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Clinical Microbiology Reviews Jul 2009An estimated 750 million people are at risk of infections with food-borne trematodes, which comprise liver flukes (Clonorchis sinensis, Fasciola gigantica, Fasciola... (Review)
Review
An estimated 750 million people are at risk of infections with food-borne trematodes, which comprise liver flukes (Clonorchis sinensis, Fasciola gigantica, Fasciola hepatica, Opisthorchis felineus, and Opisthorchis viverrini), lung flukes (Paragonimus spp.), and intestinal flukes (e.g., Echinostoma spp., Fasciolopsis buski, and the heterophyids). Food-borne trematodiases pose a significant public health and economic problem, yet these diseases are often neglected. In this review, we summarize the taxonomy, morphology, and life cycle of food-borne trematodes. Estimates of the at-risk population and number of infections, geographic distribution, history, and ecological features of the major food-borne trematodes are reviewed. We summarize clinical manifestations, patterns of infection, and current means of diagnosis, treatment, and other control options. The changing epidemiological pattern and the rapid growth of aquaculture and food distribution networks are highlighted, as these developments might be associated with an elevated risk of transmission of food-borne trematodiases. Current research needs are emphasized.
Topics: Animals; Food Parasitology; Humans; Trematoda; Trematode Infections
PubMed: 19597009
DOI: 10.1128/CMR.00012-09 -
The Korean Journal of Parasitology Feb 2015Serine proteases form one of the most important families of enzymes and perform significant functions in a broad range of biological processes, such as intra- and... (Review)
Review
Serine proteases form one of the most important families of enzymes and perform significant functions in a broad range of biological processes, such as intra- and extracellular protein metabolism, digestion, blood coagulation, regulation of development, and fertilization. A number of serine proteases have been identified in parasitic helminths that have putative roles in parasite development and nutrition, host tissues and cell invasion, anticoagulation, and immune evasion. In this review, we described the serine proteases that have been identified in parasitic helminths, including nematodes (Trichinella spiralis, T. pseudospiralis, Trichuris muris, Anisakis simplex, Ascaris suum, Onchocerca volvulus, O. lienalis, Brugia malayi, Ancylostoma caninum, and Steinernema carpocapsae), cestodes (Spirometra mansoni, Echinococcus granulosus, and Schistocephalus solidus), and trematodes (Fasciola hepatica, F. gigantica, and Schistosoma mansoni). Moreover, the possible biological functions of these serine proteases in the endogenous biological phenomena of these parasites and in the host-parasite interaction were also discussed.
Topics: Animals; Cestoda; Host-Parasite Interactions; Life Cycle Stages; Nematoda; Serine Proteases; Trematoda
PubMed: 25748703
DOI: 10.3347/kjp.2015.53.1.1 -
Parasite (Paris, France) Sep 2008As many others parasites, speciation of flukes depends on the genetic characteristics and on ploidia. Ploidia of flukes can be different in a same species. In Asia,... (Review)
Review
As many others parasites, speciation of flukes depends on the genetic characteristics and on ploidia. Ploidia of flukes can be different in a same species. In Asia, diploid, triploid and hybrid (2n/3n) populations are encountered. The comparison of morphological parameters between diploid and triploid flukes showed that they were morphologically different. Nevertheless, a genetic relationship between parthenogenetic organisms would exist regardless of their ploidia. In the Fasciola genus, the main consequence of the high level of diversity is the frequent probability of development of resistance to anthelmintics and fast adaptation to climatic changes. In the Paragonimus genus, diversity can enhance different forms of pathogenicity, can also be related to the species of intermediate hosts, and to the definitive host. The strain of flukes plays a part in the visceral localization of P. westermani adults.
Topics: Animals; Biodiversity; Diploidy; Humans; Parthenogenesis; Polyploidy; Species Specificity; Trematoda
PubMed: 18814695
DOI: 10.1051/parasite/2008153282 -
The Korean Journal of Parasitology Oct 2009In Southeast Asia, a total of 59 species of foodborne intestinal flukes have been known to occur in humans. The largest group is the family Heterophyidae, which... (Review)
Review
In Southeast Asia, a total of 59 species of foodborne intestinal flukes have been known to occur in humans. The largest group is the family Heterophyidae, which constitutes 22 species belonging to 9 genera (Centrocestus, Haplorchis, Heterophyes, Heterophyopsis, Metagonimus, Procerovum, Pygidiopsis, Stellantchasmus, and Stictodora). The next is the family Echinostomatidae, which includes 20 species in 8 genera (Artyfechinostomum, Acanthoparyphium, Echinochasmus, Echinoparyphium, Echinostoma, Episthmium, Euparyphium, and Hypoderaeum). The family Plagiorchiidae follows the next containing 5 species in 1 genus (Plagiorchis). The family Lecithodendriidae includes 3 species in 2 genera (Phaneropsolus and Prosthodendrium). In 9 other families, 1 species in 1 genus each is involved; Cathaemaciidae (Cathaemacia), Fasciolidae (Fasciolopsis), Gastrodiscidae (Gastrodiscoides), Gymnophallidae (Gymnophalloides), Microphallidae (Spelotrema), Neodiplostomidae (Neodiplostomum), Paramphistomatidae (Fischoederius), Psilostomidae (Psilorchis), and Strigeidae (Cotylurus). Various types of foods are sources of human infections. They include freshwater fish, brackish water fish, fresh water snails, brackish water snails (including the oyster), amphibians, terrestrial snakes, aquatic insects, and aquatic plants. The reservoir hosts include various species of mammals or birds.The host-parasite relationships have been studied in Metagonimus yokogawai, Echinostoma hortense, Fasciolopsis buski, Neodiplostomum seoulense, and Gymnophalloides seoi; however, the pathogenicity of each parasite species and host mucosal defense mechanisms are yet poorly understood. Clinical aspects of each parasite infection need more clarification. Differential diagnosis by fecal examination is difficult because of morphological similarity of eggs. Praziquantel is effective for most intestinal fluke infections. Continued efforts to understand epidemiological significance of intestinal fluke infections, with detection of further human cases, are required.
Topics: Animals; Asia, Southeastern; Food Parasitology; Humans; Intestines; Trematoda; Trematode Infections
PubMed: 19885337
DOI: 10.3347/kjp.2009.47.S.S69 -
Parasites & Vectors Jan 2019Division of labour has evolved in many social animals where colonies consist of clones or close kin. It involves the performance of different tasks by morphologically... (Review)
Review
Division of labour has evolved in many social animals where colonies consist of clones or close kin. It involves the performance of different tasks by morphologically distinct castes, leading to increased colony fitness. Recently, a form of division of labour has been discovered in trematodes: clonal rediae inside the snail intermediate host belong either to a large-bodied reproductive caste, or to a much smaller and morphologically distinct 'soldier' caste which defends the colony against co-infecting trematodes. We review recent research on this phenomenon, focusing on its phylogenetic distribution, its possible evolutionary origins, and how division of labour functions to allow trematode colonies within their snail host to adjust to threats and changing conditions. To date, division of labour has been documented in 15 species from three families: Himasthlidae, Philophthalmidae and Heterophyidae. Although this list of species is certainly incomplete, the evidence suggests that division of labour has arisen independently more than once in the evolutionary history of trematodes. We propose a simple scenario for the gradual evolution of division of labour in trematodes facing a high risk of competition in a long-lived snail host. Starting with initial conditions prior to the origin of castes (size variation among rediae within a colony, size-dependent production of cercariae by rediae, and a trade-off between cercarial production and other functions, such as defence), maximising colony fitness (R) can lead to caste formation or the age-structured division of labour observed in some trematodes. Finally, we summarise recent research showing that caste ratios, i.e. relative numbers of reproductive and soldier rediae per colony, become more soldier-biased in colonies exposed to competition from another trematode species sharing the same snail, and also respond to other stressors threatening the host's survival or the colony itself. In addition, there is evidence of asymmetrical phenotypic plasticity among individual caste members: reproductives can assume defensive functions against competitors in the absence of soldiers, whereas soldiers are incapable of growing into reproductives if the latter's numbers are reduced. We conclude by highlighting future research directions, and the advantages of trematodes as model systems to study social evolution.
Topics: Adaptation, Physiological; Animals; Biological Evolution; Cercaria; Ecology; Phylogeny; Reproduction; Snails; Trematoda
PubMed: 30609937
DOI: 10.1186/s13071-018-3241-6 -
Parasites & Vectors Dec 2022Glutamate carboxypeptidase 2 (GCP2) belongs to the M28B metalloprotease subfamily encompassing a variety of zinc-dependent exopeptidases that can be found in many...
BACKGROUND
Glutamate carboxypeptidase 2 (GCP2) belongs to the M28B metalloprotease subfamily encompassing a variety of zinc-dependent exopeptidases that can be found in many eukaryotes, including unicellular organisms. Limited information exists on the physiological functions of GCP2 orthologs in mammalian tissues outside of the brain and intestine, and such data are completely absent for non-mammalian species. Here, we investigate GCP2 orthologs found in trematodes, not only as putative instrumental molecules for defining their basal function(s) but also as drug targets.
METHODS
Identified genes encoding M28B proteases Schistosoma mansoni and Fasciola hepatica genomes were analyzed and annotated. Homology modeling was used to create three-dimensional models of SmM28B and FhM28B proteins using published X-ray structures as the template. For S. mansoni, RT-qPCR was used to evaluate gene expression profiles, and, by RNAi, we exploited the possible impact of knockdown on the viability of worms. Enzymes from both parasite species were cloned for recombinant expression. Polyclonal antibodies raised against purified recombinant enzymes and RNA probes were used for localization studies in both parasite species.
RESULTS
Single genes encoding M28B metalloproteases were identified in the genomes of S. mansoni and F. hepatica. Homology models revealed the conserved three-dimensional fold as well as the organization of the di-zinc active site. Putative peptidase activities of purified recombinant proteins were assayed using peptidic libraries, yet no specific substrate was identified, pointing towards the likely stringent substrate specificity of the enzymes. The orthologs were found to be localized in reproductive, digestive, nervous, and sensory organs as well as parenchymal cells. Knockdown of gene expression by RNAi silencing revealed that the genes studied were non-essential for trematode survival under laboratory conditions, reflecting similar findings for GCP2 KO mice.
CONCLUSIONS
Our study offers the first insight to our knowledge into M28B protease orthologs found in trematodes. Conservation of their three-dimensional structure, as well as tissue expression pattern, suggests that trematode GCP2 orthologs may have functions similar to their mammalian counterparts and can thus serve as valuable models for future studies aimed at clarifying the physiological role(s) of GCP2 and related subfamily proteases.
Topics: Animals; Mice; Trematoda; Fasciola hepatica; Schistosoma mansoni; Peptide Hydrolases; Mammals
PubMed: 36539882
DOI: 10.1186/s13071-022-05556-5 -
Parasitology Nov 2022The complete circular mitogenome of (Platyhelminthes: Paragonimidae) from Japan, obtained by PacBio long-read sequencing, was 17 591 bp and contained 12 protein-coding...
The complete circular mitogenome of (Platyhelminthes: Paragonimidae) from Japan, obtained by PacBio long-read sequencing, was 17 591 bp and contained 12 protein-coding genes (PCGs), 2 mitoribosomal RNA and 22 transfer RNA genes. The 8 gene was absent, and there was a 40 bp overlap between 4L and 4. The long non-coding region (4.3 kb) included distinct types of long and short repeat units. The pattern of base usage for PCGs and the mtDNA coding region overall in Asian and American species (, , and ) and the Indian form of was > > > . On the other hand, East-Asian used > > > . Five Asian and American species and had TTT/Phe, TTG/Leu and GTT/Val as the most frequently used codons, whereas the least-used codons were different in each species and between regional forms of . The phylogenetic tree reconstructed from a concatenated alignment of amino acids of 12 PCGs from 36 strains/26 species/5 families of trematodes confirmed that the Paragonimidae is monophyletic, with 100% nodal support. was resolved as a sister to The clade was clearly separate from remaining congeners. The latter clade was comprised of 2 subclades, one of the East-Asian and the other of the Indian Type 1 samples. Additional mitogenomes in the Paragonimidae are needed for genomic characterization and are useful for diagnostics, identification and genetic/ phylogenetic/ epidemiological/ evolutionary studies of the Paragonimidae.
Topics: Animals; Paragonimus; Genome, Mitochondrial; Phylogeny; Trematoda; Lung
PubMed: 36101009
DOI: 10.1017/S0031182022001184 -
Parasites & Vectors Oct 2020The use of molecular tools in the study of parasite taxonomy and systematics have become a substantial and crucial component of parasitology. Having genetic... (Review)
Review
The use of molecular tools in the study of parasite taxonomy and systematics have become a substantial and crucial component of parasitology. Having genetic characterisation at the disposal of researchers has produced mostly useful, and arguably more objective conclusions. However, there are several groups for which limited genetic information is available and, coupled with the lack of standardised protocols, renders molecular study of these groups challenging. The Diplozoidae are fascinating and unique monogeneans parasitizing mainly freshwater cyprinid fishes in Europe, Asia and Africa. This group was studied from a molecular aspect since the turn of the century and as such, limitations and variability concerning the use of these techniques have not been clearly defined. In this review, all literature and molecular information, primarily from online databases such as GenBank, were compiled and scrupulously analysed for the Diplozoidae. This was done to review the information, detect possible pitfalls, and provide a "checkpoint" for future molecular studies of the family. Hindrances detected are the availability of sequence data for only a limited number of species, frequently limited to a single sequence per species, and the heavy reliance on one non-coding ribosomal marker (ITS2 rDNA) which is difficult to align objectively and displays massive divergences between taxa. Challenging species identification and limited understanding of diplozoid species diversity and plasticity are also likely restricting factors, all of which hamper the accurate taxonomic and phylogenetic study of this group. Thus, a more integrated taxonomic approach through the inclusion of additional markers, application of more rigorous morphological assessment, more structured barcoding techniques, alongside thorough capturing of species descriptions including genetypes, genophore vouchers and reference collections in open sources are encouraged. The pitfalls highlighted are not singular to the Diplozoidae, and the study of other groups may benefit from the points raised here as well.
Topics: Africa; Animals; Asia; Cyprinidae; DNA, Ribosomal; DNA, Ribosomal Spacer; Europe; Fresh Water; Phylogeny; Trematoda
PubMed: 33126913
DOI: 10.1186/s13071-020-04417-3 -
Parasitology Research Dec 2023Snails are fascinating molluscs with unique morphological and physiological adaptive features to cope with various environments. They have traditionally been utilized as... (Review)
Review
Snails are fascinating molluscs with unique morphological and physiological adaptive features to cope with various environments. They have traditionally been utilized as food and feed sources in many regions of the world. The future exploitation of alternative nutrient sources, like snails, is likely to increase further. Snails, however, also serve as an intermediate host for several zoonotic parasites. A category of parasitic infections, known as snail-transmitted parasitic diseases (STPDs), is harmful to humans and animals and is mainly driven by various trematodes, cestodes, and nematodes. The environment plays a crucial role in transmitting these parasites, as suitable habitats and conditions can facilitate their growth and proliferation in snails. In light of diverse environmental settings and biologically categorized snail species, this review evaluates the dynamics of significant STPDs of zoological importance. Additionally, possible diagnostic approaches for the prevention of STPDs are highlighted. One-health measures must be considered when employing snails as an alternative food or feed source to ensure the safety of snail-based products and prevent any adverse effects on humans, animals, and the environment.
Topics: Animals; Humans; One Health; Parasitic Diseases; Trematoda; Parasites; Ecosystem
PubMed: 38082123
DOI: 10.1007/s00436-023-08021-z -
Scientific Reports Feb 2020Parasites comprise a huge part of the biodiversity on earth. However, on a local scale, not much is known about their diversity and community structure. Here, we assess...
Parasites comprise a huge part of the biodiversity on earth. However, on a local scale, not much is known about their diversity and community structure. Here, we assess the diversity of larval trematode communities in an interconnected freshwater system of the River Ruhr in Germany and analyse how the parasites are spatially and temporally distributed in the ecosystem. A total of 5347 snail hosts belonging to six species revealed a highly diverse parasite fauna with 36 trematode species. More abundant snail species harboured more species-rich trematode faunas and communities, with the two dominant snail species, Radix auricularia and Gyraulus albus, accounting for almost 90% of the trematode diversity and harbouring spatially and temporally stable parasite communities. The results highlight the important role of stable keystone host populations for trematode transmission, structure and diversity. This local trematode diversity reveals information on definitive host occurrence and trophic interactions within ecosystems.
Topics: Animals; Biodiversity; Ecosystem; Fresh Water; Germany; Host-Parasite Interactions; Humans; Larva; Population Dynamics; Rivers; Snails; Trematoda
PubMed: 32060320
DOI: 10.1038/s41598-020-59548-5