PCR assay was useful for differential diagnosis of human sparganosis by detecting different sizes in species-specific bands.

Spirometra decipiens (Cestoda: Diphyllobothriidae) Collected in A Heavily Infected Stray Cat from the Republic of Korea

Morphological and molecular characteristics of spirometrid tapeworms, Spirometra decipiens, were studied, which were recovered from a heavily infected stray cat road-killed in Eumseong-gun, Chungcheongbuk-do (Province), the Republic of Korea (=Korea). A total of 134 scolices and many broken immature and mature proglottids of Spirometra tapeworms were collected from the small intestine of the cat. Morphological observations were based on 116 specimens. The scolex was 22.8–32.6 mm (27.4 mm in average) in length and small spoon-shape with 2 distinct bothria. The uterus was coiled 3–4 times, the end of the uterus was ball-shaped, and the vaginal aperture shaped as a crescent moon was closer to the cirrus aperture than to the uterine aperture. PCR amplification and direct sequencing of the cox1 target fragment (377 bp in length and corresponding to positions 769–1,146 bp of the cox1 gene) were performed using total genomic DNA extracted from 134 specimens. The cox1 sequences (377 bp) of the specimens showed 99.0% similarity to the reference sequence of S. decipiens and 89.3% similarity to the reference sequence of S. erinaceieuropaei. In the present study, we report a stray cat heavily infected with S. decipiens identified by mitochondrial cox1 sequence analysis and morphological examinations of the adult worms.

Establishment of the complete life cycle of Spirometra (Cestoda: Diphyllobothriidae) in the laboratory using a newly isolated triploid clone

Methods to maintain the life cycle of pathogenic organisms become powerful tools for studying molecular and cellular bases of infectious diseases. Spirometra erinaceieuropaei is a parasitic tapeworm that causes sparganosis in humans. Because S. erinaceieuropaei has a complex life cycle with different stages and host species requirements, there have been no reports to establish the complete life cycle in the laboratory. In this study, using Cyclops as the first intermediate host, mouse as the experimental second intermediate host, and dog as the final host, we succeeded in maintaining S. erinaceieuropaei in the laboratory. By repeating the established life cycle five times, we obtained a clonal population of S. erinaceieuropaei from a single adult worm. A karyotype study showed that the chromosome of this clone is triploid (3n=27), indicating that a genetically uniform strain is established by apomictic reproduction. The strain was named Kawasaki triploid (Kt). A partial sequence of mitochondrial cytochrome c oxidase subunit 1 gene of the strain Kt showed more than 98% similarity with those of S. erinaceieuropaei isolates from Australia, China, and South Korea, and the resultant phylogeny indicated that the strain Kt is a member of a distinctive clade from East Asia and Oceania. Our system will be particularly useful for studies of S. erinaceieuropaei infection and human sparganosis.

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.

The phylogenetic diversity of Spirometra erinaceieuropaei isolates from southwest China revealed by multi genes

The larval plerocercoid of Spirometra erinaceieuropaei can parasitize humans, causing a serious food borne parasitic zoonosis known as sparganosis. Sparganosis have increased in China in recent years. In this study, the prevalence of sparganum infection in wild frogs in 9 geographical areas in southwest China was firstly investigated. Of 276 caught frogs, 55 frogs were found to be infected with sparganum. Then, the population genetic structure of these sparganum isolates was explored based on four molecular markers (cytb, cox1, rrnS and 28S rDNA D1). Highly genetic diversity and the genetic differentiation among sparganum isolates from different sites were revealed in the DNA polymorphism analyses. Both the phylogenetic inference and the analysis of the median-joining network supported two clades in the southwest S. erinaceieuropaei population. However, none demographic population expansion of the southwest S. erinaceieuropaei population was observed in the neutrality test, mismatch distribution analysis and Bayesian skyline plot analysis. Finally, the phylogenetic diversity of S. erinaceieuropaei from eastern, central, southern and southwest China was analyzed, the result suggested that Chinese S. erinaceieuropaei population should be divided into two groups (Group I and Group II), and they started to divergence in the middle Pliocene.

Invaded Invaders: Infection of Invasive Brown Treesnakes on Guam by an Exotic Larval Cestode with a Life Cycle Comprised of Non-Native Hosts

Background

Multiple host introductions to the same non-native environment have the potential to complete life cycles of parasites incidentally transported with them. Our goal was to identify a recently detected parasitic flatworm in the invasive Brown Treesnake (Boiga irregularis) on the remote Pacific island of Guam. We considered possible factors influencing parasite transmission, and tested for correlations between infection status and potential indicators of host fitness. We used genetic data from the parasite and information about the native ranges of other possible non-native hosts to hypothesize how it arrived on Guam and how its life cycle may be currently supported.

Methods

We identified the parasite by comparing larval morphology and mtDNA sequences with other Pseudophyllid tapeworms. We assessed probability of infection in individual snakes using logistic regression and examined different factors influencing presence of parasites in hosts.

Results

We identified the parasite as the pseudophyllid cestode Spirometra erinaceieuropaei, with all sampled worms from multiple snakes sharing a single mtDNA haplotype. Infection appears to be limited to the only freshwater watershed on the island, where infection prevalence was high (77.5%). Larger snakes had a higher probability of being infected, consistent with the chronic nature of such infections. While infection status was positively correlated with body condition, infected snakes tended to have lower intra-peritoneal fat body mass, potentially indicating a negative effect on energy stores.

Conclusions

We discovered that B. irregularis inhabiting a small area of forested habitat in a freshwater watershed on Guam are often infected by a novel parasite of Asian origin. While further work is needed, this species of Spirometra, itself a non-native species, likely depends on a suite of recently introduced hosts from different parts of the world to complete the life cycle. This baseline study provides little evidence of any effects on host fitness, but additional data are needed to more thoroughly explore the consequences of infection in this invasive snake population.

Human sparganosis, a neglected food borne zoonosis

Human sparganosis is a food borne zoonosis caused by the plerocercoid larvae (spargana) of various diphyllobothroid tapeworms of the genus Spirometra. Human infections are acquired by ingesting the raw or undercooked meat of snakes or frogs, drinking untreated water, or using raw flesh in traditional poultices. More than 1600 cases of sparganosis have been documented worldwide, mostly in east and southeast Asia. Sporadic cases have been reported in South America, Europe, and Africa, and several cases have been described in travellers returning from endemic regions. Epidemiological data suggest that the increased effect of sparganosis on human health is because of greater consumption of raw meat of freshwater frogs and snakes. This Review provides information about the Spirometra parasites and their lifecycles, summarises clinical features, diagnosis, and treatment of human sparganosis, and describes geographical distribution and infection characteristics of Spirometra parasites in host animals.

The genome of the sparganosis tapeworm Spirometra erinaceieuropaei isolated from the biopsy of a migrating brain lesion

BACKGROUND

Sparganosis is an infection with a larval Diphyllobothriidea tapeworm. From a rare cerebral case presented at a clinic in the UK, DNA was recovered from a biopsy sample and used to determine the causative species as Spirometra erinaceieuropaei through sequencing of the cox1 gene. From the same DNA, we have produced a draft genome, the first of its kind for this species, and used it to perform a comparative genomics analysis and to investigate known and potential tapeworm drug targets in this tapeworm.

RESULTS

The 1.26 Gb draft genome of S. erinaceieuropaei is currently the largest reported for any flatworm. Through investigation of β-tubulin genes, we predict that S. erinaceieuropaei larvae are insensitive to the tapeworm drug albendazole. We find that many putative tapeworm drug targets are also present in S. erinaceieuropaei, allowing possible cross application of new drugs. In comparison to other sequenced tapeworm species we observe expansion of protease classes, and of Kuntiz-type protease inhibitors. Expanded gene families in this tapeworm also include those that are involved in processes that add post-translational diversity to the protein landscape, intracellular transport, transcriptional regulation and detoxification.

CONCLUSIONS

The S. erinaceieuropaei genome begins to give us insight into an order of tapeworms previously uncharacterized at the genome-wide level. From a single clinical case we have begun to sketch a picture of the characteristics of these organisms. Finally, our work represents a significant technological achievement as we present a draft genome sequence of a rare tapeworm, and from a small amount of starting material.

Levels of sparganum infections and phylogenetic analysis of the tapeworm Spirometra erinaceieuropaei sparganum in wild frogs from Henan Province in central China

Sparganosis is a serious food-borne parasitic zoonosis caused by infection with Spirometra spargana. The prevalence of sparganum infection in wild frogs (Rana nigromaculata, R. limmochari, R. temporaria and Bufo gargarizans) was investigated in Henan Province of central China during 2008–2012. Of 3482 caught wild frogs, 565 (16.23%) were found to be infected with plerocercoids (spargana) of the genus Spirometra. Spargana were found in 14.85% (320/2155) of R. nigromaculata, 20.82% (233/1119) of R. limmochari and 10.91% (12/110) of R. temporaria frogs. However, no sparganum was found in B. gargarizans. To investigate the phylogenetic position of collected spargana, three mitochondrial DNA (mtDNA) regions, namely cytochrome c oxidase subunits 1 and 3 (cox1 and cox3), and NADH dehydrogenase subunit 4 (nad4), were amplified, sequenced and analysed. Sequences of cox1, cox3 and pnad4 were 417, 390 and 578 bp in length, respectively. The base composition of cox1, cox3 and pnad4 were generally AT rich with a mean of 63.5%, 68.3% and 67% AT, respectively. Phylogenetic analysis showed that all the sparganum isolates in Henan Province represented Spirometra erinaceieuropaei and were a well-supported clade. These findings demonstrated clearly the usefulness of the three mtDNA sequences for molecular identification and population genetics studies of S. erinaceieuropaei spargana of human and animal health significance.

The genome of the sparganosis tapeworm Spirometra erinaceieuropaei isolated from the biopsy of a migrating brain lesion

BACKGROUND

Sparganosis is an infection with a larval Diphyllobothriidea tapeworm. From a rare cerebral case presented at a clinic in the UK, DNA was recovered from a biopsy sample and used to determine the causative species as Spirometra erinaceieuropaei through sequencing of the cox1 gene. From the same DNA, we have produced a draft genome, the first of its kind for this species, and used it to perform a comparative genomics analysis and to investigate known and potential tapeworm drug targets in this tapeworm.

RESULTS

The 1.26 Gb draft genome of S. erinaceieuropaei is currently the largest reported for any flatworm. Through investigation of β-tubulin genes, we predict that S. erinaceieuropaei larvae are insensitive to the tapeworm drug albendazole. We find that many putative tapeworm drug targets are also present in S. erinaceieuropaei, allowing possible cross application of new drugs. In comparison to other sequenced tapeworm species we observe expansion of protease classes, and of Kuntiz-type protease inhibitors. Expanded gene families in this tapeworm also include those that are involved in processes that add post-translational diversity to the protein landscape, intracellular transport, transcriptional regulation and detoxification.

CONCLUSIONS

The S. erinaceieuropaei genome begins to give us insight into an order of tapeworms previously uncharacterized at the genome-wide level. From a single clinical case we have begun to sketch a picture of the characteristics of these organisms. Finally, our work represents a significant technological achievement as we present a draft genome sequence of a rare tapeworm, and from a small amount of starting material.

Case report: Molecular diagnosis of subcutaneous Spirometra erinaceieuropaei sparganosis in a Japanese immigrant

We report a case of subcutaneous sparganosis in a 68-year-old female Japanese immigrant in Germany. The patient complained of a painless erythema caudal of the umbilicus with a palpable subcutaneous cherry-sized lump. Polymerase chain reaction on formalin-fixed parasite tissue identified Spirometra erinaceieuropaei as the causative agent; the proliferative form of sparganosis, which is caused by the branching and disseminating Sparganum proliferum, could, thus, be excluded. From the excised sparganum, an immunofluorescence test was established and revealed an antibody response directed against the parasite's tegument. Histological key features of the plerocercoid that facilitate diagnosis with different stains are presented.

Sequence variability in three mitochondrial DNA regions of Spirometra erinaceieuropaei spargana of human and animal health significance

Sequence variability in three mitochondrial DNA (mtDNA) regions, namely cytochrome c oxidase subunit 3 (cox3), NADH dehydrogenase subunits 1 and 4 (nad1 and nad4) in Spirometra erinaceieuropaei spargana from different geographical regions in China was examined. A portion of each of the cox3 (pcox3), nad1 (pnad1) and nad4 genes (pnad4) were amplified separately from individual S. erinaceieuropaei spargana by polymerase chain reaction (PCR). Representative amplicons were subjected to sequencing in order to estimate sequence variability. The sequences of pcox3, pnad1 and pnad4 were 541, 607 and 847 bp in length, respectively. The A+T contents of the sequences were 68.39–68.76% (pcox3), 63.76–64.91% (pnad1) and 67.18–67.77% (pnad4), respectively, while the intra-specific sequence variations within each of the S. erinaceieuropaei spargana were 0–1.5% for pcox3, 0–2.8% for pnad1 and 0–2.7% for pnad4. Phylogenetic analysis using neighbour joining (NJ), maximum likelihood (ML) and maximum parsimony (MP) methods, indicated that all the spargana isolates in Hunan Province represented S. erinaceieuropaei. These findings demonstrated clearly the usefulness of the three mtDNA sequences for population genetics studies of S. erinaceieuropaei spargana of human and animal health significance.