Helminth co-infections have no additive detrimental impact on milk yield and milk quality compared to mono-infections in German dairy cows.

BACKGROUND: Infections with (tricho-)strongyles, Dictyocaulus viviparus or Fasciola hepatica have been shown to reduce milk production in dairy cows. However, the current published studies focused on one single helminth infection by neglecting helminth co-infections and their possible (additive) effects on host performance. Hence, for the first time, we investigated differences in the impact of patent helminth co-infections versus mono-infections on milk production parameters in individual cows. METHODS: A total of 1583 dairy cows from 27 herds were included in this study. Faecal samples were examined in 2015 and 2021/2022 to determine the number of eggs/larvae per gram faeces for (tricho-)strongyles, D. viviparus, F. hepatica and rumen flukes. The cows were classified as non-infected, mono-infected and co-infected. Linear mixed models were applied to analyse the association between infection status (non-infected vs. mono-infected vs. co-infected) with milk yield, milk protein and milk fat content by including potential confounders. RESULTS: Infections with (tricho-)strongyles, D. viviparus, F. hepatica and rumen flukes were detected in 100%, 28.6%, 50.0% and 21.4% of herds, and 27.4%, 2.6%, 10.8% and 0.8% of faecal samples in 2015, while 100%, 0.0%, 86.7% and 60.0% of herds and 52.3%, 0.0%, 13.3% and 26.8% of faecal samples were positive in 2021/2022. Co-infections with two or more helminth taxa were detected in 74.4% of herds and 5.0% of faecal samples in 2015, and in 93.3% of herds and 21.7% of faecal samples in 2021/2022. The correlations between strongyle EPG, D. viviparus LPG and F. hepatica EPG were significantly positive in 2015. Significantly higher mean EPGs were identified in 2015 in faecal samples presenting co-infections with F. hepatica and one or two other helminth taxa than in faecal samples presenting F. hepatica mono-infections (P = 0.013). Although expected, the infection status (mono- or co-infected) had no significant impact on milk yield, milk protein and milk fat content in the linear mixed model analyses based on individual faecal examinations. CONCLUSIONS: Patent helminth co-infections had no additive detrimental impact on milk production parameters in the present study. This might be a result of presumably low worm burdens, but should be confirmed in future studies.

The use of a Bayesian latent class model to estimate the test characteristics of three liver fluke diagnostic tests under New Zealand field conditions.

The liver fluke Fasciola hepatica is a trematode parasite of farmed livestock with worldwide distribution, causing chronic production losses and possible death from hepatobiliary damage. The effective management of liver fluke infection requires diagnostic tests which can accurately identify infected animals at both the individual and herd level. However, the accuracy of liver fluke diagnostic tests performed on individual New Zealand cattle is currently unknown. The aim of this study was to use a Bayesian latent class model (LCM) to estimate the test characteristics of three liver fluke diagnostic tests, the coproantigen ELISA, the IDEXX antibody ELISA and the faecal egg count. One hundred and twenty dairy cows each from two dairy farms were blood and faecal sampled in April 2021. The samples were transported to Massey University, Palmerston North, and the three diagnostic tests completed following the respective manufacturer instructions. A Bayesian LCM model, adapted from the original Hui and Walter 2 tests 2 populations model, was built to estimate the test characteristics of the three diagnostic tests in the two dairy herds. The model was implemented in JAGS using Markov chain Monte Carlo sampling. The first 30,000 iterations were discarded as burn-in, and the next 200,000 iterations were used to construct the posterior distributions. Uninformed priors, beta (1,1), were used as the prior distributions for the prevalence estimation and informed beta priors, based on published results, were used as the prior distributions for estimating the sensitivity and specificity of each diagnostic test. Model convergence was confirmed by inspection of trace plots and examination of the results of the Gelman and Rubin test. The results found that the coproantigen ELISA test was the most accurate for diagnosing liver fluke infection in individual animals with a sensitivity = 0.98 (95 % CI 0.95-1.00) and specificity = 0.95 (95 % CI 0.81-1.00) compared to the IDEXX antibody ELISA test, sensitivity = 0.39 (95 % CI 0.32-0.47) and specificity = 0.86 (95 % CI 0.75-0.96) or the FEC, sensitivity = 0.23 (95 % CI 0.17-0.30) and specificity = 0.92 (95 % CI 0.86-0.97). Based on these results clinicians should be encouraged to use the coproantigen ELISA test to diagnose liver fluke infection in individual cattle.

Assessment of accuracy of liver fluke diagnostic tests using the gold standard of total worm counts.

In many regions of New Zealand liver fluke is endemic, infecting most grazing ruminants, including cattle, sheep, and deer. Restricting the economic losses and welfare costs associated with liver fluke relies on accurately identifying those animals with a production limiting infection. This has proven a difficult goal and although several antemortem quantitative tests are available, including faecal egg counts (FEC), serum ELISA and copro-antigen ELISA, none can be considered a gold standard test of liver fluke infection. The accepted gold standard test for fascioliasis is the total fluke count, which is both laborious and can only be completed at post-mortem. This study aimed to compare the performance of four liver fluke diagnostic tests, against the results of a gold standard total fluke count test. Two groups of cattle were selected, 29 culled mixed age beef cows (MAC) and ten 30-month-old steers. The cattle were blood sampled and faecal sampled prior to slaughter and their whole livers recovered post slaughter at the abattoir. Liveweight was also recorded at slaughter. After collection, each liver was weighed, scored for gross pathology, then serum, faeces and livers were frozen at -20 °C for later analysis. Faecal egg counts and F. hepatica copro-antigen ELISA tests were completed on the faecal samples and total fluke counts were completed on the livers. Fasciola hepatica antibody concentration in serum samples were quantified using a commercial ELISA test. Poisson regression models were built to model the association between each diagnostic test and the total fluke count, and a linear regression model was built to examine the relationship between each diagnostic test and live weight at slaughter. The median fluke count was significantly higher in MAC than steers (p = 0.01), and F. hepatica eggs were present in 100% steers and 66% MAC. There was a significant effect of copro-antigen ELISA value on total fluke count (p < 0.0001), with a coproantigen ELISA value = 20.1 predicting 10 flukes and a value = 44.8 predicting 30 flukes. There was also a significant effect of FEC on total fluke count (p = 0.002) but the R-squared value for this model was lower. There was no association between liver fibrosis score or antibody ELISA test and total fluke count (p = 0.95, p = 0.73, respectively). There was a significant effect of total fluke count (p = 0.03) on liveweight at slaughter, with liveweight falling 20.4 kg for each unit increase in loge (total fluke count). There was no effect of FEC (p = 0.11), antibody ELISA (p = 0.55) or copro-antigen ELISA value (p = 0.16) on liveweight at slaughter. Taken together, these results show that the coproantigen ELISA test is the better test for estimating the true liver fluke burden and that the number of flukes in the liver has a negative effect on cattle live weights at slaughter.

Fosfatriclaben: Effective dose determination and comparative efficacy assessment with closantel, triclabendazole+ivermectin, triclabendazole+albendazole in artificially infected cattle.

Two controlled efficacy studies were conducted to determine the effective dose of fosfatriclaben (FTCB) and compare its fasciolicidal efficacy with that of three commercial products against eggs and adult stages of Fasciola hepatica in artificially infected cattle. In study 1, 20 trematode-free Holstein Friesian steers were infected on day 0 with 500 F. hepatica metacercariae. Ten weeks after infection and the steers were confirmed to be positive for trematode eggs through a modified sedimentation method. On day 75, they were divided into five groups of four animals each for treatment. Group 1 (G1) served as the untreated control; G2, G3, and G4 received FTCB at 4, 6, and 8 mg/kg/intramuscularly (IM), respectively. G5 received a combined treatment of triclabendazole (TCBZ) (12 mg/kg IM + ivermectin (0.2 mg/kg IM). Individual faecal analyses were performed on days -8, 0, 70, 75, and 105 to evaluate the reduction in trematode eggs. Four weeks after treatment, the steers were humanely slaughtered to harvest the livers and remove the parasites present in the bile ducts. Efficacy was evaluated by the reduction in fecal egg counts or in number of adult parasites, compared to the untreated control. The effective FTCB dose was 6 mg/kg. Once the effective dose was determined, study 2 was conducted on another 20 steers infected with 500 F. hepatica metacercariae, to compare the effectiveness of FTCB with three commercials fasciolicides. All procedures were performed as described in study 1, and treatments were as follows: Group 1 (G1), closantel (5 mg/kg subcutaneously (SC)); G2, TCBZ (12 mg/kg IM) + ivermectin (0.2 mg/kg IM); G3, FTCB (6 mg/kg IM); G4, triclabendazole (12 mg/kg) + albendazole (5 mg/kg/PO (orally); and G5 served as an untreated control. The results indicated that all tested compounds were highly effective in the reduction of faecal egg excretion (99.7-100%) and adult parasites (98.9-100%), except closantel, which exhibited low efficacy (74.4%) when tested against adult trematodes. We concluded that the effective dose of FTCB for cattle was 6 mg/kg IM, which is half the recommended clinical dose of the commercial combination of TCBZ and ivermectin. The fasciolicidal efficacy of FTCB was like the other three flukicides in reducing adult F. hepatica and Fasciola eggs; however, closantel was not sufficiently efficient against adult flukes.

Unanticipated discovery: incidental encounter with fasciola hepatica during ERCP - a case report.

Introduction and Importance: Fasciola hepatica (FH) is a rare parasitic infection in humans. Its incidental detection during endoscopic retrograde cholangiopancreatography (ERCP) is exceptionally uncommon. This case underscores the importance of considering parasitic infections, even in low-endemicity regions, and the potential implications of dietary and environmental factors in disease transmission. Case Presentation: The authors present a case of a 31-year-old female from Dhading, Nepal, who underwent ERCP for suspected biliary stone. The patient had been experiencing recurring, nonradiating, burning epigastric pain for 5 to 7 years, which had recently intensified. Previous evaluations, including abdominal ultrasonography, CT, and MRI, revealed a dilation within the common bile duct and an obstruction in the biliary system. Clinical Discussion: During ERCP, cholangiography revealed mildly dilated extra and intrahepatic bile ducts with irregular filling defects in the common hepatic duct. Sphincterotomy was performed, followed by the extraction of multiple FH worms. A 7 Fr 7 cm double pigtail plastic stent was placed with a good flow of bile. However, the patient experienced anaphylaxis during the procedure, necessitating swift and tailored administration of appropriate medications to ensure effective management and stabilization. The patient was closely monitored in the ICU postprocedure. Conclusion: After careful monitoring and treatment, the patient fully recovered. The unexpected discovery of FH during ERCP is extremely rare. Early recognition and appropriate management of such incidental findings are crucial to ensuring optimal patient outcomes.

Fasciola hepatica: Updates on egg morphology, host range, and distribution.

During a survey for helminths in reindeer (Rangifer tarandus) across the Palearctic region, eggs were found in zoo reindeer feces. These were identified as eggs of Fasciola hepatica based on their morphology, morphometrics, location, and analysis of their partial sequence of ITS rDNA region. Some of the eggs had an appendage, previously unreported. Additionally, adults of F. hepatica were studied. Eggs derived from their uteri were also appendaged. Diagnostic morphological traits of F. hepatica eggs (abopercular appendage, knob, egg shell thickening, and egg shape) are discussed in this article. Three dimensional models of F. hepatica eggs were created to demonstrate the eggs features as best as possible. Since fecal examination remains gold standard in diagnosing fasciolosis in humans and animals worldwide, our findings may contribute to improved diagnostics. This research has also shown that reindeer can be a final host for F. hepatica. We also discuss whether the Novaya Zemlya archipelago might be the northernmost site of fasciolosis.

Early stage Fasciola hepatica infection in growing cattle: impact on weight gain and liver weight determined in flukicide efficacy studies.

Although the negative impact of liver fluke (Fasciola hepatica) infection on production and health in cattle is generally accepted, results of individual research have been variable, ranging from important negative impacts on the animal to minimal or no impact. To add information on the impact of F. hepatica infection in growing cattle, weight gain and liver weight of young experimentally infected animals from seven controlled efficacy studies were analyzed. In each study, fluke naïve animals were inoculated with approximately 450 to 500 F. hepatica encysted metacercariae, blocked on body weight and randomly assigned into one untreated group (controls) and groups which were administered an experimental flukicide when the flukes were 4 weeks old (migrating) and sacrificed 8 weeks thereafter (12 weeks after inoculation). Data of groups which demonstrated >90% reduction of fluke counts following treatment and groups left untreated (total 103 and 47 animals, respectively) were compared. There was a significant (p < 0.0001) negative association between fluke count and weight gain while fluke count and liver weight and fluke count and relative liver weight were positively associated (p < 0.0001). Over the 8-week post-treatment period, flukicide-treated cattle had almost 15% more weight gain than the controls (50.9 kg vs. 44.4 kg; p = 0.0003). Absolute and relative liver weight was significantly (p < 0.0001) lower in flukicide-treated compared to untreated cattle. Overall, this analysis provided evidence of a substantial negative effect of early (migrating) liver fluke infection on the growth of young cattle, likely due to pathology of the liver and associated reduction in its function as the central organ for bioenergy and protein metabolism.

Mitochondrial genome of the fluke pond snail, Austropeplea cf. brazieri (Gastropoda: Lymnaeidae).

BACKGROUND: Lymnaeid snails of the genus Austropeplea are an important vector of the liver fluke (Fasciola hepatica), contributing to livestock production losses in Australia and New Zealand. However, the species status within Austropeplea is ambiguous due to heavy reliance on morphological analysis and a relative lack of genetic data. This study aimed to characterise the mitochondrial genome of A. cf. brazieri, an intermediate host of liver fluke in eastern Victoria. METHODS: The mitochondrial genome was assembled and annotated from a combination of second- and third-generation sequencing data. For comparative purposes, we performed phylogenetic analyses of the concatenated nucleotide sequences of the mitochondrial protein-coding genes, cytochrome c oxidase subunit 1 and 16S genes. RESULTS: The assembled mt genome was 13,757 base pairs and comprised 37 genes, including 13 protein-coding genes, 22 transfer RNA genes and 2 ribosomal RNA genes. The mt genome length, gene order and nucleotide compositions were similar to related species of lymnaeids. Phylogenetic analyses of the mt nucleotide sequences placed A. cf. brazieri within the same clade as Orientogalba ollula with strong statistical supports. Phylogenies of the cox1 and 16S mt sequences were constructed due to the wide availability of these sequences representing the lymnaeid taxa. As expected in both these phylogenies, A. cf. brazieri clustered with other Austropeplea sequences, but the nodal supports were low. CONCLUSIONS: The representative mt genome of A. cf. brazieri should provide a useful resource for future molecular, epidemiology and parasitological studies of this socio-economically important lymnaeid species.

Evaluation of Reproductive Histology Response of Adult Fasciola hepatica in Goats Vaccinated with Cathepsin L Phage-Exposed Mimotopes.

Fasciolosis, a globally re-emerging zoonotic disease, is mostly caused by the parasitic infection with Fasciola hepatica, often known as the liver fluke. This disease has a considerable impact on livestock productivity. This study aimed to evaluate the fluke burdens and faecal egg counts in goats that were administered phage clones of cathepsin L mimotopes and then infected with F. hepatica metacercariae. Additionally, the impact of vaccination on the histology of the reproductive system, specifically related to egg generation in adult parasites, was examined. A total of twenty-four goats, which were raised in sheds, were divided into four groups consisting of six animals each. These groups were randomly assigned. The goats were then subjected to two rounds of vaccination. Each vaccination involved the administration of 1 × 1013 phage particles containing specific mimotopes for cathepsin L2 (group 1: PPIRNGK), cathepsin L1 (group 2: DPWWLKQ), and cathepsin L1 (group 3: SGTFLFS). The immunisations were carried out on weeks 0 and 4, and the Quil A adjuvant was used in combination with the mimotopes. The control group was administered phosphate-buffered saline (PBS) (group 4). At week 6, all groups were orally infected with 200 metacercariae of F. hepatica. At week 22 following the initial immunisation, the subjects were euthanised, and adult F. hepatica specimens were retrieved from the bile ducts and liver tissue, and subsequently quantified. The specimens underwent whole-mount histology for the examination of the reproductive system, including the testis, ovary, vitellaria, Mehlis' gland, and uterus. The mean fluke burdens following the challenge were seen to decrease by 50.4%, 62.2%, and 75.3% (p < 0.05) in goats that received vaccinations containing cathepsin L2 PPIRNGK, cathepsin L1 DPWWLKQ, and cathepsin L1 SGTFLFS, respectively. Animals that received vaccination exhibited a significant reduction in the production of parasite eggs. The levels of IgG1 and IgG2 isotypes in vaccinated goats were significantly higher than in the control group, indicating that protection is associated with the induction of a mixed Th1/Th2 immune response. The administration of cathepsin L to goats exhibits a modest level of efficacy in inducing histological impairment in the reproductive organs of liver flukes, resulting in a reduction in egg output.

The Hepatic Phase of Fascioliasis Complicated with Liver Bleeding: Presentation of Three Cases.

Bleeding is a very rare complication of Fasciola species (F. hepatica or F. gigantica) infection. We present here three cases of subcapsular liver bleeding caused by the hepatic phase of Fasciola spp. infection in patients, two of whom were women, aged 22, 66, and 84 years in Diyarbakir Province, southeastern Turkey. They had symptoms of right upper quadrant pain (n = 3), nausea (n = 1), and vomiting (n = 2) for periods ranging from 6 hours to 15 days. All patients with clinical presentations ranging from moderate abdominal pain to hypovolemic shock and ischemic hepatitis were improved with supportive treatment without the need for surgery. They showed complete clinical and laboratory recovery after triclabendazole administration in their follow-up. In conclusion, Fasciola spp. infection should be considered in the etiology of bleeding from liver disease.

Expression of Transposable Elements throughout the Fasciola hepatica Trematode Life Cycle.

BACKGROUND: Transposable elements (TEs) are major components of eukaryotic genomes. The extensive body of evidence suggests that although they were once considered "genomic parasites", transposons and their transcripts perform specific functions, such as regulation of early embryo development. Understanding the role of TEs in such parasites as trematodes is becoming critically important. Fasciola hepatica, a parasite affecting humans and livestock, undergoes a complex life cycle in diverse environments and hosts, and knowledge about its life cycle regulation is scarce so far. METHODS: We summarized the data regarding the repetitive elements in F. hepatica and conducted bulk RNA-seq analysis across its life cycle stages. TE expression profiles were analyzed, focusing on differential expression and potential homology with previously described long non-coding RNAs (lncRNAs). RESULTS: Differential expression analysis revealed stage-specific TE transcription patterns, notably peaking during egg and metacercariae stages. Some TEs showed homology with known lncRNAs and contained putative transcription factor binding sites. Interestingly, TE transcription levels were highest in eggs and metacercariae compared to adults, suggesting regulatory roles in trematode life cycle transitions. CONCLUSIONS: These findings suggest that TEs may play roles in regulating trematode life cycle transitions. Moreover, TE homology with lncRNAs underscores their significance in gene regulation.

Correlation between the Fasciola hepatica infection rate (number of parasites in the liver parenchyma) and the antibody titration, detected by ELISA assay.

This study aimed to demonstrate the existence of a possible correlation between the level of liver fluke infection in cattle caused by Fasciola hepatica and the titers of anti-parasite antibodies in the blood. 113 blood samples were taken from non-dewormed pasture cattle in the communal slaughterhouse of the Jijel city in order to determine the serological titration of anti-fluke antibodies by the ELISA method. After slaughtering the animals studied, a count of parasites present in the inspected livers was carried out in order to assess the level of parasitic infection. The prevalence of bovine fasciolosis (due to Fasciola hepatica) based on counting the number of flukes in the inspected livers was around 61.06%, while the seroprevalence obtained is 55.75%. The sensitivity and specificity of the ELISA test used in this study were, respectively, 91.3% and 100%. A very strong correlation (r = 0.93 to p < 0.0001) was statistically demonstrated between the antibody titers and the number of flukes in the inspected livers. According to the results of this study, there is a strong statistical correlation between serum antibody titers and the number of flukes present in the liver (the higher the number of parasites in the liver, the higher the level of anti-flukes antibodies in the blood).

Water temperature and microenvironmental factors predict the presence and detection of the snail host of Fasciola hepatica in Andean Patagonia.

The transmission of Fasciola hepatica occurs only where there are -or recently were- aquatic or amphibious snails of the Lymnaeidae family, the intermediate host of this parasite. Direct detection of these snails is time-consuming and imprecise, hindering accurate and detailed mapping of transmission risk. To identify which microenvironmental factors could be used as proxies for the occurrence of the lymnaeid snail Galba viator, a major intermediate host in South America, a total of 183 1-m2 quadrants across diverse water bodies in an endemic area in Andean Patagonia were manually timed-searched for snails and microenvironmental variables were registered. Data was analyzed using a Bayesian hierarchical occupancy model that assessed the effects of the microenvironmental variables on the presence of snails while considering imperfect snail detection. The model estimated that G. viator predominantly inhabits shallow aquatic environments, in the presence of grasses, where snails of the genus Biomphalaria are also detected, and with scarce tree canopy cover. Physical factors affecting occupancy presumably act as proxies for the average water temperature, while the temperature at the time of sampling was found to affect snail detectability. The identified variables are easy, fast, and inexpensive to measure, and can complement management decisions and risk maps based on coarser remote-sensing data, particularly relevant in a context of growing resistance to anthelminthic drugs.

A PCR Test Using the Mini-PCR Platform and Simplified Product Detection Methods Is Highly Sensitive and Specific to Detect Fasciola hepatica DNA Mixed in Human Stool, Snail Tissue, and Water DNA Specimens.

Fasciola hepatica has a complex lifecycle with multiple intermediate and definitive hosts and influenced by environmental factors. The disease causes significant morbidity in children and its prevalent worldwide. There is lack of data about distribution and burden of the disease in endemic regions, owing to poor efficacy of the different diagnostic methods used. A novel PCR-based test was developed by using a portable mini-PCR® platform to detect Fasciola sp. DNA and interpret the results via a fluorescence viewer and smartphone image analyzer application. Human stool, snail tissue, and water samples were used to extract DNA. Primers targeting the ITS-1 of the 18S rDNA gene of Fasciola sp. were used. The limit of detection of the mini-PCR test was 1 fg/µL for DNA samples diluted in water, 10 fg/µL for Fasciola/snail DNA scramble, and 100 fg/µL for Fasciola/stool DNA scramble. The product detection by agarose gel, direct visualization, and image analyses showed the same sensitivity. The Fh mini-PCR had a sensitivity and specificity equivalent to real-time PCR using the same specimens. Testing was also done on infected human stool and snail tissue successfully. These experiments demonstrated that Fh mini-PCR is as sensitive and specific as real time PCR but without the use of expensive equipment and laboratory facilities. Further testing of multiple specimens with natural infection will provide evidence for feasibility of deployment to resource constrained laboratories.

Liver Histopathological and Immunohistochemical Evaluation from Fasciola hepatica Experimentally Infected and Reinfected Sheep.

Fasciolosis is an important economic disease of livestock. There is a global interest in the development of protective vaccines since the current anthelmintic therapy is no longer sustainable. A better knowledge of the host-parasite interaction is needed to design effective vaccines. To date, few studies have evaluated host-parasite interaction by comparing infected and reinfected animals. The present study evaluates the microscopical hepatic lesions in sheep infected and reinfected with Fasciola hepatica during the acute and chronic stages of infection. The histopathological study revealed the presence of necrotizing foci (NF1) associated with larvae migration during the early stages of infection in the primoinfected (PI) and reinfected (RI) groups. In the late stages of infection of the PI group and at the early and late stages of infection in the RI groups, extensive necrotizing/hemorrhagic foci (NF2) were found in the vicinity of enlarged bile ducts, some containing adult flukes, suggesting parasites may have caused NF2 while feeding. The immunohistochemical study revealed an increase in Foxp3+ T cells in both PI and RI groups with respect to the UC group and in the infiltrates adjacent to NF1 in the RI groups with respect to the PI group, suggesting the F. hepatica induce Foxp3 T cell expansion to facilitate parasite survival. In addition, in both the PI and RI groups, and during acute and chronic stages of the infection, a poor expression of iNOS was found accompanied by a strong expression of CD163, suggesting a marked M2 activation of macrophages in the hepatic lesions, which may be related with healing processes, and it also may facilitate parasite survival. The main differences between PI and RI animals were the more severe infiltration of eosinophils and Foxp3+ T cells, whereas RI did not modify M2 activation of macrophages which occurs since the early stages of primoinfection.

Unraveling new players in helminth pathology: extracellular vesicles from Fasciola hepatica and Dicrocoelium dendriticum exert different effects on hepatic stellate cells and hepatocytes.

Fasciola hepatica and Dicrocoelium dendriticum are parasitic trematodes residing in the bile ducts of mammalian hosts, causing, in some cases, impairment of liver function and hepatic fibrosis. Previous studies have shown that extracellular vesicles released by F. hepatica (FhEVs) and D. dendriticum (DdEVs) induce a distinct phenotype in human macrophages, but there is limited information on the effect of parasitic EVs on liver cells, which interact directly with the worms in natural infections. In this study, we isolated FhEVs and DdEVs by size exclusion chromatography and labeled them with a lipophilic fluorescent dye to analyze their uptake by human hepatic stellate cells (HSC) and hepatocytes, important cell types in liver pathology, using synthetic liposomes as internal labeling and uptake control. We analyzed EV uptake and the proteome profiles after the treatment with EVs for both cell types. Our results reveal that EVs establish unique and specific interactions with stellate cells and hepatocytes, suggesting a different role of EVs derived from each parasite, depending on the migration route to reach their final niche. FhEVs have a cytostatic effect on HSCs, but induce the extracellular matrix secretion and elicit anti-inflammatory responses in hepatocytes. DdEVs have a more potent anti-proliferative effect than FhEVs and trigger a global inflammatory response, increasing the levels of NF-κB and other inflammatory mediators in both cell types. These interactions may have a major influence on the progression of the disease, serving to generate conditions that may favor the establishment of the helminths in the host.

Estimation of diagnostic sensitivity and specificity of abattoir registrations and bulk tank milk ELISA as herd-level tests for Fasciola hepatica using Bayesian latent class modelling.

The common liver fluke, Fasciola hepatica, is a trematode parasite found worldwide, typically with a focal distribution due to its requirement for suitable climatic and environmental conditions to complete its lifecycle. Bovine fasciolosis causes suboptimal production and economic losses, including liver condemnation at slaughter. The lack of reliable diagnostic methods is a disadvantage to the increasing demand for surveillance and control. The aim of this study was to evaluate the diagnostic accuracy of bulk tank milk (BTM) antibody testing and aggregated abattoir registrations (AAR) of liver fluke as herd-level tests for F. hepatica infection using Bayesian latent class models. Data from the abattoirs in 2019-2021 and BTM, sampled in the winter of 2020/2021, were collected from 437 herds on the southwest coast of Norway. The BTM samples were analysed with the SVANOVIR® F. hepatica-Ab ELISA test, with results given as an optical density ratio (ODR), and later dichotomized using the recommended cut-off value from the test manufacturer (ODR ≥0.3). Based on the BTM ELISA test, 47.8% of the herds tested positive. The AAR test was defined as the herd-level proportion of female slaughtered animals registered with liver fluke infection during the study period. For this test, three cut-offs were used (a proportion of 0.05, 0.1 and 0.2). The herds were split into two subpopulations ("Coastal" and "Inland"), which were expected to differ in true prevalence of F. hepatica infection based on climate-related and geographical factors. The diagnostic accuracies of both tests were estimated using Bayesian latent class models with minimally informative priors. Post-hoc analysis revealed that the maximum sum of sensitivity (Se) and specificity (Sp) of the tests was achieved with a herd-level proportion of ≥0.1 registered with liver fluke as the AAR test. Using this cut-off, the median estimate for the diagnostic accuracy of the BTM ELISA was 90.4% (84.0-96.2 95% Posterior Credible Interval (PCI)) for Se and 95.3% (90.6-100% PCI) for Sp, while the median estimate of Se for AAR was 87.5% (81.4-93.1% PCI) and the median estimate of Sp for AAR was 91.0% (85.2-96.5% PCI). The cut-off evaluation of the SVANOVIR® F. hepatica-Ab ELISA test for BTM confirmed the manufacturer's recommended cut-off of ODR ≥0.3 to denote positive and negative herds. This study suggests that AAR and BTM ELISA test can be used as herd-level tools to monitor liver fluke infection, so that appropriate interventions against infection can be implemented as necessary.

Fasciolosis in ruminants in Brazil.

This review aims to promote discussion about the situation of fasciolosis in ruminants in Brazil. The disease is still found more frequently in the South and Southeast regions, but reports outside these areas show the spread of the disease, including human cases. Many studies have been published on the diagnosis and control of fasciolosis, but development of field diagnosis methods and drugs that control all stages of the parasite is still a challenge. Studies should be carried out of new distribution areas and alternatives for control in Brazil, which depends on understanding the complex interactions between of the environment, ecosystems and hosts of this trematode.

Esta revisão tem como objetivo levantar uma discussão sobre a situação da fasciolose em ruminantes no Brasil. A enfermidade ainda se encontra mais frequentemente nas regiões Sul e Sudeste do país, entretanto relatos fora dessas regiões evidenciam a expansão da enfermidade, inclusive casos em humanos. Muitos estudos têm sido publicados sobre o diagnóstico e controle da fasciolose, entretanto, o diagnóstico a campo e fármacos que combatam todas as fases evolutivas do parasito ainda são desafios. Novos estudos devem ser realizados sobre novas áreas de distribuição e alternativas de controle em condições brasileiras, o que depende da compreensão das complexas interações entre meio ambiente, ecossistemas e hospedeiros desse trematódeo.

New benzimidazole derivative compounds with in vitro fasciolicidal properties.

BACKGROUND: Control of the zoonotic food-borne parasite Fasciola hepatica remains a major challenge in humans and livestock. It is estimated that annual economic losses due to fasciolosis can reach US$3.2 billion in agriculture and livestock. Moreover, the wide distribution of drug-resistant parasite populations and the absence of a vaccine threaten sustainable control, reinforcing the need for novel flukicides. METHODS: The present work analyses the flukicidal activity of a total of 70 benzimidazole derivatives on different stages of F. hepatica. With the aim to select the most potent ones, and screenings were first performed on eggs at decreasing concentrations ranging from 50 to 5 µM and then on adult worms at 10 µM. Only the most effective compounds were also evaluated using a resistant isolate of the parasite. RESULTS: After the first screenings at 50 and 10 µM, four hit compounds (BZD31, BZD46, BZD56, and BZD59) were selected and progressed to the next assays. At 5 µM, all hit compounds showed ovicidal activities higher than 71% on the susceptible isolate, but only BZD31 remained considerably active (53%) when they were tested on an albendazol-resistant isolate, even with values superior to the reference drug, albendazole sulfoxide. On the other hand, BZD59 displayed a high motility inhibition when tested on adult worms from an albendazole-resistant isolate after 72 h of incubation. CONCLUSIONS: BZD31 and BZD59 compounds could be promising candidates for the development of fasciolicidal compounds or as starting point for the new synthesis of structure-related compounds.