Search Results (215)

Fasciolosis is a globally prevalent trematode infection of major veterinary and public-health relevance. Juveniles migrate through liver tissue for weeks before patency, so clinically important infection may occur while faecal egg output is undetectable, complicating control and interpretation of apparent treatment failure. Triclabendazole (TCBZ) remains central because it targets both immature and adult flukes, but sustained use has been accompanied by geographically expanding reports of reduced efficacy and confirmed resistance. Most alternative fasciolicides, such as albendazole, closantel, oxyclozanide, rafoxanide, clorsulon and nitroxynil, are largely adulticidal and used alone or in combinations, yet reports of reduced efficacy/resistance are increasing worldwide. This review summarises drugs in current use and reported resistance status, and outlines a practical pathway for detecting and confirming resistance. We then appraise leading mechanistic hypotheses for TCBZ resistance as a central case study, organised around microtubule-associated phenotypes, reduced effective drug exposure, genetic architecture with tissue context, stress response and detoxification capacity, and we highlight mechanistic gaps for other fasciolicides. Finally, we discuss management implications, including monitoring-guided stewardship, stage-appropriate drug selection, rational combinations, integrated parasite management, and identify near-term priorities for harmonised surveillance, improved diagnostics and tool development. This review updates the resistance landscape and supports practical, monitoring-guided control of fasciolosis. Full article

Background: Schistosoma spp. are trematodes occurring in tropical endemic areas but can be imported to non-endemic regions as causes of travel-associated infections. In this study, two pan-trematode-specific real-time PCR assays were evaluated for their diagnostic sensitivity in detecting Schistosoma spp. DNA in diagnostic human samples. Methods: Two previously described pan-trematode-specific real-time PCR assays were comparatively assessed using diagnostic samples containing DNA of either the S. haematobium complex or the S. mansoni complex, as confirmed by Schistosoma species complex-specific real-time PCR. Results: Out of a total of 655 samples containing Schistosoma spp. DNA, positive signals in at least one of the two pan-trematode real-time PCR assays were recorded for 17 (2.6%) nucleic acid extractions. Although sensitivity was in the >90% range for stool samples, only a few individual blood plasma and serum samples, and none of the Schistosoma spp. DNA-containing tissue or urine samples, tested positive by pan-trematode PCR. The lower sensitivity of pan-trematode PCR compared with Schistosoma spp.-specific PCR was semi-quantitatively confirmed by higher cycle threshold (Ct) values in the former. When comparing samples with concordant versus discordant positive results for Schistosoma spp.-specific and pan-trematode PCR, Ct values of the Schistosoma spp.-specific PCR were lower in concordantly positive samples than in discordantly positive samples. Conclusions: While the assessed pan-trematode PCR assays showed insufficient sensitivity as screening tools for blood plasma, blood serum, tissue, and urine samples from individuals with suspected schistosomiasis, they were sufficiently sensitive when applied to stool samples, in which substantial amounts of target DNA, as indicated by low Ct values in the Schistosoma species complex-specific real-time PCR assays, can be expected. For screening for Schistosoma spp. DNA in sample materials other than stool, the use of highly sensitive target-specific PCR remains necessary. Full article

Fascioloidosis is a parasitic disease caused by allochthonous parasite Fascioloides magna. In Europe, three types of final hosts are recognised: definitive, aberrant, and dead end. Several countries have launched disease control programmes using medicated feed, with different drugs, to control F. magna infections. In this study, we used corn treated with Albix^® 10 in a total dose of 60 mg/kg of body weight for five consecutive days (12 mg/kg per day). Following successful treatment, a destroyed pseudocyst with different amounts of degrading material and decaying flukes was detected. A total of 136 livers was examined. The average number of pseudocysts per positive liver was seven (min. 1–max. 45), while the average number of adult flukes was 14.17 (2–70). On average, 1.34 juvenile flukes in the migratory phase were detected per infected liver. The average number of pseudocysts was 7.07 per liver in total. Degrading pseudocysts were either absent or present to a maximum of 120 per liver, with an average of 7.99 per liver. Some livers had multifocal to confluent nodules bulging from the liver parenchyma, which were up to 7 cm in diameter. Histologically, these areas showed disruption, containing bands of fibrous connective tissue, dividing parenchyma into pseudolobules of varying size and shape. These septa contained dark brown to black pigment (iron porphyrin), along with remnants of elliptical, operculated, mainly empty trematode eggs. Nodules were surrounded with fibrous tissue and disorganised hyperplastic hepatocytes arranged in irregular trabeculae supported by fibrous bands occasionally containing blood vessels. This study shows the potential of liver regeneration in the case of acute and chronic liver injury, as well as in cases of fatty liver disease. Full article

Parasitism affects nearly half of all animal species and strongly influences ecosystem dynamics. Despite their sentinel value, parasitic infections in cetaceans remain understudied. This study assessed the diversity, prevalence, and burden of gastrointestinal and pulmonary parasites in seventy-five stranded cetaceans from six species along the central and northern Portuguese coastline. Coprological methods included Mini-FLOTAC^®, Willis-flotation, natural sedimentation, modified Ziehl–Neelsen staining, direct immunofluorescence, and adapted spontaneous sedimentation. Overall, 61.3% of samples tested positive for at least one parasitic taxon, with 22.7% showing coinfections. Anisakidae and Ascaridida were the most prevalent (36%), followed by Pseudaliidae larvae (5.3%), unidentified trematode eggs (8.0%), Odhneriella spp. (5.3%), Nasitrema spp. (2.7%), Zalophotrema spp. (2.7%), and Synthesium spp. (1.3%). Nematode eggs exhibited the highest mean burden, with anisakids reaching 4862 eggs per gram of feces (EPG), whereas trematodes showed a markedly lower burden, exemplified by Zalophotrema spp. with 90 EPG. All samples assessed were negative for Cryptosporidium spp. and Giardia spp. Unidentified ovoid structures were present in 76% of samples. Macroscopic sedimentation revealed anisakid larvae, one cestode, over fifty Ogmogaster antarctica specimens, and six marine arthropods. These findings provide baseline data for cetacean parasitology and support future integrative research for conservation and ecosystem health. Full article

Humboldt penguins (Spheniscus humboldti) are classified as Vulnerable and listed in Appendix I of CITES, making the investigation of stranding and mortality causes essential for their conservation. This study describes the post-mortem findings of five Humboldt penguins stranded along the Chilean coast during 2025, focusing on renal and ureteral lesions associated with trematode infection. Gross examination revealed multifocal to coalescing renal lesions, including intrapelvic white purulent material and marked thickening of the ureteral walls. Histopathological analysis demonstrated moderate to severe renal and ureteral inflammation, characterized by intratubular and intraureteral trematodes associated with tubular degeneration, interstitial inflammation and fibrosis, vascular alterations, occasional glomerular changes, and severe ureteritis. Morphological and morphometric analyses of adult parasites obtained from histological renal sections confirmed the presence of trematodes. On clinical evaluation, stranded animals presented with lethargy, no evidence of external trauma, and body condition ranging from normal to emaciated. These findings confirm the presence of trematode-associated nephropathy and ureteropathy in Humboldt penguins. To our knowledge, this is the first report worldwide linking renal and ureteral parasitosis to disease in this species. Further molecular analyses are required to achieve definitive etiological identification and to support the recognition of this condition as an emerging disease relevant to conservation strategies for Humboldt penguins. Full article

A liver fluke, Clonorchis sinensis is a representative fish-borne parasite infecting humans, and sensitive detection in fish hosts or aquatic environments is important for monitoring infection sources in endemic areas. Conventional diagnostic methods based on microscopy or conventional PCR often show limited sensitivity, particularly under low-parasite conditions. In this study, we developed a high-sensitive and species-specific molecular marker and established a real-time PCR (qPCR)-based diagnostic method targeting metacercariae isolated from freshwater fish, representing the transmission stage of C. sinensis. Primers and a hydrolysis probe targeting the mitochondrially encoded cytochrome c oxidase 1 (COI) gene were designed, and all primer combinations produced stable amplifications with single melt curves in C. sinensis-positive samples. Among them, one combination was finally selected as the optimal marker due to its high specificity, including validation against mixed trematode samples to confirm species-specific detection. The qPCR assay showed excellent linearity (R² = 0.998), with a detection limit of 10¹ copies per reaction and a quantification limit of 10² copies per reaction. In addition, the assay successfully detected C. sinensis DNA in environmental water samples spiked with metacercariae, demonstrating its applicability to aquatic samples for environmental surveillance purposes. Compared with conventional PCR, the developed qPCR method in this study exhibited markedly improved sensitivity in fish-derived samples. Overall, this qPCR assay provides a robust diagnostic tool for laboratory analysis and has potential utility for environmental DNA-based monitoring of clonorchiasis risk areas within a One Health framework. Full article

During the examination of a bicolor angelfish (Centropyge bicolor) imported from the Philippines and intended for sale on the Polish market, clinical signs of weakness and respiratory distress were observed. Mild hyperemia was noted along the lateral sides of the body and around the mouth. Necropsy revealed the presence of five orange-colored trematodes in the intestinal lumen, with an average body length of 3.12 mm. Based on morphological features and molecular analyses, the parasite was identified as Paragyiauchen sp. The following gene loci were amplified: the gene-encoding component of the large ribosomal subunit (28S rRNA), the gene-encoding NADH dehydrogenase subunit 1 (ND1), the gene cluster 5.8S rRNA-ITS2-28S rRNA and the gene cluster ITS2-28S rRNA. Bacterial species identification using MALDI-TOF MS revealed the presence of three species: Shewanella putrefaciens and Brevundimonas diminuta isolated from the head kidney, and Aeromonas caviae isolated from the liver. This study documents the first detection of representatives of Paragyliauchen genus in C. bicolor imported to Europe and highlights the potential risk of introducing new parasites and opportunistic bacterial pathogens through the ornamental fish trade. These findings emphasize the need for parasitological and microbiological screening of imported ornamental fish. Full article

Parasitic infections pose a significant threat to the wild population of Southern catfish (Silurus meridionalis) in Dongting Lake, yet the specific pathogen identity and epidemiological drivers remain unclear. This study combined morphological assessment, 28S rDNA molecular identification, and Generalized Linear Models (GLM) to elucidate the infection dynamics and pathogenicity of trematodes. Molecular analysis confirmed the pathogen as Isoparorchis eurytremus. GLM analysis revealed that apparent spatiotemporal variations in infection were actually sampling bias in fish host size structure; the total length was identified as the decisive predictor of infection risk. The infection probability followed a sigmoid growth pattern with a median infection length (L₅₀) of 70.4 cm, a phenomenon attributed to the host’s ontogenetic diet shift from insectivory to obligate piscivory. Anatomical observations indicated that the infection induced systemic pathology; beyond severe fibrosis and mechanical damage to the swim bladder, varying degrees of parenchymal lesions were evident in the liver, spleen, and kidney. These findings indicate that I. eurytremus infection in S. meridionalis is a size-dependent, accumulative process maintaining a homogenous high pressure across the lake ecosystem, necessitating a shift in perspective from localized lesions to systemic disease management. Full article

Fascioloides magna, an invasive trematode introduced to Europe in the 19th century, persists in two main foci: the Danube basin and La Mandria Natural Park (LMNP) in northern Italy. This study assessed whether the parasite has spread beyond LMNP and evaluated environmental and host-related risk factors. Between 2012 and 2023, 331 wild ruminant livers were examined, and faecal samples were analysed for fluke eggs. Gastropods from the LMNP were sampled using a predictive habitat suitability model and screened for F. magna DNA. Camera traps monitored ungulate movements across LMNP boundaries. Results confirmed the parasite’s presence in red and fallow deer within LMNP and sporadic cases in roe deer, but no evidence of infection in wildlife or gastropods outside the park. Molecular screening detected F. magna DNA in 9.2%% of snails inside LMNP only. Despite occasional crossings by potential definitive hosts, ecological conditions outside LMNP appear unsuitable for sustaining the parasite’s life cycle. These findings suggest a low current risk of spread but highlight the need for continued surveillance and barrier reinforcement. The integrated approach combining parasitology, molecular diagnostics, and GIS-based risk mapping provides a valuable framework for managing invasive parasitic diseases in wildlife. Full article

Protected national parks continue to face increased pressure from the expansion of human–wildlife interface zones, where habitat encroachment promotes human–wildlife contact and zoonotic disease transmission. Gastrointestinal parasites (GIPs) are a significant health issue in wild Asian elephants (Elephas maximus), affecting their fitness, survival, and potential for cross-species transmission. This study aimed to investigate the prevalence of GIPs among wild elephants at Khao Sip Ha Chan National Park in eastern Thailand. Direct smear, formalin-ethyl acetate sedimentation, flotation, and McMaster egg per gram (EPG) counting were used to examine 135 fecal samples from three populations. The findings showed that nematodes (Strongyle-type and Strongyloides spp.) and trematodes (Paramphistomum spp. and Fascioloides jacksoni) were identified. All samples were positive for at least one parasite species, and 84.4% were affected by mixed infections. The prevalence of Strongyle-type and Strongyloides spp. varied significantly among the studied populations, but Paramphistomum spp. had a moderate prevalence, and Fascioloides jacksoni had a low prevalence. The high parasite burden could be explained by environmental factors, host density, and movement patterns influencing parasite transmission, and these factors should be further investigated. These findings provide crucial baseline data and underscore the need for integrated parasite surveillance, alongside long-term conservation and future research. Full article

Melanoides tuberculata is one of the world’s main invasive snail species; therefore, mapping its occurrence is essential for predicting its dispersion patterns and proposing control measures. This study aimed to map the occurrence of M. tuberculata and its associated parasites in a tourist waterfall complex located in Fortaleza dos Nogueiras, Southern Maranhão, Brazil. We collected snails over three months (July, August, and September 2025) in the Castanhão, Esmeralda, and Recanto das Águias waterfalls, and in the Panela stream, to estimate their reproductive stage and to assess the presence of parasites. We demonstrated for the first time the occurrence of M. tuberculata at all evaluated collection points. Morphological data of the shells suggested that the M. tuberculata populations were in the initial phase of their reproductive cycle; however, some specimens showed a complete reproductive stage. Additionally, we found M. tuberculata infected with trematode larvae that resembled the Gymnocephalus-type cercariae in the Castanhão waterfall and Panela stream. Therefore, we updated the distribution of M. tuberculata in Brazil and discussed the possible environmental and public health impacts of this species in the study area. Full article

The role of extracellular vesicle non-coding RNAs in host–parasite interactions remains poorly understood, particularly for human liver flukes. Although tRNA-derived small RNAs (tsRNAs) are emerging as new regulatory molecules in parasite exosomes, they have not yet been characterized for the liver flukes. We performed small RNA sequencing to profile tsRNAs in the exosome-like vesicles derived from the liver fluke Opisthorchis felineus. Transcriptomic data from human cholangiocytes were analyzed to assess the enrichment of the predicted target genes among differentially expressed genes. We identified 247 functional tRNA genes in the O. felineus genome. Exosome-like vesicles were highly enriched for particular tsRNAs: derived from tRNA-Asp-GTC, tRNA-Ile-AAT, tRNA-Lys, tRNA-His, and tRNA-Tyr. This enrichment was independent of both genomic tRNA copy number and the amino acid composition of the trematode proteome. In silico prediction revealed that these tsRNAs target human genes involved in cell cycle, migration, and proliferation. Notably, these predicted target genes were significantly enriched among the differentially expressed genes in treated cholangiocytes. Our study provides the first evidence that O. felineus exosomes carry a specific repertoire of tsRNAs with the potential to regulate host gene networks. We propose that tsRNAs may contribute to host cell manipulation during O. felineus infection. Full article

The trematode Clinostomum marginatum, secretes excretory-secretory products (ESPs) which have the potential to increase the viability and antioxidant activity of probiotic strains. The aim of this study was to identify the ESP profile of C. marginatum and to evaluate its anti-inflammatory activity in RAW 264.7 macrophages, as well as its effect on the viability and antioxidant activity of a consortium of bacteria comprising Lactobacillus and/or Bifidobacterium. C. marginatum was maintained in RPMI-1640 medium for ESP collection. Anti-inflammatory activity was assessed in LPS-stimulated RAW264.7 cells treated with 800 µg/mL of ESPs, measuring cell viability, nitric oxide production, and the relative expression of pro-inflammatory cytokines (IL-6, TNF-α, INF-γ) and the COX-2 gene by qPCR. The influence of ESPs (800–1600 µg/mL) on probiotic viability and antioxidant activity was determined using MTT, DPPH, hydroxyl, and superoxide radical scavenging assays. C. marginatum showed 74% survival in vitro, and SDS-PAGE analysis revealed three major protein bands in the ESPs (47, 54, and 58 kDa). ESP treatment significantly reduced nitric oxide and the mRNA expression of pro-inflammatory markers in LPS-activated macrophages. ESPs supplemented at 1200 µg/mL optimized the growth kinetics of Lactobacillus (specific growth rate μ_L = 1.12 h⁻¹, doubling time t_d = 0.62 h) and Bifidobacterium (μ_B = 1.09 h⁻¹, t_d = 0.63 h) compared to control conditions. In conclusion, ESPs from C. marginatum exhibited significant anti-inflammatory and antioxidant effects while enhancing bacterial viability, which positions them as promising candidates for biotherapeutics agents in the management of inflammatory control and gut microbiota modulation. Full article

Human schistosomiasis is a neglected tropical disease caused by six Schistosoma species, the most widespread of which is S. mansoni. Despite its high prevalence in Africa, molecular data on the parasite remain scarce in many regions, including the Republic of Guinea. This study presents the first molecular characterization of S. mansoni from naturally infected Biomphalaria pfeifferi snails in Guinea. Eight cox1 and four nd5 mitochondrial gene fragments, 353–425 bp and 259–271 bp in length, respectively, were sequenced. A new cox1 haplotype of S. mansoni was identified in this study. High genetic diversity was observed in our samples for both cox1 (Hd = 0.75) and nd5 (Hd = 0.84). Phylogeographic analysis revealed that the dominant Guinean cox1 haplotypes are shared with other West African populations, and that one haplotype is globally dispersed, linking West Africa to South America and the Middle East. Phylogenetic reconstructions confirmed the divergence between West and Southeast African populations and supported the hypothesis of a Southeast African origin for S. mansoni, with a subsequent expansion to West Africa and the New World. These results highlight the importance of expanding molecular surveillance to improve our understanding of the spread and population structure of this human pathogen. Full article

Exosomes are important mediators of host–parasite communication and contain diverse molecules that may support the survival of Clonorchis sinensis in the biliary tract. To explore their biochemical properties, exosomes isolated from excretory–secretory products of Korean C. sinensis isolates were characterized through integrated morphological, proteomic, and gene ontology analyses. The vesicles exhibited typical exosomal size ranges and marker profiles, and their protein components were enriched for cytoskeletal, metabolic, and vesicle-trafficking components relevant to epithelial signaling and immune modulation. Among these proteins, sphingomyelin phosphodiesterase acid-like 3A (SMPDL3A) was examined in detail to obtain molecular evidence suggesting its role in sphingolipid metabolism in the parasite. The C. sinensis SMPDL3A (Cs_SMPDL3A) shared the overall structure and core catalytic residues with mammalian homologs, SMPDL3A and sphingomyelin phosphodiesterase 1 (SMPD1), a finding consistent with the possibility that Cs_SMPDL3A may retain authentic sphingomyelinase activity. Although lacking the saponin B domain of SMPD1, Cs_SMPDL3A carries a C-terminal transmembrane segment that may facilitate sphingomyelin access by positioning the enzyme on lipid bilayers. Collectively, these findings suggest that Cs_SMPDL3A participates in host sphingomyelin turnover, potentially generating ceramide for uptake by SMPD1-lacking C. sinensis or contributing to ceramide-associated immune responses in the biliary tract, offering new insight into lipid-centered host–parasite interactions during clonorchiasis. Full article