Trichinella zimbabwensis n.sp. (Nematoda), a new non-encapsulated species from crocodiles (Crocodylus niloticus) in Zimbabwe also infecting mammals

Pozio, Edoardo; Foggin, Chris; Marucci, Gianluca; Rosa, G. La; Sacchi, Luciano; Corona, S.; Rossi, P.; Mukaratirwa, Samson

doi:10.1016/s0020-7519(02)00139-x

Cited by 91 publications

(63 citation statements)

References 18 publications

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“…A deep coevolutionary association had been proposed to explain the unique ability of nonencapsulated species to infect saurians, crocodilians, other nonavian archosaurs (Trichinella papuae and Trichinella zimbabwensis), and birds (Trichinella pseudospiralis), in contrast to the restriction of encapsulated species to synapsid and mammalian hosts (10,11). However, our data undermine the view that these two parasite groups coevolved exclusively with distinct tetrapod host groups.…”

Section: Discussioncontrasting

confidence: 58%

Post-Miocene expansion, colonization, and host switching drove speciation among extant nematodes of the archaic genus Trichinella

Zarlenga

Rosenthal

Rosa

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

141

124

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Parasitic nematodes of the genus Trichinella cause significant food-borne illness and occupy a unique evolutionary position at the base of the phylum Nematoda, unlike the free-living nematode Caenorhabditis elegans. Although the forthcoming genome sequence of Trichinella spiralis can provide invaluable comparative information about nematode biology, a basic framework for understanding the history of the genus Trichinella is needed to maximize its utility. We therefore developed the first robust and comprehensive analysis of the phylogeny and biogeographic history of Trichinella using the variation in three genes (nuclear small-subunit rDNA, and second internal transcribed spacer, mitochondrial large-subunit rDNA, and cytochrome oxidase I DNA) from all 11 recognized taxa. We conclude that (i) although Trichinellidae may have diverged from their closest extant relatives during the Paleozoic, all contemporary species of Trichinella diversified within the last 20 million years through geographic colonization and pervasive host switching among foraging guilds of obligate carnivores; (ii) mammalian carnivores disseminated encapsulated forms from Eurasia to Africa during the late Miocene and Pliocene, and to the Nearctic across the Bering Land Bridge during the Pliocene and Pleistocene, when crown species ultimately diversified; (iii) the greatest risk to human health is posed by those species retaining an ancestral capacity to parasitize a wide range of hosts; and (iv) early hominids may have first acquired Trichinella on the African savannah several million years before swine domestication as their diets shifted from herbivory to facultative carnivory.biogeography ͉ mitochondrial DNA ͉ phylogeny ͉ ribosomal DNA E xceptional biological diversity among nematodes is exemplified by certain attributes of the parasite Trichinella spiralis. Organization of its mitochondrial genome more closely resembles that of coelomate metazoans than that of its presumed closest relatives, the secernentean nematodes (1). In addition, T. spiralis (Dorylaimia) shares a similar proportion (45%) of its ESTs with the nematode Caenorhabditis elegans (Rhabditina) as it does with the fruit fly Drosophila melanogaster (Arthropoda: Drosophilidae) (2). Thus, many ESTs common to T. spiralis and C. elegans are not necessarily specific to nematodes but may be conserved among diverse taxonomic groups of invertebrates. C. elegans is often thought of as a prototypical nematode because of its acceptance as a model for studying biological processes; however, genomic variation among nematodes is extensive and commensurate with their phylogenetic and ecological diversity. Therefore, the forthcoming genome sequence of T. spiralis will contribute substantially to our understanding of nematode biology and the origins of parasitism.In 1998, Blaxter et al. (3) used genetic data to delineate the phylum Nematoda into supertaxa consisting of five clades. Trichinella, a parasite of vertebrates, occupies a basal lineage (clade I) consisting of free-living Mononchida, ...

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Section: Discussioncontrasting

confidence: 58%

Post-Miocene expansion, colonization, and host switching drove speciation among extant nematodes of the archaic genus Trichinella

Zarlenga

Rosenthal

Rosa

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

141

124

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“…Trichinella zimbabwensis, very similar to T. papuae, has been detected only in wild and farmed reptiles of Africa (Zimbabwe, Mozambique, South Africa, and Ethiopia), although experimentally, it is able to infect mammals (129,130). Human infections are not known so far.…”

Section: Species and Taxonomymentioning

confidence: 99%

Epidemiology, Diagnosis, Treatment, and Control of Trichinellosis

2009

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SUMMARY Throughout much of the world, Trichinella spp. are found to be the causative agents of human trichinellosis, a disease that not only is a public health hazard by affecting human patients but also represents an economic problem in porcine animal production and food safety. Due to the predominantly zoonotic importance of infection, the main efforts in many countries have focused on the control of Trichinella or the elimination of Trichinella from the food chain. The most important source of human infection worldwide is the domestic pig, but, e.g., in Europe, meats of horses and wild boars have played a significant role during outbreaks within the past 3 decades. Infection of humans occurs with the ingestion of Trichinella larvae that are encysted in muscle tissue of domestic or wild animal meat. Early clinical diagnosis of trichinellosis is rather difficult because pathognomonic signs or symptoms are lacking. Subsequent chronic forms of the disease are not easy to diagnose, irrespective of parameters including clinical findings, laboratory findings (nonspecific laboratory parameters such as eosinophilia, muscle enzymes, and serology), and epidemiological investigations. New regulations laying down rules for official controls for Trichinella in meat in order to improve food safety for consumers have recently been released in Europe. The evidence that the disease can be monitored and to some extent controlled with a rigorous reporting and testing system in place should be motivation to expand appropriate programs worldwide.

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“…The recent discovery of new nonencapsulated isolates of T. pseudospiralis [24] and two new species, T. papuae and T. zimbabwensis [13,25], in addition to the encapsulated species (T. spiralis, T. nativa, T. britovi, T. murrelli, and T. nelsoni) has stimulated a re-examination of the classification of members within the genus [26]. As indicated by Pozio et al [26], there is increasing biological, biochemical, and molecular evidence that the nonencapsulated species constitute a complex group which is distinct from the encapsulated species.…”

Section: Discussionmentioning

confidence: 99%

“…First-stage larvae (L1s) were recovered from host muscles by pepsin (1%)-HCl (1%) digestion at 407C for 30 min, sedimented and washed extensively in physiological saline and then suspended in 90% ethanol. L1s from international reference strains representing the eight recognized species and three genotypes [12,13] were used for comparative purposes (see Table 1). Total genomic DNA from multiple ("pooled") L1s was isolated by sodium dodecyl sulphate/proteinase K digestion (377C for 12 h) [14] and then purified over a spin column (Wizard  DNA CleanUp; Promega, Madison, WI, USA), according to the manufacturer's protocol, and eluted in 30 mL H 2 0.…”

Section: Parasite Materials and Isolation Of Genomic Dnamentioning

confidence: 99%

Nonisotopic single‐strand conformation polymorphism analysis of sequence variability in ribosomal DNA expansion segments within the genus Trichinella (Nematoda: Adenophorea)

Gasser

EL-Osta

et al. 2004

Electrophoresis

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A nonisotopic single-strand conformation polymorphism (SSCP) approach was employed to 'fingerprint' sequence variability in the expansion segment 5 (ES5) of domain IV and the D3 domain of nuclear ribosomal DNA within and/or among isolates and individual muscle (first-stage) larvae representing all currently recognized species/genotypes of Trichinella. In addition, phylogenetic analyses of the D3 sequence data set, employing three different tree-building algorithms, examined the relationships among all of them. These analyses showed strong support that the encapsulated species T. spiralis and T. nelsoni formed a group to the exclusion of the other encapsulated species T. britovi and its related genotypes Trichinella T8 and T9 and T. murrelli, and T. nativa and Trichinella T6, and strong support that T. nativa and Trichinella T6 grouped together. Also, these eight encapsulated members grouped to the exclusion of the nonencapsulated species T. papuae and T. zimbabwensis and the three representatives of T. pseudospiralis investigated. The findings showed that nonencapsulated species constitute a complex group which is distinct from the encapsulated species and supported the current hypothesis that encapsulated Trichinella group external to the nonencapsulated forms, in accordance with independent biological and biochemical data sets.

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Trichinella zimbabwensis n.sp. (Nematoda), a new non-encapsulated species from crocodiles (Crocodylus niloticus) in Zimbabwe also infecting mammals

Cited by 91 publications

References 18 publications

Post-Miocene expansion, colonization, and host switching drove speciation among extant nematodes of the archaic genus Trichinella

Post-Miocene expansion, colonization, and host switching drove speciation among extant nematodes of the archaic genus Trichinella

Epidemiology, Diagnosis, Treatment, and Control of Trichinellosis

Nonisotopic single‐strand conformation polymorphism analysis of sequence variability in ribosomal DNA expansion segments within the genus Trichinella (Nematoda: Adenophorea)

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