Bioclimatic analysis and spatial distribution of fascioliasis causative agents by assessment of Lymnaeidae snails in northwestern provinces of Iran.

BACKGROUND: Snails of the Lymnaeidae family are the intermediate hosts of Fasciola species, the causative agents of fascioliasis. The purpose of this study was to determine the prevalence of Fasciola species in lymnaeid snails and to investigate the association of geoclimatic factors and Fasciola species distribution in northwestern provinces of Iran using geographical information system (GIS) data. METHODS: A total of 2000 lymnaeid snails were collected from 33 permanent and seasonal habitats in northwestern Iran during the period from June to November 2021. After identification by standard morphological keys, they were subjected to shedding and crushing methods. Different stages of Fasciola obtained from these snails were subjected to the ITS1 polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method for species identification. The associations of weather temperature, rainfall, humidity, evaporation, air pressure, wind speed, elevation, and land cover with the distribution of Fasciola species were investigated. Geographical and statistical analysis was performed using ArcMap and SPSS software, respectively, to determine factors related to Fasciola species distribution. RESULTS: Of the 2000 snails collected, 19 were infected with Fasciola hepatica (0.09%), six with F. gigantica (0.03%), and 13 with other trematodes. Among geoclimatic and environmental factors, mean humidity, maximum humidity, and wind speed were significantly higher in areas where F. hepatica was more common than F. gigantica. The altitude of F. hepatica-prevalent areas was generally lower than F. gigantica areas. No significant relationship was observed between other investigated geoclimatic factors and the distribution of infected snails. CONCLUSIONS: The present study showed the relationship of humidity and wind speed with the distribution of snails infected with F. hepatica or F. gigantica in the northwestern regions of Iran. In contrast to F. gigantica, F. hepatica was more prevalent in low-altitude areas. Further research is recommended to elucidate the relationship between geoclimatic factors and the presence of intermediate hosts of the two Fasciola species.

The soluble glutathione transferase superfamily: role of Mu class in triclabendazole sulphoxide challenge in Fasciola hepatica.

Fasciola hepatica (liver fluke), a significant threat to food security, causes global economic loss for the livestock industry and is re-emerging as a foodborne disease of humans. In the absence of vaccines, treatment control is by anthelmintics; with only triclabendazole (TCBZ) currently effective against all stages of F. hepatica in livestock and humans. There is widespread resistance to TCBZ and its detoxification by flukes might contribute to the mechanism. However, there is limited phase I capacity in adult parasitic helminths with the phase II detoxification system dominated by the soluble glutathione transferase (GST) superfamily. Previous proteomic studies have demonstrated that the levels of Mu class GST from pooled F. hepatica parasites respond under TCBZ-sulphoxide (TCBZ-SO) challenge during in vitro culture ex-host. We have extended this finding by exploiting a sub-proteomic lead strategy to measure the change in the total soluble GST profile (GST-ome) of individual TCBZ-susceptible F. hepatica on TCBZ-SO-exposure in vitro culture. TCBZ-SO exposure demonstrated differential abundance of FhGST-Mu29 and FhGST-Mu26 following affinity purification using both GSH and S-hexyl GSH affinity. Furthermore, a low or weak affinity matrix interacting Mu class GST (FhGST-Mu5) has been identified and recombinantly expressed and represents a new low-affinity Mu class GST. Low-affinity GST isoforms within the GST-ome was not restricted to FhGST-Mu5 with a second likely low-affinity sigma class GST (FhGST-S2) uncovered. This study represents the most complete Fasciola GST-ome generated to date and has supported the potential of subproteomic analyses on individual adult flukes.

Molecular characterization and phylogenetic analysis of Fasciola hepatica from high- plateau and steppe areas in Algeria.

A previous study based on mitochondrial DNA markers reported the presence of Fasciola hepatica in Algeria. However, a precise species identification is still required. In this report, a total of 68 Fasciola isolates, collected from high-plateau (Bordj-Bou-Arreridj) and steppe (Djelfa) areas of Algeria, were identified at the species level by multiplex PCR and PCR-restriction fragment length polymorphism (RFLP) for nuclear phosphoenolpyruvate carboxykinase (pepck) and DNA polymerase delta (pold), respectively. The result of the multiplex PCR conflicted with that of the PCR-RFLP; however, subsequent nucleotide sequencing of pepck clearly showed that all isolates should be classified as F. hepatica. The two mitochondrial markers, NADH dehydrogenase subunit I (nad1) and cytochrome c oxidase subunit 1 (cox1), revealed a close relationship between the parasite populations from the plateau and those from the steppe. A dispersal direction from the high plateau to the steppe was indicated because the former population was more diversified than the latter. Moreover, these populations were more closely related to populations from Spain than those from Egypt or Afghanistan. Given the population characteristic of F. hepatica in Spain and the history of cattle trade, it seems likely that the parasite was introduced to Algeria from Europe through a route across the Mediterranean Sea.

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.

Molecular Confirmation of a Fasciola gigantica × Fasciola hepatica Hybrid in a Chadian Bovine.

Fascioliasis is a zoonotic infection of humans and, more commonly, ruminants. It is caused by 2 liver fluke species, Fasciola hepatica and Fasciola gigantica, which differ in size. The traditional morphological methods used to distinguish the 2 species can be unreliable, particularly in the presence of hybrids between the 2 species. The development of advanced molecular methods has allowed for more definitive identification of Fasciola species, including their hybrids. Hybrids are of concern, as it is thought that they could acquire advantageous traits such as increased pathogenicity and host range. In 2013, we collected flukes from Fasciola-positive cattle, sheep, and goats slaughtered in 4 Chadian abattoirs. DNA from 27 flukes was extracted, amplified, and analyzed to identify species using the ITS1+2 locus. Twenty-six of the 27 flukes were identified as F. gigantica, while the remaining fluke showed heterozygosity at all variable sites that distinguish F. hepatica and F. gigantica. Cloning and sequencing of both alleles confirmed the presence of 1 F. hepatica and 1 F. gigantica allele. To our knowledge, this is the first unambiguous, molecular demonstration of the presence of such a hybrid in a bovine in sub-Saharan Africa.

Drug resistance in liver flukes.

Liver flukes include Fasciola hepatica, Fasciola gigantica, Clonorchis sinensis, Opisthorchis spp., Fascioloides magna, Gigantocotyle explanatum and Dicrocoelium spp. The two main species, F. hepatica and F. gigantica, are major parasites of livestock and infections result in huge economic losses. As with C. sinensis, Opisthorchis spp. and Dicrocoelium spp., they affect millions of people worldwide, causing severe health problems. Collectively, the group is referred to as the Food-Borne Trematodes and their true significance is now being more widely recognised. However, reports of resistance to triclabendazole (TCBZ), the most widely used anti-Fasciola drug, and to other current drugs are increasing. This is a worrying scenario. In this review, progress in understanding the mechanism(s) of resistance to TCBZ is discussed, focusing on tubulin mutations, altered drug uptake and changes in drug metabolism. There is much interest in the development of new drugs and drug combinations, the re-purposing of non-flukicidal drugs, and the development of new drug formulations and delivery systems; all this work will be reviewed. Sound farm management practices also need to be put in place, with effective treatment programmes, so that drugs can be used wisely and their efficacy conserved as much as is possible. This depends on reliable advice being given by veterinarians and other advisors. Accurate diagnosis and identification of drug-resistant fluke populations is central to effective control: to determine the actual extent of the problem and to determine how well or otherwise a treatment has worked; for research on establishing the mechanism of resistance (and identifying molecular markers of resistance); for informing treatment options; and for testing the efficacy of new drug candidates. Several diagnostic methods are available, but there are no recommended guidelines or standardised protocols in place and this is an issue that needs to be addressed.

Distribution Status of Hybrid Types in Large Liver Flukes, Fasciola Species (Digenea: Fasciolidae), from Ruminants and Humans in Vietnam.

The aim of this study is to delineate 'admixed hybrid' and 'introgressive' Fasciola genotypes present in the Fasciola population in Vietnam. Adult liver flukes collected from ruminants in 18 Provinces were morphologically sorted out by naked eyes for small (S), medium (M) and large (L) body shapes; and human samples (n=14) from patients. Nuclear ribosomal (rDNA) ITS1 and ITS2, and mitochondrial (mtDNA) nad1 markers were used for determination of their genetic status. Total 4,725 worm samples of ruminants were tentatively classified by their size: 6% (n=284) small (S)-, 13% (n=614) medium (M)-, and 81% (n=3,827) large (L)-forms. All the representative (n=120, as 40 each group) and 14 human specimens, possessed maternal mtDNA of only F. gigantica and none of F. hepatica. Paternally, all (100%) of the L-(n=40) and 77.5% (n=31) of the M-flukes had single F. gigantica rDNA indicating 'pure' F. gigantica. A majority (90%, n=36) of the S- and 15% (n=6) of the M-worms had single F. hepatica rDNA, indicating their introgressive; the rest (10%, n=4) of the S- and 7.5% (n=3) of the M-flukes had mixture of both F. gigantica and F. hepatica rDNAs, confirming their admixed hybrid genetic status. Fourteen human samples revealed 9 (64%) of pure F. gigantica, 3 (22%) of introgressive and 2 (14%) of admixed hybrid Fasciola spp. By the present study, it was confirmed that the small worms, which are morphologically identical with F. hepatica, are admixed and/or introgressive hybrids of Fasciola spp., and able to be the pathogens of human fascioliasis.

First phenotypic and genotypic description of Fasciola hepatica infecting highland cattle in the state of Mexico, Mexico.

Fascioliasis is a plantborne and zoonotic parasitic disease caused by fasciolid liver flukes. Fasciola hepatica is the only fasciolid species described in the Americas. Human fascioliasis endemic areas are mainly located in high altitude areas of the Americas. Given the necessity to characterize F. hepatica populations involved, the phenotypic and genotypic features of fasciolid adults infecting cattle in the highland area of Toluca, State of Mexico, Mexico, were analyzed and compared to fasciolid materials from the Northern Bolivian Altiplano, representing the altiplanic transmission pattern in a hyperendemic scenario. A computer image analysis system (CIAS) was applied on the basis of standardized measurements. The aforementioned F. hepatica highland populations were compared to standard lowland natural populations of European origin (Spain and France) and F. gigantica of African origin (Burkina Faso). Liver-fluke size was studied by principal component analysis (PCA). Two phenotypic patterns could be distinguished in the F. hepatica material analyzed from the Americas: the valley pattern (Toluca, Mexico) and the altiplanic pattern (Northern Altiplano, Bolivia). PCA showed that the Altiplano population presented a large body size range with a pronouncedly lower minimum size. Mahalanobis distances demonstrated that American populations are very close to European populations. Genetic haplotyping was performed using the ribosomal DNA intergenic region, including ITS-1, 5.8S and ITS-2. The intergenic region was 951 bp-long, providing 2 combined haplotypes due to one mutation appearing in the ITS-2 sequence. Molecular results showed that Fh-1A and Fh-2A, the most frequent haplotypes of F. hepatica from southern Europe, are present in Mexican cattle. Nuclear rDNA biomarkers correlated with adult fluke phenotypic characteristics. Results showed that the Mexican population analyzed and European standard populations presented a phenotypic and genotypic homogeneity, suggesting an introduction with livestock transported during the early colonization period. Results are moreover analyzed in terms of altitude and permanent/seasonal transmission characteristics.

Detection of Galba truncatula, Fasciola hepatica and Calicophoron daubneyi environmental DNA within water sources on pasture land, a future tool for fluke control?

BACKGROUND: Increasing trematode prevalence and disease occurrence in livestock is a major concern. With the global spread of anthelmintic resistant trematodes, future control strategies must incorporate approaches focusing on avoidance of infection. The reliance of trematodes on intermediate snail hosts to successfully complete their life-cycle means livestock infections are linked to the availability of respective snail populations. By identifying intermediate snail host habitats, infection risk models may be strengthened whilst farmers may confidently apply pasture management strategies to disrupt the trematode life-cycle. However, accurately identifying and mapping these risk areas is challenging. METHODS: In this study, environmental DNA (eDNA) assays were designed to reveal Galba truncatula, Fasciola hepatica and Calicophoron daubneyi presence within water sources on pasture land. eDNA was captured using a filter-based protocol, with DNA extracted using the DNeasy® PowerSoil® kit and amplified via PCR. In total, 19 potential G. truncatula habitats were analysed on four farms grazed by livestock infected with both F. hepatica and C. daubneyi. RESULTS: Galba truncatula eDNA was identified in 10/10 habitats where the snail was detected by eye. Galba truncatula eDNA was also identified in four further habitats where the snail was not physically detected. Fasciola hepatica and C. daubneyi eDNA was also identified in 5/19 and 8/19 habitats, respectively. CONCLUSIONS: This study demonstrated that eDNA assays have the capabilities of detecting G. truncatula, F. hepatica and C. daubneyi DNA in the environment. Further assay development will be required for a field test capable of identifying and quantifying F. hepatica and C. daubneyi infection risk areas, to support future control strategies. An eDNA test would also be a powerful new tool for epidemiological investigations of parasite infections on farms.

Lethal Fascioliasis in Capybaras ( Hydrochoerus hydrochaeris) in Brazil.

The liver fluke Fasciola hepatica (Trematoda: Fasciolidae) causes fascioliasis, which affects mostly domestic ruminants and humans worldwide. This parasite has an Old World origin and was introduced into the New World by European colonizers. Capybara ( Hydrochoerus hydrochaeris) is the largest living rodent species, with adults weighing over 60 kg. We report a fascioliasis outbreak caused by F. hepatica that reduced a capybara group from 21 to 2 animals within a 9-mo period. Animal infection and associated lesions were confirmed by postmortem examinations that revealed extensive liver damage associated with the presence of large number of adult and immature forms of F. hepatica. Both macroscopic and microscopic alterations in the liver were compatible with acute fascioliasis, which is characterized by a large parasite burden in the liver. Taxonomic identification of flukes collected from capybara livers were confirmed by molecular methods, which generated a mitochondrial NADH dehydrogenase I (NDI) gene partial sequence that was 100% identical to a F. hepatica NDI sequence from the United Kingdom. This is the first report of deleterious effects caused by F. hepatica in capybaras, highlighting the potential harm caused by this exotic parasite in the capybara.

Is Galba schirazensis (Mollusca, Gastropoda) an intermediate host of Fasciola hepatica (Trematoda, Digenea) in Ecuador?

Fasciolosis is a widely distributed disease in livestock in South America but knowledge about the epidemiology and the intermediate hosts is relatively scarce in Ecuador. For three months, lymnaeid snails were sampled (n = 1482) in Pichincha Province at two sites located in a highly endemic area. Snails were identified (based on morphology and ITS-2 sequences) and the infection status was established through microscopic dissection and a multiplex polymerase chain reaction (PCR)-based technique. Techniques based on morphology were not useful to accurately name the collected snail species. Comparison with available DNA sequences showed that a single snail species was collected, Galba schirazensis. Live rediae were observed in 1.75% (26/1482) and Fasciola sp. DNA was detected in 6% (89/1482) of collected snails. The COX-1 region permitted identification of the parasite as Fasciola hepatica. The relative sensitivity and specificity of the microscope study, compared to PCR results, were 25.84% and 99.78%, respectively. The mean size of the snails recorded positive for F. hepatica through crushing and microscopy was significantly higher than the mean size of negative snails, but there was no such difference in PCR-positive snails. The role of G. schirazensis as an intermediate host of F. hepatica in Ecuador is discussed and the hypothesis of an adaptation of the parasite to this invasive snail is proposed. For the first time, an epidemiological survey based on molecular biology-based techniques assessed the possible role of lymnaeid snails in the epidemiology of fasciolosis in Ecuador.

Caracterização do imunofenótipo das células envolvidas no processo fibrótico de fígados bovinos cronicamente infectados por Fasciola hepatica / Immunophenotype characterization of the cells involved in the fibrotic process of bovine livers chronically infected by Fasciola hepatica

A fasciolose é uma doença parasitária causada por trematódeo do gênero Fasciola sp., que pode ocasionar fibrose hepática. Objetivou-se caracterizar o imunofenótipo das células que participam da fibrogênese de fígados bovinos frente à infecção por F. hepatica. Foram utilizados fragmentos dos lobos direito e esquerdo de 74 fígados bovinos com fasciolose. Os fragmentos foram submetidos a processamento histológico, coloração com tricrômico de Masson e imuno-histoquímica. Utilizaram-se análise estatística descritiva e teste de correlação de Spearmann com 5% de probabilidade. Na classificação do grau de fibrose, observou-se prevalência do grau 1, com associação positiva e significativa entre o grau de fibrose e o lobo hepático esquerdo (ρ=0,41; P<0,0001). Os imunofenótipos observados foram células estreladas hepáticas (CEHs) no parênquima e miofibroblastos (MFs) no espaço porta (EP). Não foram encontrados fibroblastos. Não houve correlação significativa entre o grau de fibrose e a quantidade de CEH nos lobos hepáticos, direito e esquerdo. Verificou-se aumento do número de estruturas portais, bem como do número de camadas circundando cada estrutura no EP, contudo não houve influência de qualquer estrutura sobre o grau de fibrose hepática (P>0,05). Concluiu-se que as células CEH e os MFs participam da fibrogênese de fígados bovinos com fasciolose crônica.(AU)

Fascioliasis is a parasitic disease caused by a fluke of the genus Fasciola sp., which can lead to end liver fibrosis. This study aimed to characterize the immunophenotype of cells that participate in the fibrogenesis of livers of cattle that face infection by F. hepatica. Fragments of the right and left lobes of 74 cattle livers with fascioliasis were used. The fragments were subjected to histological analysis, Masson's trichrome special stain, and immunohistochemistry. A descriptive statistical analysis was used, with a 5% probability in Spearman correlation test. The classification of degree of fibrosis revealed prevalence of grade 1, with a positive and significant association between the degree of fibrosis and the left hepatic lobe (ρ = 0.41; p <0.0001). The observed immunophenotypes corresponded to hepatic stellate cells (HSCs) in the parenchyma and myofibroblasts (MFs) in the portal tract (PT). Fibroblasts were not found. There was no significant correlation between the degree of fibrosis and the amount of HSC in right and left hepatic lobes. There was an increase in the number of portal structures, as well as in the number of layers surrounding each structure of the PT, but there was no influence of any structure of the PT on the degree of liver fibrosis (P>0.05). HSCs and MFs were concluded to play a role in the fibrogenesis of cattle livers with chronic fascioliasis.(AU)

Human Cases of Fascioliasis in Fujian Province, China.

Fascioliasis is a foodborne zoonotic parasitic disease. We report 4 cases occurring in the same family, in whom diagnosis of acute fascioliasis was established after series of tests. One case was hospitalized with fever, eosinophilia, and hepatic lesions. MRI showed hypodense changes in both liver lobes. The remaining 3 cases presented with the symptom of stomachache only. Stool analysis was positive for Fasciola eggs in 2 adult patients. The immunological test and molecular identification of eggs were confirmed at the National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, China. The results of serological detection were positive in all the 4 patients. DNA sequencing of PCR products of the eggs demonstrated 100% homology with ITS and cox1 of Fasciola hepatica. The conditions of the patients were not improved by broad-spectrum anti-parasitic drugs until administration of triclabendazole.

DNA multigene characterization of Fasciola hepatica and Lymnaea neotropica and its fascioliasis transmission capacity in Uruguay, with historical correlation, human report review and infection risk analysis.

BACKGROUND: Fascioliasis is a pathogenic disease transmitted by lymnaeid snails and recently emerging in humans, in part due to effects of climate changes, anthropogenic environment modifications, import/export and movements of livestock. South America is the continent presenting more human fascioliasis hyperendemic areas and the highest prevalences and intensities known. These scenarios appear mainly linked to altitude areas in Andean countries, whereas lowland areas of non-Andean countries, such as Uruguay, only show sporadic human cases or outbreaks. A study including DNA marker sequencing of fasciolids and lymnaeids, an experimental study of the life cycle in Uruguay, and a review of human fascioliasis in Uruguay, are performed. METHODOLOGY/PRINCIPAL FINDINGS: The characterization of Fasciola hepatica from cattle and horses of Uruguay included the complete sequences of the ribosomal DNA ITS-2 and ITS-1 and mitochondrial DNA cox1 and nad1. ITS-2, ITS-1, partial cox1 and rDNA 16S gene of mtDNA were used for lymnaeids. Results indicated that vectors belong to Lymnaea neotropica instead of to Lymnaea viator, as always reported from Uruguay. The life cycle and transmission features of F. hepatica by L. neotropica of Uruguay were studied under standardized experimental conditions to enable a comparison with the transmission capacity of F. hepatica by Galba truncatula at very high altitude in Bolivia. On this baseline, we reviewed the 95 human fascioliasis cases reported in Uruguay and analyzed the risk of human infection in front of future climate change estimations. CONCLUSIONS/SIGNIFICANCE: The correlation of fasciolid and lymnaeid haplotypes with historical data on the introduction and spread of livestock into Uruguay allowed to understand the molecular diversity detected. Although Uruguayan L. neotropica is a highly efficient vector, its transmission capacity is markedly lower than that of Bolivian G. truncatula. This allows to understand the transmission and epidemiological differences between Andean highlands and non-Andean lowlands in South America. Despite rainfall increase predictions for Uruguay, nothing suggests a trend towards a worrying human infection scenario as in Andean areas.

Occurrence of Fasciola hepatica (Linnaeus, 1758) in capybara (Hydrochoerus hydrochaeris) (Linnaeus, 1766) in Minas Gerais, Brazil / Ocorrência de Fasciola hepatica (Linnaeus, 1758) em capivara (Hydrochoerus hydrochaeris) (Linnaeus, 1766) em Minas Gerais, Brasil

Abstract Fasciola hepatica is a parasite that affects the hepatic ducts of several species of domestic and wild vertebrates, causing huge economic losses to livestock rearing worldwide. Reports on occurrences of F. hepatica in capybaras are an important epidemiological aspect of this disease, since these rodents can be a source of contamination for other animals and humans. In the present study, conducted in a rural area of the municipality of Confins, Minas Gerais, fresh feces from capybaras were collected from the ground near a lagoon at the edge of the Ribeirão da Mata river. These were examined using the technique of four metal sieves. F. hepatica eggs were recovered. This trematode species was confirmed by observing morphological characteristics and measuring the eggs recovered from the capybara feces, and through experimental infection of Lymnaea columella (Say, 1817) by miracidia from these eggs and subsequent infection of C57/BL06 mice with metacercariae originating from these infected mollusks. The data suggest the occurrence of natural cycle of F. hepatica in this region and provide a warning that expansion of the geographical distribution of this parasite by means of this rodent is possible. It is therefore important to adopting measures for epidemiological control of this helminthiasis.

Resumo Fasciola hepatica é um parasito que acomete os ductos hepáticos de diversas espécies de vertebrados domésticos e silvestres, causando grandes perdas econômicas na pecuária global. Relatos sobre a ocorrência de F. hepatica em capivaras constituem um importante aspecto epidemiológico dessa parasitose, visto que esses roedores podem ser fonte de contaminação para outros animais e humanos. No presente estudo realizado em área rural do município de Confins, Minas Gerais, foram coletadas no solo, próximo à lagoa marginal do rio Ribeirão da Mata, fezes frescas de capivaras. Essas foram examinadas pela técnica de quatro tamises metálicos. Foram recuperados ovos de F. hepatica. A confirmação da espécie desse trematódeo foi realizada por observação de características morfológica e mensuração dos ovos recuperados das capivaras, infecção experimental de moluscos Lymnaea columella (Say, 1817) por miracídios oriundos desses ovos e pela infecção de camundongos C57/BL06 com metacercárias oriundas desses moluscos infectados. Os dados obtidos sugerem a ocorrência do ciclo natural de F. hepatica na região, alertando que a expansão da distribuição geográfica deste parasito por esse roedor é possível. Portanto, é importante a adoção de medidas para o controle epidemiológico desta helmintíase.

Complete mitochondrial genome of the giant liver fluke Fascioloides magna (Digenea: Fasciolidae) and its comparison with selected trematodes.

BACKGROUND: Representatives of the trematode family Fasciolidae are responsible for major socio-economic losses worldwide. Fascioloides magna is an important pathogenic liver fluke of wild and domestic ungulates. To date, only a limited number of studies concerning the molecular biology of F. magna exist. Therefore, the objective of the present study was to determine the complete mitochondrial (mt) genome sequence of F. magna, and assess the phylogenetic relationships of this fluke with other trematodes based on the mtDNA dataset. FINDINGS: The complete F. magna mt genome sequence is 14,047 bp. The gene content and arrangement of the F. magna mt genome is similar to those of Fasciola spp., except that trnE is located between trnG and the only non-coding region in F. magna mt genome. Phylogenetic relationships of F. magna with selected trematodes using Bayesian inference (BI) was reconstructed based on the concatenated amino acid sequences for 12 protein-coding genes, which confirmed that the genus Fascioloides is closely related to the genus Fasciola; the intergeneric differences of amino acid composition between the genera Fascioloides and Fasciola ranged 17.97-18.24 %. CONCLUSIONS: The determination of F. magna mt genome sequence provides a valuable resource for further investigations of the phylogeny of the family Fasciolidae and other trematodes, and represents a useful platform for designing appropriate molecular markers.

Occurrence of Fasciola hepatica (Linnaeus, 1758) in capybara (Hydrochoerus hydrochaeris) (Linnaeus, 1766) in Minas Gerais, Brazil.

Fasciola hepatica is a parasite that affects the hepatic ducts of several species of domestic and wild vertebrates, causing huge economic losses to livestock rearing worldwide. Reports on occurrences of F. hepatica in capybaras are an important epidemiological aspect of this disease, since these rodents can be a source of contamination for other animals and humans. In the present study, conducted in a rural area of the municipality of Confins, Minas Gerais, fresh feces from capybaras were collected from the ground near a lagoon at the edge of the Ribeirão da Mata river. These were examined using the technique of four metal sieves. F. hepatica eggs were recovered. This trematode species was confirmed by observing morphological characteristics and measuring the eggs recovered from the capybara feces, and through experimental infection of Lymnaea columella (Say, 1817) by miracidia from these eggs and subsequent infection of C57/BL06 mice with metacercariae originating from these infected mollusks. The data suggest the occurrence of natural cycle of F. hepatica in this region and provide a warning that expansion of the geographical distribution of this parasite by means of this rodent is possible. It is therefore important to adopting measures for epidemiological control of this helminthiasis.

Effect of Fascioloides magna (Digenea) on fecundity, shell height, and survival rate of Pseudosuccinea columella (Lymnaeidae).

Infection with Fascioloides magna (Digenea) causes serious damage to liver tissue in definitive hosts represented by ruminants, especially cervids. The distribution of F. magna includes the indigenous areas in North America, and the areas to which F. magna was introduced-Central Europe, Southeast Europe, and Italy. The North American intermediate host of F. magna, the freshwater snail Pseudosuccinea columella (Lymnaeidae), is an invasive species recorded in South America, the Caribbean, Africa, Australia, and west and Southeast Europe. In Europe, Galba truncatula is the snail serving for transmission, but P. columella has potential to become here a new intermediate host of F. magna. Little is known about interactions between F. magna and P. columella. In this study, the susceptibility of P. columella (Oregon, USA) to the infection by a single miracidium of the Czech strain of F. magna and the influence of F. magna on snail fecundity, shell height, and survival were evaluated. The data show that the Oregon strain of P. columella is a highly suitable host for the Czech strain of F. magna, with the infection rate of 74 %. In addition, a negative effect on survival rate of infected snails was recorded only in the late phase of infection. The infection was accompanied by a major reduction in egg mass production and by a decrease in the number of eggs per egg mass. The shell height of infected snails did not significantly differ from that in unexposed controls.

Genetic and infective diversity of the liver fluke Fasciola hepatica (Trematoda: Digenea) from Cuba.

In this study we present the first approach to exploration of the genetic diversity of Cuban Fasciola hepatica populations using microsatellite markers, coupled with observed prevalence in slaughterhouses. Nine populations of flukes recovered from cows and buffalos were studied in the central-western region of Cuba. The observed infection rates of definitive hosts (bovines) were 70-100% in most cases. An important amount of polymorphism was found in the four loci explored. However, no apparent genetic differences were found between populations from different provinces or bovine species. The absence of deviations from Hardy-Weinberg equilibrium suggests a high rate of cross-fertilization between F. hepatica individuals. This result was confirmed when all multilocus genotypes were tested for clonal reproduction and only four individuals differed statistically (P sex< 0.05). High values of expected heterozygosity coupled with highly probable mixing among strains make the metapopulation genetically diversified but similar in terms of certain alleles (low F ST values). These results suggest a close relationship between parasite diversity and cattle management in Cuba. Our findings should be taken into consideration by veterinary authorities to help mitigate fasciolosis transmission.

Molecular characterization and phylogenetic analysis of Fasciola hepatica from Peru.

The causative agent of fasciolosis in South America is thought to be Fasciola hepatica. In this study, Fasciola flukes from Peru were analyzed to investigate their genetic structure and phylogenetic relationships with those from other countries. Fasciola flukes were collected from the three definitive host species: cattle, sheep, and pigs. They were identified as F. hepatica because mature sperms were observed in their seminal vesicles, and also they displayed Fh type, which has an identical fragment pattern to F. hepatica in the nuclear internal transcribed spacer 1. Eight haplotypes were obtained from the mitochondrial NADH dehydrogenase subunit 1 (nad1) sequences of Peruvian F. hepatica; however, no special difference in genetic structure was observed between the three host species. Its extremely low genetic diversity suggests that the Peruvian population was introduced from other regions. Nad1 haplotypes identical to those of Peruvian F. hepatica were detected in China, Uruguay, Italy, Iran, and Australia. Our results indicate that F. hepatica rapidly expanded its range due to human migration. Future studies are required to elucidate dispersal route of F. hepatica from Europe, its probable origin, to other areas, including Peru.