Fasciola hepatica in Brazil: genetic diversity provides insights into its origin and geographic dispersion

Intra- and interspecies variation and population dynamics of Fasciola gigantica among ruminants in Sudan

Fasciola gigantica is a widespread parasite that causes neglected disease in livestock worldwide. Its high transmissibility and dispersion are attributed to its ability to infect intermediate snail hosts and adapt to various mammalian definitive hosts. This study investigated the variation and population dynamics of F. gigantica in cattle, sheep, and goats from three states in Sudan. Mitochondrial cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit 1 (ND1) genes were sequenced successfully to examine intra and interspecific differences. ND1 exhibited higher diversity than COI, with 15 haplotypes and 10 haplotypes, respectively. Both genes had high haplotype diversity but low nucleotide diversity, with 21 and 11 polymorphic sites for ND1 and COI, respectively. Mismatch distribution analysis and neutrality tests revealed that F. gigantica from different host species was in a state of population expansion. Maximum likelihood phylogenetic trees and median networks revealed that F. gigantica in Sudan and other African countries had host-specific and country-specific lineages for both genes. The study also indicated that F. gigantica-infected small ruminants were evolutionarily distant, suggesting deep and historical interspecies adaptation.

First morphometric and molecular characterization of Fasciola spp. in Northwest Tunisia

The aim of this study was to characterize the Tunisian Fasciola spp. flukes by morphometric and molecular analyses. Flukes were collected from livers of sheep slaughtered in Sejnane slaughterhouses (Bizerte gouvernorate, Northwest Tunisia) between January and March 2021.Five morphometric parameters were determined for all the liver flukes, as follows: (i) total body length (BL), (ii) distance between ventral sucker and the tail (VS-T), (iii) distance between oral sucker and ventral sucker (OS-VS), (iv) abdomen diameter (AD), (v) tail diameter (TD) and the body length to width ratio (BL/BW). Molecular identification of the fluke specimens was carried out by polymerase chain reaction, restriction fragment polymorphism (PCR-RFLP) of a 680 bp sequence of the internal transcribes spacer 1 (ITS1) gene and by amplification, sequencing, and phylogenetic analysis of a 500 bp sequence of the ITS2 gene. Morphometric measurements showed that the mean of the total body length of the adult flukes was 21.1 ± 2.7 mm with minimum and maximum lengths of 13 and 31 mm, respectively. The PCR-RFLP analysis revealed a single profile consisting of three bands of approximately 370, 100, and 60 bp. Fasciola sequences described in the present study (GenBank numbers: OQ457027 and OQ457028) showed 99.58-100% identity to Fasciola hepatica. In conclusion, the results of this study show that molecular and phylogenetic analyses confirm the presence of a single species of F. hepatica in the Sejnane region Northwest of Tunisia. However, further studies are needed to identify the occurrence of Fasciola species in other Tunisian regions.

Global phylogeographical distribution of Gloeoporus dichrous

Phylogeographic analyses are efficient in ecological and evolutionary studies to discover the origin of a lineage, its dispersal routes, and the divergence of ancestral traits. Studies on widespread wood-decay fungi have revealed the phylogenetic division of several polypores based on geographical distribution. In this study, specimens of Gloeoporus dichrous, a cosmopolitan polypore species, were collected globally and analyzed for their geographic distribution. Multi-marker Bayesian molecular clock and haplotype analyses revealed a clear division of G. dichrous populations by continent. The species diverged from its neighboring clades 10.3 (16.0-5.6) million years ago, with Asian and North American populations at the center of divergence. Possible dispersal mechanisms and pathways are predicted and discussed based on the evaluated transfer routes. The biogeography of G. dichrous analyzed in this study represents a fraction of the polypore evolution and may advance the understanding of the overall evolution of wood-decay fungi.

Molecular characterization of Fasciola hepatica in endemic regions of Colombia

Fasciola hepatica is a zoonotic trematode that affects a wide range of hosts, including cattle, sheep, and goats. The economic impact of the parasite on the cattle industry is significant, with high losses reported worldwide. While its impact on human health was previously underestimated, recent years have seen a rise in fascioliasis cases, leading to increased interest among researchers globally. To characterize the genetic diversity and intraspecific variation of this parasite in South America, specifically in Colombia, we collected 105 adult parasites from cattle bile ducts in seven Colombian departments (Antioquia, Boyacá, Santander, Cauca, Cundinamarca, Nariño, Norte de Santander, and Santander) to assess the parasite's phenotypic analyses, genetic diversity, and population structure. A computer image analysis system (CIAS) was applied based on standardized morphological measurements. Liver-fluke size was studied by principal component analysis (PCA). DNA sequences were obtained for nuclear markers such as the 28S, β-tubulin 3, ITS1, ITS2, and the mitochondrial marker Cytochrome Oxidase I (COI). Multiple statistical tests were performed, and the parasite's population structure was analyzed. Maximum Likelihood (ML) phylogenetic reconstructions were carried out using the sequences obtained herein and sequences available in GenBank. Morphological results revealed that all the obtained individuals matched F. hepatica's morphology. There was no evidence of high genetic diversity, and the absence of genetic structure at the country-level was notable, possibly caused by a demographic expansion of this trematode in Colombia or the low resolution of the molecular markers employed. Future studies are still needed to unveil the genetic population structure of F. hepatica across the country.

Human and Animal Fascioliasis: Origins and Worldwide Evolving Scenario

Fascioliasis is a plant- and waterborne zoonotic parasitic disease caused by two trematode species: (i) Fasciola hepatica in Europe, Asia, Africa, the Americas, and Oceania and (ii) F. gigantica, which is restricted to Africa and Asia. Fasciolid liver flukes infect mainly herbivores as ruminants, equids, and camelids but also omnivore mammals as humans and swine and are transmitted by freshwater Lymnaeidae snail vectors. Two phases may be distinguished in fasciolid evolution. The long predomestication period includes the F. gigantica origin in east-southern Africa around the mid-Miocene, the F. hepatica origin in the Near-Middle East of Asia around the latest Miocene to Early Pliocene, and their subsequent local spread. The short postdomestication period includes the worldwide spread by human-guided movements of animals in the last 12,000 years and the more recent transoceanic anthropogenic introductions of F. hepatica into the Americas and Oceania and of F. gigantica into several large islands of the Pacific with ships transporting livestock in the last 500 years. The routes and chronology of the spreading waves followed by both fasciolids into the five continents are redefined on the basis of recently generated knowledge of human-guided movements of domesticated hosts. No local, zonal, or regional situation showing disagreement with historical records was found, although in a few world zones the available knowledge is still insufficient. The anthropogenically accelerated evolution of fasciolids allows us to call them "peridomestic endoparasites." The multidisciplinary implications for crucial aspects of the disease should therefore lead the present baseline update to be taken into account in future research studies.

Life history strategies of Cotylurus spp. Szidat, 1928 (Trematoda, Strigeidae) in the molecular era – Evolutionary consequences and implications for taxonomy

Species of Cotylurus Szidat, 1928 (Diplostomoidea: Strigeidae) are highly specialized digeneans that parasitize the gastrointestinal tract and bursa of Fabricius of water and wading birds. They have a three-host life cycle; the role of first intermediate host is played by pulmonate snails, while a wide range of water snails (both pulmonate and prosobranch) and leeches are reported as second intermediate hosts.

Unfortunately, species richness, molecular diversity and phylogeny of metacercariae of Cotylurus spp. (tetracotyle) occurring in snails remain poorly understood. Thus, we have performed the parasitological and taxonomical examination of tetracotyles form freshwater snails from Poland, supplemented with adult Strigeidae specimens sampled from water birds. In this study we report our use of recently obtained sequences of two molecular markers (28S nuclear large ribosomal subunit gene (28S rDNA) and the cytochrome c oxidase subunit 1 (CO1) fragment), supplemented by results of a method of species delimitation (GMYC) and haplotype analysis to analyse some aspects of the ecology, taxonomy, and phylogeny of members of the genus Cotylurus.

The provided phylogenetic reconstructions discovered unexpectedly high molecular diversity within Cotylurus occurring in snails, with clearly expressed evidence of cryptic diversity and the existence of several novel-species lineages. The obtained results revealed the polyphyletic character of C. syrius Dubois, 1934 (with three separate molecular species-level lineages) and C. cornutus (Rudolphi, 1809) Szidat, 1928 (with four separate molecular species-level lineages). Moreover, we demonstrated the existence of two divergent phylogenetical and ecological lineages within Cotylurus (one using leeches and other snails as second intermediate hosts), differing significantly in their life history strategies.

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Within Cotylurus existed two divergent phylogenetical and ecological lineages.

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The lineages within Cotylurus sp. differing significantly in their routes of transmission.

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Molecular analysis revealed high genetic diversity with evidence of cryptic species.

Geospatial analysis of the associations between environmental contamination with livestock feces and children with chronic fascioliasis in the Anta province of Cusco, Peru

Fasciola hepatica is a neglected parasitic infection with significant human health and livestock industry impact. The Andean Altiplano harbors an estimated 50% of the Fasciola’s world infection burden. There is scarce data regarding the spatial associations between different Fasciola hosts. In this project, we aimed to determine the geospatial relationships between Fasciola eggs passed in feces of different livestock species and the risk of infection among each household as a unit. We used data from a cross-sectional study evaluating children and livestock feces for Fasciola infection around households in three districts of Anta province, in the Cusco region of Peru. Each sample was geographically tagged and evaluated for fascioliasis using microscopy methods. A total of 2070 households were included, the median age was 9.1 years (6.7–11.8), 49.5% were female, and 7.2% of the households had at least one infected child. A total of 2420 livestock feces samples were evaluated. The infection rate in livestock samples was 30.9%. The highest infection rate was found in sheep with 40.8%, followed by cattle (33.8%), and swine (26.4%). The median distance between a household with an infected child to a positive animal sample was 44.6 meters (IQR 14.7–112.8) and the distance between a household with no infected children to a positive animal sample was 62.2 meters (IQR 18.3–158.6) (p = 0.025). The multivariable logistic regression adjusted by presence of poor sanitation, unsafe water consumption, altitude, and presence of multiple infected children per household demonstrated an association between household infection and any cattle feces at a 50 meters radius (Uninfected: OR 1.42 (95%CI 1.07–1.89), p = 0.017. Infected: OR 1.89 (95%CI 1.31–2.73), p = 0.001), positive cattle feces at a 100 meters radius (OR 1.35 (95% CI 1.08–1.69), p = 0.008), and negative cattle feces at a 200 meters radius (OR 1.08 (95% CI 1.01–1.15), p = 0.022). We identified potential hot and cold spots for fascioliasis in the Anta province. An association between environmental contamination with feces from different livestock species and infected children in rural households was found in our study. Local health authorities may apply this strategy to estimate the risk of infection in human populations and apply targeted interventions.

Fasciola hepatica is the parasite that causes fascioliasis in the Andes region. The factors associated with transmission of the disease among humans have not been well described in the area studied. In this study, we evaluate the spatial relationships between infected households and the environmental burden of Fasciola eggs passed by different livestock in the Cusco region of Peru. We geographically marked and tested for fascioliasis feces provided by children and livestock. Infected and uninfected cattle as well as sheep feces were more likely to be in proximity to human households with infected children than to households without infected children. We were able to identify and map the areas of higher and lower infections rates. This information and strategy may be used in the control of the disease.

A checklist of larval Digenea (Platyhelminthes: Trematoda) in molluscs from inland waters of Argentina: one hundred years of research

A checklist of larval digeneans parasitising molluscs from inland waters of Argentina is presented here. Based on the bibliographical survey of 113 scientific articles and nine theses published between 1930 and 2021, 213 digeneans were found, which were distributed within 13 superfamilies and 35 families. The parasites were identified in 102 locations, encompassing eight of the sixteen biogeographical provinces in Argentina. Digeneans were found in 34 mollusc species (31 gastropods and three bivalves) belonging to 17 genera. The available data are presented for each digenean species, and included host information, localities, prevalence values, type of habitat, life cycle information (natural or experimental host), and information on material and genetic sequences deposited in repositories. Only 21.1% of individuals were identified to species level, and 8.5% to genus level. In addition, the genetic sequences of only 10 species (4.7%) were available at GenBank. This survey constitutes the first checklist of parasitic helminths in molluscs from inland waters of Argentina.

Liver Fluke Infection Throughout Human Evolution

The species of liver fluke that infect humans are zoonotic parasites that we share with other animals. The complex way in which humans have interacted with their environment, and the animals that live alongside them, has affected our ancestors' risk of infection by these helminths for millions of years. Here, we describe the range of flukes that can survive in the human liver and the health consequences that result from infection. Our focus is on Clonorchis sinensis (Chinese liver fluke), Fasciola hepatica (sheep liver fluke), F. gigantica (giant liver fluke), Opisthorchis viverrini (Southeast Asian liver fluke), O. felineus (cat liver fluke), and Dicrocoelium dendriticum (lancet liver fluke). We use our knowledge of where different kinds of liver flukes are endemic to estimate when and where human ancestors would have been exposed to infection over deep time. DNA evidence is used to investigate the evolutionary origins of the major species of liver flukes. The archaeological evidence for different species of fluke helps to show in which periods of human history they were most common. These flukes spread to humans from wild animals in early prehistory because of our ancestor's hunter-gatherer lifestyle and later from farm animals after the development of agriculture. We explore when and how some species have been able to spread across the world, whereas others are limited to particular geographic regions because of the endemic distribution of snail and vertebrate intermediate hosts. It is clear that human activity and migrations have played a key role in the expanding geographical range where we find liver flukes endemic today.

Molecular characteristics and genetic diversity of Fasciola hepatica from sheep in Xinjiang, China

Introduction

Fasciola hepatica is a trematode infecting ruminants worldwide and occasionally affecting other animal species, including humans. It causes significant economic losses. Geographic distribution and patterns of infection must be considered before control and management measures are developed for this parasite. DNA molecular markers are useful for the identification of flukes and elucidation of their genetic evolution. Therefore, the population structure of F. hepatica was studied using this method in sheep in Xinjiang, China.

Material and Methods

The molecular characteristics, genetic relationships within the population and dispersal patterns of F. hepatica isolates were analysed based on the cox1 and nad1 genes. The population structure of F. hepatica from three regions of Xinjiang was explored and a neutrality test was conducted.

Results

The cox1 and nad1 genes have 21 and 42 variable sites, respectively, which can be classified into 34 and 33 haplotypes. Median-joining network and phylogenetic tree analyses showed that there was no significant variation in F. hepatica isolates between the three geographical regions. Analysis of variance revealed that the genetic variation of F. hepatica was mainly present within the populations. The neutrality test indicated that the populations were relatively stable but the Hami population may have undergone short-term expansion.

Conclusion

This study revealed for the first time the molecular characteristics, genetic diversity and dispersal patterns of F. hepatica isolates from sheep in Xinjiang, thus providing new insights into the genetic variation and haplotype diversity of F. hepatica from indigenous sheep.

Fasciola gigantica-Derived Excretory-Secretory Products Alter the Expression of mRNAs, miRNAs, lncRNAs, and circRNAs Involved in the Immune Response and Metabolism in Goat Peripheral Blood Mononuclear Cells

Fasciola gigantica produces excretory-secretory products (ESPs) with immune-modulating effects to promote its own survival. In this study, we performed RNA-seq to gain a comprehensive global understanding of changes in the expression of mRNAs, miRNAs, lncRNAs, and circRNAs in goat peripheral blood mononuclear cells (PBMCs) treated with F. gigantica ESPs. A total of 1,544 differently expressed mRNAs (790 upregulated and 754 downregulated genes), 30 differently expressed miRNAs (24 upregulated and 6 downregulated genes), 136 differently expressed circRNAs (83 upregulated and 53 downregulated genes), and 1,194 differently expressed lncRNAs (215 upregulated and 979 downregulated genes) were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that F. gigantica ESPs altered the expression of genes associated with the host immune response, receptor signaling, disease and metabolism. Results from RNA-seq were validated by qRT-PCR. These findings provide an important resource for future investigation of the role of mRNAs and non-coding RNAs in mediating the immune-modulating effects of F. gigantica ESPs.

Molecular characterization revealed Fasciola specimens in Ecuador are all Fasciola hepatica, none at all of Fasciola gigantica or parthenogenic Fasciola species

All 225 Fasciola flukes obtained from domestic animals (73 cattle, 7 sheep and 1 pig) of 18 distinct geographic areas in Ecuador-South America, were identified as Fasciola hepatica, based on molecular analyses of nuclear pepck and pold genes, and mitochondrial nad1gene as well as the morphological observation of sperm within the seminal vesicles. Fasciola gigantica and parthenogenic Fasciola forms endemic to Asian countries were not found in this study, although zebu cattle and water buffalos have introduced into South America from Asia; this could be due to the absence of suitable intermediate host snails. The results of pepck analysis using multiplex PCR developed previously showed that 32 of the flukes could not be confirmed as F. hepatica, suggesting that the method is unreliable for the accurate discrimination of F. hepatica, and that pepck gene of the species consists of multiple loci, not a single locus. The results of genetic diversity, phylogenetic, and network analyses based on mitochondrial nad1 sequences suggest that F. hepatica populations in South America, including Ecuador, formed from the ancestral F. hepatica individuals introduced into the continent along with anthropogenic movement of livestock infected with the species.

Genetic diversity and relationships of the liver fluke Fasciola hepatica (Trematoda) with native and introduced definitive and intermediate hosts

Fasciolosis is a worldwide spread parasitosis mainly caused by the trematode Fasciola hepatica. This disease is particularly important for public health in tropical regions, but it can also affect the economies of many developed countries due to large infections in domestic animals. Although several studies have tried to understand the transmission by studying the prevalence of different host species, only a few have used population genetic approaches to understand the links between domestic and wildlife infections. Here, we present the results of such genetic approach combined with classical parasitological data (prevalence and intensity) by studying domestic and wild definitive hosts from Camargue (southern France) where fasciolosis is considered as a problem. We found 60% of domestic hosts (cattle) infected with F. hepatica but lower values in wild hosts (nutria, 19%; wild boars, 4.5%). We explored nine variable microsatellite loci for 1,148 adult flukes recovered from four different populations (non-treated cattle, treated cattle, nutria and wild boars). Populations from the four groups differed, though we found a number of migrants particularly non-treated cattle and nutria. Overall, we detected 729 different multilocus genotypes (from 783 completely genotyped individuals) and only 46 genotypes repeated across samples. Finally, we experimentally infected native and introduced intermediate snail hosts to explore their compatibility with F. hepatica and assess the risks of fasciolosis expansion in the region. The introduced species Galba truncatula and Pseudosuccinea columella attained the higher values of overall compatibility in relation to the European species. However, concerning the origin, sympatric combinations of G. truncatula were more compatible (higher prevalence, intensity and survival) than the allopatric tested. According to our results, we should note that the assessment of epidemiological risks cannot be limited to a single host-parasite system, but should focus on understanding the diversity of hosts in the heterogeneous environment through space and time.