Fascioliasis

Geographic expansion of Fasciola hepatica (Linnaeus, 1758) due to changes in land use and cover in Brazil

Fasciolosis is caused by parasites of the genus Fasciola, affecting animals and humans worldwide. In South America, the disease is a result of infection with Fasciola hepatica and although animal infections are more frequently reported, the full extent of the impact on human health due to underdiagnosis remains uncertain. This study analyzed changes in land use and the distribution of F. hepatica in bovine livers in Brazil over 18 years. Data on land use and land cover were collected from the Mapbiomas Project. Data on 414,481,963 slaughtered cattle and condemned livers due to F. hepatica infection were obtained from 4,433 municipalities. Joinpoint analysis was used to study the time series, and the Susceptible-Infected-Recovered (SIR) model was utilized to explore the behavior of F. hepatica infection. In the North, pasture areas significantly increased (P = 0.000001), while forested areas decreased (P = 0.000001). The midwestern and northern regions concentrated the highest number (>290 million) of cattle slaughtered in Brazil. More than 2 million bovine livers were infected by F. hepatica. The infected cattle originated from 194 municipalities in 2002, increasing to 747 in 2020. We consider that the changes in land use and intense cattle transportation may have caused the expansion of F. hepatica. The SIR model analyzed the spread of the disease looking at all six biomes: Caatinga, Amazon Forest, Cerrado, Pantanal, Atlantic Forest, and Pampa. Moreover, this infection not only threatens the health of animals but is also a major concern to biodiversity and vulnerable human communities in South America. Emblematic biomes such as the Amazon basin already face challenges with logging, desertification, and loss of biodiversity. Therefore, strategies for mitigating infection should include controlling illegal pasture areas, establishing health inspections of animal transport, quarantine of newly arrived animals, and livestock zoning, as well as clear One Health policies.

Coproprevalence, seroprevalence, and geographic distribution of Fasciola spp. infection in beef and dairy cattle in Pak Chong highland, Nakhon-Ratchasima Province, Northeast Thailand

Fasciola spp. is a major livestock parasite, especially in cattle, water buffalo, sheep, and goats. Infection reduces animal productivity, e.g., meat, dairy, wool and might cause death. In Thailand, reports of Fasciola spp. infection in livestock, especially dairy and beef cattle, are sparse. Pakchong district in Nakhon Ratchasima province is one of Thailand's largest farming areas for dairy and beef cattle, but the prevalence of Fasciola spp. infection has never been reported in this district. The landscape of this area is mainly a hilltop plateau with many water sources suitable for the development of lymnaeid snails, the intermediate host of Fasciola spp., which are essential for the parasite life cycle. This study surveyed the copro- and seroprevalence of Fasciola spp. infection in dairy and beef cattle farmed in Pakchong district by microscope-based examination, PCR, and indirect ELISA. Associated risk factors and geographic information data were collected and analyzed. Paired stool and serum samples were collected from 102 dairy cattle and 99 beef cattle from April to November 2021. Sample analyses demonstrated a high prevalence of Fasciola spp. infection, especially in beef cattle. The overall copro-prevalence was 5.97%, with 0.99% in dairy cattle and 11.11% in beef cattle. The overall seroprevalence was 23.88%, with 2.94% in dairy cattle and 45.45% in beef cattle. Moreover, the data indicated that infection status was not correlated with animal sex and age whereas consumption of natural grasses, water resources, housing floor, and farming system were significant risk factors. Data analysis by a geographic information system (GIS) demonstrated that an associated risk could be farmed in lowering areas, especially in Chan Thuck, Nong Sa Rai, and Khlong Muang subdistricts. In conclusion, this study reports the prevalence of Fasciola spp. infection in cattle in a major farming area of Thailand which could be beneficial for designing parasite control policies in this region as well as adapting this knowledge to other Fasciola spp. endemic areas.

Yolk proteins of the schistosomiasis vector snail Biomphalaria glabrata revealed by multi-omics analysis

Vitellogenesis is the most important process in animal reproduction, in which yolk proteins play a vital role. Among multiple yolk protein precursors, vitellogenin (Vtg) is a well-known major yolk protein (MYP) in most oviparous animals. However, the nature of MYP in the freshwater gastropod snail Biomphalaria glabrata remains elusive. In the current study, we applied bioinformatics, tissue-specific transcriptomics, ovotestis-targeted proteomics, and phylogenetics to investigate the large lipid transfer protein (LLTP) superfamily and ferritin-like family in B. glabrata. Four members of LLTP superfamily (BgVtg1, BgVtg2, BgApo1, and BgApo2), one yolk ferritin (Bg yolk ferritin), and four soma ferritins (Bg ferritin 1, 2, 3, and 4) were identified in B. glabrata genome. The proteomic analysis demonstrated that, among the putative yolk proteins, BgVtg1 was the yolk protein appearing in the highest amount in the ovotestis, followed by Bg yolk ferritin. RNAseq profile showed that the leading synthesis sites of BgVtg1 and Bg yolk ferritin are in the ovotestis (presumably follicle cells) and digestive gland, respectively. Phylogenetic analysis indicated that BgVtg1 is well clustered with Vtgs of other vertebrates and invertebrates. We conclude that, vitellogenin (BgVtg1), not yolk ferritin (Bg yolk ferritin), is the major yolk protein precursor in the schistosomiasis vector snail B. glabrata.

Checklist of digeneans (Platyhelminthes, Trematoda, Digenea) of Georgia

Background

In the present study, we aim to provide an inventory of digenetic trematodes (Platyhelminthes, Trematoda, Digenea) from Georgia including records from the freshwater, marine and terrestrial realms. The checklist is based on a critical review of data from 109 papers, 11 monographs and four Ph.D. theses published between 1935 and 2019 and our new records. The checklist includes information on synonymy, the host species, site of infection, geographical distribution and bibliographical references. The present data will serve as a baseline for further studies on trematodes from Georgia focused on integrative taxonomy, life-cycle elucidation, parasite ecology and epidemiology.

New information

We compiled data on the digenean trematode fauna of Georgia, which is represented by 186 species (of these 173 identified to species level) belonging to 108 genera, 47 families and 17 superfamilies. This is the first checklist of the digeneans of Georgia. The majority of digenean species were recorded as adults (160 species), only a small fraction being found as cercariae (33 species) or metacercariae (24 species), in their first or second intermediate hosts, respectively. Predominantly, records of trematodes (62 species) from birds were found, followed by those parasitising fish (50 species, i.e. 32 species as adults and 18 as metacercariae), mammals (33 species) and amphibians (25 species, i.e. 23 species as adults and 2 as metacercariae), with the least number of species reported from reptiles (12 species, i.e. 9 species as adults and 3 as metacercariae). Adult digeneans recorded together with another life-cycle stage (metacercariae and/or cercariae) comprised 28 species, i.e. for 15% of the total trematode species number, a part of their life-cycle is known.

One-health approach on the future application of snails: a focus on snail-transmitted parasitic diseases

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.

Fasciolosis: pathogenesis, host-parasite interactions, and implication in vaccine development

Fasciola hepatica is distributed worldwide, causing substantial economic losses in the animal husbandry industry. Human fasciolosis is an emerging zoonosis in Andean America, Asia, and Africa. The control of the disease, both in humans and animals, is based on using anthelmintic drugs, which has resulted in increased resistance to the most effective anthelmintics, such as triclabendazole, in many countries. This, together with the concerns about drug residues in food and the environment, has increased the interest in preventive measures such as a vaccine to help control the disease in endemic areas. Despite important efforts over the past two decades and the work carried out with numerous vaccine candidates, none of them has demonstrated consistent and reproducible protection in target species. This is at least in part due to the high immunomodulation capacity of the parasite, making ineffective the host response in susceptible species such as ruminants. It is widely accepted that a deeper knowledge of the host-parasite interactions is needed for a more rational design of vaccine candidates. In recent years, the use of emerging technologies has notably increased the amount of data about these interactions. In the present study, current knowledge of host-parasite interactions and their implication in Fasciola hepatica vaccine development is reviewed.

Efficacy of flukicides against Fasciola hepatica and first report of triclabendazole resistance on German sheep farms

Fasciola hepatica infections lead to severe health problems and production losses in sheep farming, if not treated effectively. Triclabendazole has been used extensively over decades due to its unique efficacy range against all definitive hostfluke stages but published data about the susceptibility of F. hepatica to anthelmintics in Germany are lacking. This study aimed to identify current F. hepatica infections in German sheep flocks by coproscopic examinations and to evaluate the efficacy of anthelmintics with a focus on triclabendazole in a field study conducted from 2020 to 2022. Initial screening included 71 sheep farms, many of them with known history of fasciolosis. In this highly biased sample set, the frequency of F. hepatica infection at individual sheep and farm level were 12.8% and 35.2%, respectively. Additionally, eggs of Paramphistominae were found at frequencies of 4.8% and 15.5% at individual sheep and farm level, respectively. Due to low egg shedding intensity, faecal egg count reduction (FECR) tests could only be conducted on a few farms. The efficacy of triclabendazole was tested on 11 farms and albendazole on one farm, including 3-53 sheep/farm. Individual faecal samples were collected before and two weeks after treatment to evaluate the FECR using the sedimentation or FLUKEFINDER® or a modified FLUKEFINDER® method. On all farms a coproantigen reduction test was conducted in parallel. Lacking efficacy of triclabendazole even at double dosage was shown on one farm associated with a high number of animal losses due to acute fasciolosis. On this farm, the Fasciola miracidium development test was additionally performed, revealing a high in vitro ovicidal activity of albendazole while closantel was effective in vivo. On all other farms, sufficient efficacy of triclabendazole was observed. In conclusion, triclabendazole resistance appears not to be widespread on German sheep farms but, when present, can have serious effects on animal health.

Effects of temperature on the life history traits of intermediate host snails of fascioliasis: A systematic review

BACKGROUND

The impact of climate change has led to variations in various biological processes, leading to altered transmission dynamics of infectious diseases, including snail-borne diseases (SBDs). Fascioliasis is one of the neglected zoonotic tropical snail-borne diseases caused by the trematode of the genus Fasciola. This review focused on laboratory experimental and model studies that evaluate the potential effect of temperature change on the ecology and biology of the intermediate host snails (IHS) of Fasciola.

METHODS

A literature search was conducted on Google Scholar, EBSCOhost, and PubMed databases using predefined medical subject heading terms, Boolean operators, and truncation symbols in combination with direct keywords: Fasciolosis AND Temperature, Lymnaea OR Austropeplea OR Radix OR Galba OR Fossaria OR Pseudosuccinea AND growth, fecundity, AND survival at the global scale. Other search terms used were (Fascioliasis AND Temperature), (Lymnaea AND Temperature), (Austropeplea AND Temperature), (Fossaria AND Temperature), (Galba AND Temperature), (Pseudosuccinea AND Temperature), and (Radix AND Temperature).

RESULTS

The final synthesis included thirty-five published articles. The studies reviewed indicated that temperature rise may alter the distribution, and optimal conditions for breeding, growth, and survival of IHS, ultimately resulting in changing the transmission dynamics of fascioliasis. The literature also confirmed that the life history traits of IHS and their interaction with the liver fluke parasites are driven by temperature, and hence climate change may have profound outcomes on the population size of snails, parasite density, and disease epidemiology.

CONCLUSION

We concluded that understanding the impact of temperature on the growth, fecundity, and survival of IHS may broaden our knowledge of the possible effects of climate change and hence inform fascioliasis control programs.

Antibody detection against Kunitz-type protein in Fasciola hepatica experimentally infected sheep using enzyme-linked immunosorbent assay (ELISA)

Fasciolosis is a parasitic disease considered as emerging and neglected by the WHO. Sheep are highly susceptible to this disease, and affected flocks experience decreased productivity due to increased mortality, and the reduced quality of their products, such as wool and meat. To effectively control this disease, reliable and early diagnosis is essential for making decisions regarding antiparasitic application and/or the removal of affected animals. Currently, the diagnosis of F. hepatica in sheep relies on the detection of parasite eggs in faeces, a method that becomes reliable from week 10 post-infection. Consequently, there is a need for earlier diagnostic tools based on immune response. However, obtaining antigens for antibody detection has proven to be difficult and expensive. The aim of this study was to evaluate members of the Kunitz protein family of F. hepatica expressed in the form of a fusion protein in the serological diagnosis of F. hepatica in sheep. The performance of three recombinant F. hepatica Kunitz-type inhibitors (FhKT1.1, FhKT1.3, and FhKT4) was compared with a synthetic Kunitz-type peptide (sFhKT) in sera from sheep experimentally infected with F. hepatica, using an ELISA. Of these, FhKT1.1 showed the most promising diagnostic indicators, exhibiting high precision and low cross-reactivity, and thus potential for standardized production. The results of our study demonstrated that the application of FhKT1.1 is a valuable tool for early-stage diagnosis of F. hepatica in sheep. Such an early diagnosis can aid in implementing timely interventions and effectively managing the disease in sheep populations.

Fasciola hepatica soluble antigens (FhAg) induce ovine PMN innate immune reactions and NET formation in vitro and in vivo

Fasciola hepatica causes liver fluke disease, a worldwide neglected and re-emerging zoonotic disease, leading to hepatitis in humans and livestock. In the pathogenesis, flukes actively migrate through liver parenchyma provoking tissue damage. Here, parasites must confront leukocytes of the innate immune system in vivo. Polymorphonuclear neutrophils (PMN) are the most abundant granulocytes and first ones arriving at infection sites. PMN may display neutrophil extracellular traps (NETs), consisting of nuclear DNA, decorated with histones, enzymes, and antimicrobial peptides. We investigated for the first time whether F. hepatica soluble antigens (FhAg) can also trigger NETosis and innate immune reactions in exposed ovine PMN. Thus, isolated PMN were co-cultured with FhAg and NET formation was visualized by immunofluorescence and scanning electron microscopy analyses resulting in various phenotypes with spread NETs being the most detected in vitro. In line, NETs quantification via Picogreen®-fluorometric measurements revealed induction of anchored- and cell free NETs phenotypes. Live cell 3D-holotomographic microscopy revealed degranulation of stimulated PMN at 30 min exposure to FhAg. Functional PMN chemotaxis assays showed a significant increase of PMN migration (p = 0.010) and intracellular ROS production significantly increased throughout time (p = 0.028). Contrary, metabolic activities profiles of FhAg-exposed PMN did not significantly increase. Finally, in vivo histopathological analysis on F. hepatica-parasitized liver tissue sections of sheep showed multifocal infiltration of inflammatory cells within liver parenchyma, and further fluorescence microscopy analyses confirmed NETs formation in vivo. Overall, we hypothesized that NET-formation is a relevant host defence mechanism that might have a role in the pathogenesis of fasciolosis in vivo.

Multinomial logistic regression based on neural networks reveals inherent differences among dairy farms depending on the differential exposure to Fasciola hepatica and Ostertagia ostertagi

Fasciola hepatica and Ostertagia ostertagi are cattle parasites with worldwide relevance for economic outcome as well as animal health and welfare. The on-farm exposure of cattle to both parasites is a function of host-associated, intrinsic, as well as environmental and farm-specific, extrinsic, factors. Even though knowledge on the biology of both parasites exists, sophisticated and innovative modelling approaches can help to deepen our understanding of key aspects fostering the exposure of dairy cows to these pathogens. In the present study, multiple multinomial logistic regression models were fitted via neural networks to describe the differences among farms where cattle were not exposed to either F. hepatica or O. ostertagi, to one parasite, or to both, respectively. Farm-specific production and management characteristics were used as covariates to portray these differences. This elucidated inherent farm characteristics associated with parasite exposure. In both studied regions, pasture access for cows, farm-level milk yield, and lameness prevalence were identified as relevant factors. In region 'South', adherence to organic farming principles was a further covariate of importance. In region 'North', the prevalence of cows with a low body condition score, herd size, hock lesion prevalence, farm-level somatic cell count, and study year appeared to be of relevance. The present study broadens our understanding of the complex epidemiological scenarios that could predict differential farm-level parasite status. The analyses have revealed the importance of awareness of dissimilarities between farms in regard to the differential exposure to F. hepatica and O. ostertagi. This provides solid evidence that dynamics and relevant factors differ depending on whether or not cows are exposed to F. hepatica, O. ostertagi, or to both.

Genetic variation and population structure of Fasciola hepatica: an in silico analysis

Fasciola hepatica is a trematode leading to heavy economic setbacks to the livestock sector globally. The population's genetic information and intimate kinship level are frequently assessed using analysis of mitochondrial DNA. In this analysis, we retrieved cox1 (n = 247) and nad1 (n = 357) sequences of F. hepatica from the NCBI GenBank database and aligned the sequences with the respective reference sequences using MEGA software. The median joining network was drawn using PopArt software while neutrality and diversity indices were estimated with the help of DnaSp software. Neighbor-joining phylogenetic tree was constructed using the MEGA software package. A total of 46 and 98 distinctive haplotypes were observed for cox1 and nad1 genes, respectively. Diversity indices indicated high haplotype and nucleotide diversities in both genes. Positive Tajima's D and Fu's Fs values were found for the entire population of both the genes under study. The cox1 and nad1 gene segments in this study showed high Tajima's D values, suggesting a low likelihood of future population growth. The Tajima's D value of the nad1 gene sequence is lower (2.14910) than that of the cox1 gene sequence (3.40314), which suggests that the former is growing at a slower rate. However, the region-wise analysis revealed that both the cox1 and nad1 genes showed deviation from neutrality suggesting a recent population expansion as a result of an excess of low-frequency polymorphism. Furthermore, the overall host-wise analysis showed positive and significant Tajima's D values for the cox1 and nad1 gene sequences. To the best of our knowledge, this is the first attempt to provide insights into genetic variations and population structure of F. hepatica at a global scale using cox1 and nad1 genes. Our findings suggest the existence of specific variants of F. hepatica in different parts of the world and provide information on the molecular ecology of F. hepatica. The results of this study also mark a critical development in upcoming epidemiological investigations on F. hepatica and will also contribute to understanding the global molecular epidemiology and population structure of F. hepatica.

Comparison of Mini-FLOTAC, Flukefinder and sedimentation techniques for detection and quantification of Fasciola hepatica and Calicophoron daubneyi eggs using spiked and naturally infected bovine faecal samples

BACKGROUND

Fasciolosis (Fasciola hepatica) and paramphistomosis (Calicophoron daubneyi) are two important infections of livestock. Calicophoron daubneyi is the predominant Paramphistomidae species in Europe, and its prevalence has increased in the last 10-15 years. In Italy, evidence suggests that the prevalence of F. hepatica in ruminants is low in the southern part, but C. daubneyi has been recently reported at high prevalence in the same area. Given the importance of reliable tools for liver and rumen fluke diagnosis in ruminants, this study evaluated the diagnostic performance of the Mini-FLOTAC (MF), Flukefinder(R) (FF) and sedimentation (SED) techniques to detect and quantify F. hepatica and C. daubneyi eggs using spiked and naturally infected cattle faecal samples.

METHODS

Briefly, negative bovine faecal samples were artificially spiked with either F. hepatica or C. daubneyi eggs to achieve different egg count levels: 10, 50 and 100 eggs per gram (EPG) of faeces. Moreover, ten naturally infected cattle farms from southern Italy with either F. hepatica and/or C. daubneyi were selected. For each farm, the samples were analysed individually only with MF technique and as pools using MF, FF and SED techniques. Bayesian latent class analysis (LCA) was used to estimate sensitivity and accuracy of the predicted intensity of infection as well as the infection rate in the naturally infected farms.

RESULTS

The outcome of this study showed that the highest number of eggs (F. hepatica and C. daubneyi) recovered was obtained with MF, followed by FF and SED in spiked infected samples at 50 and 100 EPG, while at lower infection levels of 10 EPG, FF gave the best results. Moreover, the sensitivity for all the techniques included in the study was estimated at > 90% at infection levels > 20 EPG for both F. hepatica and C. daubneyi eggs. However, MF was the most accurate of the three techniques evaluated to estimate fluke infection intensity. Nevertheless, all three techniques can potentially estimate infection rate at farm level accurately.

CONCLUSIONS

Optimization and standardization of techniques are needed to improve the FEC of fluke eggs.

Antigens from the Helminth Fasciola hepatica Exert Antiviral Effects against SARS-CoV-2 In Vitro

SARS-CoV-2, the causal agent of COVID-19, is a new coronavirus that has rapidly spread worldwide and significantly impacted human health by causing a severe acute respiratory syndrome boosted by a pulmonary hyperinflammatory response. Previous data from our lab showed that the newly excysted juveniles of the helminth parasite Fasciola hepatica (FhNEJ) modulate molecular routes within host cells related to vesicle-mediated transport and components of the innate immune response, which could potentially be relevant during viral infections. Therefore, the aim of the present study was to determine whether FhNEJ-derived molecules influence SARS-CoV-2 infection efficiency in Vero cells. Pre-treatment of Vero cells with a tegument-enriched antigenic extract of FhNEJ (FhNEJ-TEG) significantly reduced infection by both vesicular stomatitis virus particles pseudotyped with the SARS-CoV-2 Spike protein (VSV-S2) and live SARS-CoV-2. Pre-treatment of the virus itself with FhNEJ-TEG prior to infection also resulted in reduced infection efficiency similar to that obtained by remdesivir pre-treatment. Remarkably, treatment of Vero cells with FhNEJ-TEG after VSV-S2 entry also resulted in reduced infection efficiency, suggesting that FhNEJ-TEG may also affect post-entry steps of the VSV replication cycle. Altogether, our results could potentially encourage the production of FhNEJ-derived molecules in a safe, synthetic format for their application as therapeutic agents against SARS-CoV-2 and other related respiratory viruses.

Molecular Characterization of the Interplay between Fasciola hepatica Juveniles and Laminin as a Mechanism to Adhere to and Break through the Host Intestinal Wall

Fasciola hepatica is the main causative agent of fasciolosis, a zoonotic parasitic disease of growing public health concern. F. hepatica metacercariae are ingested by the host and excyst in the intestine, thereby releasing the newly excysted juveniles (FhNEJ), which traverse the gut wall and migrate towards the biliary ducts. Since blocking F. hepatica development is challenging after crossing of the intestinal wall, targeting this first step of migration might result in increased therapeutic success. The intestinal extracellular matrix (ECM) is constituted by a network of structural proteins, including laminin (LM) and fibronectin (FN), that provide mechanical support while acting as physical barrier against intestinal pathogens. Here, we employed ELISA and immunofluorescent assays to test for the presence of LM- and FN-binding proteins on a tegument-enriched antigenic fraction of FhNEJ, and further determined their identity by two-dimensional electrophoresis coupled to mass spectrometry. Additionally, we performed enzymatic assays that revealed for the first time the capability of the juvenile-specific cathepsin L3 to degrade LM, and that LM degradation by FhNEJ proteins is further potentiated in the presence of host plasminogen. Finally, a proteomic analysis showed that the interaction with LM triggers protein changes in FhNEJ that may be relevant for parasite growth and adaptation inside the mammalian host. Altogether, our study provides valuable insights into the molecular interplay between FhNEJ and the intestinal ECM, which may lead to the identification of targetable candidates for the development of more effective control strategies against fasciolosis.

Artemisia vulgaris anthelmintic activities to ova and adult stages of Fasciola gigantica in vitro

Background and Aim

Fasciolosis due to Fasciola gigantica is endemic to tropical countries and Fasciola hepatica in temperate climates, highly detrimental to livestock and known as foodborne zoonotic diseases. The strategic control of the disease is mainly the use of chemical anthelmintic. This study aimed to evaluate the anthelmintic properties of Artemisia vulgaris extract on the ova and adult stages of F. gigantica.

Materials and Methods

Samples were collected from the Ampel Abbatoir, Boyolali District, Central Java, Indonesia. The ova from 20-gallbladders of cattle which were naturally infected with F. gigantica and 270 living F. gigantica worms were used in this study. The ovicidal assay was performed by incubating the ova with A. vulgaris in different concentrations, that is, 5%, 2.5%, and 1.25% for 5, 9, 11, 14, and 16 days. The efficacies were evaluated by quantification of ova degeneration during developmental stages in different time points and egg-hatch assay. The flukicidal effects were observed by mortality assay in 5, 10, 20, 40, 80, 160, 320, and 640 min incubations followed by scanning electron microscopy for surface morphology and histology of the fluke's transversal sections.

Results

The concentration of 5% A. vulgaris showed the strongest ovicidal activities. The percentage of hatching ova on day 16 at concentrations of 5%, 2.5%, and 1.25% were 3.33%, 6.67%, and 16.67%. These ova hatch assay showed a significant reduction (p < 0.001) compared to untreated control. The flukicidal effect was significant (p < 0.001) at a concentration of 20%, with a mortality rate reaching 66.67% in the 40 min of incubation time. The surface properties of the adult worms, including the spine, tegument, acetabulum, intestine, and vitelline follicles, were disintegrated.

Conclusion

The results showed that A. vulgaris has the potential ovicidal and flukicidal properties to F. gigantica. The active compounds remained necessary to be elucidated further and its modes of action would be interesting to be predicted by molecular docking modeling.

Fasciola hepatica juveniles interact with the host fibrinolytic system as a potential early-stage invasion mechanism

BACKGROUND

The trematode Fasciola hepatica is the most widespread causative agent of fasciolosis, a parasitic disease that mainly affects humans and ruminants worldwide. During F. hepatica infection, newly excysted juveniles (FhNEJ) emerge in the duodenum of the mammalian host and migrate towards their definitive location, the intra-hepatic biliary ducts. Understanding how F. hepatica traverses the intestinal wall and migrates towards the liver is pivotal for the development of more successful strategies against fasciolosis. The central enzyme of the mammalian fibrinolytic system is plasmin, a serine protease whose functions are exploited by a number of parasite species owing to its broad spectrum of substrates, including components of tissue extracellular matrices. The aim of the present work is to understand whether FhNEJ co-opt the functions of their host fibrinolytic system as a mechanism to facilitate trans-intestinal migration.

METHODOLOGY/PRINCIPAL FINDINGS

A tegument-enriched antigenic extract of FhNEJ (FhNEJ-Teg) was obtained in vitro, and its capability to bind the zymogen plasminogen (PLG) and enhance its conversion to the active protease, plasmin, were analyzed by a combination of enzyme-linked immunosorbent, chromogenic and immunofluorescence assays. Additionally, PLG-binding proteins in FhNEJ-Teg were identified by bidimensional electrophoresis coupled to mass spectrometry analysis, and the interactions were validated using FhNEJ recombinant proteins.

CONCLUSIONS/SIGNIFICANCE

Our results show that FhNEJ-Teg contains proteins that bind PLG and stimulate its activation to plasmin, which could facilitate the traversal of the intestinal wall by FhNEJ and contribute to the successful establishment of the parasite within its mammalian host. Altogether, our findings contribute to a better understanding of host-parasite relationships during early fasciolosis and may be exploited from a pharmacological and/or immunological perspective for the development of treatment and control strategies against this global disease.

Fasciola gigantica Cathepsin L1H: High Sensitivity and Specificity of Immunochromatographic Strip Test for Antibody Detection

Fasciolosis is a zoonotic disease caused by Fasciola gigantica or F. hepatica infections, which are frequently occurring parasites in animals and humans. The present gold-standard diagnostic technique involves finding parasite eggs through microscopy. However, this method is also restricted due to low specificity and low sensitivity. An alternative to coprological diagnosis is the immunochromatographic strip (ICS) test, which is rapid, simple, convenient, and cost-effective, with high sensitivity and high specificity. Cathepsin L1H (CathL1H) is a cysteine protease secreted by F. gigantica, which is found in high amounts in newly excysted juvenile (NEJ) and juvenile stages. Cathepsin L1H plays an important role in both the immune response to invading pathogens and in the ability of some pathogens to evade the host immune system. The present study aims to develop an ICS test and detect antibodies against CathL1H in mice and cattle serum using the recombinant F. gigantica Cathepsin L1H (rFgCathL1H) and rabbit anti-rFgCathL1H antibody. The F. gigantica-infected serum and non-infected serum of mice and cattle were tested using the ICS test. Moreover, the strip results were confirmed with an indirect enzyme-linked immunosorbent assay (indirect ELISA). The relative sensitivity, specificity, and accuracy of the ICS strip were 97.5, 99.99, and 99.00%, respectively. Therefore, these data suggest that the ICS method could be used to detect F. gigantica antibodies to highly enhance throughput, reduce costs, and determine the best alternative on-site method.

Assessment of genetic markers for multilocus sequence typing (MLST) of Fasciola isolates from Iran

BACKGROUND

Several markers have been described to characterise the population structure and genetic diversity of Fasciola species (Fasciola hepatica (F. hepatica) and Fasciola gigantica (F. gigantica). However, sequence analysis of a single genomic locus cannot provide sufficient resolution for the genetic diversity of the Fasciola parasite whose genomes are ∼1.3 GB in size.

OBJECTIVES

To gain a better understanding of the gene diversity of Fasciola isolates from western Iran and to identify the most informative markers as candidates for epidemiological studies, five housekeeping genes were evaluated using a multilocus sequence typing (MLST) approach.

METHODS

MLST analysis was developed based on five genes (ND1, Pepck, Pold, Cyt b and HSP70) after genomic DNA extraction, amplification and sequencing. Nucleotide diversity and phylogeny analysis were conducted on both concatenated MLST loci and each individual locus. A median joining haplotype network was created to examine the haplotypes relationship among Fasciola isolates.

RESULTS

Thirty-three Fasciola isolates (19 F. hepatica and 14 F. gigantica) were included in the study. A total of 2971 bp was analysed for each isolate and 31 sequence types (STs) were identified among the 33 isolates (19 for F. hepatica and 14 for F. gigantica isolates). The STs produced 44 and 42 polymorphic sites and 17 and 14 haplotypes for F. hepatica and F. gigantica, respectively. Haplotype diversity was 0.982 ± 0.026 and 1.000 ± 0.027 and nucleotide diversity was 0.00200 and 0.00353 ± 0.00088 for F. hepatica and F. gigantica, respectively. There was a high degree of genetic diversity with a Simpson's index of diversity of 0.98 and 1 for F. hepatica and F. gigantica, respectively. While HSP70 and Pold haplotypes from Fasciola species were separated by one to three mutational steps, the haplotype networks of ND1 and Cyt b were more complex and numerous mutational steps were found, likely due to recombination.

CONCLUSIONS

Although HSP70 and Pold genes from F. gigantica were invariant over the entire region of sequence coverage, MLST was useful for investigating the phylogenetic relationship of Fasciola species. The present study also provided insight into markers more suitable for phylogenetic studies and the genetic structure of Fasciola parasites.

In Vitro Anthelmintic Effect of Ferula assa-foetida Hydroalcoholic Extract Against Flukes of Fasciola hepatica and Dicrocoelium dendriticum

Background: Dicrocoeliasis and fascioliasis are foodborne parasitic diseases of the biliary tract, resulting from Dicrocoelium dendriticum and Fasciola hepatica causing extensive financial losses and serious health problems in ruminants. Due to low-performance medications, drug delivery is a tremendous project to improve interventions available for these diseases. Objectives: This study aimed to determine the anthelmintic properties of Ferula assa-foetida extract against F. hepatica and D. dendriticum using in vitro assay. Methods: The effects of diverse concentrations of F. assa-foetida extract (400 - 1000 µg/mL) for 12-24 hours were examined for the treatment of D. dendriticum and F. hepatica. The anthelmintic efficacies were evaluated using scanning electron microscopy (SEM). The MTT assay was carried out to evaluate the cell viability of all cells in culture media. Results: The SEM images of treated worms by F. assa-foetida extract (200 µg/mL) confirmed excessive damage, which included an entire lack of sensory papillae and destruction of distinguished network structures and tegument vesicles. Variables of duration and concentration presented a considerable effect on both the mortality rate and the anthelmintic properties of F. assa-foetida; accordingly, as the time and concentration increased, the mortality rate became higher. Based on the MTT assay, the toxicity of F. assa-foetida at 800 µg/mL concentration was 8.7%. Therefore, it can be argued that F. assa-foetida had anthelmintic properties. Conclusions: This is the first study that evaluated the impact of F. assa-foetida on liver flukes of D. dendriticum and F. hepatica. Therefore, it paved the way for further studies on the control of those trematodes. It is recommended to document and look into the indigenous understanding of viable medicinal plants to provide evidence for their use.

The global prevalence of human fascioliasis: a systematic review and meta-analysis

Background

Fascioliasis is a parasitic zoonosis that can infect humans and be a source of significant morbidity. The World Health Organization lists human fascioliasis as a neglected tropical disease, but the worldwide prevalence of fascioliasis data is unknown.

Objective

We aimed to estimate the global prevalence of human fascioliasis.

Data sources and methods

We performed a systematic review and prevalence meta-analysis. We used the following inclusion criteria: articles published in the English, Portuguese, or Spanish languages from December 1985 to October 2022 and studies assessing the prevalence of Fasciola in the general population with an appropriate diagnostic methodology, including longitudinal studies, prospective and retrospective cohorts, case series, and randomized clinical trials (RCTs). We excluded animal studies. Two reviewers independently reviewed the selected studies for methodological quality, performing critical standard measures from JBI SUMARI. A random-effects model was conducted of the summary extracted data on the prevalence proportions. We reported the estimates according to the GATHER statement.

Results

In all, 5617 studies were screened for eligibility. Fifty-five studies from 15 countries were selected, including 154,697 patients and 3987 cases. The meta-analysis revealed a pooled prevalence of 4.5% [95% confidence interval (CI): 3.1-6.1; I² = 99.4%; T² = 0.07]. The prevalence in South America, Africa, and Asia was 9.0%, 4.8%, and 2.0%, respectively. The highest prevalence was found in Bolivia (21%), Peru (11%), and Egypt (6%). Subgroup analysis showed higher prevalence estimates in children, in studies from South America, and when Fas2-enzyme-linked immunosorbent assay (ELISA) was used as a diagnostic method. A larger study sample size (p = 0.027) and an increase in female percentage (p = 0.043) correlated with a decrease in prevalence. Multiple meta-regression showed a higher prevalence for hyperendemic than hypoendemic (p = 0.002) or mesoendemic (p = 0.013) regions.

Conclusion

The estimated prevalence and projected disease burden of human fascioliasis are high. Study findings support that fascioliasis continues to be a globally neglected tropical disease. Strengthening epidemiological surveillance and implementing measures to control and treat fascioliasis is imperative in the most affected areas.

Fasciola hepatica primoinfections and reinfections in sheep drive distinct Th1/Th2/Treg immune responses in liver and hepatic lymph node at early and late stages

The expression of proinflammatory (IL-1β, IFN-γ, TNF-α) and regulatory (IL-10, TGF-β, IL-4) cytokines, as well as the transcription factor FoxP3, was quantified in the liver and hepatic lymph node (HLN) of sheep primoinfected and reinfected with Fasciola hepatica at early (4, 8 and 16 days post-infection [dpi]) and late (100 dpi) stages. The liver exerted a Th2 immune response at very early stages after the primoinfection with F. hepatica that induced the downregulation of IFN-γ, followed by a Th1/Th2/Treg response although the late stages were characterised by the expression of Th1/Th2 immune mediators. Contrarily, in reinfected sheep a robust mixed Th1/Th2/Treg immune response was found at very early stages meanwhile at late stages we observed a Th2/Treg immune response overcoming the expression of Th1 immune mediators. However, the HLN displayed a completely different Th1/Th2/Treg expression profile compared to the liver. Primoinfections with F. hepatica in HLN induced a mixed Th1/Th2/Treg environment from early stages, establishing a Th2 immune response at a late stage. However, the reinfected sheep exerted a Th2 immune response at early stages led by the IL-4 expression in opposition to the Th1/Th2/Treg found in the liver, meanwhile at late stages the HLN of reinfected sheep exerted a mixed Th1/Th2/Treg immune response. This is the first work publishing the expression of immune mediators in the liver and HLN from reinfected sheep with F. hepatica. The study of the immune responses exerted by the natural host in the target organs directly implied in the development of F. hepatica are crucial to better understand the immunopathogenesis of the fasciolosis being a key factor to develop effective vaccines.

Changes in the Populations of Two Lymnaeidae and Their Infection by Fasciola hepatica and/or Calicophoron daubneyi over the Past 30 Years in Central France

Field investigations were carried out during three periods (from 1976 to 1997, in 2013-2014, and in 2020-2021) on 39 cattle-raising farms on acidic soils to track changes in the populations of two Lymnaeidae (Galba truncatula and Omphiscola glabra) and their infection with Fasciola hepatica and/or Calicophoron daubneyi. Compared to the survey between 1976 and 1997 on these farms, there was a significant decrease in the number of the two lymnaeid populations and the size of the G. truncatula populations in both 2013-2014 and 2020-2021. This decline was significantly faster in the last nine years than it was before 2013. The area of habitats colonized by G. truncatula showed no significant variation over the years, while that of habitats with O. glabra significantly decreased in the period covered by the three surveys. The prevalence of F. hepatica infection in snails significantly decreased over the years, while C. daubneyi infection increased over time in both lymnaeid species. These changes are due to the use of triclabendazole to treat fasciolosis in ruminants since the 1990s, and are probably a consequence of the successive heatwaves that have occurred since 2018 in the region.

Multiplex PCR and Sequence Analysis to Investigate Genetic Diversity of Fasciola Isolates from Cattle and Sheep in Turkey

Fasciolosis is a highly prevalent helminthic infection caused by Fasciola hepatica and F. gigantica. With the aim of identifying hybrid Fasciola flukes, multiplex PCR was performed to amplify the pepck gene. Furthermore, to determine Fasciola haplotypes, mitochondrial nad1 gene was amplified and sequenced, and phylogenetic analyses were performed. Adult Fasciola isolates were collected from 51 cattle and 51 sheep, genomic DNA was isolated, and one-step multiplex PCR was subsequently performed to amplify pepck. Isolates that generated a 510 bp band were identified as F. gigantica, those that generated a 241 bp band were identified as F. hepatica, and those that generated both bands were identified as hybrid (aspermic) flukes. Multiplex PCR data identified four isolates as F. gigantica and 84 as F. hepatica. Fourteen hybrid isolates (five cattle and nine sheep) were identified. On unidirectional DNA sequence analysis of nad1 PCR products, three sequences were identified as F. gigantica and 99 as F. hepatica. In addition, only 4 of 87 haplotypes detected for F. hepatica nad1 sequences were found to be previously reported, while the remaining 83 are unique to this study. To summarize, this study is the first to report the existence of hybrid Fasciola flukes and 83 unique haplotypes of F. hepatica in Turkey.

Macrophage Gal/GalNAc lectin 2 (MGL2)+ peritoneal antigen presenting cells during Fasciola hepatica infection are essential for regulatory T cell induction

Fasciola hepatica, one of the agents that causes fasciolosis, modulates the host immune system to allow parasite survival in the host. F. hepatica expresses carbohydrate-containing glycoconjugates that are decoded by C-type lectin receptors, such as Dectin-1, mannose receptor, DC-SIGN and MGL, that are mainly present on myeloid antigen presenting cells (APCs) and can mediate immunoregulatory properties on T cells. In particular, Macrophage Gal/GalNAc lectin 2 (MGL2) expands modified Th2 immune responses, while suppressing Th1 polarization, upon recognition of GalNAc-glycosylated parasite components. In this study, by using MGL2-DTR transgenic mice that encode human diphtheria toxin receptor in MGL2⁺ cells, we demonstrate the role of peritoneal APCs during F. hepatica infection in favoring parasite survival. This process might be mediated by the induction of splenic Tregs in vivo, since the depletion of MGL2⁺ cells conferred mice with partial resistance to the infection and abrogated the increase of CD4⁺/CD25⁺ FoxP3⁺ Tregs induced by the parasite. Therefore, MGL2⁺ cells are critical determinants of F. hepatica infection and could constitute immune checkpoints to control parasite infection.

Study of the migration of Fasciola hepatica juveniles across the intestinal barrier of the host by quantitative proteomics in an ex vivo model

Fasciola hepatica is a trematode parasite that infects animals and humans causing fasciolosis, a worldwide-distributed disease responsible for important economic losses and health problems. This disease is of growing public health concern since parasite isolates resistant to the current treatment (triclabendazole) have increasingly been described. F. hepatica infects its vertebrate host after ingestion of the encysted parasite (metacercariae), which are found in the water or attached to plants. Upon ingestion, newly excysted juveniles of F. hepatica (FhNEJ) emerge in the intestinal lumen and cross the intestinal barrier, reach the peritoneum and migrate to the biliary ducts, where adult worms fully develop. Despite the efforts made to develop new therapeutic and preventive tools, to date, protection against F. hepatica obtained in different animal models is far from optimal. Early events of host-FhNEJ interactions are of paramount importance for the infection progress in fasciolosis, especially those occurring at the host-parasite interface. Nevertheless, studies of FhNEJ responses to the changing host environment encountered during migration across host tissues are still scarce. Here, we set-up an ex vivo model coupled with quantitative SWATH-MS proteomics to study early host-parasite interaction events in fasciolosis. After comparing tegument and somatic fractions from control parasites and FhNEJ that managed to cross a mouse intestinal section ex vivo, a set of parasite proteins whose expression was statistically different were found. These included upregulation of cathepsins L3 and L4, proteolytic inhibitor Fh serpin 2, and a number of molecules linked with nutrient uptake and metabolism, including histone H4, H2A and H2B, low density lipoprotein receptor, tetraspanin, fatty acid binding protein a and glutathione-S-transferase. Downregulated proteins in FhNEJ after gut passage were more numerous than the upregulated ones, and included the heath shock proteins HSP90 and alpha crystallin, amongst others. This study brings new insights into early host-parasite interactions in fasciolosis and sheds light on the proteomic changes in FhNEJ triggered upon excystment and intestinal wall crossing, which could serve to define new targets for the prevention and treatment of this widespread parasitic disease.

Fasciolosis caused by the helminth parasite Fasciola hepatica is a serious health and economic problem worldwide. Treatment and prevention of this disease pose several drawbacks that have so far not been solved. The definition of suitable parasite molecular targets to overcome such drawbacks should be based on thoroughly deciphering host-parasite interactions, and in this regard most studies have focused on the adult stages of F. hepatica. Nevertheless, in this context, the study of the transient juvenile stages of this parasite could be of higher utility due to the importance of early interactions with the host for parasite migration and the successful establishment of infection. In this work, we set-up an ex vivo model and performed a quantitative proteomics approach to study the changes in F. hepatica juveniles upon gut passage. We found that the parasite tegument and somatic compartments experienced deep changes in their composition and showed that the host triggers the expression of specific molecules that are important for parasite migration and survival at this stage. The molecules described here could serve to better understand host-parasite interactions and to define new targets against fasciolosis.

Prevalence, risk factors, and infection intensity of fasciolosis in dairy cattle in Boyolali, Indonesia

Background and Aim: Fasciolosis is a significant problem in veterinary and public health, causing huge economic losses. Epidemiological studies of fasciolosis in dairy cattle in Indonesia are few and existing reports primarily focus on prevalence. This study aimed to determine the prevalence, risk factors, and infection intensity of fasciolosis in dairy cattle in Boyolali, Indonesia. Materials and Methods: This cross-sectional study included 400 dairy cattle from 72 household farms in eight subdistricts. Fecal samples (n=400) were examined using the Flukefinder® kit and the simple sedimentation technique was the gold standard for fasciolosis. In-person interviews using questionnaires collected data on farmers, farms, and animal characteristics. Chi-square and logistic regression analyses were performed to evaluate the associated risk factors for fasciolosis, and p < 0.05 was considered statistically significant. Results: The overall prevalence of fasciolosis in dairy cattle in Boyolali, Indonesia, was 16.50% (95% confidence interval [CI] 12.85-20.15) at the animal level (n = 400), whereas 40.28% at household farms (n = 72) level (95% CI 18.67-51.88). The relative sensitivity and specificity of the Flukefinder® kit compared with those of the gold standard were 79.49% and 92.52%, respectively, with a moderate agreement (kappa=0.59; p < 0.001). Fasciolosis was more likely in cattle originating from the Mojosongo subdistrict than from other subdistricts (odds ratio (OR)=5.28, 95% CI 1.22-22.94); from farms that did not process manure versus from those that did (OR = 3.03, 95% CI 1.43-4.71); and with farmers that had never attended extension programs compared with those who had (OR = 4.72, 95% CI 1.99-11.19). Studied cattle were mostly affected by light Fasciola spp. infections (92.4%, 95% CI 77.8-100%) followed by moderate (6.1%, 95% CI 0-22.2%) and heavy (1.5%, 95% CI 0-5.6%) infections. Conclusion: Fasciolosis is prevalent in dairy cattle in Boyolali, Indonesia. Control efforts should target the high-risk Mojosongo subdistrict, emphasize the importance of processing manure, and encourage farmers to attend extension programs. Flukefinder® is a practical on-site diagnostic kit for fasciolosis in Indonesian dairy farms. Parasite species identification and a malacological survey of intermediate hosts of Fasciola spp. in the farming environment are required for further research.

Fasciolosis—An Increasing Challenge in the Sheep Industry

Simple Summary

Fasciolosis caused by Fasciola hepatica is a serious disease and a huge challenge in the sheep industry. The disease has several clinical manifestations including acute death, anemia, ill-thrift and loss of body condition. Climate change with milder temperatures and heavier rainfall will increase the risk of fasciolosis. Grazing management and treatment with flukicide are at present the only options to restrain F. hepatica infection. However, control possibilities are challenging, and resistance to flukicide drugs is increasing. Diagnostic improvements, targeted treatment and vaccines will hopefully increase animal health and welfare on fluke infested pastures in the future.

Abstract

The liver fluke Fasciola hepatica may cause severe infection in several mammalian species, including sheep and humans. Fasciolosis is a parasitic disease occurring worldwide in temperate climates and involves intermediate lymnaeid snails as vectors, in Europe the pond snail Galba truncatula in particular. In the sheep industry, the disease is a serious welfare and health problem. Fasciolosis is usually classified as acute, subacute or chronic according to the number and stage of flukes present in the liver, but with a considerable overlap. Acute disease, associated with a large number of migrating larvae, often results in sudden death due to acute and massive hemorrhage, while chronic fasciolosis is characterized by anemia, hypoalbuminaemia and weight loss. The management of fasciolosis is an increasing challenge in the sheep industry. Early diagnostic tests are limited. Protective immunity against liver flukes in sheep is low or lacking, and vaccines are not yet available. Treatment and control possibilities are challenging, and resistance to flukicide drugs is increasing. In addition, climate change with warmer and more humid weather will have a substantial effect on the establishment of both flukes and snails and will most likely increase the future distribution of F. hepatica.

Epidemiology of Fasciola spp. in the intermediate host in China: A potential risk for fasciolosis transmission

Fasciolosis is a zoonotic disease as 600 million animals have been infected, and 180 million people are at risk of the infection in the world. Snail as the intermediate host of Fasciola is an essential and important factor in the transmission of fasciolosis, while its potential risk for transmission has not been studied. In this study, 3561 snails collected from large-scale regions of China were examined by nest-PCR method. A total of 345 snails were positive for Fasciola spp., with an overall prevalence of 9.7%. Prevalence in central and southern China, characterized by a subtropical monsoon climate, was relatively low (8.0%), while a high infection rate (36.9%) was found on the plateau area (altitude > 500 m). In combination with previous findings, the study showed a highly positive correlation between snails and animal infection in central and eastern China, thus indicating that infected snails could be an indispensable risk factor for fasciolosis transmission. Epidemiological surveillance of snails will help assess the risk of fasciolosis in humans or ruminants, which promotes future prevention of this zoonotic disease.

Liver function markers and haematological dynamics during acute and chronic phases of experimental Fasciola hepatica infection in cattle treated with triclabendazole

Fasciola hepatica, a worldwide-distributed liver fluke, is one of the causative agents of fasciolosis, a zoonotic disease that affects livestock and humans. In livestock, fasciolosis causes huge economic losses worldwide, reducing animal fertility, milk production, weight gain and condemnation of livers. In spite of the availability of drugs, such as triclabendazole (TCZ), for the treatment of fasciolosis, they do not necessarily prevent liver damage or parasite reinfection and can eventually increase parasite resistance. The aim of this research was to relate the hepatic function, haematological parameters, leukocyte counts in circulation and parasite egg shedding during F. hepatica acute and chronic phases of infection in cattle as well as to determine how these parameters change with TCZ-treatment of chronically infected cattle. Our results show that increased levels of serum aspartate aminotransferase (AST) and gamma glutamyltransferase (GGT) were detected in early stages of the experimental infection. Moreover, high circulating eosinophil count and plateletcrit levels were correlated with fluke number in livers from infected cattle. On the other hand, although TCZ-treatment in the chronic phase of infection reduced parasite burden and damage in the liver, it was not able to completely avoid them. In conclusion, our work sheds light into the physiopathological mechanisms induced during fluke infection in cattle, revealing the complexity of the host response to the infection, together with the effects of TCZ-treatment in chronically infected animals.

General overview of the current status of human foodborne trematodiasis

Foodborne trematodes (FBT) of public health significance include liver flukes (Clonorchis sinensis, Opisthorchis viverrini, O. felineus, Fasciola hepatica and F. gigantica), lung flukes (Paragonimus westermani and several other Paragonimus spp.) and intestinal flukes, which include heterophyids (Metagonimus yokogawai, Heterophyes nocens and Haplorchis taichui), echinostomes (Echinostoma revolutum, Isthmiophora hortensis, Echinochasmus japonicus and Artyfechinostomum malayanum) and miscellaneous species, including Fasciolopsis buski and Gymnophalloides seoi. These trematode infections are distributed worldwide but occur most commonly in Asia. The global burden of FBT diseases has been estimated at about 80 million, however, this seems to be a considerable underestimate. Their life cycle involves a molluscan first intermediate host, and a second intermediate host, including freshwater fish, crustaceans, aquatic vegetables and freshwater or brackish water gastropods and bivalves. The mode of human infection is the consumption of the second intermediate host under raw or improperly cooked conditions. The major pathogenesis of C. sinensis and Opisthorchis spp. infection includes inflammation of the bile duct which leads to cholangitis and cholecystitis, and in a substantial number of patients, serious complications, such as liver cirrhosis and cholangiocarcinoma, may develop. In lung fluke infections, cough, bloody sputum and bronchiectasis are the most common clinical manifestations. However, lung flukes often migrate to extrapulmonary sites, including the brain, spinal cord, skin, subcutaneous tissues and abdominal organs. Intestinal flukes can induce inflammation in the intestinal mucosa, and they may at times undergo extraintestinal migration, in particular, in immunocompromised patients. In order to control FBT infections, eating foods after proper cooking is strongly recommended.

Transcriptomic landscape of hepatic lymph nodes, peripheral blood lymphocytes and spleen of swamp buffaloes infected with the tropical liver fluke Fasciola gigantica

The tropical liver fluke Fasciola gigantica is a parasitic helminth that has been frequently reported to infect mammals, typically involving water buffaloes. In this study, we characterized the tissue transcriptional landscape of buffaloes following infection by F. gigantica. RNAs were isolated from hepatic lymph nodes (hLNs), peripheral blood lymphocytes (pBLs), and spleen at 3-, 42- and 70-days post-infection (dpi), and all samples were subjected to RNA sequencing analyses. At 3 dpi, 2603, 460, and 162 differentially expressed transcripts (DETs) were detected in hLNs, pBLs, and spleen, respectively. At 42 dpi, 322, 937, and 196 DETs were detected in hLNs, pBLs, and spleen, respectively. At 70 dpi, 376, 334, and 165 DETs were detected in hLNs, pBLs, and spleen, respectively. Functional enrichment analysis identified upregulated immune-related pathways in the infected tissues involved in innate and adaptive immune responses, especially in hLNs at 42 and 70 dpi, and pBLs at 3 and 42 dpi. The upregulated transcripts in spleen were not enriched in any immune-related pathway. Co-expression network analysis further identified transcriptional changes associated with immune response to F. gigantica infection. Receiver operating characteristic (ROC) curve analysis showed that 107 genes in hLNs, 32 genes in pBLs, and 36 genes in spleen correlated with F. gigantica load. These findings provide new insight into molecular mechanisms and signaling pathways associated with F. gigantica infection in buffaloes.

Fasciola gigantica is a socioeconomically important tropical liver fluke of mammals, causing fascioliasis–a neglected tropical disease. In the present study, RNA sequencing and bioinformatic approach were employed to explore the global transcriptional changes of hepatic lymph nodes (hLNs), peripheral blood lymphocytes (pBLs), and spleen of water buffaloes during F. gigantica infection at 3-, 42-, and 70-days post-infection (dpi). The results revealed significant transcriptional upregulation of genes associated with innate and adaptive immune responses in infected hLNs (42 and 70 dpi) and pBLs (3 and 42 dpi). However, downregulation of transcripts involved in immune response was detected in pBLs at 70 dpi. The downregulated transcripts were enriched in metabolic pathways, such as drug metabolism-cytochrome P450 in infected hLNs at 3 dpi. These findings provide new insight into the pathogenesis of F. gigantica in its natural mammalian host.

RNA-seq analysis of murine peyer's patches at 6 and 18 h post infection with Fasciola hepatica metacecariae

Fasciola hepatica is a zoonotic parasite that not only economically burdens the agribusiness sector, but also infects up to 1 million people worldwide, with no commercial vaccine yet available. An ideal vaccine would induce protection in the gut, curtailing the extensive tissue damage associated with parasite's migration from the gut to the bile ducts. The design of such a vaccine requires greater knowledge of gut mucosal responses during the early stage of infection. We examined total mRNA expression of the peyer's patches at 6 and 18 h post F. hepatica infection using RNA sequencing. Differential expression analysis revealed 1341 genes upregulated and 61 genes downregulated at 6 h post infection, while 1562 genes were upregulated and 10 genes downregulated after 18 h. Gene-set enrichment analysis demonstrated that immune specific biological processes were amongst the most downregulated. The Toll-like receptor pathway in particular was significantly affected, the suppression of which is a well-documented immune evasive strategy employed by F. hepatica. In general, the genes identified were associated with suppression of inflammatory responses, helminth induced immune responses and tissue repair/homeostasis. This study provides a rich catalogue of the genes expressed in the early stages of F. hepatica infection, adding to the understanding of early host-parasite interactions and assisting in the design of future studies that look to advance the development of a novel F. hepatica vaccine.

A global phosphoproteomics analysis of adult Fasciola gigantica by LC-MS/MS

Protein phosphorylation plays key roles in a variety of essential cellular processes. Fasciola gigantica is a tropical liver fluke causing hepatobiliary disease fascioliasis, leading to human health threats and heavy economic losses. Although the genome and protein kinases of F. gigantica provided new insights to understand the molecular biology and etiology of this parasite, there is scant knowledge of protein phosphorylation events in F. gigantica. In this study, we characterized the global phosphoproteomics of adult F. gigantica by phosphopeptide enrichment-based LC–MS/MS, a high-throughput analysis to maximize the detection of a large repertoire of phosphoproteins and phosphosites. A total of 1030 phosphopeptides with 1244 phosphosites representing 635 F. gigantica phosphoproteins were identified. The phosphoproteins were involved in a wide variety of biological processes including cellular, metabolic, and single-organism processes. Meanwhile, these proteins were found predominantly in cellular components like membranes and organelles with molecular functions of binding (51.3%) and catalytic activity (40.6%). The KEGG annotation inferred that the most enriched pathways of the phosphoproteins included tight junction, spliceosome, and RNA transport (each one contains 15 identified proteins). Combining the reports in other protozoa and helminths, the phosphoproteins identified in this work play roles in metabolic regulation and signal transduction. To our knowledge, this work performed the first global phosphoproteomics analysis of adult F. gigantica, which provides valuable information for development of intervention strategies for fascioliasis.

Recombinant Fasciola hepatica Fatty Acid Binding Protein as a Novel Anti-Inflammatory Biotherapeutic Drug in an Acute Gram-Negative Nonhuman Primate Sepsis Model

Due to their phylogenetic proximity to humans, nonhuman primates (NHPs) are considered an adequate choice for a basic and preclinical model of sepsis. Gram-negative bacteria are the primary causative of sepsis. During infection, bacteria continuously release the potent toxin lipopolysaccharide (LPS) into the bloodstream, which triggers an uncontrolled systemic inflammatory response leading to death. Our previous research has demonstrated in vitro and in vivo using a mouse model of septic shock that Fh15, a recombinant variant of the Fasciola hepatica fatty acid binding protein, acts as an antagonist of Toll-like receptor 4 (TLR4) suppressing the LPS-induced proinflammatory cytokine storm. The present communication is a proof-of concept study aimed to demonstrate that a low-dose of Fh15 suppresses the cytokine storm and other inflammatory markers during the early phase of sepsis induced in rhesus macaques by intravenous (i.v.) infusion with lethal doses of live Escherichia coli. Fh15 was administered as an isotonic infusion 30 min prior to the bacterial infusion. Among the novel findings reported in this communication, Fh15 (i) significantly prevented bacteremia, suppressed LPS levels in plasma, and the production of C-reactive protein and procalcitonin, which are key signatures of inflammation and bacterial infection, respectively; (ii) reduced the production of proinflammatory cytokines; and (iii) increased innate immune cell populations in blood, which suggests a role in promoting a prolonged steady state in rhesus macaques even in the presence of inflammatory stimuli. This report is the first to demonstrate that a F. hepatica-derived molecule possesses potential as an anti-inflammatory drug against sepsis in an NHP model.

IMPORTANCE Sepsis caused by Gram-negative bacteria affects 1.7 million adults annually in the United States and is one of the most important causes of death at intensive care units. Although the effective use of antibiotics has resulted in improved prognosis of sepsis, the pathological and deathly effects have been attributed to the persistent inflammatory cascade. There is a present need to develop anti-inflammatory agents that can suppress or neutralize the inflammatory responses and prevent the lethal consequences of sepsis. We demonstrated here that a small molecule of 14.5 kDa can suppress the bacteremia, endotoxemia, and many other inflammatory markers in an acute Gram-negative sepsis rhesus macaque model. These results reinforce the notion that Fh15 constitutes an excellent candidate for drug development against sepsis.

Case Report: Fascioliasis Hepatica Precisely Diagnosed by Metagenomic Next-Generation Sequencing and Treated With Albendazole

The clinical manifestations of fascioliasis hepatica in humans are unspecific. Traditional diagnosis relies on evidence of live parasites or eggs in the bile or feces. However, due to similar imaging manifestations, they are often misdiagnosed as malignant tumors. Here, we report a case of a 43-year-old woman with fever and space-occupying liver disease. Liver biopsy, parasite-specific antibody screening, and stool testing did not find any pathogens. Therefore, metagenomic next-generation sequencing (mNGS) and routine microbiological examinations were performed. Finally, Fasciola hepatica was only identified by mNGS. The body temperature of the patient and the eosinophil count remained normal, and the space-occupying liver lesions were significantly absorbed after more than 7 months of treatment with albendazole. The details of this case highlight the timely use of mNGS to identify parasites and judge therapeutic effects after treatment, providing important help for clinical decision-making.

Heme-Oxygenase-1 Attenuates Oxidative Functions of Antigen Presenting Cells and Promotes Regulatory T Cell Differentiation during Fasciola hepatica Infection

Fasciola hepatica is a fluke that infects livestock and humans causing fasciolosis, a zoonotic disease of increasing importance due to its worldwide distribution and high economic losses. The parasite regulates the host immune system by inducing a strong Th2 and regulatory T (Treg) cell immune response through mechanisms that might involve the expression or activity of heme-oxygenase-1 (HO-1), the rate-limiting enzyme in the catabolism of free heme that also has immunoregulatory and antioxidant properties. In this paper, we show that F. hepatica-infected mice upregulate HO-1 on peritoneal antigen-presenting cells (APC), which produce decreased levels of both reactive oxygen and nitrogen species (ROS/RNS). The presence of these cells was associated with increased levels of regulatory T cells (Tregs). Blocking the IL-10 receptor (IL-10R) during parasite infection demonstrated that the presence of splenic Tregs and peritoneal APC expressing HO-1 were both dependent on IL-10 activity. Furthermore, IL-10R neutralization as well as pharmacological treatment with the HO-1 inhibitor SnPP protected mice from parasite infection and allowed peritoneal APC to produce significantly higher ROS/RNS levels than those detected in cells from infected control mice. Finally, parasite infection carried out in gp91^phox knockout mice with inactive NADPH oxidase was associated with decreased levels of peritoneal HO-1⁺ cells and splenic Tregs, and partially protected mice from the hepatic damage induced by the parasite, revealing the complexity of the molecular mechanisms involving ROS production that participate in the complex pathology induced by this helminth. Altogether, these results contribute to the elucidation of the immunoregulatory and antioxidant role of HO-1 induced by F. hepatica in the host, providing alternative checkpoints that might control fasciolosis.

Distribution of bovine <em>Fasciola gigantica</em> (Cobbold, 1885) in the district des Savanes, northern Côte d'Ivoire

Fascioliasis, caused by an infection with liver flukes of the genus Fasciola, is an important disease of livestock in most parts of the world. However, little is known about the distribution of fascioliasis in sub-Saharan Africa. We report results of a cross-sectional study conducted in 2014 in the district des Savanes in the northern part of Côte d'Ivoire. We obtained 275 livers from bovine suspected with fascioliasis and 51 unsuspected livers from 24 slaughterhouses. Livers were dissected using a standard operating procedure and all Fasciola gigantica flukes were removed from the tissues of the liver and the biliary ducts. We found F. gigantica in 125 livers from bovines suspected with fascioliasis (45.5%) in 10 departments of the district des Savanes. Among the unsuspected livers, five were positive for F. gigantica (9.8%). The distribution of fascioliasis showed considerable spatial heterogeneity, both at regional (ranging from 18.0% to 52.3%) and departmental level (ranging from 14.3% to 64.0%). Poro region was the most affected (52.3%) with a relatively homogeneous distribution. The departments most affected by fascioliasis were M'Bengué (64.0%), Sinématiali (62.1%) and Ferkessédougou (52.9%). Our study confirms that fascioliasis is an important veterinary disease in the northern part of Côte d'Ivoire, and hence, high-risk areas need to be targeted for prevention and control measures.

Pathogenicity and virulence of the liver flukes Fasciola hepatica and Fasciola Gigantica that cause the zoonosis Fasciolosis

Fasciolosis caused by the liver flukes Fasciola hepatica and Fasciola gigantica is one of the most important neglected parasitic diseases of humans and animals. The ability of the parasites to infect and multiply in their intermediate snail hosts, and their adaptation to a wide variety of mammalian definitive hosts contribute to their high transmissibility and distribution. Within the mammalian host, the trauma caused by the immature flukes burrowing through the liver parenchyma is associated with most of the pathogenesis. Similarly, the feeding activity and the physical presence of large flukes in the bile ducts can lead to anemia, inflammation, obstruction and cholangitis. The high frequency of non-synonymous polymorphisms found in Fasciola spp. genes allows for adaptation and invasion of a broad range of hosts. This is also facilitated by parasite’s excretory-secretory (ES) molecules that mediate physiological changes that allows their establishment within the host. ES contains cathepsin peptidases that aid parasite invasion by degrading collagen and fibronectin. In the bile ducts, cathepsin-L is critical to hemoglobin digestion during feeding activities. Other molecules (peroxiredoxin, cathepsin-L and Kunitz-type inhibitor) stimulate a strong immune response polarized toward a Treg/Th2 phenotype that favors fluke’s survival. Helminth defense molecule, fatty acid binding proteins, Fasciola-specific glycans and miRNAs modulate host pro-inflammatory responses, while antioxidant scavenger enzymes work in an orchestrated way to deter host oxidant-mediated damage. Combining these strategies Fasciola spp. survive for decades within their mammalian host, where they reproduce and spread to become one of the most widespread zoonotic worm parasites in the world.

A Partially Protective Vaccine for Fasciola hepatica Induced Degeneration of Adult Flukes Associated to a Severe Granulomatous Reaction in Sheep

Simple Summary

Fasciolosis is a parasitic disease of livestock causing important economic losses worldwide and it is also a zoonosis. Current therapy relies on the use of anthelmintic drugs, which is no longer sustainable due to the increase of anthelmintic resistance and the risk of drug residues in food. A deep understanding of the host-parasite interaction is required to develop protective vaccines for the control of fasciolosis. The aim of the present study is to evaluate the hepatic lesions in sheep vaccinated with a partly protective vaccine for F. hepatica, a non-protective vaccine and an infected control group. The protective vaccine showed less severe hepatic lesions than the infected control group. In addition, in the protective vaccine group dead flukes surrounded by a severe granulomatous inflammation were observed, which taken together with the lower fluke burden, suggests that the host response induced by the partially protective vaccine may have been involved in the death of adult flukes of F. hepatica. This is the first study reporting the presence of degenerated flukes associated to a severe granulomatous inflammation in bile ducts in a vaccine trial, a finding that would be useful for improving vaccine efficacy in future trials.

Abstract

Fasciolosis is an important economic disease of livestock. There is a global interest in the development of protective vaccines since current anthelmintic therapy is no longer sustainable. A better knowledge of the host-parasite interaction is needed for the design of effective vaccines. The present study evaluates the microscopical hepatic lesions in sheep immunized with a partially protective vaccine (VAC1), a non-protective vaccine (VAC2), and an infected control group (IC). The nature of granulomatous inflammation associated with degeneration of adult flukes found in the VAC1 group was characterized by immunohistochemistry. Hepatic lesions (fibrous perihepatitis, chronic tracts, bile duct hyperplasia, infiltration of eosinophils and lymphocytes and plasma cells) were significantly less severe in the VAC1 group than in the IC group. Dead adult flukes within bile ducts were observed only in the VAC1 group and were surrounded by a severe granulomatous inflammation composed by macrophages and multinucleate giant cells with a high expression of lysozyme, CD163 and S100 markers, and a low expression of CD68. Numerous CD3+ T lymphocytes and scarce infiltrate of FoxP3+ Treg and CD208+ dendritic cells were present. This is the first report describing degenerated flukes associated to a severe granulomatous inflammation in bile ducts in a F. hepatica vaccine trial.

Recognition Pattern of the Fasciola hepatica Excretome/Secretome during the Course of an Experimental Infection in Sheep by 2D Immunoproteomics

Excretory/secretory products released by helminth parasites have been widely studied for their diagnostic utility, immunomodulatory properties, as well as for their use as vaccines. Due to their location at the host/parasite interface, the characterization of parasite secretions is important to unravel the molecular interactions governing the relationships between helminth parasites and their hosts. In this study, the excretory/secretory products from adult worms of the trematode Fasciola hepatica (FhES) were employed in a combination of two-dimensional electrophoresis, immunoblot and mass spectrometry, to analyze the immune response elicited in sheep during the course of an experimental infection. Ten different immunogenic proteins from FhES recognized by serum samples from infected sheep at 4, 8, and/or 12 weeks post-infection were identified. Among these, different isoforms of cathepsin L and B, peroxiredoxin, calmodulin, or glutathione S-transferase were recognized from the beginning to the end of the experimental infection, suggesting their potential role as immunomodulatory antigens. Furthermore, four FhES proteins (C2H2-type domain-containing protein, ferritin, superoxide dismutase, and globin-3) were identified for the first time as non-immunogenic proteins. These results may help to further understand host/parasite relationships in fasciolosis, and to identify potential diagnostic molecules and drug target candidates of F. hepatica.

Use of the PCR in a Combined Methodological Approach for the Study of Human Fascioliasis in an Endemic Area

PURPOSE

Fascioliasis is a worldwide distributed trematodiasis considered a neglected disease. Diagnosis in humans has been traditionally based on parasitological and immunological techniques. Recently we reported the use of the PCR in stool samples for the individual diagnosis. The purpose of this study was to evaluate human fascioliasis by a combination of diagnostic methods in an area where the disease is highly endemic in animals.

METHODS

We studied all the inhabitants (N = 240) of Tatón village, Argentina, by Fasciola hepatica rproCL1-ELISA. Among them, we continued the study with 13 cases that had at least two positive serological tests, who performed a questionnaire, physical examination, abdominal ultrasonography, and collection of blood and faeces. Blood/serum samples were used for Fh rproCL1-ELISA and liver function tests. Faeces were used for parasitological analysis and PCR of a repetitive fragment of Fasciola sp.

RESULTS

Among the 13 patients, 9 presented symptoms of biliary colic. All patients repeated positive serology. F. hepatica eggs were not detected. PCR was positive in 11 cases.

CONCLUSION

This is the first report employing an approach based on the combination of methods for the evaluation of human fascioliasis in an endemic area, which includes molecular tools with a high value in detecting low infections.

Albendazole and Mebendazole as Anti-Parasitic and Anti-Cancer Agents: an Update

The use of albendazole and mebendazole, i.e., benzimidazole broad-spectrum anthelmintics, in treatment of parasitic infections, as well as cancers, is briefly reviewed. These drugs are known to block the microtubule systems of parasites and mammalian cells leading to inhibition of glucose uptake and transport and finally cell death. Eventually they exhibit ovicidal, larvicidal, and vermicidal effects on parasites, and tumoricidal effects on hosts. Albendazole and mebendazole are most frequently prescribed for treatment of intestinal nematode infections (ascariasis, hookworm infections, trichuriasis, strongyloidiasis, and enterobiasis) and can also be used for intestinal tapeworm infections (taeniases and hymenolepiasis). However, these drugs also exhibit considerable therapeutic effects against tissue nematode/cestode infections (visceral, ocular, neural, and cutaneous larva migrans, anisakiasis, trichinosis, hepatic and intestinal capillariasis, angiostrongyliasis, gnathostomiasis, gongylonemiasis, thelaziasis, dracunculiasis, cerebral and subcutaneous cysticercosis, and echinococcosis). Albendazole is also used for treatment of filarial infections (lymphatic filariasis, onchocerciasis, loiasis, mansonellosis, and dirofilariasis) alone or in combination with other drugs, such as ivermectin or diethylcarbamazine. Albendazole was tried even for treatment of trematode (fascioliasis, clonorchiasis, opisthorchiasis, and intestinal fluke infections) and protozoan infections (giardiasis, vaginal trichomoniasis, cryptosporidiosis, and microsporidiosis). These drugs are generally safe with few side effects; however, when they are used for prolonged time (>14-28 days) or even only 1 time, liver toxicity and other side reactions may occur. In hookworms, Trichuris trichiura, possibly Ascaris lumbricoides, Wuchereria bancrofti, and Giardia sp., there are emerging issues of drug resistance. It is of particular note that albendazole and mebendazole have been repositioned as promising anti-cancer drugs. These drugs have been shown to be active in vitro and in vivo (animals) against liver, lung, ovary, prostate, colorectal, breast, head and neck cancers, and melanoma. Two clinical reports for albendazole and 2 case reports for mebendazole have revealed promising effects of these drugs in human patients having variable types of cancers. However, because of the toxicity of albendazole, for example, neutropenia due to myelosuppression, if high doses are used for a prolonged time, mebendazole is currently more popularly used than albendazole in anti-cancer clinical trials.

Autonomous Non Antioxidant Roles for Fasciola hepatica Secreted Thioredoxin-1 and Peroxiredoxin-1

Trematode parasites of the genus Fasciola are the cause of liver fluke disease (fasciolosis) in humans and their livestock. Infection of the host involves invasion through the intestinal wall followed by migration in the liver that results in extensive damage, before the parasite settles as a mature egg-laying adult in the bile ducts. Genomic and transcriptomic studies revealed that increased metabolic stress during the rapid growth and development of F. hepatica is balanced with the up-regulation of the thiol-independent antioxidant system. In this cascade system thioredoxin/glutathione reductase (TGR) reduces thioredoxin (Trx), which then reduces and activates peroxiredoxin (Prx), whose major function is to protect cells against the damaging hydrogen peroxide free radicals. F. hepatica expresses a single TGR, three Trx and three Prx genes; however, the transcriptional expression of Trx1 and Prx1 far out-weighs (>50-fold) other members of their family, and both are major components of the parasite secretome. While Prx1 possesses a leader signal peptide that directs its secretion through the classical pathway and explains why this enzyme is found freely soluble in the secretome, Trx1 lacks a leader peptide and is secreted via an alternative pathway that packages the majority of this enzyme into extracellular vesicles (EVs). Here we propose that F. hepatica Prx1 and Trx1 do not function as part of the parasite’s stress-inducible thiol-dependant cascade, but play autonomous roles in defence against the general anti-pathogen oxidative burst by innate immune cells, in the modulation of host immune responses and regulation of inflammation.

Observational study on the effectiveness and safety of multiple regimens of triclabendazole in human fascioliasis after failure to standard-of-care regimens

OBJECTIVES

Triclabendazole (TCBZ) is the recommended anthelmintic against Fasciola hepatica at a dose of 10 mg/kg body weight administered as a single or double dose. However, treatment failures to TCBZ standard-of-care (SOC) doses have been reported in humans. The aim of this study was to describe the effectiveness and tolerability of alternative TCBZ regimens in those patients who failed the SOC regimen for fascioliasis in Peru.

METHODS

A retrospective study was conducted at a major referral centre for fascioliasis in Peru between 2002 and 2018. Inclusion criteria were cases with chronic F. hepatica infection who failed the SOC regimen for human fascioliasis with TCBZ at 10 mg/kg orally as single dose with food.

RESULTS

A total of 27 cases (59% female; mean age 39.4 years, range 6-71 years) with chronic fascioliasis failed at least once the current SOC regimen of TCBZ. Of 27 cases, 21 failed a second treatment regimen. Multiple regimens of TCBZ were given to these patients until three consecutive stool examinations were negative for Fasciola eggs. The overall cure rate was 74%. TCBZ was well tolerated with minimal side effects.

CONCLUSION

According to the results of this study, patients labelled as having 'TCBZ resistance' may respond to multiple regimens of TCBZ with a cure rate of 74%. Thus, the term 'TCBZ resistance' should be re-evaluated using biomarkers.

Towards the comprehension of fasciolosis (re-)emergence: an integrative overview

The increasing distribution and prevalence of fasciolosis in both human and livestock are concerning. Here, we examine the various types of factors influencing fasciolosis transmission and burden and the interrelations that may exist between them. We present the arsenal of molecules, 'adjusting' capabilities and parasitic strategies of Fasciola to infect. Such features define the high adaptability of Fasciola species for parasitism that facilitate their transmission. We discuss current environmental perturbations (increase of livestock and land use, climate change, introduction of alien species and biodiversity loss) in relation to fasciolosis dynamics. As Fasciola infection is directly and ultimately linked to livestock management, living conditions and cultural habits, which are also changing under the pressure of globalization and climate change, the social component of transmission is also discussed. Lastly, we examine the implication of increasing scientific and political awareness in highlighting the current circulation of fasciolosis and boosting epidemiological surveys and novel diagnostic techniques. From a joint perspective, it becomes clear that factors weight differently at each place and moment, depending on the biological, environmental, social and political interrelating contexts. Therefore, the analyses of a disease as complex as fasciolosis should be as integrative as possible to dissect the realities featuring each epidemiological scenario. Such a comprehensive appraisal is presented in this review and constitutes its main asset to serve as a fresh integrative understanding of fasciolosis.

Enzyme-linked immunosorbent assay (ELISA) using recombinant Fasciola cathepsin L1 for the diagnosis of human fasciolosis caused by Fasciola hepatica/gigantica hybrid type

Recombinant Fasciola cathepsin L-1 (rCatL1) was evaluated in enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of human fasciolosis in Japan. Quality characteristics of the test were accessed by receiver operating characteristic (ROC) analysis, with sera from fasciolosis patients (n = 10), patients with no evidence of parasitic infections (n = 29), and patients with other helminth infections (n = 119). Both the sensitivity and specificity of the test achieved 100% with the control samples. To test the performance of the assay in an authentic situation, 311 serum samples, which had been sent to our laboratory for the diagnosis of parasitic infections from January 2018 to February 2019, were re-assessed using the rCatL1 ELISA. In this case, the sensitivity of the rCatL1 ELISA was 100%, giving positive results to all fasciolosis sera (n = 7), and the specificity was 99.0%, in which three of the 304 non-fasciolosis samples were judged positive. Careful re-examination of the laboratory data and medical imaging of these three patients revealed that one of the patients, who had been diagnosed as having larva migrans syndrome, was judged to be infected with Fasciola, in addition to ascarid nematodes. Thus the true specificity of the assay in the authentic reached 99.3% (302/304). As the rCatL1 ELISA exhibited a highly significant positive likelihood ratio (152.0) and negative likelihood ratio (0.0), calculated from the 311 sample data, this rCatL1 ELISA can be used for routine screening and definitive diagnosis test for fasciolosis in reference laboratories.

Surgically resected hepatic mass caused by fascioliasis

Fascioliasis is a parasitic infestation caused by the digenetic trematodes Fasciola hepatica and F. gigantica. It is not commonly seen in developed countries, so diagnosis there is always difficult as a result of confusion with other hepatic or biliary disorders. A 56-year-old man presented at our hospital with a hepatic mass that had been inadvertently discovered by ultrasonography. Abdominal computed tomography revealed a multi-cystic lesion distributed along the branch of the right bile duct. Endoscopic retrograde cholangiopancreatography showed serrated changes ranging from the upper level of the common bile duct to the right hepatic bile duct. Eosinophilia was not observed and tumor marker levels were within normal ranges. Following right lobectomy combined with bile duct reconstruction, a histological examination revealed cholangitis with inflammatory cell infiltration accompanied by parasite egg-like structures and Charcot-Leyden crystals. An additional serologic test was positive for F. hepatica antibodies. A diagnosis of fascioliasis was thus confirmed by histopathology and serology. Fascioliasis should be suspected if imaging findings such as multiple small hypodense lesions in the liver are observed, and serologic tests can be useful for differential diagnosis.