Genome of the fatal tapeworm Sparganum proliferum uncovers mechanisms for cryptic life cycle and aberrant larval proliferation.

The cryptic parasite Sparganum proliferum proliferates in humans and invades tissues and organs. Only scattered cases have been reported, but S. proliferum infection is always fatal. However, S. proliferum's phylogeny and life cycle remain enigmatic. To investigate the phylogenetic relationships between S. proliferum and other cestode species, and to examine the mechanisms underlying pathogenicity, we sequenced the entire genomes of S. proliferum and a closely related non-life-threatening tapeworm Spirometra erinaceieuropaei. Additionally, we performed larvae transcriptome analyses of S. proliferum plerocercoid to identify genes involved in asexual reproduction in the host. The genome sequences confirmed that the S. proliferum has experienced a clearly distinct evolutionary history from S. erinaceieuropaei. Moreover, we found that nonordinal extracellular matrix coordination allows asexual reproduction in the host, and loss of sexual maturity in S. proliferum are responsible for its fatal pathogenicity to humans. Our high-quality reference genome sequences should be valuable for future studies of pseudophyllidean tapeworm biology and parasitism.

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.

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.

Nine human sparganosis cases in Thailand with molecular identification of causative parasite species.

Human sparganosis is one of the neglected diseases but important food-borne parasitic zoonoses. The disease is caused by larvae (spargana) of diphyllobothriidean tapeworm. Here, we describe nine cases of human sparganosis, caused by Spirometra erinaceieuropaei in a hospital in Thailand during 2001-2012. Clinical characteristics, treatment, and outcome of cases were revealed. Diagnosis and identification of causative parasite species was made by histopathological investigations followed by a polymerase chain reaction-based molecular method using formalin-fixed paraffin embedded tissues. The DNA samples were extracted from tissues and a partial fragment of cytochrome c oxidase subunit 1 (cox1) gene was amplified for the detection of parasitic DNA. Infection could be prevented by increasing activities on health communication by responsible public health agencies.

Proliferative peritonitis with larval and cystic parasitic stages in a dog.

A six year old Labrador mix dog, born in Spain, was imported to Germany in young age. After a period of vague abdominal pain and negative laboratory results, the dog was referred to a local veterinary clinic for laparotomy, where the tentative diagnosis of echinococcus alveolaris was made and the dog was euthanized. At necropsy, many cystic structures and a massive proliferative peritonitis were visible. Furthermore a few solid larval cestodal stages were found in the peritoneal and chest cavity. Histological the cysts contained a small eosinophillic tegument, a cell poor stroma, basophilic somatic nuclei and a variable amount of amorphous bodies. The solid cestodes exhibited a quite similar composition with neither scolices nor any head structures. Histological features of the parasitic stages resembled cysts and asexual stages of Sparganum proliferum. Distinctions to other larval cestode infestations in body cavities were discussed.

[Collective group Sparganum and validity of Spirometra erinacei].

Parasites and their hosts are animals, their scientific names are subject to the International Code of Zoological Nomenclature. The core principles of the Code are the Principle of Name-Bearing Types, the Principle of Priority and the Principle of Homonymy. The Code provides guidance for zoologists to use correctly the available names. An assemblages of identifiable species of uncertain generic position are treated as a genus-group level for taxonomic convenience known as "collective groups" which requires no types and does not compete in priority with other genus-group names. The vernacular of plerocercoid metacestode of pseudophyllid tapeworm is known as sparganum, and has been treated as collective group Sparganum. The author makes a rectification for the Chinese terms of Diphyllobothrium and Spirometra according to their etymology. The original designation of the type species of the genus Spirometra is Diphyllobothrium decipiens (Diesing, 1850) by Faust et al, in 1929, but not Spirometra erinacei (Rudolphi) by Mueller in 1937, and the authorship of the latter species is Faust et al and the valid name as Spirometra erinacei (Faust, Campbell & Kellogg, 1929) synonymic with S. erinaceieuropaei (Rudolphi, 1819) and Diphyllobothrium mansoni (Joyeux et Houdemer, 1928), not vise versa, which is verified by CAB Thesaurus in 2010.

[Human plerocercoidosis and sparganosis: II. A historical review on pathology, clinics, epidemiology and control].

This article is the second part of the previous review and summarizes the research advances on pathology, clinical manifestation, diagnosis, treatment, epidemiology, and control of human plerocercoidosis and sparganosis.

Phylogenetic identification of Sparganum proliferum as a pseudophyllidean cestode by the sequence analyses on mitochondrial COI and nuclear sdhB genes.

Sparganum proliferum is a larval cestode for which the adult stage is unknown. It is characterized by the continuous branching and budding when parasitized to humans, and causes fatal human sparganosis. However, the biological features of S. proliferum, including its taxonomic status, still remain obscure. Our previous investigation suggested that S. proliferum might be phylogenetically distinct from Spirometra erinaceieuropaei, by the analysis on mitochondrial NADH dehydrogenase subunit 3 (ND3) gene. However, mitochondrial DNA sequence in Platyhelminth is known to have heteroplasmy within a species. Therefore, in the present study, we have investigated the complete nucleotide sequences of mitochondrial cytochrome c oxidase subunit I (COI) gene and the partial nucleotide sequences of nuclear coded succinate dehydrogenase iron-sulfur protein subunit gene (sdhB). The results clearly demonstrated that S. proliferum is a distinct species from S. erinaceieuropaei, and that S. proliferum belongs to the order Pseudophyllidea.

Esparganose em alguns vertebrados do Brasil: dificuldades na identificaçao das espécies de Luheella (Spirometra) / Sparganum in some brazilian vertebrates: problems in the identification of species of Luheella (Spirometra)

Sparganum in some Brazilian vertebrates. Problems in the identification of species of Luheella (Spirometra) - Some species of Amphibia and Reptilia are listed as new hosts of spargana, from material deposited in the Helminthological Collection of Oswaldo Cruz Institute. It is discussed the difficulties in identifying the larvae (Sparganum) and also the identification of adults of Luheella species from South America. The histopathology induced by spargana in the liver of a species of Amphibia is briefly described

[Two European Spirometra forms (Cestoidea: Diphyllobothriidae) with different Sparganum growth factors]. / Zwei europäische Spirometra-Formen (Cestoidea: Diphyllobothriidae) mit unterschiedlichem Sparganum Growth Factor.

European Spirometra forms corresponding to S. erinaceieuropaei in morphology, host specificity and periodical destrobilation were tested for a Sparganum Growth Factor (SGF "mansonoides") acting upon hypophysectomized male rats. A Polish form as well as Thai and Burmese forms did not show a SGF "mansonoides". The Polish form partially caused increased growth in normal laboratory mice (similar to a form from Thailand) and in Cricetulus griseus (SGF "non-mansonoides", restricted by host resistance). Procyon lotor can act both as paratenic and as definitive host for the Polish form. The Polish, Thai and Burmese forms are attributed to S. erinaceieuropaei. A Bulgarian form showed a typical SGF "mansonoides". 4 hyposectomized 100 g rats, each of which were implanted 5 spargana subcutaneously, showed weight gains up to 400 g within 7 to 8 weeks. Therefore, this Bulgarian form is treated provisionally as Spirometra sp.