This lecture examines contemporary therapeutic strategies for opisthorchiasis, focusing on infections caused by the liver fluke Opisthorchis felineus , endemic to Western Siberia. While praziquantel remains the first-line treatment, its clinical utility is constrained by several factors, including lack of efficacy against juvenile parasite forms and emerging drug resistance. The discussion explores alternative pharmacological approaches, encompassing novel synthetic agents, combination therapies, and compounds targeting parasite-specific metabolic pathways. Special attention is given to plant-derived bioactive substances with experimentally confirmed anti-opisthorchiasis activity, including curcumin, Thunbergia laurifolia and Allium sativum extracts, and xanthohumol. These phytochemicals demonstrate dual therapeutic potential: direct antiparasitic effects and modulation of infection-associated pathophysiological processes, such as oxidative/nitrosative stress attenuation, inflammatory response suppression, and hepatobiliary fibrosis progression delay. A synergistic treatment paradigm combining praziquantel’s anthelmintic properties with the pleiotropic effects of plant-based antioxidants and anti-inflammatory compounds shows particular promise. This strategy may improve parasite clearance rates, reduce treatment-related adverse events, and prevent chronic complications. Further investigation is warranted to refine combination protocols, develop targeted delivery systems, and identify next-generation anthelmintic compounds capable of addressing the limitations of current synthetic therapies.

Effect of artesunate and artemether against Opisthorchis felineus in rodent model.

The problem of opisthorchiasis caused by Opisthorchis felineus requires a search for alternative treatments, because the trematode can develop drug resistance and the existing drugs, such as praziquantel, may have undesirable side effects. This study aimed to identify the anti- opisthorchiasis and hepatoprotective properties of Populus tremula L. bark extract using in vitro methods. The PGF-PT active fraction with a high content of phenol glycosides was obtained though extraction. PGF-PT showed a dose-dependent anti-opisthorchiasis effect: the relative mobility index of maritae decreased from 98.2% at 250 µg/ml to 54.5% at 2000 µg/ml (p < 0.05), and the proportion of immobile specimens at 2000 µg/ml was 30% (p < 0.05). The probable mechanism of action is focal damage to the cells of the parasite’s superficial epithelium (tegument). PGF-PT exhibited a pronounced hepatoprotective effect in a lipotoxicity model based on HepG2 cells, as evidenced by normalized intracellular lipid accumulation and reduced oxidative stress. A high antioxidant activity of PGF-PT was shown in the model system (IC50 = 79.3 ± 1.0 µg/ml). Thus, the PGF-PT fraction has a complex effect — eliminating parasites and correcting metabolic disorders in the liver — which makes it a promising basis for new effective anthelmintic drugs.

Can flukes cause cancer? Insight into molecular links between parasites and carcinogenesis.

In this research, we studied the synthesis and characterization of a novel amidine derivative of benzoperimidine derived from 1-aminoanthraquinone, focusing on its emission properties and potential applications in confocal laser scanning microscopy. The synthesized compound exhibited pronounced solvatochromic behavior in various solvents. Spectroscopic analysis, including 1H-, 13C-, and mass spectrometry, confirmed the chemical structure. The structure of three compounds was also determined using X-ray diffraction analysis; this study revealed the structural features of these substances in the solid state. The compound’s antimicrobial activity was evaluated using the agar diffusion method with the bacterium Bacillus subtilis subsp. Spizizenii. Furthermore, the study introduces a dye designed for imaging of the parasitic flatworm Opisthorchis felineus, demonstrating its potential in visualizing biological specimens.

ABSTRACTBackground and Aim:Opisthorchiasis and metorchiasis are significant zoonotic fish-borne trematodiases caused by Opisthorchis felineus and Metorchis bilis. These parasites exhibit overlapping geographic ranges and morphologically similar larval stages, complicating species-level identification. In Kazakhstan, where raw or undercooked freshwater fish is widely consumed, opisthorchiasis remains an endemic concern. This study aimed to investigate the prevalence of O. felineus and M. bilis in cyprinid fish from Akmola Region and to establish molecular tools for their differential diagnosis.Materials and Methods:A total of 818 freshwater cyprinid fish were collected from Lakes Sholak, Esey, and Karazhar between 2021 and 2023. Muscle tissue was examined using the compression method for metacercariae detection. Morphological identification was complemented with a newly designed multiplex polymerase chain reaction (PCR) assay targeting the mitochondrial cytochrome c oxidase subunit 1 (COX1) gene. Selected amplicons were sequenced and subjected to phylogenetic analysis. Prevalence and infection intensity were calculated, and statistical comparisons were made among fish species and lakes.Results:Opisthorchiidae metacercariae were detected in ide, bream, and roach, with prevalence varying across lakes. Lake Sholak exhibited the highest infection rate (42.9%), with ide showing the greatest susceptibility (40.4%). No infections were detected in fish from Lake Karazhar. Morphological differentiation between O. felineus and M. bilis was inconclusive due to overlapping features. Multiplex PCR successfully distinguished O. felineus (307 bp) from M. bilis (252 bp), with >99% sequence identity to GenBank references. Two representative sequences (PQ669120 and PQ669125) were deposited in GenBank. Phylogenetic analysis confirmed distinct clustering of both species.Conclusion:This study provides the first molecular confirmation of O. felineus and M. bilis in freshwater fish of the Akmola region, Kazakhstan. The developed multiplex PCR assay offers a sensitive and reliable diagnostic tool for species-level differentiation. These findings highlight moderate to high prevalence in local fish, underline the zoonotic risks associated with fish consumption, and emphasize the need for integrated One Health surveillance to inform control strategies and food safety policies.

BackgroundOpisthorchiasis infected by Opisthorchis felineus has represented a significant but understudied public health issue for the population residing in Western Siberia and the Ural Region of the Russian Federation. This study aimed to produce high-resolution spatial–temporal disease risk maps for guiding prevention strategy in the above region.MethodsData on prevalence and surveillance data reflecting reported annual incidence rate of O. felineus infection in the study region were collected through systematic review and the annual reports of the Ministry of Health of the Russian Federation. Environmental, socioeconomic and demographic data were downloaded from different open-access data sources. An advanced multivariate Bayesian geostatistical modeling approach was developed to estimate the O. felineus infection risk at high-resolution spatial–temporal by joint analysis of survey and surveillance data, incorporating potential influencing factors and spatial–temporal random effects. The annual spatial–temporal risk maps of O. felineus infection at a resolution of 5 × 5 km2 were produced.ResultsThe final dataset included 76 locations of survey data and 303 locations of surveillance data on O. felineus infection. The infection risk was high (> 25%) in most part of central and eastern regions, and relatively low (< 25%) in most part of western region, while temporal variations were observed across the sub-regions in recent decades. Particularly, in the densely populated eastern region, there was an increased trend of infection risk from 30.46% (95% Bayesian credible intervals, BCI 10.78–53.45%) in 1980 to 53.39% (95% BCI 13.77–91.93%) in 2019 and gradually transformed into high-risk. In the study region (excluding the western region due to data sparsity), the population-adjusted estimated prevalence was 46.61% (95% BCI 15.09–76.50%) in 2019, corresponding to approximately 7.91 million (95% BCI 2.56–12.98 million) people infected.ConclusionsThe high-resolution risk maps of O. felineus in Western Siberia and the Ural Region of the Russian Federation have effectively captured the risk profiles, suggesting the infection risk remains high in recent years and providing substantial evidence for spatial-target control and preventive strategies.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40249-025-01363-z.

Возбудитель описторхоза, трематода Opisthorchis felineus (Rivolta, 1884) - один из наиболее распространенных видов паразитов человека и животных на территории России, Казахстана, стран Восточной Европы. Вместе с близкородственными видами печеночных трематод O. viverrini (Poirier, 1886) и Clonorchis sinensis (Loos, 1907), ареалы которых расположены в Юго-Восточной Азии и на Дальнем Востоке, О. felineus составляет триаду эпидемиологически значимых трематод семейства Opisthorchiidae. Половозрелые особи O. felineus паразитируют в гепатобилиарной системе млекопитающих, включая человека и при длительной инфекции провоцируют развитие тяжелых осложнений. Однако, несмотря на значимость, описторхоз относится к группе забытых заболеваний (neglected tropical diseases). Данные заболевания, поражающие 1,65 миллиарда человек в мире, получили свое название не просто так: эти заболевания, люди и регионы, которые они поражают, обычно остаются без внимания. В обзоре кратко суммированы результаты современных исследований биологии и эпидемиологии трематод семейства Opisthorchiidae, обсуждены результаты исследований, полученных как на модельных животных, так и данные по пациентам. Актуальность исследований трематод подчеркивается их сложным жизненным циклом, длительным бессимптомным периодом заболевания; отсутствием достаточной информации о влиянии гельминтов на органы, не относящиеся к местам их непосредственной локализации, широкое распространение в эндемичных регионах. Открытая миграционная политика и гастрономический туризм расширяет географию проблемы этих инфекций за пределы локальных очагов, когда пациенты с описторхозом и клонорхозом могут обнаруживаться вдали от эндемичных территорий. Ключевые слова: трематоды, описторхоз, системное заболевание

Foodborne trematode infections are recognized as a significant risk factor for cholangiocarcinoma (CCA) in endemic regions. Infection with the liver fluke Opisthorchis felineus induces precursor lesions of CCA, including the biliary intraepithelial neoplasia. The mechanisms underlying liver-fluke-associated neoplasia remain poorly understood. This study aims to identify the role of EGFR and Toll-like receptor 4-associated signaling pathways in bile duct epithelial neoplasia linked to liver fluke infection in patients, animal models, and cell models. Elevated levels of EGFR and phosphorylated EGFR were observed in the bile duct epithelium of patients with cholangiocarcinoma, as well as in the bile duct epithelium of laboratory hamsters. The EGFR content correlated with the degree of bile duct epithelial neoplasia. Additionally, a significant increase in the cell proliferation and migration rates of human H69 cholangiocytes was found, whereas those of HepG2 hepatoma cells remained unaffected following the helminth excretory–secretory product (ESP) treatment. An EGFR inhibitor eliminated the enhanced cell proliferation (p = 0.005) and migration (p = 0.001) rates. Similar outcomes were achieved using Marimastat, an inhibitor of TLR-4-associated metalloproteinases. Thus, our study unveils novel avenues for exploring the mechanisms of helminth-associated carcinogenesis and for identifying key components of ESPs that mediate their mitogenic effects.

Introduction. Clinical manifestations of Opisthorchis felineus (O. felineus) invasion are characterized by pronounced polymorphism and can include lesions of various organs and systems, including the development of hepatitis and cirrhosis of the liver. Aim. To study the frequency of clinical manifestations of O. felineus invasion in patients with opisthorchiasis with a FIB-4 index value of more than 1.45.Materials and methods. A total of 360 patients with O. felineus invasion (158 men and 202 women, average age 40.6 years) aged 18 to 70 years were examined. Clinical examination of patients was carried out using standard questionnaires that allowed assessing the frequency and intensity of symptoms. O. felineus invasion was diagnosed using duodenal bile microscopy and coproovoscopy. All patients underwent esophagogastroduodenoscopy, abdominal ultrasound, complete blood count and biochemical blood assay. The FIB-4 index was calculated, the value of which was more than 1.45 indicated a high probability of liver fibrosis.Results. In patients with opisthorchiasis with FIB-4 index more than 1.45, weekly pain in the right hypochondrium, obesity, erosions of the stomach and duodenum, hepatomegaly, liver steatosis, signs of cholecystitis by ultrasound, biliary sludge, polyps in the gallbladder, increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the blood were more often registered compared to individuals with FIB-4 index less than 1.45. Hepatomegaly was associated with weekly pain in the right hypochondrium, obesity, liver steatosis, signs of cholecystitis, the presence of biliary sludge, cholecystectomy, neutropenia, elevated ALT and AST levels, FIB-4 index above 1.45.Conclusions. The FIB-4 index is a useful diagnostic tool, since it is easily calculated from the indicators of routine blood tests. Patients with elevated FIB-4 values and hepatomegaly have more pronounced intensity of clinical symptoms of the disease and require active diagnostic and therapeutic measures to prevent complications.

The purpose of the research is to analyze biochemical blood parameters in the chronic opisthorchosis stage in long-term infection in a compensation status by the example of the rabbit.Materials and methods. The experiment compared the control and experimental groups of sexually mature rabbits (Oryctolagus cuniculus domesticus), 10 animals each. The rabbits were infected with 50 metacercariae of Opisthorchis felineus S. Rivolta, 1884. Five years after infection, a biochemical analyzer determined glucose, creatinine, urea, blood urea nitrogen to creatinine ratio, total calcium and phosphorus, total protein, albumin, globulin, albumin to globulin ratio, alanine aminotransferase, alkaline phosphatase, gamma-glutamine transferase, bilirubin, and cholesterol in the animals' blood plasma.Results and discussion. The blood plasma in the experimental rabbits was found to have statistically significantly increased urea, the urea nitrogen to creatinine ratio, albumins, and the albumins to globulins ratio versus the control group. Glucose, creatinine, phosphorus, calcium, alkaline phosphatase, and cholesterol were higher in the experimental group. The data were not statistically significant. On the contrary, the amount of globulins, alanine aminotransferase, total protein and total bilirubin was lower versus the control group. The evaluation of bilirubin fractions between the groups found a lower indirect fraction versus the control. The data analysis results developed a diagnostic panel where probable involvement in the pathological process was assessed for the host's organs and systems using the example of O. felineus infection based on the values of biochemical blood parameters. The biochemical blood parameters in the chronic stage of opisthorchosis were normal or deviated slightly in a comprehensive snapshot analysis.

The purpose of the research is to study of the fauna of helminths of the pine marten (Martes martes) in the Ryazan region.Materials and methods. The material for the work was carcasses or individual organs of the pine marten, delivered from the territory of hunting grounds of the Ryazan region, obtained as a result of licensed hunting. Whole carcasses were examined by the method of complete helminthological dissection, in case of receipt of individual organs, an incomplete dissection was performed. The material from 91 animals was examined.Results and discussion. According to the results of helminthological examination of the pine martens 23 species of parasites were identified: 13 species of nematodes, 2 species of cestodes, 6 trematodes and 2 acanthocephalans. All examined animals were infected (100%). The following nematodes were found in the gastrointestinal tract: Aonchotheca putorii (86.6%), Molineus patens (13.4%), Strongyloides martis (4.9%); cestodes Taenia martis (15.4%), Mesocestoides lineatus (1.2%); acanthocephalans Centrorhynchus sp. (19.5%); trematodes Isthmiophora melis (29.3%), Apophallus donicus (9.8%). Three species of trematodes were found in the liver: Metorchis bilis (6.8%), Pseudamphystomum truncatum (5.1%) and Opisthorchis felineus (1.7%). The paranal glands contained nematodes Capillaria paranalis (55.3%). In the lungs and trachea, 5 species of nematodes were found: Eucoleus aerophilus (96.4%), Filaroides martis (50.6%), Sobolevingylus skrjabini (36.1%), Crenosoma petrovi (25.3%), Aelurostrongylus falciformis (2.4%). In the nasal cavity of 73.1% of martens, the nematode Skrjabingylus petrowi was found. In the urinary bladder of 40.9% of martens, there were nematodes Pearsonema mucronata. In the muscle tissue, Trichinella were found in 6.8% of martens. Alaria larvae were found in the connective tissue of 15.4% of martens. The most common are Eu. aerophilus (96.4%), Ao. putorii (86.6%) and Skr. petrowi (73.1%). High infection rates in the natural environment indicate the formation of stable foci of parasitosis in the region.

Our purpose was to model a combination of a prolonged consumption of ethanol with Opisthorchis felineus infection in mice. Four groups of C57BL/6 mice were compiled: OF, mice infected with O. felineus for 6 months; Eth, mice consuming 20 % ethanol; Eth+OF, mice subjected to both adverse factors; and CON, control mice not exposed to these factors. In the experimental mice, especially in Eth+OF, each treatment caused well-pronounced periductal and cholangiofibrosis, proliferation of bile ducts, and enlargement of areas of inflammatory infiltration in the liver parenchyma. Simultaneously with liver disintegration, the infectious factor caused - in the frontal cerebral cortex - the growth of pericellular edema (OF mice), which was attenuated by the administration of ethanol (Eth+OF mice). Changes in the levels of some proteins (Iba1, IL-1β, IL-6, and TNF) and in mRNA expression of genes Aif1, Il1b, Il6, and Tnf were found in the hippocampus and especially in the frontal cortex, implying region-specific neuroinflammation. Behavioral testing of mice showed that ethanol consumption influenced the behavior of Eth and Eth+OF mice in the forced swimming test and their startle reflex. In the open field test, more pronounced changes were observed in OF mice. In mice of all three experimental groups, especially in OF mice, a disturbance in the sense of smell was detected (fresh peppermint leaves). The results may reflect an abnormality of regulatory mechanisms of the central nervous system as a consequence of systemic inflammation under the combined action of prolonged alcohol consumption and helminth infection.

Potential impact of climate change on Opisthorchis viverrini and Opisthorchis felineus transmission in Eurasia.

Infection with the fish-borne liver fluke Opisthorchis felineus, which is transmitted through the consumption of raw or undercooked fish, results in serious liver damage in humans. Currently, limited clinical and experimental data reveal kidney damage co-occurring with chronic opisthorchiasis. We conducted a retrospective analysis of kidney autopsy samples over a five-year period (n = 84). The aim of the study was to assess pathomorphological changes in the kidneys and evaluate whether there is an association between IgA nephropathy and liver fluke infection. Histological analysis, immunohistochemistry, and statistical analysis were performed. In this study, we demonstrated for the first time that chronic O. felineus infection in humans was associated with tubular dystrophy, the accumulation of renal tubular casts, and glomerulosclerosis. The hypertension increases the pathomorphological changes associated with chronic opisthorchiasis. We also detected IgA and the O. felineus total antigen in glomeruli of infected people. Fisher's test showed a significant association between O. felineus infection and IgA nephropathy, as well as between O. felineus infection and glomerulosclerosis. Therefore, the findings of this study highlight the importance of recognising O. felineus infection as a more than hepatobiliary disease and emphasise the need for careful, personalised monitoring of kidney function in infected individuals.

Transcriptome analysis reveals significant discrepancies between two in vitro models of host-trematode interaction.

Epidemiologically important food-borne trematodes Opisthorchis viverrini and Clonorchis sinensis are recognized as biological carcinogens of Group 1A, while Opisthorchis felineus is in Group 3 as noncarcinogenic to humans. Mechanisms of the biological carcinogenesis are still elusive. Some studies highlight chronic inflammation as a key factor and common pathway for cancer initiation and progression. Nonetheless, the chronic inflammation alone does not explain why these three species differ in carcinogenicity. We focused this study on genome-wide landscapes of liver gene expression and activation of cellular pathways in Mesocricetus auratus golden hamsters infected with C. sinensis (South Korea), O. viverrini (Thailand), or O. felineus (Russia) at 1 and 3 months after infection initiation. Liver transcriptomes of golden hamsters (HiSeq Illumina, 2X150 bp) were sequenced at 1 and 3 months postinfection. Data processing was carried out using the following bioinformatic and experimental approaches: analysis of differential gene expression, estimates of proportions of affected liver cell types, liver histopathology, and examination of weighted gene coexpression networks. All infections caused enrichment with inflammatory response signaling pathways, fibrogenesis and cell proliferation, and IL2-STAT5, TNF-NF-κB, TGF-β, Hippo, MAPK, and PI3K-Akt signaling pathways. Nevertheless, species-specific responses to each infection were noted too. We also identified species-specific responses of liver cell types, differentially expressed gene clusters, and cellular pathways associated with structural liver damage (such as periductal fibrosis, epithelial neoplasia, and inflammation). This is the first comparative analysis of gene expression landscapes in the liver of experimental animals infected with O. viverrini, O. felineus, or C. sinensis. The trematodes have species-specific effects on the hepatobiliary system by triggering signaling pathways, thereby leading to differences in the severity of hepatobiliary structural lesions and contributing to the pathogenicity of closely related foodborne trematodes.

The purpose of the research is to validate an optimized protocol for studying helminths using an improved staining method to improve the quality of diagnostics of trematodosis caused by representatives of the Opisthorchidae family. An additional objective was to study the prevalence of infection of definitive hosts within the identified focus of opisthorchiasis in the Lipetsk region.Materials and methods. Liver samples from 10 cats and 5 dogs that died in the Sosna River area (Lipetsk region), where an opisthorchiasis focus had previously been identified, were examined. Helminthological dissection was performed using the Skryabin method. The isolated trematode metacercariae were stained using an improved, previously patented technique based on the method of B. V. Romashov et al. (2003), using Gooch crucibles to improve the quality and convenience of staining. Morphometric studies and species identification of trematodes were carried out. The level of infection was assessed using the indices of number, intensity and prevalence of infection.Results and discussion. A higher prevalence of infection (60%) was found in cats compared to dogs (20%). Among cats, the dominant species was Pseudamphistomum truncatum (infection rate 20.1 ind.). Opisthorchis felineus and Metorchis bilis were also identified. P. truncatum (infection rate 60 ind.) and O. felineus were identified in the infected dog. The improved staining method reduced the examination time and improved the quality of visualization of trematode morphology. The results obtained indicate a wide distribution of P. truncatum among animals of the Lipetsk region and emphasize the significant role of domestic cats as the main reservoirs of infection.

Chronic nonhealing wounds, such as diabetic ulcers, are among the most serious complications of diabetes mellitus. Consequently, the search for new therapeutic strategies remains highly relevant. Based on our previous data on acute wounds, bioactive molecules derived from the liver fluke Opisthorchis felineus hold promise as a novel approach to wound healing. The aim of this study was to investigate the wound-healing properties of excretory-secretory products (ESP) and inactivated eggs of O. felineus in a model of type 2 diabetes mellitus. Two-month-old mice of the BKS.Cg + Leprdb/+Leprdb/OlaHsd (db/db) strain were inflicted with superficial wounds of 5 mm in diameter. Mouse groups included several controls (methylcellulose as the vehicle and human recombinant PDGF as the positive control) and specific-treatment groups (ESP and inactivated O. felineus eggs). Histopathological, immunohistochemical, and RT-PCR studies using markers for M1/M2 polarization, angiogenesis, and extracellular matrix remodeling were carried out. Additionally, an image analysis of Masson's trichrome-stained skin sections was performed. The proliferation of HaCaT cells under ESP and egg treatment was also assessed. The present study reveals a significant increase in the percentage of wound healing in ESP- and egg-treated groups, which significantly exceeded the control values after 14 days. Wound treatment with either ESP or worm eggs resulted in (i) a reduction in inflammation with a canonical M1-to-M2 polarization shift, (ii) the modulation of the vascular response, and (iii) dermal extracellular matrix remodeling. All results are comparable to those of the positive control group treated with PDGF. This study also reveals that ESP, but not O. felineus eggs, stimulated keratinocyte proliferation in vitro. The results indicate the high wound-healing potential of liver fluke bioactive molecules and open prospects for further research on these new promising therapeutic approaches.

Using the mechanochemical method, supramolecular compositions of a potential anthelmintic, artesunate (ARS) with sodium glycyrrhizinate (Na2GA), were obtained in different mass ratios of the components included in ARS-Na2GA complex (1 : 5, 1 : 10, and 1 : 20). The formation of an inclusion complex of ARS with Na2GA micelles was confirmed by NMR relaxation and the nuclear Overhauser effect (NOESY). It has been established that the ARS-Na2GA complex (1 : 10) has optimal physicochemical properties for further biological studies on the helminths Opisthorchis felineus, which cause opisthorchiasis in humans and animals. Experiments in vitro showed that ARS-Na2GA complex (1 : 10) had a more pronounced inhibition of motility both in invasive individuals of O. felineus (metacercariae) and in adult trematodes (maritae), compared with pure ARS, and even at low concentrations (0.1-10 μg/mL) for maritae. Despite the fact that the dose of ARS in the composition of ARS-Na2GA (1:10) was 11 times lower, the efficiency coefficient (IC50) declined 2.4-fold (for metacercariae) and 1.45-fold (for maritae) with respect to pure ARS. The results obtained indicate the availability of using the new complex for further studies on O. felineus-infected animals