The Fasciola hepatica egg development and hatching test (EDHT) using commercial drugs: a simple protocol for tackling anthelminthic resistance and promoting cattle productivity.

Fasciolosis is an important zoonotic disease caused by the trematode Fasciola hepatica, and it causes great losses in bovine production. The anthelmintic resistance is a major problem in the control of fasciolosis. In this study, the F. hepatica egg development and hatching test (EDHT) was used for the evaluation of the ovicidal activity of commercial drugs, commonly used for treating infected cattle, which reflects F. hepatica anthelminthic resistance in infected bovines, according to recent literature. Bile samples from F. hepatica naturally parasitized cattle were obtained from slaughterhouses in the cities of Lages and Otacílio Costa, Santa Catarina State, Brazil. The bile was washed, the eggs were recovered, quantified, and distributed in universal collectors, with a minimum of 1,000 eggs per vial. Four commercial drugs were used in this study, containing albendazole sulfoxide (ABDZ), closantel (CSTL), nitroxynil (NTXL), and triclabendazole with fenbendazole (TBZF). The drugs were diluted according to the manufacturer instructions. All drugs, and the respective control, were tested in triplicates, with the quantity of recovered eggs determining the number of drugs to be tested. The vials were incubated for 28 days at 27 °C, and the eggs were classified according to their degree of development under a stereomicroscope. In total, 121 egg samples were analyzed. Two samples were identified as resistant to TBZF. Undetermined resistance/susceptibility has been found in two isolates treated with ABDZ, one treated with NTXL and six treated with TBZF. CSTL did not present ovicidal activity and cannot be used in EDHT. This is the first time that commercial drugs were used in F. hepatica EDHT.

[A case of fascioliasis].

A 38-year-old rice farmer visited a hospital for abdominal pain. Computed tomography (CT) showed a liver tumor and magnetic resonance imaging (MRI) revealed a hypovascular tumor, both in segment 4. Thus, he was diagnosed with liver abscess. Ten days later, CT showed a new liver tumor in segment 8, but the size of the liver tumor in segment 4 had decreased. He was suspected with parasitic disease because of eosinophilia. Enzyme-linked immunosorbent assay showed a high level of serum Fasciola antibody. The patient was diagnosed with fascioliasis and was treated with triclabendazole. Post-treatment, CT revealed that the liver tumors had shrunk. Eosinophilia and multiple lesions were characteristic findings of parasitic disease.

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.

Triclabendazole resistance in Fasciola hepatica: First report in sheep from the Santa Cruz province, Argentinian Patagonia.

In the fall of 2022, decreased triclabendazole (TCBZ) efficacy against F. hepatica was suspected in a sheep farm located in the Santa Cruz province, Argentinian Patagonia. Since TCBZ-resistance in F. hepatica has never been reported in this province, this study aimed to confirm potential TCBZ-resistance in F. hepatica and to evaluate the efficacy of closantel (CLO) and nitroxinil (NTX), through faecal egg count reduction test (FECRT), and the efficacy of albendazole (ABZ) through the in vitro egg hatch test (EHT) in sheep. Sixty-eight (68) animals were selected from a herd of eighty (80) female Merino naturally infected with F. hepatica based on eggs per gram of F. hepatica (EPGFh) counts and assigned into four (4) groups (n = 17 per group): Group Control, animals did not receive anthelmintic treatment; Group TCBZ, animals were orally treated with TCBZ (12 mg/kg); Group CLO, animals were orally treated with CLO (10 mg/kg); and Group NTX, animals were subcutaneously treated with NTX (10 mg/kg). The fluke egg output was monitored on days 0 and 21 post-treatment. For the EHT, liver fluke eggs were isolated from faecal samples (approx. 50 g) collected from animals of the control group. TCBZ efficacy against liver fluke was 53.4%, confirming the presence of TCBZ-resistant isolates on the farm. CLO and NTX were highly effective (100%) for the treatment of F. hepatica on this farm. The EHT was carried out in two different laboratories, in which was observed an ABZ efficacy of 95.8 (Bariloche) and 96.5% (Tandil). These results indicate the ABZ susceptibility of this F. hepatica isolate and the inter-laboratory precision of the test.

Emerging Human Fascioliasis: A Retrospective Study of Epidemiological Findings in Dali, Yunnan Province, China (2012-2021).

BACKGROUND Human fascioliasis is an emerging zoonotic disease caused by the trematodes, or flatworms, Fasciola hepatica and Fasciola gigantica, also known as liver flukes. This retrospective study aimed to report the epidemiological findings in 95 cases of human fascioliasis in Dali, Yunnan Province, southwestern China, diagnosed between 2012 and 2021. MATERIAL AND METHODS The epidemiologic and clinical data of 95 patients diagnosed with human fascioliasis in Dali area from January 2012 to December 2021 were collected and retrospectively analyzed. The diagnosis of fascioliasis was based on the Chinese National Standard of Diagnosis of Fascioliasis (WS/T566-2017). RESULTS The mean age of patients was 38.54±15.68 years, and there were more female patients than male (61.05% vs 38.95%). The high-incidence seasons were identified as summer and autumn. The patients with human fascioliasis lived in pastoral areas or were infected F. gigantica by consuming contaminated vegetables or water containing metacercaria. Meanwhile, human fascioliasis was diagnosed by positive serologic tests (1: 640), and Fasciola eggs (144-180×73-96 µm) were detected in stool samples of 6 patients. The most common clinical features were abdominal pain (70.53%), accompanied by elevated eosinophils in 89.5% of these patients. Antiparasitic treatment with triclabendazole at 10 mg/kg/day for 2 days led to symptom relief in all patients. CONCLUSIONS The findings from this observational epidemiological study have highlighted the importance of recognizing, diagnosing, and managing fascioliasis, which is an emerging zoonosis associated with increased human proximity to plant-eating domestic and farmed animals.

Toxocara canis and Fasciola hepatica Co-Infection Leading to Hepatic Abscess: A Case Report.

Toxocariasis is a zoonotic disease caused by ingesting eggs from soil contaminated with Toxocara canis and Toxocara cati, commonly found in feces of infected dogs and cats, leading to a range of clinical symptoms including fever, abdominal pain and gastrointestinal manifestations. Fascioliasis is also a zoonotic disease caused by liver flukes Fasciola hepatica and Fasciola gigantica, which can be contracted through consumption of contaminated water or aquatic plants, leading to various clinical features. Here, we report a case of a 39-year-old woman diagnosed with a liver abscess caused by co-infection of T. canis and F. hepatica, as confirmed by serological tests. Although the existence of a pet dog and an experience of eating raw water dropwort are potential clues for diagnosis, it cannot be determined as the source of infection because the source of infection has not been clearly identified. After administrating albendazole and triclabendazole sequentially, the patient showed improvement in blood test and imaging findings. Clinicians should be aware of parasitic co-infection and take appropriate management.

Clinical characteristics of human fascioliasis in Egypt.

There is a lack of epidemiological data on fascioliasis in Egypt regarding disease characteristics and treatment outcomes across different governorates. We aimed to identify the demographic, epidemiologic, clinical, laboratory, and radiological characteristics and treatment outcomes of patients diagnosed with fascioliasis in Egypt. Data on human fascioliasis were collected retrospectively from patients' medical records in the period between January 2018 and January 2020. The study included 261 patients. More than 40% of enrolled patients were in the age group of 21-40 years old. Geographically, 247 (94.6%) were from Assiut Governorate with 69.3% were from rural areas. The most frequent symptoms were right upper quadrant pain (96.9%), and fever (80.1%). Eosinophilia was found in 250 cases (95.8%). Hepatic focal lesions were detected in 131 (50.2%); out of them 64/131 (48.9%) had a single lesion. All patients received a single dose of 10 mg/kg of triclabendazole, 79.7% responded well to a single dose, while in 20.3% a second ± a third dose of treatment was requested. After therapy, there was a reduction in leucocytes, Fasciola antibodies titer, eosinophilic count, bilirubin, and liver enzymes with an increase in hemoglobin level. According to our findings, a high index of suspicion should be raised in cases with fever, right upper abdominal pain, and peripheral eosinophilia, and further imaging workup is mandated to detect hepatic focal lesions. Prompt treatment by triclabendazole can serve as a standard-of-care regimen even for suspected cases.

In vitro and in vivo studies on a group of chalcones find promising results as potential drugs against fascioliasis.

About a third of the world population is infected by helminth parasites implicated in foodborne trematodiasis. Fascioliasis is a worldwide disease caused by trematodes of the genus Fasciola spp. It generates huge economic losses to the agri-food industry and is currently considered an emerging zoonosis by the World Health Organization (WHO). The only available treatment relies on anthelmintic drugs, being triclabendazole (TCBZ) the drug of choice to control human infections. The emergence of TCBZ resistance in several countries and the lack of an effective vaccine to prevent infection highlights the need to develop new drugs to control this parasitosis. We have previously identified a group of benzochalcones as inhibitors of cathepsins, which have fasciolicidal activity in vitro and are potential new drugs for the control of fascioliasis. We selected the four most active compounds of this group to perform further preclinical studies. The compound's stability was determined against a liver microsomal enzyme fraction, obtaining half-lives of 34-169 min and low intrinsic clearance values (<13 µL/min/mg), as desirable for potential new drugs. None of the compounds were mutagenic or genotoxic and no in vitro cytotoxic effects were seen. Compounds C31 and C34 showed the highest selectivity index against liver fluke cathepsins when compared to human cathepsin L. They were selected for in vivo efficacy studies observing a protective effect, similar to TCBZ, in a mouse model of infection. Our findings strongly encourage us to continue the drug development pipeline for these molecules.

Activity of cumin essential oil to control fascioliasis: Efficacy and changes in the tegument of Fasciola hepatica.

Fasciola hepatica, the liver trematode, infects ruminants and causes economic loss. Because parasites are developing resistance to commercial drugs, the negative effects of parasitism are increasing. In this study, we aimed to evaluate the efficacy of cumin (Cuminum cyminum) essential oil against F. hepatica eggs and adults. The eggs were incubated with eight concentrations of the essential oil (0.031125-4.15 mg/mL), and viable eggs were counted after 14 days and classified as embryonated or non-embryonated. Adult flukes were incubated in Roswell Park Memorial Institute medium to ensure their viability and then incubated in essential oil. They were observed for 24 h after treatment. The adults were assessed with the two lowest effective oil concentrations used in the ovicidal test. Three controls were used for both tests: nitroxynil, a negative control, and Tween®80. After incubation in oil, the adult specimens were processed for histological analysis and stained with hematoxylin-eosin. In addition, the oil was tested for cytotoxicity using Madin-Darby bovine kidney cells to assess any possible effect on them. The oil was effective in ovicidal and adulticidal inhibition of the trematode, with statistically significant results. All concentrations assessed in the ovicidal test were 100% effective. The adult test was effective within 15 h and inactivated all the specimens at the highest concentration evaluated (0.06225 mg/mL). Histological analysis showed that cumin essential oil resulted in marked areas of vacuolization. The spines showed no structural changes but were surrounded by microvesicles. These findings indicated that cumin oil could be a potential compound in the control of fasciolosis.

ON LIVER FLUKE (FASCIOLA HEPATICA) IN CAPTIVE VICUÑAS (VICUGNA VICUGNA) AT KNOWSLEY SAFARI, PRESCOT, UNITED KINGDOM.

Knowsley Safari (KS), Prescot, United Kingdom houses a variety of captive exotic ungulates. As part of their animal welfare plan, a prospective coprological survey was undertaken for liver fluke. In June 2021, 330 fecal samples, representative of 18 exotic ungulate species, were processed by sedimentation and filtration, with examination by coproscopy. Finding fascioliasis in all five vicuña alone, with fecal egg counts ranging from one to eight eggs per gram, anthelminthic treatment was attempted twice, with three coprological reviews. While the first anthelminthic treatment (oxyclozanide) was equivocal, the second anthelminthic treatment (triclabendazole) was proven effective upon two later follow-ups. An initial malacological survey of 16 freshwater sites in KS, first found Galba truncatula at two sites in June 2021, then upon more extensive searching subsequently within the vicuña's enclosure. It appears that F. hepatica was locally acquired, being the first report of fascioliasis within captive vicuñas in the United Kingdom. To develop a better fluke-management plan, regular coprological and malacological surveillance is justified, perhaps with molecular xenomonitoring of snails, alongside prompt administration of appropriate flukicide as required.

A common presentation of uncommon disease - Biliary Fasciola Hepatica.

Hepatobiliary fascioliasis is one of the rare but important parasitic infection in endemic areas such as Pakistan. Clinical manifestations overlap with common clinical conditions such as hepatitis and biliary stones causing common bile duct obstruction. Fascioliasis is a zoonotic infection caused by a leaf-shaped organism known as Fasciola Hepatica. Humans are accidentally infected by consuming contaminated water or food, especially undercooked cattle and sheep liver or raw green vegetables. We report three cases with similar clinical manifestations presenting in two different cities in Pakistan. After detailed clinical evaluation and laboratory investigations, the diagnosis was established by abdominal ultrasound and diagnostic and therapeutic cholangiography. Patients were followed till complete resolution of their symptoms and normalisation of liver function tests.

Brief report first report of the in vitro ovicidal activity of camel milk and its fractions on zoonotic-liver fluke (Fasciola gigantica) eggs.

Fasciola gigantica is one of the worldwide parasites that cause livestock and human illnesses. Chemotherapy is now the primary therapeutic option for its treatment. Drug abuse has led to the emergence of drug-resistant strains. As a result, there is an urgent need to discover natural and efficient anthelmintics against Fasciola spp. The study aims to evaluate the ovicidal activities of camel milk and its fractions on F. gigantica eggs. In the in vitro assay of F. gigantica eggs were submitted to different concentrations (0.5% and 1%) of camel milk fractions; Camel Milk Whey (CMW), Camel Milk Casein (CMC), and Skimmed Camel Milk (SCM) as well as a positive control (PC) of Nitroxynil (100 mg/ml) and a negative control (NC) with physiological saline. The Egg Hatching Assay (EHA) results showed that camel milk fractions exhibited ovicidal activity, especially CMW, and CMC, which showed 97.58 ± 0.58 and 96.9 ± 1.99 ovicidal activity, respectively, at a concentration of 1% after 15 days of treatment compared to PC, which exhibited 91.75 ± 4.95 ovicidal activity. The egg hatching ratios were 1.67% and 2.33% for CMW and CMC, respectively, compared to 70.17% for the NC and 6% for the PC. The LC50 values for CMW and CMC on the 15th day of treatment were 0.20 and 9.13, respectively. From the results above, we can infer that camel milk and its fractions are promising as a new alternative for fascioliasis control.

[A case report:the progress of fascioliasis from hepatic phase to biliary phase].

This is a case report of fascioliasis that progressed from the hepatic to the biliary phases over 2 years. A woman in her late 60s ate Zingiber mioga from the field, which was followed by abdominal pain that occurred 1 month later. Although CT and MRI studies revealed an increase in blood eosinophils as well as multiple hepatic nodules, they vanished quickly. After 2 years, an MRCP study revealed multiple flat lesions, which were diagnosed as adult fascioliasis. Definitive diagnosis was provided by enzyme-labeled antibody method using fasciola-specific antigen. Triclabendazole was administered once to complete the treatment.

Comparison of the therapeutic efficacy of five anthelmintics against natural Fasciola hepatica infections in dairy cattle from the Mantaro Valley, Peru.

The intensive use of anthelmintic drugs to control Fasciola hepatica infections in dairy cattle has resulted in the emergence of anthelmintic resistance. Cases of resistance to triclabendazole (TCBZ) have been reported worldwide. The main goal of this research was to evaluate the main five fasciolicides to control fasciolosis in dairy cattle in the Mantaro Valley, Peru. Two fecal egg count reduction tests were performed. In a first study, 24 naturally F. hepatica infected cattle were randomly grouped into three experimental groups (n = 8). Groups were treated with either TCBZ, nitroxynil (NTX) or closantel (CLOS). In a second experiment, 55 naturally infected cows were grouped into three experimental groups and treated with either TCBZ (n = 18), rafoxanide (RFX) + albendazole (ABZ) (n = 19) or clorsulon (CLN) + ivermectin (IVM) (n = 18). Therapeutic efficacy was determined following the WAAVP guidelines by measuring reduction in fluke egg output at days 15 and 30 post-treatment. Bootstrapping method was used to obtain the 95% confidence intervals. The efficacy of TCBZ was inadequate in both studies (≤80.8%). Closantel showed high efficacy (≥ 90%) at both days, while NTX showed 92.9% (83-100) and 82.1% (53.6-100), efficacy, at days 15 and 30, respectively. Efficacy for RFX were 92.1% (79.6-98.9) and 97.4% (94.1-99.4); and for CLN, 98.8% (97.6-100) and 80.1% (44.7-99.4), at days 15 and 30, respectively. The outcome of this study indicates reduced therapeutic efficacy of TCBZ against F. hepatica in an important dairy area of the Peruvian central highlands but also demonstrates the validity of four alternatives.

A major locus confers triclabendazole resistance in Fasciola hepatica and shows dominant inheritance.

Fasciola hepatica infection is responsible for substantial economic losses in livestock worldwide and poses a threat to human health in endemic areas. The mainstay of control in livestock and the only drug licenced for use in humans is triclabendazole (TCBZ). TCBZ resistance has been reported on every continent and threatens effective control of fasciolosis in many parts of the world. To date, understanding the genetic mechanisms underlying TCBZ resistance has been limited to studies of candidate genes, based on assumptions of their role in drug action. Taking an alternative approach, we combined a genetic cross with whole-genome sequencing to localise a ~3.2Mbp locus within the 1.2Gbp F. hepatica genome that confers TCBZ resistance. We validated this locus independently using bulk segregant analysis of F. hepatica populations and showed that it is the target of drug selection in the field. We genotyped individual parasites and tracked segregation and reassortment of SNPs to show that TCBZ resistance exhibits Mendelian inheritance and is conferred by a dominant allele. We defined gene content within this locus to pinpoint genes involved in membrane transport, (e.g. ATP-binding cassette family B, ABCB1), transmembrane signalling and signal transduction (e.g. GTP-Ras-adenylyl cyclase and EGF-like protein), DNA/RNA binding and transcriptional regulation (e.g. SANT/Myb-like DNA-binding domain protein) and drug storage and sequestration (e.g. fatty acid binding protein, FABP) as prime candidates for conferring TCBZ resistance. This study constitutes the first experimental cross and genome-wide approach for any heritable trait in F. hepatica and is key to understanding the evolution of drug resistance in Fasciola spp. to inform deployment of efficacious anthelmintic treatments in the field.

To treat or not to treat: diagnostic thresholds in subclinical helminth infections of cattle.

Helminth infections of cattle place significant burdens on livestock production and farm economic efficiency. Heavy infections are relatively easy to detect and treat with anthelmintics. However, subclinical infections have major but often hidden impacts on animals, necessitating more refined diagnostics to detect them and ideally inform farmers about the likely impact of anthelmintic treatment on animal and herd performance. Here, we review recent advances in diagnosing three major cattle helminth infections - gastrointestinal nematodes (GINs), liver flukes, and lungworms - and the search for subclinical infection thresholds to guide treatment decisions. Combining refined diagnostic thresholds with farm-specific information on grazing systems and animal history enables farmers to tailor helminth treatments to specific epidemiological circumstances, thereby limiting anthelmintic resistance (AR) and boosting agricultural efficiency and food security.

Fumarate respiration of Fasciola flukes as a potential drug target.

Fascioliasis is a neglected tropical zoonotic disease caused by liver flukes belonging to the genus Fasciola. The emergence of resistance to triclabendazole, the only World Health Organization-recommended drug for this disease, highlights the need for the development of new drugs. Helminths possess an anaerobic mitochondrial respiratory chain (fumarate respiration) which is considered a potential drug target. This study aimed to evaluate the occurrence of fumarate respiration in Fasciola flukes. We analyzed the properties of the respiratory chain of Fasciola flukes in both adults and newly excysted juveniles (NEJs). Fasciola flukes travel and mature through the stomach, bowel, and abdominal cavity to the liver, where oxygen levels gradually decline. High fumarate reductase activity was observed in the mitochondrial fraction of adult Fasciola flukes. Furthermore, rhodoquinone-10 (RQ10 Em'= -63 mV), a low-potential electron mediator used in fumarate respiration was found to be predominant in adults. In contrast, the activity of oxygen respiration was low in adults. Rotenone, atpenin A5, and ascochlorin, typical inhibitors of mitochondrial enzymes in complexes I, II, and III, respectively, inhibit the activity of each enzyme in the adult mitochondrial fraction. These inhibitors were then used for in vitro viability tests of NEJs. Under aerobic conditions, NEJs were killed by rotenone or ascochlorin, which inhibit aerobic respiration (complex I-III), whereas atpenin A5, which inhibits complex II involved in fumarate respiration, did not affect NEJs. Moreover, ubiquinone-10 (UQ10 Em'= +110 mV), which is used in oxidative respiration, was detected in NEJs, in addition to RQ10. In contrast, under anaerobic conditions, rotenone and atpenin A5, which inhibit fumarate respiration (complex I-II), were crucial for NEJs. These findings demonstrate that NEJs have active hybrid respiration, in which they can properly use both oxygen and fumarate respiration, depending on oxygen availability. Thus, fumarate respiration is a promising drug target for Fasciola flukes, because it plays an essential role in both adults and NEJs.

A survey of sheep and/or cattle farmers in the UK shows confusion over the diagnosis and control of rumen fluke and liver fluke.

Calicophoron daubneyi (rumen fluke) is an emerging parasitic infection of livestock across Europe. Despite increasing in prevalence, little is known about the level of awareness of rumen fluke or current control practices used by UK farmers. Fasciola hepatica (liver fluke) is a common parasitic infection of cattle and sheep in the UK. Co-infections with these parasites can present in sheep and cattle, but the only drug with reported efficacy against rumen fluke is oxyclozanide. Between December 2019 and March 2020, 451 sheep and/or cattle farmers completed an online questionnaire, capturing their awareness and current means of control for liver fluke and rumen fluke. Most respondents (70%) were aware of rumen fluke, with 14% recording its presence on their farms and 18% having previously treated for rumen fluke. Almost all respondents (99%) were aware of liver fluke and higher numbers of respondents reported its presence on farm (67%) with 88% having previously treated for liver fluke. Respondents who were aware of rumen fluke said they were concerned about the parasite (81%), although rumen fluke was less of a concern than liver fluke (p < 0.05). Of respondents who reported rumen fluke presence on their farm, 42% cited incorrect diagnostic methods, including those traditionally used to detect liver fluke. Respondents were more likely to treat annually for liver fluke, as opposed to rumen fluke (p < 0.05). The most frequently used drug for the treatment of liver fluke infection was triclabendazole (53% sheep treatments, 34% cattle treatments) and only a minority of farmers treated with a product effective against rumen fluke (oxyclozanide; 42% cattle treatments, 35% sheep treatments). A small proportion of farmers stated that they used a non-flukicide drug to treat sheep for liver fluke infection (1.6% sheep treatments). These results demonstrate a broad awareness of liver and rumen fluke in sheep and cattle, but reveal confusion amongst farmers about their diagnosis and treatment, highlighting the need to provide best practice advice to the livestock industry for the control of both parasites.

Flukicidal effects of abietane diterpenoid derived analogues against the food borne pathogen Fasciola hepatica.

Control of liver fluke infections remains a significant challenge in the livestock sector due to widespread distribution of drug resistant parasite populations. In particular, increasing prevalence and economic losses due to infection with Fasciola hepatica is a direct result of drug resistance to the gold standard flukicide, triclabendazole. Sustainable control of this significant zoonotic pathogen, therefore, urgently requires the identification of new anthelmintics. Plants represent a source of molecules with potential flukicidal effects and, amongst their secondary metabolites, the diterpenoid abietic acids can be isolated in large quantities. In this study, nineteen (19) chemically modified abietic acid analogues (MC_X) were first evaluated for their anthelmintic activities against F. hepatica newly excysted juveniles (NEJs, from the laboratory-derived Italian strain); from this, 6 analogues were secondly evaluated for their anthelmintic activities against adult wild strain flukes. One analogue, MC010, was progressed further against 8-week immature- and 12-week mature Italian strain flukes. Here, MC010 demonstrated moderate activity against both of these intra-mammalian fluke stages (with an adult fluke EC50 = 12.97 µM at 72 h post culture). Overt mammalian cell toxicity of MC010 was inferred from the Madin-Darby bovine kidney (MDBK) cell line (CC50 = 17.52 µM at 24 h post culture) and demonstrated that medicinal chemistry improvements are necessary before abietic acid analogues could be considered as potential anthelmintics against liver fluke pathogens.