Browsing by Subject "GENUS ECHINOCOCCUS"

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  • Ito, Akira; Nakao, Minoru; Lavikainen, Antti; Hoberg, Eric (2017)
    Human cystic echinococcosis (CE) has been considered to be caused predominantly by Echinococcus granulosus sensu stricto (the dog-sheep strain). Molecular approaches' on CE, however, have revealed that human cases are also commonly caused by another species, Echinococcus canadensis. All indices for classification and standardization of CE pathology including available images, epidemiology, diagnostics and treatment are currently based largely on a mixture of infections which include at least E. granulosus s.s. and E. canadensis. Involvement of other species of Echinococcus in CE including E. ortleppi or otherwise cryptic diversity demonstrated recently in Africa requires further elucidation. Molecular identification of the causative species in CE cases is essential for better understanding of pathogenesis and disease. This article stresses the importance of molecular species identification of human CE as a foundation for re-evaluation of evidence-based epidemiology. (C) 2016 Elsevier B.V. All rights reserved.
  • Kinkar, Liina; Laurimae, Teivi; Simsek, Sami; Balkaya, Ibrahim; Casulli, Adriano; Manfredi, Maria Teresa; Ponce-Gordo, Francisco; Varcasia, Antonio; Lavikainen, Antti; Miguel Gonzalez, Luis; Rehbein, Steffen; Van der Giessen, Joke; Sprong, Hein; Saarma, Urmas (2016)
    Echinococcus granulosus is the causative agent of cystic echinococcosis. The disease is a significant global public health concern and human infections are most commonly associated with E. granulosus sensu stricto (s. s.) genotype G1. The objectives of this study were to: (i) analyse the genetic variation and phylogeography of E. granulosus s. s. G1 in part of its main distribution range in Europe using 8274 bp of mtDNA; (ii) compare the results with those derived from previously used shorter mtDNA sequences and highlight the major differences. We sequenced a total of 91 E. granulosus s. s. G1 isolates from six different intermediate host species, including humans. The isolates originated from seven countries representing primarily Turkey, Italy and Spain. Few samples were also from Albania, Greece, Romania and from a patient originating from Algeria, but diagnosed in Finland. The analysed 91 sequences were divided into 83 haplotypes, revealing complex phylogeography and high genetic variation of E. granulosus s. s. G1 in Europe, particularly in the high-diversity domestication centre of western Asia. Comparisons with shorter mtDNA datasets revealed that 8274 bp sequences provided significantly higher phylogenetic resolution and thus more power to reveal the genetic relations between different haplotypes.
  • Kinkar, Liina; Laurimae, Teivi; Sharbatkhori, Mitra; Mirhendi, Hossein; Kia, Eshrat Beigom; Ponce-Gordo, Francisco; Andresiuk, Vanessa; Simsek, Sami; Lavikainen, Antti; Irshadullah, Malik; Umhang, Gerald; Oudni-M'rad, Myriam; Acosta-Jamett, Gerardo; Rehbein, Steffen; Saarma, Urmas (2017)
    Cystic echinococcosis, a zoonotic disease caused by Echinococcus granulosus sensu lato (s.l.), is a significant global public health concern. Echinococcus granulosus s. l. is currently divided into numerous genotypes (G1-G8 and G10) of which G1-G3 are the most frequently implicated genotypes in human infections. Although it has been suggested that G1-G3 could be regarded as a distinct species E. granulosus sensu stricto (s. s.), the evidence to support this is inconclusive. Most importantly, data from nuclear DNA that provide means to investigate the exchange of genetic material between G1-G3 is lacking as none of the published nuclear DNA studies have explicitly included G2 or G3. Moreover, the commonly used relatively short mtDNA sequences, including the complete coxl gene, have not allowed unequivocal differentiation of genotypes G1-G3. Therefore, significantly longer mtDNA sequences are required to distinguish these genotypes with confidence. The main aim of this study was to evaluate the phylogenetic relations and taxonomy of genotypes G1-G3 using sequences of nearly complete mitogenomes (11,443 bp) and three nuclear loci (2984 bp). A total of 23 G1-G3 samples were analysed, originating from 5 intermediate host species in 10 countries. The mtDNA data demonstrate that genotypes G1 and G3 are distinct mitochondrial genotypes (separated by 37 mutations), whereas G2 is not a separate genotype or even a monophyletic cluster, but belongs to G3. Nuclear data revealed no genetic separation of G1 and G3, suggesting that these genotypes form a single species due to ongoing gene flow. We conclude that: (a) in the taxonomic sense, genotypes G1 and G3 can be treated as a single species E. granulosus s. s.; (b) genotypes G1 and G3 should be regarded as distinct genotypes only in the context of mitochondrial data; (c) we recommend excluding G2 from the genotype list. (C) 2017 Elsevier B.V. All rights reserved.
  • Lavikainen, Antti; Iwaki, Takashi; Haukisalmi, Voitto; Konyaev, Sergey V.; Casiraghi, Maurizio; Dokuchaev, Nikolai E.; Galimberti, Andrea; Halajian, Ali; Henttonen, Heikki; Ichikawa-Seki, Madoka; Itagaki, Tadashi; Krivopalov, Anton V.; Meri, Seppo; Morand, Serge; Nareaho, Anu; Olsson, Gert E.; Ribas, Alexis; Terefe, Yitagele; Nakao, Minoru (2016)
    The common cat tapeworm Hydatigera taeniaeformis is a complex of three morphologically cryptic entities, which can be differentiated genetically. To clarify the biogeography and the host spectrum of the cryptic lineages, 150 specimens of H. taeniaeformis in various definitive and intermediate hosts from Eurasia, Africa and Australia were identified with DNA barcoding using partial mitochondrial cytochrome c oxidase subunit 1 gene sequences and compared with previously published data. Additional phylogenetic analyses of selected isolates were performed using nuclear DNA and mitochondrial genome sequences. Based on molecular data and morphological analysis, Hydatigera kamiyai n. sp. Iwaki is proposed for a cryptic lineage, which is predominantly northern Eurasian and uses mainly arvicoline rodents (voles) and mice of the genus Apodemus as intermediate hosts. Hydatigera taeniaeformis sensu stricto (s.s.) is restricted to murine rodents (rats and mice) as intermediate hosts. It probably originates from Asia but has spread worldwide. Despite remarkable genetic divergence between H. taeniaeformis s.s. and H. kamiyai, interspecific morphological differences are evident only in dimensions of rostellar hooks. The third cryptic lineage is closely related to H. kamiyai, but its taxonomic status remains unresolved due to limited morphological, molecular, biogeographical and ecological data. This Hydatigera sp. is confined to the Mediterranean and its intermediate hosts are unknown. Further studies are needed to classify Hydatigera sp. either as a distinct species or a variant of H. kamiyai. According to previously published limited data, all three entities occur in the Americas, probably due to human-mediated introductions. (C) 2016 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.