Trematode Genomics and Proteomics.

Trematode infections stand out as one of the frequently overlooked tropical diseases, despite their wide global prevalence and remarkable capacity to parasitize diverse host species and tissues. Furthermore, these parasites hold significant socio-economic, medical, veterinary and agricultural implications. Over the past decades, substantial strides have been taken to bridge the information gap concerning various "omic" tools, such as proteomics and genomics, in this field. In this edition of the book, we highlight recent progress in genomics and proteomics concerning trematodes with a particular focus on the advances made in the past 5 years. Additionally, we present insights into cutting-edge technologies employed in studying trematode biology and shed light on the available resources for exploring the molecular facets of this particular group of parasitic helminths.

Diagnosis of Human Trematode Infections.

Digenetic trematodes form a major group of human parasites, affecting a large number of humans, especially in endemic foci. Over 100 species have been reported infecting humans, including blood, lung, liver and intestinal parasites. Traditionally, trematode infections have been diagnosed by parasitological methods based on the detection and the identification of eggs in different clinical samples. However, this is complicated due to the morphological similarity between eggs of different trematode species and other factors such as lack of sensitivity or ectopic locations of the parasites. Moreover, the problem is currently aggravated by migratory flows, international travel, international trade of foods and changes in alimentary habits. Although efforts have been made for the development of immunological and molecular techniques, the detection of eggs through parasitological techniques remains as the gold standard for the diagnosis of trematodiases. In the present chapter, we review the current status of knowledge on diagnostic techniques used when examining feces, urine, and sputum and also analyze the most relevant characteristics used to identify eggs with a quick key for the identification of eggs.

Helminth Control Practices in Sheep and Cattle in Urban and Peri-Urban Areas of Adea District, Central Ethiopia.

Introduction: Gastrointestinal helminth parasitism is an important problem of livestock in many places of the globe. Despite the fact that the disease is one of the leading causes of economic losses, there is little information on the occurrence of the infection in cattle and sheep in Ethiopia. Methods: A cross-sectional study was conducted from June 2022 to February 2023 in urban and peri-urban areas of the Ada'a District with the objective of estimating the prevalence of gastrointestinal helminth parasites (GIHPs) in sheep and cattle and to assess the commercial anthelmintic utilization practices and associated risk factors in sheep and cattle. A total of 351 randomly selected fecal samples (192 cattle and 159 sheep) were collected from the rectum and examined using flotation and sedimentation. One hundred respondents were interviewed for questionnaire surveys on anthelmintic utilization practices. Results and Discussion: The overall prevalence of GIHPs (61.25%) was recorded during the study. Among the animals, 55.21% and 68.55% prevalence of the infection was observed in cattle and sheep, respectively. There was a statistically significant difference (P < 0.05) in gastrointestinal helminth parasite (GIHP) infection between the study animal species, breeds, body condition of the animals, and production systems. However, there were no significant differences in gastrointestinal helminth parasite (GIHP) infection (P > 0.05) according to sex and age of the animals. A higher prevalence of strongyle (55.34%), fasciola (13.48%), and moniezia eggs (10.69%) was recorded. According to a questionnaire survey, ivermectin was found to be the most used anthelmintic drug. This study addresses the challenge of anthelmintic resistance (AR) against currently available anthelmintics; highly prevalent parasitic infections are causing tremendous economic losses to the animal industry.

Schistosomiasis.

Schistosomiasis is a major cause of morbidity in the world and almost 800 million people worldwide are at risk for schistosomiasis; it is second only to malaria as a major infectious disease. Globally, it is estimated that the disease affects more than 250 million people in 78 countries of the world and is responsible for some 280,000-500,000 deaths each year. The three major schistosomes infecting humans are Schistosoma mansoni, S. japonicum, and S. haematobium. This chapter covers a wide range of aspects of schistosomiasis, including basic biology of the parasites, epidemiology, immunopathology, treatment, control, vaccines, and genomics/proteomics. In this chapter, the reader will understand the significant toll this disease takes in terms of mortality and morbidity. A description of the various life stages of schistosomes is presented, which will be informative for both those unfamiliar with the disease and experienced scientists. Clinical and public health aspects are addressed that cover acute and chronic disease, diagnosis, current treatment regimens and alternative drugs, and schistosomiasis control programs. A brief overview of genomics and proteomics is included that details recent advances in the field that will help scientists investigate the molecular biology of schistosomes. The reader will take away an appreciation for general aspects of schistosomiasis and the current research advances.

Paragonimiasis.

Paragonimiasis is a zoonotic disease caused by lung flukes of the genus Paragonimus. Humans usually become infected by eating freshwater crabs or crayfish containing encysted metacercariae of these worms. However, an alternative route of infection exists: ingestion of raw meat from a mammalian paratenic host. Adult worms normally occur in pairs in cysts in the lungs from which they void their eggs via air passages. The pulmonary form is typical in cases of human infection due to P. westermani, P. heterotremus, and a few other species. Worms may occupy other sites in the body, notably the brain, but lung flukes have made their presence felt in almost every organ. Ectopic paragonimiasis is particularly common when infection is due to members of the P. skrjabini complex. Human paragonimiasis occurs primarily in the tropics and subtropics of Asia, Africa, and the Americas, with different species being responsible in different areas (Table 6.1).

Echinostomes and Other Intestinal Trematode Infections.

Intestinal trematodes are among the most common types of parasitic worms. About 76 species belonging to 14 families have been recorded infecting humans. Infection commonly occurs when humans eat raw or undercooked foods that contain the infective metacercariae. These parasites are diverse in regard to their morphology, geographical distribution and life cycle, which make it difficult to study the parasitic diseases that they cause. Many of these intestinal trematodes have been considered as endemic parasites in the past. However, the geographical limits and the population at risk are currently expanding and changing in relation to factors such as growing international markets, improved transportation systems, new eating habits in developed countries and demographic changes. These factors make it necessary to better understand intestinal trematode infections. This chapter describes the main features of human intestinal trematodes in relation to their biology, epidemiology, host-parasite relationships, pathogenicity, clinical aspects, diagnosis, treatment and control.

Global distribution of zoonotic digenetic trematodes: a scoping review.

BACKGROUND: Digenetic trematodes, including blood flukes, intestinal flukes, liver flukes, lung flukes, and pancreatic flukes, are highly diverse and distributed widely. They affect at least 200 million people worldwide, so better understanding of their global distribution and prevalence are crucial for controlling and preventing human trematodiosis. Hence, this scoping review aims to conduct a comprehensive investigation on the spatio-temporal distribution and epidemiology of some important zoonotic digenetic trematodes. METHODS: We conducted a scoping review by searching PubMed, Web of Science, Google Scholar, China National Knowledge Infrastructure, and Wanfang databases for articles, reviews, and case reports of zoonotic digenetic trematodes, without any restrictions on the year of publication. We followed the inclusion and exclusion criteria to identify relevant studies. And relevant information of the identified studies were collected and summarized. RESULTS: We identified a total of 470 articles that met the inclusion criteria and were included in the review finally. Our analysis revealed the prevalence and global distribution of species in Schistosoma, Echinostoma, Isthmiophora, Echinochasmus, Paragonimus, Opisthorchiidae, Fasciolidae, Heterophyidae, and Eurytrema. Although some flukes are distributed worldwide, developing countries in Asia and Africa are still the most prevalent areas. Furthermore, there were some overlaps between the distribution of zoonotic digenetic trematodes from the same genus, and the prevalence of some zoonotic digenetic trematodes was not entirely consistent with their global distribution. The temporal disparities in zoonotic digenetic trematodes may attribute to the environmental changes. The gaps in our knowledge of the epidemiology and control of zoonotic digenetic trematodes indicate the need for large cohort studies in most countries. CONCLUSIONS: This review provides important insights into the prevalence and global distribution of some zoonotic digenetic trematodes, firstly reveals spatio-temporal disparities in these digenetic trematodes. Countries with higher prevalence rate could be potential sources of transmitting diseases to other areas and are threat for possible outbreaks in the future. Therefore, continued global efforts to control and prevent human trematodiosis, and more international collaborations are necessary in the future.

An insulin-like signalling pathway model for Fasciola gigantica.

BACKGROUND: The insulin/insulin-like signalling (IIS) pathway is common in mammals and invertebrates, and the IIS pathway is unknown in Fasciola gigantica. In the present study, the IIS pathway was reconstructed in F. gigantica. We defined the components involved in the IIS pathway and investigated the transcription profiles of these genes for all developmental stages of F. gigantica. In addition, the presence of these components in excretory and secretory products (ESPs) was predicted via signal peptide annotation. RESULTS: The core components of the IIS pathway were detected in F. gigantica. Among these proteins, one ligand (FgILP) and one insulin-like molecule binding protein (FgIGFBP) were analysed. Interestingly, three receptors (FgIR-1/FgIR-2/FgIR-3) were detected, and a novel receptor, FgIR-3, was screened, suggesting novel functions. Fg14-3-3ζ, Fgirs, and Fgpp2a exhibited increased transcription in 42-day-old juveniles and 70-day-old juveniles, while Fgilp, Fgigfb, Fgsgk-1, Fgakt-1, Fgir-3, Fgpten, and Fgaap-1 exhibited increased transcription in metacercariae. FgILP, FgIGFBP, FgIR-2, FgIR-3, and two transcription factors (FgHSF-1 and FgSKN-1) were predicted to be present in FgESPs, indicating their exogenous roles. CONCLUSIONS: This study helps to elucidate the signal transduction pathway of IIS in F. gigantica, which will aid in understanding the interaction between flukes and hosts, as well as in understanding fluke developmental regulation, and will also lay a foundation for further characterisation of the IIS pathways of trematodes.

Development and utilization of a visual loop-mediated isothermal amplification coupled with a lateral flow dipstick (LAMP-LFD) assay for rapid detection of Echinostomatidae metacercaria in edible snail samples.

Trematodes belonging to the family Echinostomatidae are food-borne parasites which cause echinostomiasis in animals and humans. This is a global public health issue, particularly in East and Southeast Asia. A method to detect the infective stage of Echinostomatidae species is required to prevent transmission to humans. In this study, a loop-mediated isothermal amplification coupled with a lateral flow dipstick (LAMP-LFD) assay was developed for visual detection of the metacercarial stage in edible snails of the genus Filopaludina from local markets in Thailand. The LAMP-LFD method can be performed within 70 min at a consistent temperature of 66 °C, and the results can be interpreted with the naked eye. The detection limits of the assay using Echinostoma mekongi, E. macrorchis, E. miyagawai and Hypoderaeum conoideum genomic DNA were equal between the four species at 50 pg/µL. A specificity evaluation demonstrated that the LAMP-LFD assay had no cross-reaction with another parasite (Thapariella species) or with the snail host species (Filopaludina martensi martensi, F. sumatrensis speciosa, and F. s. polygramma). Clinical test assessments were compared to microscopic examination in 110 edible snail samples. The clinical sensitivity and specificity of the tests were 84.62 % and 100 %, respectively, with a strong level of agreement based on the kappa statistic and the results of both methods were not significantly different (p > 0.05) per McNemar's test. The test successfully developed in this study may be useful for the detection of the metacercarial stage in edible snails for epidemiological investigations, control, surveillance, and to prevent future echinostomiasis health issues.

Trematode infection in ruminants and diversity of snail hosts across three agro-ecological zones in Ethiopia.

The occurrence of trematodes among ruminants and their snail vectors is a major concern across various agro-ecological regions of Ethiopia. Trematodes pose significant threats to animals, causing considerable economic losses and impacting public health. In this study, we have investigated 784 ruminant fecal samples, and 520 abattoir samples, alongside the collection and identification of snail vectors from various agro-ecological regions. Fecal examinations revealed Fasciola, Paramphistomum and Schistosoma species infected 20.5% (95% CI: 17.6, 23.8), 11.7% (95% CI: 9.6, 14.2), and 6.3% (95% CI: 4.1, 9.1) of the animals, respectively. The overall prevalence of trematodes among ruminants was 28.8% (95% CI: 25.7, 32.1%), with 6.0% (95% CI: 4.3, 7.7) showing mixed infections. Fasciola was more prevalent in Asela (26%) compared to Batu (19%) and Hawassa (11.5%), while a higher proportion of animals in Batu were infected with Paramphistomum. Schistosoma eggs were detected only in Batu (12.5%), but not in other areas. Sheep and cattle exhibited higher infection rates with Fasciola, Paramphistoma, and Schistosoma compared to goats. Significant associations were observed between trematode infections and risk factors including agro-ecology, animal species, body condition score, and deworming practices. About 20.8% and 22.7% of the slaughtered animals harbored Fasciola and Paramphistomum flukes, respectively, with a higher prevalence in Asela and Hawassa abattoirs compared to Batu abattoir. Additionally, a total of 278 snails were collected from the study areas and identified as lymnae natalensis, lymnae trancatula, Biomphalaria pffiferi, Biomphlaria sudanica, and Bulinus globosus. In conclusion, the study highlights the widespread occurrence of trematode infections, emphasizing the need for feasible control measures to mitigate their economic and public health impacts.

Identification of Lepidapedon oregonense as the current world's deepest trematode.

The deepest recorded depth for trematodes currently stands at approximately 6200 m. This depth record was achieved solely through sequence datasets of Lepidapedon sp. obtained from a gastropod. Given that trematodes of this genus typically use fish as definitive hosts, the origin of the trematode sequence was thought to be larval stages. However, the specific species remained unclear owing to the absence of reported adult-stage sequences. In the present study, we definitively identified the deepest trematode as Lepidapedon oregonense by comparing 28S ribosomal DNA sequences from adult worms from the macrourid fish Coelorinchus gilberti with data from the gastropod in the previous study.

Assessing the Combined Effects of Host and Parasite Exposure to Forever Chemicals in an Amphibian-Echinostome System.

Per- and polyfluoroalkyl substances (PFAS) are environmental contaminants of growing concern due to their potential negative effects on wildlife and human health. Per- and polyfluoroalkyl substances have been shown to alter immune function in various taxa, which could influence the outcomes of host-parasite interactions. To date, studies have focused on the effects of PFAS on host susceptibility to parasites, but no studies have addressed the effects of PFAS on parasites. To address this knowledge gap, we independently manipulated exposure of larval northern leopard frogs (Rana pipiens) and parasites (flatworms) via their snail intermediate host to environmentally relevant PFAS concentrations and then conducted trials to assess host susceptibility to infection, parasite infectivity, and parasite longevity after emergence from the host. We found that PFAS exposure to only the host led to no significant change in parasite load, whereas exposure of parasites to a 10-µg/L mixture of PFAS led to a significant reduction in parasite load in hosts that were not exposed to PFAS. We found that when both host and parasite were exposed to PFAS there was no difference in parasite load. In addition, we found significant differences in parasite longevity post emergence following exposure to PFAS. Although some PFAS-exposed parasites had greater longevity, this did not necessarily translate into increased infection success, possibly because of impaired movement of the parasite. Our results indicate that exposure to PFAS can potentially impact host-parasite interactions. Environ Toxicol Chem 2024;43:1537-1546. © 2024 SETAC.

Freshwater trematodes differ from marine trematodes in patterns connected with division of labor.

Background: Prior research suggests that trematode rediae, a developmental stage of trematode parasites that reproduce clonally within a snail host, show evidence of division of labor (DOL). Single-species infections often have two morphologically distinct groups: small rediae, the 'soldiers', are active, aggressive, and do not appear to reproduce; large rediae, the 'reproductives', are larger, sluggish, and full of offspring. Most data supporting DOL come from trematodes infecting marine snails, while data from freshwater trematodes are more limited and generally do not supported DOL. The shorter lifespan typical of freshwater snails may partially explain this difference: defending a short-lived host at the expense of reproduction likely provides few advantages. Here, we present data from sixty-one colonies spanning twenty species of freshwater trematode exploring morphological and behavioral patterns commonly reported from marine trematodes believed to have DOL. Methods: Trematode rediae were obtained from sixty-one infected snails collected in central Vermont, USA. A portion of the COI gene was sequenced to make tentative species identifications ('COI species'). Samples of rediae were photographed, observed, and measured to look for DOL-associated patterns including a bimodal size distribution, absence of embryos in small rediae, and pronounced appendages and enlarged pharynges (mouthparts) in small rediae. Additional rediae were used to compare activity levels and likelihood to attack heterospecific trematodes in large vs. small rediae. Results: Many of the tests for DOL-associated patterns showed mixed results, even among colonies of the same COI species. However, we note a few consistent patterns. First, small rediae of most colonies appeared capable of reproduction, and we saw no indication (admittedly based on a small sample size and possibly insufficient attack trial methodology) that small rediae were more active or aggressive. This differs from patterns reported from most marine trematodes. Second, the small rediae of most colonies had larger pharynges relative to their body size than large rediae, consistent with marine trematodes. We also observed that colonies of three sampled COI species appear to produce a group of large rediae that have distinctly large pharynges. Conclusions: We conclude that these freshwater species likely do not have a group of specialized non-reproductive soldiers because small rediae of at least some colonies in almost every species do appear to produce embryos. We cannot rule out the possibility that small rediae act as a temporary soldier caste. We are intrigued by the presence of rediae with enlarged pharynges in some species and propose that they may serve an adaptive role, possibly similar to the defensive role of small 'soldier' rediae of marine trematodes. Large-pharynx rediae have been documented in other species previously, and we encourage future efforts to study these large-pharynx rediae.

Transversotrema hafniensis n. sp. infection in Poecilia reticulata by cercariae released from Melanoides tuberculata in Denmark.

BACKGROUND: Exotic and ornamental fish are highly popular companion animals resulting in a significant transcontinental trade of fish, invertebrates and aquatic plants. A major issue is the diseases associated with these organisms, as they have a major impact on health of the fish in both public and private household aquaria. A secondary issue is the trade with these products, which potentially may expand the distribution area and spread a range of diseases to new habitats. RESULTS: We here describe how Poecilia reticulata (guppy), produced in a private household aquarium, were invaded by cercariae of an exotic trematode released by imported Melanoides tuberculata snails. The fish presented with severe clinical signs (tremor, flashing, scraping of body against objects). A standard parasitological examination and morphometric identification showed scale pocket infections with a digenean trematode species within the genus Transversotrema. Molecular identification by PCR, sequencing and phylogenetic analyses of a 2646 bp sequence encoding ribosomal RNA (partial 18 S, ITS1, 5.8 S, ITS2, partial 28 S) was performed. The 1107 bp sequence of mitochondrial DNA (cox1) showed that the parasite differed from previously described Transversotrema species in M. tuberculata. Morphometrics of adult and larval specimens of this isolate also differed from previously described freshwater species within the genus. The new species was described and is named after Copenhagen, for its geographic origin. CONCLUSIONS: The genus Transversotrema comprises a range of species, adapted to a microhabitat in scalepockets of teleosts. A combination of morphological and molecular characterization techniques has been shown to provide a good differentiation between species. The fish were not purchased from a pet shop but produced in the home aquarium. This indicated that an infection pressure existed in the aquarium, where the source of infection was found to be exotic intermediate host snails M. tuberculata, which originally were imported and purchased from a pet shop. The potential spread of fish diseases associated with trade of fish and snails to new geographic regions, where climate conditions are favourable, is discussed.

RNAscope: a novel method for the detection of Heterobilharzia americana ova in canine liver.

Canine schistosomiasis caused by Heterobilharzia americana can lead to severe morbidity and eventual mortality, in part due to the deposition of fluke ova in the liver and gastrointestinal tract, which promotes an influx of peri-ova inflammatory cells. Although fluke eggs can be identified in H&E-stained histologic sections, cases exist in which only fragments of the ova persist, or the egg is obscured by inflammatory infiltrates, which can confound definitive histologic diagnosis. Unfortunately, antibodies specific to Heterobilharzia are not commercially available for immunohistochemical labeling. Therefore, we aimed to use an RNA in situ hybridization strategy to fluorescently label Heterobilharzia ova. Using the H. americana 18S rRNA sequence, we developed an RNA probe and validated its performance on archival formalin-fixed, paraffin-embedded canine tissue. A positive signal was observed for all identifiable ova, fragmented and whole. Use of this methodology could aid understanding of the pathogenesis of H. americana infection in dogs. This technique augments standard diagnostic methodology, enabling spatial colocalization of fluke ova and inflammatory infiltrates when using fluorescent techniques.

Demographic and Clinical Profile of Pediatric Uveitis in Delta Region, Egypt.

PURPOSE: Pediatric uveitis poses unique challenges, characterized by difficulties in performing comprehensive examinations, potential delays in diagnosis, and a heightened risk of ocular complications. This study evaluate the etiologic and clinical characteristics of uveitis in children presenting to the Mansoura Ophthalmic Center, Mansoura, Egypt. METHODS: A cross-sectional observational study was undertaken involving children diagnosed with uveitis attending the uveitis outpatient clinic at Mansoura University Ophthalmic Center. Comprehensive clinical evaluations were carried out, including detailed history taking and exhaustive ophthalmological examinations. Whenever deemed necessary, Spectral Domain Optical Coherence Tomography (OCT) and Fluorescein Fundus Angiography (FFA) were utilized to secure retinal images. An extensive systemic evaluation was also conducted to discern the diverse causes of uveitis among the participants. RESULTS: The cohort comprised 63 children, impacting 97 eyes. Bilateral involvement was seen in 54% of cases, with a male predominance of 58.7%. The predominant etiologies of uveitis were presumed trematode-induced (36.7%), Juvenile Idiopathic Arthritis (JIA) accounting for 28.6%, and in 12.7% of cases, the cause remained undetermined. Anterior uveitis emerged as the primary presentation in 79.4% of cases. Regarding visual loss, cataract was the leading cause at 56.4%, followed by vitritis at 38.4%, and macular edema at 20.5%. CONCLUSION: Anterior uveitis was the most frequent presentation in our pediatric cohort. Despite the challenges, the majority of children with uveitis exhibited no significant visual impairment, with most causes of visual loss being reversible.

Integrative taxonomy of Anaporrhutum mundae sp. nov. (Trematoda: Gorgoderidae), a parasite of the Munda round ray Urotrygon munda (Urotrygonidae) in Costa Rica.

A new species of trematode of anaporrhutine gorgoderid, from the gill chambers of the Munda round ray Urotrygon munda in Costa Rica is described, based on an integrative taxonomic approach that includes the use of light and scanning electron microscopy, ITS2 and 28S rDNA sequencing, and phylogenetic analysis. Anaporrhutum mundae sp. nov. can be distinguished from congeneric species by a combination of morphological traits and particularly by having the genital pore opening at the level of the intestinal bifurcation. The new species also can be distinguished from all other species of Anaporrhutum, except A. euzeti Curran, Blend & Overstreet, 2003, by having fewer testicular follicles per testis. Anaporrhutum mundae sp. nov. also differs from A. euzeti in its forebody shape and by having different morphology and location of the vitellaria. The study of the tegumental surface of A. mundae sp. nov., as revealed by scanning electron microscopy, allowed detection of new morphological characters for a member of Anaporrhutinae that may be of taxonomic value. These are: a stylet cavity dorsal to the oral sucker with a large penetration gland opening on each side of the cavity and small penetration gland openings located ventral to the stylet cavity, arranged in a circle around the mouth. This represents the first record of an Anaporrhutum species from Costa Rica. Further, A. mundae sp. nov. represents the first parasite described or reported in this host.

Expanding the swimmer's itch pool of the Benelux: a first record of the neurotropic Trichobilharzia regenti and potential link to human infection.

BACKGROUND: Swimmer's itch, an allergic contact dermatitis caused by avian and mammalian blood flukes, is a parasitic infection affecting people worldwide. In particular, avian blood flukes of the genus Trichobilharzia are infamous for their role in swimmer's itch cases. These parasites infect waterfowl as a final host, but incidental infections by cercariae in humans are frequently reported. Upon accidental infections of humans, parasite larvae will be recognized by the immune system and destroyed, leading to painful itchy skin lesions. However, one species, Trichobilharzia regenti, can escape this response in experimental animals and reach the spinal cord, causing neuroinflammation. In the last few decades, there has been an increase in case reports across Europe, making it an emerging zoonosis. METHODS: Following a reported case of swimmer's itch in Kampenhout in 2022 (Belgium), the transmission site consisting of a private pond and an adjacent creek was investigated through a malacological and parasitological survey. RESULTS: Six snail species were collected, including the widespread Ampullaceana balthica, a well-known intermediate host for Trichobilharzia parasites. Shedding experiments followed by DNA barcoding revealed a single snail specimen to be infected with T. regenti, a new species record for Belgium and by extension the Benelux. Moreover, it is the most compelling case to date of the link between this neurotropic parasite and cercarial dermatitis. Additionally, an Echinostomatidae sp. and Notocotylus sp. were isolated from two other specimens of A. balthica. However, the lack of reference DNA sequences for these groups in the online repositories prevented genus- and species-level identification, respectively. CONCLUSIONS: The presence of T. regenti in Belgium might have severe clinical implications and its finding highlights the need for increased vigilance and diagnostic awareness among medical professionals. The lack of species-level identification of the other two parasite species showcases the barcoding void for trematodes. Overall, these findings demonstrate the need for a Belgian framework to rapidly detect and monitor zoonotic outbreaks of trematode parasites within the One Health context.

Morphological and molecular characteristics of Paralecithodendrium longiforme (Digenea: Lecithodendriidae) adults and cercariae from Chinese pipistrelle bats and viviparid snails in Thailand.

This study aimed to describe the morphological and molecular characteristics of Paralecithodendrium longiforme (Digenea: Lecithodendriidae) adults and cercariae isolated in Thailand. Adult flukes were isolated from the Chinese pipistrelle bat (Hypsugo sp.), and cercariae were detected in the viviparid snail (Filopaludina martensi martensi) from Chiang Mai province. The morphological characteristics were observed and described using conventional methods, and the molecular characteristics with internal transcribed spacer 2 (ITS2) and 28S rDNA gene sequences. The adult flukes were fusiform, 0.84-0.98 mm in length, and 0.37-0.49 mm in width, and were distinguishable from other species by the presence of longitudinal uterine coils. The cercariae were nonvirgulate xiphidiocercariae, with the oral sucker bigger than the acetabulum, the tail without fin fold, a body size of 117.5-138.3 × 48.3-52.2 µm, and a tail size of 100.7-103.7 × 15.0-18.9 µm. Molecular studies revealed that the adults and cercariae shared 99.3% (ITS2) and 99.6% (28S rDNA) homology with each other. They were phylogenetically close to P. longiforme with an identity of 94.5% for ITS2 and 98.7% for 28S rDNA. This study provides new information on the natural definitive host and first intermediate host of P. longiforme in Thailand. The discovery of its cercarial stage in Filopaludina snails highlights the importance of monitoring the associated second intermediate host and prevention and control of this potentially zoonotic trematode.