Climatic variations and Fasciola: a review of impacts across the parasite life cycle.

Fasciolosis, caused by the liver fluke Fasciola spp., is a significant parasitic disease of livestock and humans worldwide. Fasciola transmission and life cycle are highly dependent on climatic conditions, especially temperature and humidity. This dependency has gained significance in the context of ongoing climate change. This literature review examined evidence on the effects of temperature variability on the developmental stages of Fasciola spp. and the snail intermediate hosts. We reviewed free larval stages of Fasciola spp. development, as well as snail intermediate hosts, while investigating the climate-related factors influencing each stage. We found that Fasciola spp. egg hatching and development were inhibited below 10 °C and optimal between 20 and 30 °C, miracidia hatching time decreased with higher temperatures and cercarial shedding by snail hosts accelerated around 27 °C. Further, metacercarial viability declined at higher temperatures but was prolonged by higher humidity. Snail intermediate host growth rates peaked at 25 °C, and their susceptibility to Fasciola infection depends on temperature, underscoring its importance in transmission dynamics. Overall, the Fasciola life cycle and snail host development exhibit stage-specific temperature thresholds, indicating a complex relationship between temperature fluctuations and parasite transmission potential. This research highlights the key role of temperature and humidity on Fasciola spp. and snail development, shedding light on the potential consequences of climate change on their survival, development, and disease transmission. Data limitations, primarily from the scarcity of high-resolution climate-related experiments, should drive future research to enhance predictive models and deepen our understanding of the impact of climate change on this parasitic disease.

Fasciola gigantica: Ultrastructural localisation of neoblast recruitment in somatic tissues during growth and development in the hepatic parenchyma of experimentally infected mice.

Application of 'omics' technology, and advances in in vitro methods for studying the growth of Fasciola hepatica, have highlighted the central role of migrating neoblasts in driving forward development and differentiation towards the adult-like form. Neoblast populations present molecular heterogeneity, morphological variation and changes associated with recruitment of these stem cells into their final tissue locations. However, terminal differentiation towards function, has received much less attention than has been the case for the free-living Platyhelminths. An actively replicating neoblast population, comprising cells with heterochromatic nuclei consistent with regulation of gene expression, has been identified in the parenchyma of juvenile Fasciola gigantica migrating in the liver of experimentally infected mice. In some of these cells, early cytoplasmic differentiation towards myocyte function was noted. Neoblasts have also been identified close to, and incorporated in, the subtegumental zone, the gastrodermis and the excretory ducts. In these locations, progressive morphological differentiation towards terminal function has been described. This includes the appearance of specific progenitors of type-1, type-2 and type-3 tegumental cells, the latter possibly contributing to tegumental spine development. 'Cryptic' surface molecular differentiation is postulated to account for recognition and 'docking' of migrating neoblasts with their final site for terminal differentiation.

Extracellular vesicles from Fasciola gigantica induce cellular response to stress of host cells.

Extracellular vesicles (EVs) from parasitic helminths play an important role in immunomodulation. However, EVs are little studied in the important parasite Fasciola gigantica. Here the ability of EVs from F. gigantica to induce cellular response to stress (reactive oxygen species generation, autophage and DNA damage response) in human intrahepatic biliary epithelial cells (HIBEC) was investigated. F. gigantica-derived EVs were isolated by ultracentrifugation, and identified with transmission electron microscopy, nanoparticle size analysis and parasite-derived EV markers. Internalization of EVs by HIBEC was determined by confocal immunofluorescence microscopy and flow cytometry. ROS levels in HIBEC were detected by molecular probing. EVs-induced autophagy and DNA-damaging effects were determined by evaluating expression levels of light chain 3B protein (LC3B), phosphor- H2A.X and phosphor-Chk1, respectively. Results revealed that EVs with sizes predominately ranging from 39 to 110 nm in diameter were abundant in adult F. gigantica and contained the parasite-derived marker proteins enolase and 14-3-3, and EVs were internalized by HIBEC. Further, uptake of EVs into HIBEC was associated with increased levels of reactive oxygen species, LC3Ⅱ, phosphor-H2A.X and phosphor-Chk1, suggesting EVs are likely to induce autophagy and DNA damage & repair processes. These results indicate F. gigantica EVs are associated with modulations of host cell responses and have a potential important role in the host-parasite interactions.

High-quality reference genome of Fasciola gigantica: Insights into the genomic signatures of transposon-mediated evolution and specific parasitic adaption in tropical regions.

Fasciola gigantica and Fasciola hepatica are causative pathogens of fascioliasis, with the widest latitudinal, longitudinal, and altitudinal distribution; however, among parasites, they have the largest sequenced genomes, hindering genomic research. In the present study, we used various sequencing and assembly technologies to generate a new high-quality Fasciola gigantica reference genome. We improved the integration of gene structure prediction, and identified two independent transposable element expansion events contributing to (1) the speciation between Fasciola and Fasciolopsis during the Cretaceous-Paleogene boundary mass extinction, and (2) the habitat switch to the liver during the Paleocene-Eocene Thermal Maximum, accompanied by gene length increment. Long interspersed element (LINE) duplication contributed to the second transposon-mediated alteration, showing an obvious trend of insertion into gene regions, regardless of strong purifying effect. Gene ontology analysis of genes with long LINE insertions identified membrane-associated and vesicle secretion process proteins, further implicating the functional alteration of the gene network. We identified 852 predicted excretory/secretory proteins and 3300 protein-protein interactions between Fasciola gigantica and its host. Among them, copper/zinc superoxide dismutase genes, with specific gene copy number variations, might play a central role in the phase I detoxification process. Analysis of 559 single-copy orthologs suggested that Fasciola gigantica and Fasciola hepatica diverged at 11.8 Ma near the Middle and Late Miocene Epoch boundary. We identified 98 rapidly evolving gene families, including actin and aquaporin, which might explain the large body size and the parasitic adaptive character resulting in these liver flukes becoming epidemic in tropical and subtropical regions.

Genetic diversity and population structure analyses based on microsatellite DNA of parthenogenetic Fasciola flukes obtained from cattle and sika deer in Japan.

Understanding the population structure of Fasciola flukes in domestic and wild animals is important for determining the extent of cross-infection between them. Although the parthenogenetic Fasciola flukes in Japan have been shown to comprise five genetic types based on the ribosomal internal transcribed spacer 1 (ITS1) and mitochondrial NADH dehydrogenase subunit 1 (nad1) regions, these genetic regions are not suitable for analyzing their population structure. In the present study, the genetic diversity and population structure of the parthenogenetic Fasciola flukes in Japan were studied using microsatellite DNA, ITS1, and nad1 regions. A total of 144 parthenogenetic Fasciola flukes, obtained from cattle and sika deer in 16 localities, were individually analyzed using PCR-RFLP for ITS1, PCR-direct sequence analysis for nad1, and post-labeling PCR and capillary electrophoresis for microsatellite DNA regions. The flukes showed higher genetic diversity in the microsatellite DNA regions than ITS1 and nad1. The population structures of parthenogenetic Fasciola flukes were unclear, however, it was suggested that the flukes are more diverse populations. We hypothesized that their distribution throughout Japan is closely related to livestock movement dependent on human activity. Moreover, it is considered that cross-infection of the flukes between cattle and sika deer possibly has occurred in the past.

Oxidative status and changes in the adenosine deaminase activity in experimental host infected with tropical liver fluke, Fasciola gigantica.

Fine tuning of the metabolic, physiological and immunological cues along with interplay between the biomolecules of the host and the parasite could be responsible for the successful establishment of parasitic infections. The present investigation was aimed at evaluating the oxidative status and the level of adenosine deaminase (ADA) in the serum and liver of rabbits experimentally infected with Fasciola gigantica. A significant increase in level of ROS, MDA and 4-HNE along with a decline in the SOD, CAT, GR and GST activity was evident in rabbits experimentally infected with Fasciola gigantica. However, there was an increase in the GPX activity in the sera of infected rabbits. The increased GPX activity and decreased GR activity would have resulted in the depletion of GSH, a key non-enzymatic antioxidant, in the infected animals. The level of GSSG was also found to be higher in the sera and liver tissues of the infected rabbits along with a decline in the GSH/GSSG ratio, indicating a high level of oxidative stress in the infected animals, which also showed a significant increase in the activity of the marker enzymes of liver pathology, AST and ALT. Further, a significant inhibition of the adenosine deaminase (ADA) activity in the infected rabbits was accompanied with the reduction in the level of pro-inflammatory cytokine, IL-6 while the anti-inflammatory cytokine, IL-4 level was significantly elevated. In conclusion, the F. gigantica induced significant oxidative stress as evident from the increased levels of ROS and lipid peroxidation along with the disruption of antioxidant and detoxification cascade ultimately lead to pathogenic and inflammatory responses in the experimental host. Whereas, the altered ADA activity could modulate the host's immune responses toward Th-2 type and would facilitate the successful establishment of flukes within their host, thus indicating that ADA could be exploited as a target for the development of novel anthelmintic drugs against fasciolosis.

Genome-wide identification and characterization of eukaryotic protein kinases.

The tropical liver fluke, Fasciola gigantica is a food-borne parasite responsible for the hepatobiliary disease fascioliasis. The recent completion of F. gigantica genome sequencing by our group has provided a platform for the systematic analysis of the parasite genome. Eukaryotic protein kinases (ePKs) are regulators of cellular phosphorylation. In the present study, we used various computational and bioinformatics tools to extensively analyse the ePKs in F. gigantica (FgePKs) genome. A total of 455 ePKs were identified that represent ~2% of the parasite genome. Out of these, 214 ePKs are typical kinases (Ser/Thr- and Tyr-specific ePKs), and 241 were other kinases. Several FgePKs were found to possess unusual domain architectures, which suggests the diverse nature of the proteins that can be exploited for designing novel inhibitors. 115 kinases showed <35% query coverage when compared to human ePKs highlighting significant divergences in their respective kinomes, further providing a platform for novel structure-based drug designing. This study provides a platform that may open new avenues into our understanding of helminth biochemistry and drug discovery.

Newly excysted juveniles (NEJs) of Fasciola gigantica induce mice liver fibrosis and M2 macrophage-like phenotype in vivo.

Liver flukes of animals are parasitic flatworms of major socioeconomic importance in many countries. Particularly, Fasciola gigantica is a leading cause of production losses to the livestock (mainly sheep and cattle) and meat industries due to clinical disease, reduced weight gain and milk production, and deaths. Immune responses induced by helminth have been extensively studied, but there is limited information on this aspect by F. gigantica, especially on macrophages induced with this parasite. Studies have shown that host immune responses induced by parasitic infection is greatly correlated with the macrophage polarization axis. In the present study, we used the murine model of F. gigantica to explore the interaction of host and F. gigantica. We found F. gigantica NEJs promoted pathology and fibrosis of mice liver, and the enlargement of mice spleen. We also showed that macrophages were recruited to mice peritoneal cavity at 5 days post infection. By evaluating the expression of genetic markers of M2 macrophages such as Arg-1, Ym1 and RELMɑ, and genetic marker of M1 macrophages iNOS, we showed that M2 macrophages were induced by F. gigantica. M2 macrophages are central to the immune response during helminth infection, and our findings in this study provided insight into the immune interaction between F. gigantica and host.

Fasciola gigantica: Ultrastructural cytochemistry of the tegumental surface in newly- excysted metacercariae and in vitro-penetrated juvenile flukes informs a concept of parasite defence at the interface with the host.

Cytochemical staining techniques were carried out en bloc with in vitro excysted and gut-penetrated Fasciola gigantica larvae in order to visualise the glycocalyx of the tegument, a structure which comprises the parasite component of the host-parasite interface, yet is incompletely preserved by conventional fixation and preparation techniques for electron microscopy. Positive reactivity with ruthenium red and periodic acid-thiocarbohydrazine-osmium (PATCO) techniques revealed that the glycocalyx is polyanionic and carbohydrate-rich throughout its depth. It comprises a trilaminate arrangement, with a thin dense zone and fibrillar layer closely apposed to the outer aspect of the apical plasma membrane, invested by an irregular thick mucopolysaccharide capsule. The latter, not recorded in adult flukes, may represent a specific adaptation to facilitate invasion in the face of host immunity, and may also protect the parasite surface from the action of host- and parasite-derived proteases. Early in the invasion of a naïve host, the glycocalyx may be partly responsible for triggering the responses of innate immunity, while later in infection, or when an anamnestic response is initiated in an immunocompetent host, the antibodies and activated lymphocytes of specific acquired immunity are invoked to interact with the parasite surface. The cytochemical properties of the glycocalyx, together with its potential for dynamic turnover due to exocytosis of the T0 tegumental secretory bodies, are likely to aid neutralisation of potentially damaging immune effectors and ensure their removal from the vicinity of the parasite by sloughing in complex with glycocalyx components.

Profiling circulating microRNAs in serum of Fasciola gigantica-infected buffalo.

Circulating miRNAs are stably existed in serum and plasma and can serve as a novel class of biomarkers for the diagnosis of helminthic infection. Fasciola gigantica, the causative agents of fascioliasis, live in the liver of in humans and ruminants, especially cattle, goat and sheep. In this study, a total of 121 host circulating miRNAs were differentially expressed (2 ≥ fold change, p < 0.05), of which 44 miRNAs were up-regulated and 77 miRNAs were significantly down-regulated. Consistent with the sequencing data, qRT-PCR results showed that the expression levels of bta-miR-21-5p and bta-miR-23a were elevated gradually and bta-miR-125a was decreased gradually at the F. gigantica infection time points. Four F. gigantica-specific miRNAs, including three known miRNAs (fgi-miR-87, fgi-miR-71, and fgi-miR-124), and one novel miRNA (novel miR-1) were identified in the sera of F. gigantica-infected buffaloes. Further analyses demonstrated that two parasite-derived miRNAs (fgi-miR-87 and fgi-miR-71) were specifically detected in sera of F. gigantica-infected buffaloes. These findings will be helpful to understand the roles of circulating miRNAs in host-parasite interaction and to potentiate serum miRNAs as diagnostic targets for F. gigantica.

Fasciola species and their vertebrate and snail intermediate hosts in East and Southern Africa: a review.

A systematic review was conducted focusing on the distribution of Fasciola species and their snail intermediate hosts (IHs) in East and Southern Africa. The reviewed literature showed that both Fasciola hepatica and F. gigantica are present in East and Southern Africa, and infect a wide range of domestic and wild ruminants. Fasciola gigantica was reported in six East African and five Southern African countries, where Radix natalensis (found in low altitudes) was reported to be the main IH. Fasciola hepatica was reported in Tanzania and Ethiopia (East Africa), and in South Africa and Zimbabwe (Southern Africa), where Galba truncatula (found in high altitudes) was documented as the IH in all countries except in Zimbabwe. Both Fasciola species were documented in Tanzania, Ethiopia, Zimbabwe and South Africa. An overlap of the two was observed in areas with an intermediate altitude in Ethiopia and South Africa, where Pseudosuccinea columella was widespread and assumed to transmit both species. Pseudosuccinea columella has been reported in South Africa and Namibia, and proven to transmit F. gigantica in South Africa; its role in Namibia in the transmission of Fasciola species has not been reported. Other lymnaeid species such as R. rubiginosa were reported in South Africa, and R. auricularia in South Africa and Botswana; their role in the transmission of Fasciola species has not been proven. Future studies should aim to determine the role of P. columella in the geographical spread of the two species in East and Southern African countries.

Molecular detection of natural infection of Lymnaea (Pseudosuccinea) columella (Gastropoda: Lymnaeidae) with Fasciola gigantica (Digenea: Fasciolidae) from two provinces of South Africa.

The main intermediate host of Fasciola gigantica in sub-Saharan Africa is Lymnaea (Radix) natalensis. Lymnaea (Pseudosuccinea) columella is capable of transmitting both F. gigantica and F. hepatica and has been reported to be present in South Africa. To date, no natural infection with F. gigantica has been reported despite the wide distribution of the snail. The aim of this study was to confirm whether L. (P.) columella was transmitting F. gigantica and/or F. hepatica in selected locations of KwaZulu-Natal and Eastern Cape provinces of South Africa. Lymnaea (Pseudosuccinea) columella snails were collected from two locations in two provinces of South Africa and screened for cercariae shedding. This was followed by humanely sacrificing the screened snails, and whole tissue of each individual snail was homogenized and amplified using primers designed to amplify the ITS-1 region of Fasciola spp. No cercariae were shed from the screened snails and molecular analysis showed that snails from the two locations were infected with F. gigantica. This study confirms natural infection of L. (P.) columella with F. gigantica in South Africa, where F. gigantica and F. hepatica have already been reported to coexist. Although L. (P.) columella is able to transmit the two species, surprisingly no infection with F. hepatica was detected from the screened snails. The natural intermediate host of F. gigantica in southern Africa, including South Africa, is Lymnaea (Radix) natalensis and comparative studies are needed to determine the competence of the two snail species in the transmission of F. gigantica.

First report of Fasciola larva infection in Galba truncatula (Müller, 1774) (Gastropoda, Lymnaeidae) occurring in the natural environment in Hokkaido, Japan.

In Hokkaido, Japan, wild sika deer are highly infected with Fasciola flukes, suggesting that the flukes complete their life cycle via intermediate host snails and definitive host animals occurring in the natural environment. However, infected snails have been found only in cattle farms contaminated with fasciolosis. This study reports the first Fasciola larva infection in Galba truncatula snails occurring in the Shoro and Atsuma rivers in the natural environment. Molecular analysis revealed that the nad1 haplotype of the larvae was consistent with that of Fasciola adults obtained from sika deer in Hokkaido. These results indicated that Fasciola flukes complete their life cycle via G. truncatula and sika deer occurring in the natural environment.

Purification and characterization of two-domain glutaredoxin in the parasitic helminth Fasciola gigantica.

Glutaredoxins (Grxs) are small thiol-dependent proteins and key elements of redox signaling as they regulate the redox state of important cellular proteins. In the present study, the complete sequence of a glutaredoxin protein, obtained from the liver fluke Fasciola gigantica, was PCR-amplified and cloned. The 690-bp open reading frame (ORF) encodes a 230-amino acid protein with two conserved domains (FgGrxD1 and FgGrxD2) and has similarities with two monothiol Grxs of Saccharomyces cerevisiae, i.e., ScGrx3 and ScGrx4. The full-length FgGrx along with its two constituent domains were overexpressed in Escherichia coli as hexahistidyl-tagged proteins. The affinity chromatography resulted in almost pure and soluble proteins. The full-length FgGrx and the FgGrxD2 showed reddish-brown color, indicating the presence of bound iron in the second domain. In the insulin based reduction assay, both FgGrx and FgGrxD2 containing the active site motif CGFS exhibited a weak reducing activity, whereas FgGrxD1 was inactive. Additionally, FgGrx did not show any GSH-disulfide transhydrogenase activity when 2-hydroxyethyl disulfide (HED) or de-hydroascorbate (DHA) were taken as substrates. These results indicated the probable role of FgGrx in cellular iron-sulfur homeostasis. FgGrx was found to be reversibly S-glutathionylated, suggesting a potential redox regulation that is likely to take place at the active site Cys158. Since there is only one Cys in FgGrxD2, the Cys158 might be involved in FeS binding. This study is the first report on the presence of Grx in platyhelminthic parasites and provides a starting point for further characterization of the redox network in liver flukes.

Re-infection with Fasciola gigantica 6-month post-treatment with triclabendazole in cattle from mobile pastoralist husbandry systems at Lake Chad.

At Lake Chad in central Africa, livestock fascioliasis caused by Fasciola gigantica represents a major veterinary health problem, particularly in cattle reared in mobile pastoralist husbandry systems. We assessed re-infection after a single dose of triclabendazole with fascioliasis in cattle in a mobile pastoralist setting towards the end of the dry season. Within the cattle herds of 14 groups of mobile pastoralists, 375 cattle were randomly selected. A faecal sample was obtained from each animal to determine the prevalence of F. gigantica. Animals were administered a single oral dose of triclabendazole (12mg/kg). A second faecal sample was obtained 6-month post-treatment after cattle had returned from the annual migration cycle. Faecal samples were fixed in sodium acetate-acetic acid-formalin (SAF), and examined for F. gigantica using the sedimentation technique. From the 375 cattle enrolled at baseline, 198 animals (53%) in 12 groups of mobile pastoralists were re-sampled at the 6-month follow-up. Baseline prevalence did not differ noteworthy between animals lost to follow-up and those re-examined. At baseline, bovine fascioliasis prevalence in cattle with follow-up data was 41.9% (95% confidence interval (CI) 35.2-48.9%). At the 6-month post-treatment follow-up, the prevalence was 46.0% (95% CI 39.2-52.9%), ranging between 0% and 75% at the herd level. The mean faecal egg counts at the unit of the herd were higher at follow-up compared to baseline. The observed persistent high prevalence of F. gigantica infection in cattle shows that a single pre-rainy season treatment does not prevent rapid re-infection despite the partial migration away from the high-risk areas at Lake Chad into drier areas. A locally adapted strategic control package for fascioliasis in cattle in the Lake Chad area ought to integrate targeted triclabendazole treatment and seasonal transhumance practices.

Animal Fascioliasis: Perspectives from high altitudinal regions.

The parasitic flukes of the genus Fasciola (Platyhelminthes: Trematoda: Digenea) cause fascioliasis or liver-rot disease in ruminant livestock in tropical and sub-tropical regions of the world. Classically, two species of Fasciola- F. hepatica and F. gigantica, are universally recognized as taxonomically valid species. Our survey studies on ovid and bovid animals including yak and mithun from high altitudinal mountainous regions in Northeast India revealed the occurrence of Fasciola gigantica and also Fasciola sp.- an intermediate form, at altitudes between 5000 and 14,085 feet above sea level (asl). Two morphotypes- F. hepatica - like and F. gigantica - like, of Fasciola species were reported from the high altitudinal areas of Northeast India; most of these locales constitute new-locality and first records for the occurrence of these liver flukes.

Immunodiagnosis of Fasciola gigantica Infection Using Monoclonal Antibody-Based Sandwich ELISA and Immunochromatographic Assay for Detection of Circulating Cathepsin L1 Protease.

BACKGROUND: Tropical fasciolosis caused by Fasciola gigantica infection is one of the major diseases infecting ruminants in the tropical regions of Africa and Asia including Thailand. Parasitological diagnosis of fasciolosis is often unreliable and possesses low sensitivity. Therefore, the detection of circulating parasite antigens is thought to be a better alternative for diagnosis of fasciolosis, as it reflects the real parasite burden. METHODS: In this study, we have produced a monoclonal antibody (MoAb) against recombinant F. gigantica cathepsin L1 (rFgCatL1), and developed both sandwich enzyme-linked immunosorbent assay (sandwich ELISA) and immunochromatographic (IC) test for rapid detection of circulating cathepsin L1 protease (CatL1) in the sera from mice experimentally and cattle naturally infected with Fasciola gigantica. MoAb 4E3 and biotinylated rabbit anti-recombinant CatL1 antibody were selected due to their high reactivities and specificities. RESULTS: The lower detection limits of sandwich ELISA and IC test were 3 pg/ml and 0.256 ng/ml, respectively. Sandwich ELISA and IC test could detect F. gigantica infection from day 1 to 35 post infection. In experimental mice, the sensitivity, specificity and accuracy were 95%, 100% and 98.6% (for sandwich ELISA), and 93%, 100% and 98.2% (for IC test), while in natural cattle they were 98.3%, 100% and 99.5% (for sandwich ELISA), and 96.7%, 100% and 99.1% (for IC test). CONCLUSIONS: These two assay methods showed high efficiencies and precisions for diagnosis of fasciolosis by F. gigantica.

In vitro screening of Cymbopogon jwarancusa and Conyza canadensis against liver flukes.

Aim of present study was to screen medicinal plants for flukicidal activity in vitro to develop alternative sources of treatment for trematodes infection. For this purpose, crude methanolic extracts (CME) of Cymbopogn jwarancusa and Conyza canadensis were prepared and live adult flukes viz; Fasciola gigantica, and Paramphistomum cervi isolated from liver and bile ducts of slaughtered buffalo were subjected to different drug concentrations as well as positive and negative control. Motility inhibition and paralysis leading to the death of parasites was considered as flukicidal activity of plants extracts. The results revealed that CME of C. jwarancusa and C. canadensis showed significant (P<0.05) flukicidal activity compared to positive control. Also there was a significant effect of different concentrations (P<0.05) and exposure of time on the flukes (P<0.05). Furthermore, ED50 for C. jwarancusa and C. canadensis against F. gigantica were 13.1 and 41.4 mg/ml, respectively. In the case of P. cervi, it was 10.8 and 29.0 mg/ml. It can be concluded that both tested plants showed greater flukicidal activity as compared to positive control with Albendazole till the 8(th) hr. These potent plants needs further studies invivo to elucidate their mode of action.

Experimental life history and biological characteristics of Fasciola gigantica (Digenea: Fasciolidae).

This study was conducted to investigate the life history, morphology, and maturation of larval stages and adult worms of Fasciola gigantica in experimental mice. Lymnaea auricularia rubiginosa was used as the intermediate host, and Oryza sativa was used for encystment of the metacercariae, while Mus musculus was used as the definitive host for maturation study. Fresh eggs from the gall bladder of water buffaloes fully developed into embryonated ones and hatched out at days 11-12 after incubation at about 29ºC. Free-swimming miracidia rapidly penetrated into the snail host, and gradually developed into the next larval stages; sporocyst, redia, and daughter redia with cercariae. Fully-developed cercariae were separated from the redia and shed from the snails on day 39 post-infection (PI). Free-swimming cercariae were immediately allowed to adhere to rice plants, and capsules were constructed to protect metacercariae on rice plants. Juvenile worms were detected in intestines of mice at days 3 and 6 PI, but they were found in the bile duct from day 9 PI. Juvenile and adult flukes were recovered from 16 mice experimentally infected with metacercariae, with the average recovery rate of 35.8%. Sexually mature adult flukes were recovered from day 42 PI. It could be confirmed that experimentally encysted metacercariae could infect and develop to maturity in the experimental host. The present study reports for the first time the complete life history of F. gigantica by an experimental study in Thailand. The obtained information can be used as a guide for prevention, elimination, and treatment of F. gigantica at environment and in other hosts.