Morphological and molecular differentiation between Dicrocoelium dendriticum (Rudolphi, 1819) and Dicrocoelium chinensis (Sudarikov and Ryjikov, 1951) Tang and Tang, 1978 (Platyhelminthes: Digenea)

Ovine dicrocoeliosis in Castellón province, eastern Spain: Prevalence, dynamics, and comparative study of different diagnostic techniques

Dicrocoeliosis is a parasitic disease that mainly affects ruminants during grazing, caused by trematodes of the genus Dicrocoelium, with D. dendriticum being the most common species worldwide. This parasitosis is a chronic and generally subclinical process, with nonspecific signs, which makes its diagnosis challenging. This study aimed to determine the prevalence and seasonal dynamics of D. dendriticum infection in adult sheep from the Valencian Community, eastern Spain, as well as to evaluate the efficacy of flotation and sedimentation techniques when compared with the macroscopic exam of the liver. From February to May 2018, 2019, 2020, 2021, and 2022, a total of 290 adult sheep were examined. The animals were sourced from Castellón province, where a semi-intensive production system predominates. Each animal was euthanized and underwent a macroscopic examination of the liver, as well as a fecal analysis. Among the sampled animals, 117 (40.6%) tested positive for adult trematodes in their liver, while 87 (30%) showed evidence of trematode eggs in the coprological exam, reaching a total of 126 sheep parasitized, with a prevalence of 43.4%. The parasitic burden was established in 90.3 adults per animal when the liver was examined and in 54.5 eggs per gram when the sedimentation coprological exam was performed. No eggs were observed when the flotation technique was employed. A positive correlation was found between the number of adults in the liver and the fecal egg count. No significant differences were detected in the prevalence or parasitic burden throughout the study. Considering the difficulty in controlling the intermediate hosts and the complexity of the life cycle, effective diagnostic methods, combined with the adoption of other preventive measures, is crucial to achieving proper management of this parasitic disease.

Helminth Prevalence in European Deer with a Focus on Abomasal Nematodes and the Influence of Livestock Pasture Contact: A Meta-Analysis

Deer are susceptible to infection with parasitic helminths, including species which are of increasing economic concern to the livestock industry due to anthelmintic drug resistance. This paper systematically collates helminth prevalence data from deer across Europe and explores patterns in relation to host and parasite species, as well as landscape factors. A livestock pasture contact index (LPCI) is developed to predict epidemiological overlap between deer and livestock, and hence to examine deer helminth fauna in the context of their surrounding environment. Fifty-eight studies comprising fallow (Dama dama), red (Cervus elaphus), roe (Capreolus capreolus) and sika (Cervus nippon) deer were identified. Deer populations in "likely" contact with livestock pasture had a higher mean prevalence of the abomasal nematodes Haemonchus contortus, Ostertagia ostertagi, Teladorsagia circumcincta and Trichostrongylus axei (p = 0.01), which are common in livestock and not primarily associated with deer. Roe deer populations had a higher prevalence of T. circumcincta (p = 0.02) and T. axei (p = 0.01) than fallow deer and a higher prevalence of H. contortus than both red (p = 0.01) and fallow deer (p = 0.02). Liver fluke and lungworm species were present sporadically at low prevalence, while the abomasal nematode Ashworthius sidemi occurred locally at high prevalence. Insights from this research suggest that deer helminth fauna is reflective of their surrounding environment, including the livestock species which inhabit areas of shared grazing. This is explored from an epidemiological perspective, and the prospect of helminth transmission between wild and domestic hosts is discussed, including drug-resistant strains, alongside the role of helminths as indicators relevant to the transmission of other pathogens at the wildlife-livestock interface.

Validation of deep amplicon sequencing of Dicrocoelium in small ruminants from Northern regions of Pakistan

Dicrocoelium lancet flukes cause significant production loss in ruminant livestock. Although co-infection with multiple Dicrocoelium species within a host is common, techniques for studying the composition of these complex parasite communities are lacking. The pathogenicity, epidemiology, and therapeutic susceptibility of different helminth species vary, and little is known about the interactions that take place between co-infecting species and their hosts. Here, we describe the first applicationof metabarcoding deep amplicon sequencing method to studythe Dicrocoelium species in sheep and goats. First, rDNA ITS-2 sequences of four Dicrocoelium species (Dicrocoelium dendriticum, Dicrocoelium hospes, Dicrocoelium orientalis, and Dicrocoelium chinensis) were extracted from the NCBI public database. Phylogenetic analysis revealed separate clades of Dicrocoelium species; hence, molecular differentiation between each species is possible in co-infections. Second, 202 flukes belonging to seventeen host populations (morphologically verified as belonging to the Dicrocoelium genus) were evaluated to determine the deep amplicon sequencing read threshold of an individual fluke for each of the four species. The accuracy of the method in proportional quantification of samples collected from single hosts was further assessed. Overall, 198 (98.01%) flukes were confirmed as D. dendriticum and 1.98% produced no reads. The comparison of genetic distances between rDNA ITS-2 revealed 86% to 98% identity between the Dicrocoelium species. Phylogenetic analysis demonstrated a distinct clustering of species, apart from D. orientalis and D. chinensis, which sit very close to each other in a single large clade whereas D. hospes and D. dendriticum are separated into their own clade. In conclusion each sample was identified as D. dendriticum based on the proportion of MiSeq reads and validated the presence of this group of parasites in the Gilgit Baltistan and Khyber Pakhtunkhwa provinces of Pakistan. The metabarcoding deep amplicon sequencing technology and bioinformatics pathway have several potential applications, including species interactions during co-infections, identifying the host and geographical distribution of Dicrocoelium in livestock, drug therapy response evaluation and understanding of the emergence and spread of drug resistance.

Dicrocoeliidae Family: Major Species Causing Veterinary Diseases

This chapter analyses the taxonomic position of the Dicrocoeliidae family and several of its genera and species. The chapter reviews the biology of major veterinary disease-causing species, including Dicrocoelium dendriticum, Dicrocoelium hospes, Dicrocoelium chinensis, Eurytrema pancreaticum and Platynosomum fastosum. All these species have indirect life cycles with two intermediate hosts: molluscs as the first host and ants, grasshoppers and lizards as the second host. Dicrocoelium dendriticum is a widespread liver fluke found in ruminants across Europe, Asia, North Africa and North America. It can also infect humans. Dicrocoelium hospes is widely distributed in the savanna areas of Africa south of the Sahara, while D. chinensis is mainly found in ruminants in East Asia and some European countries (probably imported from Asia). Eurytrema pancreaticum is a common parasite that lives in the bile ducts, gall bladder, pancreatic ducts and intestines of ruminants. It is found in Europe, Madagascar, Asia and South America. Adults of P. fastosum live in the liver, gall bladder and pancreas of birds and mammals in Europe, Africa, Asia, North, Central and South America. Information on the epidemiology, pathology, clinical aspects, diagnosis, treatment, control, prevention and economic impact of Dicrocoeliosis caused by D. dendriticum, Eurytrematodosis and Platynosomiosis have been included.

Morphological and molecular characterization of Eurytrema spp. Looss, 1907 detected in domestic water buffaloes and cattle in northern Vietnam

Eurytrema spp. are pancreatic flukes belonging to the Dicrocoeliidae family. They are the cause of neglected diseases in Vietnam and are responsible for economic losses in ruminant production, particularly in water buffaloes and cattle. Eurytrema spp. have been widely reported in several Asian countries. Recently, morphological and molecular analyses to discriminate Eurytrema spp. have been conducted in Brazil, China, Bangladesh, Nepal, and Indonesia; however, similar analyses have not been performed in Vietnam. In the present study, we identified Eurytrema flukes collected from water buffaloes and cattle in northern Vietnam based on their morphology. Morphometric analyses were conducted on 15 samples each of Eurytrema cladorchis and Eurytrema coelomaticum. Representative samples from both species were selected for molecular analyses, and the nucleotide sequences of the 18S ribosomal RNA (18S rRNA) gene and internal transcribed spacer 2 (ITS2) were determined. Phylogenetic analyses based on 18S rRNA sequences revealed that E. cladorchis from Vietnam belongs to the same clade as that from Bangladesh. Similarly, E. coelomaticum isolates from Vietnam and China belonged to the same clade. Both clades were isolated from E. pancreaticum. This is the first study to describe the coexistence of E. cladorchis and E. coelomaticum in Vietnam and the first report of the ITS2 nucleotide sequence for E. coelomaticum, which can be used for molecular species discrimination.

Neuromuscular system of the causative agent of dicrocoeliosis, Dicrocoelium lanceatum. II. Neuropeptide FMRFamide immunoreactivity in nervous system

The parasitic flatworm, trematoda Dicrocoelium lanceatum or lancet fluke is the causative agent of a widespread parasite disease of grazing ruminants, dicrocoeliosis. The aim of this work is the study of the presence and localization of neuropeptide FMRFamide immunoreactive elements in the nervous system of D. lanceatum using immunocytochemical technique and confocal scanning laser microscopy. For the first time the data on the presence and distribution of the FMRFamide-immunopositive components in the central and peripheral departments of the nervous system of D. lanceatum has been obtained. FMRFamidergic neurons and neurites were identified in paired brain ganglia, in the brain commissure, longitudinal nerve cords and connective nerve commissures. The innervation of the oral and ventral suckers by peptidergic nerve structures was revealed. The distal part of the reproductive system is innervated by FMRFamide immunopositive neurites. The data obtained suggest that the neuropeptides of FMRFamide family can be involved in the regulation of functions of the attachment organs and the reproductive system in D. lanceatum. The study of neurotransmitters and their functions in flatworms expand our knowledge on the structure and function of the nervous system of trematodes of various taxonomic groups. The results obtained on the morphological organization of D. lanceatum nervous system support the exploitation of the FMRFamidergic components as an anthelmintic target.

Survey of Dicrocoelium dendriticum infection in imported Romani and local sheep (Ovis aries), and potential epidemiological role in Saudi Arabia

The epidemiology of parasite infection in local and imported breeds is quite an essential topic in the meat industry and human health. This study aims to determine the prevalence of Dicrocoelium dendriticum in local sheep breeds (Naemi, Najdi, and Harri) and imported breeds from Romania (Romani breed) and the epidemiology of the infection in Saudi Arabia. Morphological description, the relationship between dicrocoeliasis and sex, age, and histological changes were also presented. A total of 6845 slaughtered sheep at Riyadh Automated slaughterhouse were investigated and followed up for 4 months between 2020-2021. It included 4,680 local breeds and 2,165 imported Romanian breeds. Fecal samples and livers and gallbladders from slaughtered animals were examined for apparent pathological lesions. The results indicated that the infection rate in slaughtered animals was 10.6% in imported Romani sheep and 0.9% in the local Naeimi breed. After identifying the parasite morphologically, negative results were obtained from examining feces, gallbladders, and livers of Najdi and Harry sheep breeds. The mean number of eggs per 20 µL/gallbladder was low (72.78 ± 17.8: 76.11 ± 5.07), medium (334.59 ± 90.6: 292.91 ± 26.63), and high (1113.2 ± 22.3: 1004 ± 143.4) in imported and Naeime sheep, respectively. Significant differences were found between gender and age (males and females were 3.67% and 6.31%; > 2 years 4.39%, 1-2 years 4.22%, and 1 year 3.53%) respectively. Histopathological lesions in the liver were more pronounced. Our survey confirmed the presence of D. dendriticum in imported Romani and local Naeimi sheep, and the potential role of imported sheep in the epidemiology of dicrocoeliasis in Saudi Arabia.

MORPHOLOGIC OBSERVATION AND FIRST MOLECULAR CHARACTERIZATION OF ENCYCLOMETRA JAPONICA (DIGENEA: ENCYCLOMETRIDAE) IN THE DIGESTIVE TRACT OF WILD TIGER KEELBACKS (RHABDOPHIS TIGRINUS) IN JAPAN

Encyclometra japonica Yoshida and Ozaki, 1929 is a fluke that parasitizes the digestive tract of snakes. When the species was first reported, it was originally characterized on the basis of morphologic features, namely, the characteristics of the 2 testes located obliquely in the anterior-posterior direction, and the position of the ventral sucker one-fourth to one-third from the anterior extremity. Thereafter, more specimens with other morphologic variations were reported, and a new morphologic feature for species discrimination was proposed. However, the proposal is uncertain, and the criteria for morphologic discrimination between E. japonica and other Encyclometra species remain debatable. Thus, morphologically discriminable characteristics on the basis of a sufficient number of specimens are required, and molecular methods for species identification that allow for a more objective assessment need to be established. Therefore, in the present study, nucleotide sequences of 18S, 28S ribosomal deoxyribonucleic acid and cytochrome c oxidase subunit I (COI) of E. japonica were determined along with detailed morphologic observations for the first time. Key characteristics were observed in all specimens, whereas some morphologic variations were observed in the symmetry of the cecum. The COI sequences, which are known to be variable genetic regions, were identical among all specimens; therefore, all of them were considered the same species. This result clarifies the high morphologic variation in E. japonica. The 18S and 28S sequences were 99.78% and 99.11-99.19% similar to those of Encylometra colubrimurorum. The high degree of homology between these genes indicates that E. japonica and E. colubrimurorum are closely related but independent species. The present data will be used for the identification of E. japonica and to evaluate the relationships within the genus Encyclometra.

Molecular analysis of internal transcribed spacer 2 of Dicrocoelium dendriticum isolated from cattle, sheep, and goat in Iran

Background

Dicrocoelium dendriticum is a broadly distributed zoonotic helminth, which is mainly reported from domesticated and wild ruminants. There is little data covering the molecular features of this trematode; therefore, current study aimed to molecularly analyze D. dendriticum in livestock.

Methods

Totally, 23 samples of D. dendriticum were collected from cattle, sheep, and goat from Ilam, Lorestan, and Khuzestan, three west and south-west provinces of Iran from February to August 2018. After genomic DNA extraction, the internal transcribed spacer (ITS) 2 fragment was amplified and sequenced in samples. To investigate genetic variations through the ITS 2 fragment of obtained D. dendriticum, phylogenetic tree and network analysis were employed.

Results

All 23 samples were successfully amplified and sequenced. Phylogenetic tree showed that our samples were clearly grouped in a clade together with reference sequences. There was no grouping based on either geographical regions or hosts. Network analysis confirmed the phylogenetic findings and showed the presence of nine distinct haplotypes, while our samples together most of sequences, which were previously submitted to the GenBank, were grouped in the Hap1.

Conclusions

Our findings indicated that although ITS 2 fragment discriminate D. dendriticum, this fragment is not suitable to study intra-species genetic variations. Therefore, exploring and describing new genetic markers could be more appropriate to provide new data about the genetic distribution of this trematode.

A survey of sheep dicrocoeliosis in Sulaymaniyah slaughterhouse, northern Iraq in 2013-2014

Dicrocoelium dendriticum is a helminth which lives in the bile ducts and gall bladder of mammalian definitive hosts. Dicrocoeliosis is thought to be endemic in some countries and it has an increasing prevalence in Northern Iraq, potentially due to increased importation of infected animals, particularly sheep, in high numbers from neighboring countries. The parasite's ability to infect rodents, wild animals, livestock and humans means this parasite is of significant interest in veterinary and human medicine. While D. dendriticum causes relatively mild clinical disease in animals, infection leads to liver condemnation at slaughter and subsequent economic losses to farmers. In this study, the livers of 91,486 sheep slaughtered at Sulaymaniyah New Slaughterhouse (Northern Iraq) were visually inspected for D. dendriticum infection between November 2013 and March 2014, with 1269 livers rejected due to D. dendriticum in this period, representing 29.4% of all condemned livers. The highest rate of rejection due to D. dendriticum infection was seen in December, possibly linked to increased numbers of intermediate host snails during the wet season. Routine inspection of condemned livers revealed adult flukes of D. dendriticum and eggs were seen in the faeces of imported sheep, indicating these animals may be a vector for introduction of D. dendriticum to this region. Due to the complex life cycle and wide range of animals which it infects, we cannot establish the exact route of introduction into Iraq; however, our study suggests that slaughterhouse workers, farmers and local health authorities should be aware of the presence of D. dendriticum, and the potential risks it represents to both human and animal health. Our data also suggest that some level of quarantine or border checks may be useful to prevent further introduction of D. dendriticum or other pathogens into Iraq, although this may prove difficult until accurate diagnostic assays are developed.

Prevalence of gastrointestinal helminths in ruminants in Ukraine: a 5-year meta-analysis

The production of environmentally friendly livestock products is currently receiving much attention, especially in the European Union. The problem of monitoring the quality and safety of meat and milk in modern conditions is relevant not only for Ukraine but also for the world community. The scientific substantiation of the methods of research on meat for sale subject to invasive diseases is especially important, as the product may pose risks to the consumer. One of the criteria for assessing the welfare of a herd is the prevalence of helminthiases in cattle. Ruminant parasitoses in Ukraine have always been and remain a separate, often significant, problem for veterinary specialists. Helminths have evolved to use a wide range of ecological niches. In this study, we tried to quantify the prevalence of helminthiases among ruminants (cattle, sheep and goats) in Ukraine. The relevant studies were searched for in the online databases. The meta-analysis included 15 publications from January 2015 to December 2020 which reported the spread of parasites in Ukraine. The research results show that the infestation of ruminants with gastrointestinal helminths on the territory of Ukraine is 56.7%. Egger’s regression test revealed no significant publication bias. During the period of pastured farming, stable parasitocenoses are formed in the body of ruminants. The parasitoses are caused by helminths (gastrointestinal strongyles, liver flukes, paramphistomas, dicrocelia). They are recorded in monoinvasions or mixed invasions. Ruminants, according to helminthological examination in different climatic zones, are constantly infested with trematodes. In Ukraine, the presence of three species of flukes has been confirmed in ruminants: Fasciola hepatica, Dicrocoelium dendriticum and Paramphistomum cervi. Parasitization by those species negatively affects the profitability of dairy farming. Trematodes cause significant economic losses: reduced milk productivity of cows, reduced live weight gain of young animals, negative impact on reproduction. At the same time, fascioliasis is socially significant and dangerous to humans. According to the analyzed literature sources, two types of cestodes have been registered in Ukraine: Moniezia benedeni and M. expansa. The epizootic situation regarding nematodes is just as fraught. That is the most numerous group of helminths, their fauna is represented by the following species: Strongyloides papillosus, Nematodirus spathiger, Bunostomum spp., Oesophagostomum radiatum, Haemonchus contortus, Toxocara vitulorum, Trichuris skrjabini, T. ovis and T. globulosa. It is proven that in cattle parasitocenoses are recorded more often than monoinvasions. The highest rates of prevalence of infection were observed when polyinvasion included gastrointestinal strongyles, namely from the order Strongylida. Strongyloides papillosus is the most common taxonomic representative, while Fasciola hepatica has the lowest prevalence of infection, especially in sheep. Updated data on helminthiasis will expand the screening strategy to maintain the health of farm ruminants and reduce economic losses.

The first detection of Dicrocoelium chinensis sporocysts from the land snail Aegista vulgivaga in Gifu Prefecture, Japan

Trematodes of the genus Dicrocoelium are one of the most common parasites in ruminant animals; however, their life cycles in Japan are unclear. To find the sporocysts of D. chinensis in the natural field, we sampled 269 land snails (14 species) at a location with high level infection of sika deer in Gifu Prefecture, Honshu Island, Japan in autumn between 2017 and 2019. During the sampling period, we found mother sporocysts in the hepatopancreas of Aegista vulgivaga and Cyclophorus herklotsi. DNA barcoding based on the sequences of cytochrome c oxidase subunit 1 showed that the sporocysts from A. vulgivaga belonged to D. chinensis, indicating that this snail has potential as the first intermediate host of D. chinensis at this location.

Molecular confirmation of Dicrocoelium dendriticum in the Himalayan ranges of Pakistan

Lancet liver flukes of the genus Dicrocoelium (Trematoda: Digenea) are recognised parasites of domestic and wild herbivores. The aim of the present study was to confirm the species identity of Dicrocoeliid flukes collected from the Chitral valley in the Himalayan ranges of Pakistan. The morphology of 48 flukes belonging to eight host populations was examined; but overlapping traits prevented accurate species designation. Phylogenetic comparison of published D. dendriticum ribosomal cistron DNA, and cytochrome oxidase-1 (COX-1) mitochondrial DNA sequences with those from D. chinensis was performed to assess within and between species variation and re-affirm the use of species-specific single nucleotide polymorphism markers. PCR and sequencing of 34 corresponding fragments of ribosomal DNA and 14 corresponding fragments of mitochondrial DNA from the Chitral valley flukes, revealed 10 and 4 unique haplotypes, respectively. These confirmed for the first time the molecular species identity of Pakistani lancet liver flukes as D. dendriticum. This work provides a preliminary illustration of a phylogenetic approach that could be developed to study the ecology, biological diversity, and epidemiology of Dicrocoeliid lancet flukes when they are identified in new settings.

Molecular characterization and immunodiagnostics of Dicrocoelium dendriticum species isolated from sheep of north-west Himalayan region

Despite its extensive presence among grazing ruminants, dicrocoeliosis, also known as 'small liver fluke' disease, is poorly known and often underestimated by researchers and practitioners in many countries. The accurate identification and prepatent diagnosis of Dicrocoelium dendriticum infection is an essential prerequisite for its prevention and control. In the present study, the morphologically identified specimens isolated from the bile ducts of sheep (Ovis aries) were validated through molecular data. The sequence analysis of the second internal transcribed spacer (ITS-2) of our isolates showed a high degree of similarity with D. dendriticum using the BLAST function of the National Center for Biotechnology Information (NCBI). The phylogenetic analysis of our isolates showed a close relationship with previously described D. dendriticum isolates from different countries. The antigenic profiles of somatic and excretory/secretory (E/S) antigens of D. dendriticum were revealed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting using sera from sheep naturally infected with D. dendriticum. By SDS-PAGE, 16 distinct bands were revealed from crude somatic fraction. Immunoblotting analysis of these proteins with positive sera exhibited six seroreactive bands ranging from 27 to 130 kDa. Among these, the 84 and 130 kDa bands were quite specific, with high diagnostic specificity and sensitivity. The E/S fraction comprised nine distinct bands, as revealed by SDS-PAGE analysis. Immunoblotting analysis of these proteins with positive sera exhibited five antigenic bands ranging from 27 to 130 kDa. Among these, the 130 kDa band was found to be quite specific, with high diagnostic specificity and sensitivity. The present study concludes that the protein bands of 84 and 130 kDa in somatic fraction and 130 kDa in E/S fraction can be used for the immunodiagnostic purpose for this economically important parasite, which may also encourage further studies regarding their vaccine potential.

Morphologic and molecular analysis of Dicrocoelium dendriticum species from Iranian native sheep

Dicrocoeliosis is a worldwide parasitic disease of ruminants which affects the liver. In this current study, the phylogenic pattern of Dicrocoelium species in Iranian native sheep from three different geographical regions was investigated by investigating a 520 bp fragment of mitochondirial NAD1 gene. The analysis of the NAD1 oligo nucleotide sequences from 10 D. dendriticum (GenBank accession numbers: MG889399 to MG889408) revealed few non-significant differences, suggesting limited application for NAD1 gene as a biomarker for study of genetic variation in Dicrocoelium. The morphometrical study also showed a significant relationship for the several morphometric indices among the Dicrocoelium spp. isolates from different regions of Iran.

First isolation of Dicrocoelium dendriticum among cattle in some Northern Algerian slaughterhouses

Background and Aim:

Dicrocoelium dendriticum or small liver fluke often causes unnoticed clinical manifestations in cattle. For a live animal, its diagnosis is mainly based on the detection of eggs by coproscopic examination. The objective of this study was to determine the presence or absence of Dicrocoelium spp. never previously reported in the study area but also to establish its prevalence, as well as an association between dicrocoeliasis and sex, age and season of the year, and histological characteristics.

Materials and Methods:

The study was carried out in slaughterhouses of three districts (Bouira, Tizi-Ouzou, and Bejaia) from January 2017 to December 2017. To this end, of 4053 cattle, representing more than 10% of the total number of animals slaughtered, stool and bile samples were collected and a liver inspection was carried out to investigate lesions of distomial cholangitis. They were processed for histological analysis. The specimens were morphologically identified according to the orientation of the testicles, the length and width of the body, and the level of the maximum width of the body.

Results:

The total prevalence of dicrocoeliasis obtained of the 4053 cattle inspected is 0.52% with a prevalence of 0.66% in Tizi-Ouzou, 0.54% in Bouira, and 0.27% in Bejaia. About 0.52% of livers had distomial cholangitis (21 of the 4053 livers examined had adult D. dendriticum and 15% had non-distomial cholangitis. About 0.25% of cattle had D. dendriticum eggs in the stool versus 0.52% of cattle had parasite eggs in the bile. Statistical analysis revealed no significant association between dicrocoeliasis infection and the season of the year (p>0.05). However, a significant association was found between dicrocoeliasis infection and sex and age of the animal (p<0.05); females and older animals are more likely to have dicrocoeliasis. Histological analysis of the fluke revealed an anterior positioning of the testicles with a slightly oblique tandem orientation, an average body length of 3.69 mm and an average body width of 1 mm. The maximum body width level is either in the middle of the fluke body or in the rear position.

Conclusion:

The histological study confirms that the collected fluke is D. dendriticum. Thus, this work reveals for the 1^st time in Algeria the presence of D. dendriticum in three districts (Bouira, Tizi-Ouzou, and Bejaia). The results indicate that many cattle farms in the North Central Province of Algeria are infested with D. dendriticum.

Predicting environmental suitability and geographical distribution of Dicrocoelium dendriticum at littoral of Caspian Sea: An ecological niche-based modeling

Dicrocoeliasisis caused by the small liver fluke (Dicrocoelium spp.), mainly Dicrocoelium dendriticum in domestic and wild ruminants. The small liver fluke is the probable predisposing cause of economic burden. The impact of geographic and climatic factors on the incidence of dicrocoeliasis has been severely ignored in different geographical areas. Due to the lack of data regarding dicrocoeliasis in Iran, this study was aimed to investigate the prevalence and intensity of ovine and bovine Dicrocoelium infection in the coastal strip south of the Caspian Sea. Fecal samples were obtained from the cattle and sheep in three provinces of Guilan, Mazandaran and Golestan at the littoral of the Caspian Sea. All collected samples were then tested by flotation methods for determining the number of eggs per gram of feces (EPG). Moreover, we applied maximum entropy niche-based modeling (MaxEnt), coupled with remote sensing and the Geographical Information System (GIS) to visualize the spatial distribution and risk factors of Dicrocoelium dendriticum at the littoral of Caspian Sea. A total of 2688 stool samples were collected from cattle (n = 1344) and sheep (n = 1344) in coastal provinces of the Caspian Sea including Guilan (n = 1280), Mazandaran (n = 768) and Golestan (n = 640) provinces. Based on the data presented here, the highest rate of infection was observed in Guilan and Mazandaran provinces. The results revealed the prevalence rates of 36.72% and 6.09% for sheep and cattle in Guilan province, respectively. This rate was 22.4% for sheep and 3.91% for cattle in Mazandaran province. However, the rate of sheep infection was 90% in some point locations. Dicrocoelium infection was found to be significantly different between three provinces in sheep (P < 0.00001, Chi = 111.633). Our findings exhibited a high reliability of the MaxEnt model, and area under the curve (AUC) values of the training and test data sets were determined to be 0.852 and 0.818, respectively. Jackknife analysis showed the relative variable contribution to the model performance, where four variables were found as key influential factors that highly affected the habitat suitability of the presence of the lancet fluke including the precipitation of driest quarter (Bio17), altitude, temperature seasonality (Bio4), and precipitation of driest month (Bio14). The findings of this study demonstrated a high presence rate of Dicrocoelium infection at the littoral of Caspian Sea, Iran. Moreover, climatic variables can be considered as important predictive factors affecting the distribution of infection in the studied areas. Further studies based on the findings of the GIS are also very important in the country for planning control programs.

Dicrocoeliosis in extensive sheep farms: a survey

Background

This study investigated the epidemiological and molecular aspects of dicrocoeliosis in extensive sheep farms.

Methods

From 2013 to 2014, copromicroscopical analyses in 190 dairy sheep farms and anatomo-pathological inspections in six slaughterhouses were carried in Sardinia, Italy. Rectal faecal samples were analyzed using the FLOTAC® method, and anatomo-pathological examinations were based on detecting thickened terminal bile ducts (TTBDs). In addition, genetic analyses were conducted on representative DNA samples of adult Dicrocoelium spp.

Results

Ninety-seven (51.1%) out of 190 sheep farms were coprologically positive for Dicrocoelium spp. In the liver, on the surface and cut surface, TTBDs were reported in 40.1% (309/770) and 15.3% (118/770) of the animals examined, respectively, with an overall prevalence of 25.5% (196/770). No intraspecific genetic variation was observed among the Dicrocoelium dendriticum isolates.

Conclusions

Our survey reveals the widespread presence of D. dendriticum in Sardinia, although seasonal, geographical and climatic conditions might be key factors in modulating the infection prevalence. Examining typical lesions due to D. dendriticum in the liver in abattoirs can be used as a marker for tracking chronic dicrocoeliosis infection.

Characterization of the complete mitochondrial genome of Uvitellina sp., representative of the family Cyclocoelidae and phylogenetic implications

Mitochondrial (mt) DNA has been useful in revealing the phylogenetic relationship of eukaryotic organisms including flatworms. Therefore, the use of mitogenomic data for the comparative and phylogenetic purposes is needed for those families of digenetic trematodes for which the mitogenomic data are still missing. Molecular data with sufficiently rich informative characters that can better resolve species identification, discrimination, and membership in different genera is also required for members of some morphologically difficult families of trematodes bearing few autapomorphic characters among its members. Here, the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (rDNA) and the complete mt genome of the trematode Uvitellina sp. (Cyclocoelidae: Haematotrephinae) was determined and annotated. The mt genome of this avian trematode is 14,217 bp in length, containing 36 genes plus a single non-coding region. The ITS rDNA sequences were used for the pairwise sequence comparison of Uvitellina sp. with European cyclocoelid species, and the mitochondrial 12 protein-coding genes (PCGs) and two ribosomal RNA genes were used to evaluate the position of the family within selected trematodes. The ITS rDNA analysis of Uvitellina sp. showed less nucleotide differences with Hyptiasmus oculeus (16.77%) than with other European cyclocoelids (18.63-23.58%). The Bayesian inference (BI) analysis using the 12 mt PCGs and two rRNA genes supported the placement of the family Cyclocoelidae within the superfamily Echinostomatoidea (Plagiorchiida: Echinostmata). The availability of the mt genome sequences of Uvitellina sp. provides a novel resource of molecular markers for phylogenetic studies of Cyclocoelidae and other trematodes.

Dicrocoeliidae Family: Major Species Causing Veterinary Diseases

This chapter analyses the taxonomic position of Dicrocoeliidae family and several of its genus and species. The biology of the major species causing veterinary diseases such Dicrocoelium dendriticum, Dicrocoelium hospes, Dicrocoelium chinensis, Eurytrema pancreaticum and Platynosomum fastosum, has been reviewed. All these species have an indirect life cycle, involving two intermediate hosts (molluscs as first and ants, grasshoppers and lizards as second). Dicrocoelium dendriticum is a very widespread hepatic trematode in the ruminants of many countries in Europe, Asia, North Africa and North America, even affecting humans. Dicrocoelium hospes is widely distributed in the savanna areas of Africa south of the Sahara, whilst D. chinensis has mainly been found in ruminants in East Asia and some European countries (probably imported from Asia). Eurytrema pancreaticum is a common parasite whose adults live in ruminant bile ducts, gall bladder, pancreatic ducts and intestines in Europe, Madagascar, Asia and South America. Adult P. fastosum live in the liver, gall bladder and pancreas of birds and mammals in Europe, Africa, Asia, North, Central and South America. Information about the epidemiology, pathology, clinical aspect, diagnosis, treatment, control, prevention and economic impact mainly of Dicrocoeliosis produced by D. dendriticum, as well as of Eurytrematodosis and Platynosomiosis, has been included.

Genotyping of Fasciola hepatica Isolated from Domestic Animals in the West of Iran

OBJECTIVES

The most common parasites responsible for fascioliasis are F. hepatica and F. gigantica. Fascioliasis is an important problem in terms of health and economics. The western part of Iran is one of the major hubs of animal husbandry and the prevalence of fascioliasis is high. The aim of the current study was to determine the Fasciola spp. present in the western part of Iran. In the present study, 45 samples were collected from slaughterhouses in three provinces in the western part of Iran, including Ilam, Lorestan and Kermanshah.

METHODS

The flukes were detected using morphological methods and the DNA of all samples was extracted. The ribosomal internal transcribed spacer (ITS1) was identified by PCR and PCR-RFLP techniques using the Rsa1 restriction enzyme. Then, 15% of the samples were sequenced.

RESULTS

Based on their ITS1 sequence, all samples showed 700 bp bands. The results of sequencing showed a similarity of 99% to 100% across samples. Using the Rsa1 restriction enzyme, all samples produced three distinct bands (60 bp, 100 bp, and 360 bp). These results demonstrated that the most common fasciola in the western part of Iran in sheep and cattle is F. hepatica.

CONCLUSION

The results of the present study showed that only the species F. hepatica is parasitizing livestock in the western part of Iran. Further studies using new molecular markers for more accurate identification of fasciola-causing species will be useful in the control and prevention of fascioliasis.

Central European Strigeidae Railliet, 1919 (Trematoda: Strigeidida): Molecular and comparative morphological analysis suggests the reclassification of Parastrigea robusta Szidat, 1928 into Strigea Abildgaard, 1790

Strigeidae Railliet, 1919 are digenean parasites of birds and mammals that are characteristic by their cup-shaped forebody and bilobed holdfast organ. Despite that the family is taxonomically unsettled, particularly due to a very limited number of visible autapomorphic identification features, molecular phylogenetics have never been applied to analyze the relationships among European members of Strigeidae except for the genus Ichthyocotylurus. Here, we analyze the Strigeidae found during the examination of Czech birds performed from 1962 to 2017, and we provide comparative measurements and host spectra, including prevalence and intensity; we also provide and analyze sequences of four DNA loci of 12 of the Strigeidae species. We suggest the reclassification of Parastrigea robusta Szidat, 1928 as Strigea robusta (Szidat, 1928) Heneberg and Sitko, 2018 comb. n. The genera Strigea Abildgaard, 1790 and Parastrigea Szidat, 1928 appear paraphyletic, and morphological diagnostic features of genera within Strigeini Dubois, 1936 are invalid. The mute swan Cygnus olor hosts two Cotylurus spp., Cotylurus syrius Dubois, 1934 and a second species with molecular identification features shared in part with Cotylurus cornutus (Rudolphi, 1808) and Cotylurus gallinulae Lutz, 1928. New host records are provided for seven species. Analyses of non-European genera of the Strigeidae are needed to provide an updated key to Strigeini.

Helminth endoparasites of the smooth newt Lissotriton vulgaris: linking morphological identification and molecular data

The helminth endoparasites of many European amphibian species are often known exclusively from morphological descriptions. A molecular library of DNA sequence data linked to morphological identifications is still in its infancy. In this paper, we aim to contribute to such a library on the smooth newt Lissotriton vulgaris, the intermediate and definitive host of 31 helminth parasites, according to evidence published so far. Newts (n = 69) were collected at two study sites in western Germany and examined for the presence of helminths. A total of five helminth species were detected in 56 (81%) of the newts, but only one or two species infected a single host. Four out of five helminth species were identified morphologically and based on DNA sequences as Parastrigea robusta (metacercariae), Oswaldocruzia filiformis, Megalobatrachonema terdentatum (adults and larvae) and Cosmocerca longicauda, and the corresponding sequences were provided subsequently. Oswaldocruzia molgeta was confirmed to be a junior synonym of O. filiformis. Molecular data on a fifth species (a cosmocercid nematode) that could not be identified at species level were added to GenBank. These findings increased the molecular library on morphologically identified smooth newt parasites significantly, from 12 to 15 entries.

Phylogenetic relationships between Dicrocoelium chinensis populations in Japan and China based on mitochondrial nad1 gene sequences

We carried out phylogenetic analyses of the relationships between Dicrocoelium chinensis populations in Japan and China using molecular markers. One hundred nine lancet flukes collected from Japan and China were identified as D. chinensis based on their testis orientation and the nucleotide sequences of their ribosomal ITS2. These flukes were analyzed phylogenetically using mitochondrial nad1 gene sequences. An analysis of molecular variance found that the percentage of variation between the countries was extremely high, indicating that the D. chinensis populations in Japan and China are differentiated genetically. D. chinensis mainly parasitizes wild sika deer, which is thought to originate in northeast Asia and to have colonized into Japan from the Eurasia continent in the Pleistocene glaciations. In addition, phylogenic analyses indicated that Japanese sika deer is genetically differentiated from Chinese population; therefore, we hypothesize that D. chinensis might have been introduced into Japan along with the migration of infected wild ruminants in the Pleistocene, and then the population became differentiated from the Chinese population. This study provides the nucleotide sequences of the nad1 gene of D. chinensis in Japan for the first time and shows that these sequences are useful for elucidating the phylogenetic relationships of the Dicrocoelium species prevalent in Asia.

Characterization of the complete nuclear ribosomal DNA sequences of Eurytrema pancreaticum

Eurytrema pancreaticum is one of the most common trematodes of cattle and sheep, and also infects humans occasionally, causing great economic losses and medical costs. In this study, the sequences of the complete nuclear ribosomal DNA (rDNA) repeat units of five E. pancreaticum individuals were determined for the first time. They were 8306–8310 bp in length, including the small subunit (18S) rDNA, internal transcribed spacer 1 (ITS1), 5.8S rDNA, internal transcribed spacer 2 (ITS2), large subunit (28S) rDNA and intergenic spacer (IGS). There were no length variations in any of the investigated 18S (1996 bp), ITS1 (1103 bp), 5.8S (160 bp), ITS2 (231 bp) or 28S (3669 bp) rDNA sequences, whereas the IGS rDNA sequences of E. pancreaticum had a 4-bp length variation, ranging from 1147 to 1151 bp. The intraspecific variations within E. pancreaticum were 0–0.2% for 18S rDNA, 0–0.5% for ITS1, 0% for 5.8S rDNA and ITS2, 0–0.2% for 28S rDNA and 2.9–20.2% for IGS. There were nine types of repeat sequences in ITS1, two types in 28S rDNA, but none in IGS. A phylogenetic analysis based on the 18S rDNA sequences classified E. pancreaticum in the family Dicrocoeliidae of Plagiorchiata, closely related to the suborder Opisthorchiata. These results provide useful information for the further study of Dicrocoeliidae trematodes.

A review of bovine fasciolosis and other trematode infections in Nigeria

Trematode infections cause serious economic losses to livestock worldwide. Global production losses due to fasciolosis alone exceed US$3 billion annually. Many trematode infections are also zoonotic and thus a public health concern. The World Health Organization has estimated that about 56 million people worldwide are infected by at least one zoonotic trematode species, and up to 750 million people are at risk of infection. Fasciolosis caused by the fluke Fasciola gigantica is endemic in Nigeria and is one of the most common causes of liver condemnation in abattoirs. Total cattle losses from Fasciola infection in Nigeria have been estimated to cost £32.5 million. Other trematode infections of cattle, including paramphistomosis, dicrocoeliasis and schistosomiasis, have all been reported in various parts of Nigeria, with varying prevalence. Most publications on trematode infections are limited to Nigerian local and national journals, with very few international reports. This paper therefore summarized the current data on distribution, control and zoonotic trematode infections in Nigeria and other African countries. We also identified research gaps and made recommendations for future research and areas for funding for policy/planning.

Platynosomum fastosum (Trematoda: Dicrocoeliidae) from Cats in Vietnam: Morphological Redescription and Molecular Phylogenetics

The present study was performed to reveal the morphological characteristics and molecular phylogenetic position of Platynosomum fastosum Kossack, 1910. A total 167 specimens of P. fastosum were collected in 8 (4.9%) out of 163 sets of gall-bladders and bile ducts of cats. The number of worms was 1–105 per infected cat. This species was characterized by having a long and slender body, slightly larger ventral sucker than the oral sucker, indistinct prepharynx, small pharynx, short esophagus, bifurcation midway between 2 suckers, and ceca extending to the posterior end of the body. The length of the partial sequences of ITS1 and 5.8S rDNA of P. fastosum were 990 bp, GC-rich. AT/GC ratio was 0.9, there were 9 polymorphic sites, and intraspecific variations ranged from 0.1% to 0.9%. Phylogenetic analyses by neighbor-joining phylogram inferred from ITS1 rDNA sequences revealed that the genetic distance between P. fastosum specimens ranged from 0.3 to 1.5% while the smallest interspecific distance among dicrocoeliid species was 20.9 %. The redescription and genetic characters of P. fastosum are taxonomically important to recognize future different species of the genus Platynosomum showing high intraspecific and morphological variability.

Morphological and molecular identification of Explanatum explanatum in domestic water buffalo in Pakistan

More than 70 species of the family Paramphistomatidae, have been identified in ruminants in different parts of the world. Most are pathogenic, causing amphistomosis. Adult flukes of this Family have a predilection for the rumen, liver or bile duct of ruminants where they may cause damage to the epithelium. Identification of adult paramphistomes to the species level based on morphology alone requires specialized knowledge, whereas, molecular genetic marker analysis is more precise and transferable. In the present study, we performed both morphological and molecular characterization of fifteen adult flukes collected from the liver of domesticated buffalo in the Punjab province of Pakistan. The morphology of five of these flukes was examined in detail and on this basis these were identified as either Explanatum explanatum or Explanatum bathycotyle. PCR and sequencing of the ITS-2 rDNA region from these 5 flukes, plus 10 others, revealed a single haplotype in all cases. This differed by just a single nucleotide polymorphism from a previously described E. explanatum ITS-2 rDNA sequence. Phylogenetic comparison of these E. explanatum ITS2-rDNA sequences with those from other Paramphistomatidae, Fasciola and Dicrocoelium species was performed to assess within and between species variation and validate the use of ITS-2 rDNA as a robust species-specific marker for E. explanatum. This work provides a validated species-specific marker of E. explanatum and the first report of this parasite species from Pakistan.

Central European parasitic flatworms of the Cyclocoelidae Stossich, 1902 (Trematoda: Plagiorchiida): molecular and comparative morphological analysis suggests the reclassification of Cyclocoelum obscurum (Leidy, 1887) into the Harrahium Witenberg, 1926

Cyclocoelidae Stossich, 1902 are medium-sized to large digenean bird parasites. Although these parasites bear few visible autapomorphic signs, and their diagnostic characters are unstable in response to the pressure applied during preparation, the numerous hitherto suggested re-classifications within the family have not been supported by any molecular analysis. We analyse here cyclocoelids found during the extensive examination of central European birds performed from 1962 to 2016, provide comparative measurements, host spectra, prevalence and intensity, and provide and analyse sequences of four DNA loci of five of the cyclocoelid species. Cyclocoleum Brandes, 1892 appears paraphyletic; thus we suggest the re-classification of Cyclocoleum obscurum (Leidy, 1887) as Harrahium obscurum (Leidy, 1887) Sitko and Heneberg comb. n. Molecular phylogenetics questioned also the validity of Cyclocoelinae Stossich, 1902 and Hyptiasminae Dollfus, 1948, which formed a single clade, whereas Allopyge Johnston, 1913, Prohyptiasmus Witenberg, 1923 and Morishitium Witenberg, 1928 formed another clade. Haematotrephinae Dollfus, 1948 are newly characterized as having a pretesticular or intertesticular ovary that forms a triangle with the testes. Analyses of non-European genera of the Cyclocoelidae and an examination of the position of families within Echinostomata La Rue, 1926 are needed.

Central European parasitic flatworms of the family Renicolidae Dollfus, 1939 (Trematoda: Plagiorchiida): molecular and comparative morphological analysis rejects the synonymization of Renicola pinguis complex suggested by Odening

The Renicolidae are digenean parasites of piscivorous and molluscivorous birds. Although they exhibit few morphological autapomorphies and are highly variable, the numerous suggested re-classifications within the family have never been supported by any molecular analyses. We address the possible synonymization of species within the Renicola pinguis complex suggested previously by Odening. We provide and analyse sequences of two nuclear (ITS2, 28S rDNA) and two mitochondrial (CO1, ND1) DNA loci of central European species of the Renicolidae, namely Renicola lari, Renicola pinguis and Renicola sternae sp. n., and we also provide first sequences of Renicola sloanei. The combined molecular and comparative morphological analysis confirms the previously questioned validity of the three Renicola spp. of highly similar morphology, which display strict niche separation in terms of host specificity and selectivity. We identify two previously unreported clades within the genus Renicola; however, only one of them is supported by the analysis of adult worms. We also provide comparative measurements of the three examined closely related central European renicolids, and describe the newly proposed tern-specialized species Renicola sternae sp. n., which was previously repeatedly misidentified as Renicola paraquinta. Based on the extensive dataset collected in 1962-2015, we update the host spectrum of Renicolidae parasitizing central European birds (Renicola bretensis, R. lari, Renicola mediovitellata, R. pinguis, Renicola secunda and R. sternae sp. n.) and discuss their host-specific prevalence and intensity of infections.

Molecular and comparative morphological analysis of central European parasitic flatworms of the superfamily Brachylaimoidea Allison, 1943 (Trematoda: Plagiorchiida)

The Brachylaimoidea are digenean parasites of vertebrates, including humans, domestic animals, poultry and wild game. Numerous Brachylaimoidea, particularly adults ofBrachylaimaandLeucochloridium, are difficult to identify to species. We provide and analyse sequences of two nuclear (18S rDNA, ITS2) and two mitochondrial (CO1, ND1) DNA loci of central European species of the Brachylaimoidea, namelyLeucochloridium holostomum, Leucochloridium paradoxum, Leucochloridium perturbatum, Leucochloridium subtilis, Leucochloridium vogtianum, Urotocus rossitensis, Urogonimus macrostomus, Michajlovia migrata, Leucochloridiomorpha lutea, Brachylaima arcuatus, Brachylaima fuscataandBrachylaima mesostoma. We identified three clades in the genusLeucochloridium, which do not correspond to the previously suggested subgeneraNeoleucochloridium, PapilloleucochloridiumandLeucochloridium. We reject classification ofUrotocusandUrogonimusin Leucochloridiinae, and, instead, re-establish the subfamilies Urotocinae and Urogoniminae. We synonymize the genusRenylaimawith the genusBrachylaima. We rejectM. migrataas a member of Leucochloridiinae sensu stricto or Brachylaimidae suggested by some previous authors. We found that the previously sequencedGlaphyrostomumsp. does not cluster with any hitherto sequenced Brachylaimidae. We also provide comparative measurements of the examined central European Brachylaimoidea, address the the specificity of their localization in the host and discuss their host-specific prevalence and intensity of infections based on the extensive dataset of birds examined in 1962–2015.

Infections of Larval Stages of Dicrocoelium dendriticum and Brachylaima sp. in Brown Garden Snail, Helix aspersa, in Turkey

The aim of this study was to determine the presence and prevalence of larval stages of Dicrocoelium dendriticum and Brachylaima sp. in the first intermediate host, a species of land snail, Helix aspersa, in Turkey. A total of 211 snails were collected in April-May 2014 from pastures in Mersin District. Larval stages of D. dendriticum were identified under a light microscope. Hepatopancreas from naturally infected H. aspersa snails were examined histologically. The prevalence of larval stages of D. dendriticum and Brachylaima sp. in H. aspersa snails was found to be 2.4% and 1.9%, respectively, in Mersin, Turkey. Cercariae were not matured in sporocysts at the beginning of April; however, it was observed that cercariae matured and started to leave sporocysts by early-May. Thus, it was concluded that H. aspersa acts as an intermediate host to D. dendriticumin and Brachylaima sp. in Mersin, Turkey. A digenean trematode Brachylaima sp. was seen for the first time in Turkey.

Mitochondrial and nuclear ribosomal DNA dataset supports that Paramphistomum leydeni (Trematoda: Digenea) is a distinct rumen fluke species

BACKGROUND

Rumen flukes parasitize the rumen and reticulum of ruminants, causing paramphistomiasis. Over the years, there has been considerable debate as to whether Paramphistomum leydeni and Paramphistomum cervi are the same or distant species.

METHODS

In the present study, the complete mitochondrial (mt) genome of P. leydeni was amplified using PCR-based sequencing and compared with that of P. cervi. The second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA (rDNA) of P. leydeni specimens (n = 6) and P. cervi specimens (n = 8) was amplified and then sequenced. Phylogenetic relationship of the concatenated amino acid sequence data for 12 protein-coding genes of the two rumen flukes and selected members of Trematoda was evaluated using Bayesian inference (BI).

RESULTS

The complete mt genome of P. leydeni was 14,050 bp in size. Significant nucleotide difference between the P. leydeni mt genome and that of P. cervi (14.7%) was observed. For genetic divergence in ITS-2, sequence difference between P. leydeni and P. cervi was 3.1%, while no sequence variation was detected within each of them. Phylogenetic analysis indicated that P. leydeni and P. cervi are closely-related but distinct rumen flukes.

CONCLUSIONS

Results of the present study support the proposal that P. leydeni and P. cervi represent two distinct valid species. The mt genome sequences of P. leydeni provide plentiful resources of mitochondrial markers, which can be combined with nuclear markers, for further comparative studies of the biology of P. leydeni and its congeners from China and other countries.

Molecular characterization of Eurytrema coelomaticum in cattle from Paraná, Brazil

This study investigated the occurrence of Eurytremaspp. in cattle by analysis of the partial 18S rRNA gene sequence. Trematodes from 44 bovine pancreas were collected and classified based on typical morphological features. PCR assay and sequence analyses of amplified products confirmed that the trematodes classified as Eurytrema coelomaticum were phylogenetically distinct from those identified as E. pancreaticum. The results of this study represent the first molecular characterization of E. coelomaticum within the Americas, and provide an efficient method to differentiate digenean trematodes of domestic animals.

Characterization of the complete nuclear ribosomal DNA sequences of Paramphistomum cervi

Sequences of the complete nuclear ribosomal DNA (rDNA) gene from five individual Paramphistomum cervi were determined for the first time. The five complete rDNA sequences, which included the 18S rDNA, the internal transcribed spacer 1 (ITS1), the 5.8S rDNA, the internal transcribed spacer 2 (ITS2), the 28S rDNA, and the intergenic spacer (IGS) regions, had a length range of 8,493–10,221 bp. The lengths of the investigated 18S, ITS1, 5.8S, ITS2, and 28S rDNA sequences, which were 1,994 bp, 1,293 bp, 157 bp, 286 bp, and 4,186 bp, respectively, did not vary. However, the IGS rDNA sequences had a length range of 577–2,305 bp. The 5.8S and ITS-2 rDNA sequences had 100% identity among the five investigated samples, while the identities among the IGS had a range of 53.7–99.8%. A comparative analysis revealed that different types and numbers of repeats were found within each ITS1 and IGS region, which may be related to the length polymorphism of IGS. The phylogenetic position of P. cervi in Paramphistomatidae was analyzed based on the 18S rDNA sequences. These results will aid in studying the intra- and interspecific variation of the Paramphistomatidae and the systematics and phylogenetics of Digenea.

Distinct distribution of Dicrocoelium dendriticum and D. chinensis in Iwate Prefecture, Japan, and a new final host record for D. chinensis

This study dealt with the morphological and molecular identification of Dicrocoelium flukes obtained from Japanese serow (Capricornis crispus) and sika deer (Cervus nippon centralis) in the twelve districts of Iwate Prefecture, Japan. Dicrocoelium dendriticum and D. chinensis were exclusively detected in the western, and coastal and eastern areas of Iwate Prefecture, respectively. This geographically distinct occurrence of the two Dicrocoelium species would be associated with the distribution of the final hosts, sika deer for D. chinensis and Japanese serow for D. dendriticum. This study also reports that Capricornis crispus is a new final host of D. chinensis.

Characterization of Dicrocoelium dendriticum haplotypes from sheep and cattle in Iran based on the internal transcribed spacer 2 (ITS-2) and NADH dehydrogenase gene (nad1)

The present study assessed whether the genetic variation among different hosts (sheep and cattle) and geographical isolates (n= 28) of Dicrocoelium dendriticum from Iran is present based on mitochondrial (nad1) and ribosomal (ITS-2) DNA markers. Molecular analysis revealed the presence of at least ten and two distinct haplotypes in the NADH dehydrogenase gene (nad1) and internal transcribed spacer 2 (ITS-2), respectively. The nad1 and ITS-2 sequence data were deposited in GenBank under accession numbers, JX050110–134 and JQ966972–3. According to the results of our study, ND-D and ITS-A are established as being the predominant haplotypes of D. dendriticum in Iran. The Iranian isolates showed a higher intraspecific genetic diversity of 0–0.97% for nad1, compared to 0–0.42% for ITS-2. The alignment and comparison of nad1 and ITS-2 sequences revealed eight and one polymorphic sites, respectively. In the nad1 sequences, six were silent and two nucleotide substitutions were responsible for amino acid alterations. A phylogenetic analysis of the sequence data revealed that host associations and geographic location are not likely useful markers for D. dendriticum haplotype classification. Consequently, sequencing results obtained from the nad1 gene as a mitochondrial marker for the first time in this study would provide a valuable tool to analyse further molecular details of D. dendriticum worldwide.

Characterization ofDicrocoelium dendriticumisolates from small ruminants in Shaanxi Province, north-western China, using internal transcribed spacers of nuclear ribosomal DNA

The genetic variations in internal transcribed spacers (ITS) spanning ITS-1, 5.8S and ITS-2 rDNA ofDicrocoelium dendriticum, isolated from sheep and goats in four geographical regions in Shaanxi province, were examined. The lengths of ITS-1, 5.8S and ITS-2 rDNA sequences forD. dendriticumwere 749 bp, 161 bp and 234 bp, respectively. Intra-specific sequence variations ofD. dendriticumwere 0–0.5% for ITS-1 and 0–1.3% for ITS-2 rDNA, while the inter-specific variations among species in genusDicrocoeliumin ITS-2 rDNA were 3.4–12.3%. Phylogenetic analysis based on sequences of ITS-2 rDNA showed that allD. dendriticumisolates in the present study were grouped with referenceD. dendriticumisolates from sheep and goats, andD. dendriticumisolates from cattle and Japanese serow were clustered in a sister clade. However, the phylogenetic tree could not reveal geographically genetic relationships ofD. dendriticumisolates in different origins and hosts. These findings provided basic information for further study of molecular epidemiology and control ofD. dendriticuminfection in Shaanxi province as well as in the world.

Genetic variability among Dicrocoelium dendriticum isolates from different regions in Shaanxi Province, China revealed by sequences of three mitochondrial genes

The genetic variations in three mitochondrial DNA (mtDNA) regions, namely portion of cytochrome c oxidase subunit 1 (pcox1), NADH dehydrogenase subunit 1 (pnad1) and cytochrome b (pcytb), were examined for Dicrocoelium dendriticum samples isolated from different origins in Shaanxi Province, northwestern China. The intra-specific sequence differences within D. dendriticum samples were 0-0.52% for pcox1, 0-0.73% for pnad1 and 0-0.58% for pcytb. Phylogenetic analyses based on combined sequences of three mtDNA showed that all D. dendriticum samples were clustered together in same clade of Paragonimus westermani. But the phylogenetic trees could not reveal geographically genetic relationships of D. dendriticum isolates in this province. These findings will provide basic information for further study of molecular epidemiology and control of D. dendriticum infection in this province as well as in China.

A tool for diagnosis of Dicrocoelium dendriticum infection: hatching eggs and molecular identification of the miracidium

DNA primers were designed from the 18S rRNA sequence from the relevant digenean trematode Dicrocoelium dendriticum to evaluate a polymerase chain reaction-based diagnostic method of this parasite from its eggs in faeces of naturally and experimentally infected sheep. In order to get DNA from D. dendriticum eggs, several hatching mechanisms were studied. Successful results were obtained when the eggs were frozen to -80 °C and/or in liquid nitrogen and then defrosted. This method allowed the opening of the egg operculum and the liberation of the miracidium. DNA from D. dendriticum adults and from hatching egg miracidia was obtained and an amplification single band of 1.95 kb was observed using primers designed for the total 18S rRNA sequence in both cases as well as when the template DNA was from adults of the closely related parasite Fasciola hepatica; in addition, a single and specific 0.8-kb band was obtained when primers based on an internal partial 18S rRNA sequence were used. The method showed to be useful not only in samples coming from adults, but in eggs from gall bladder and faeces as well. F. hepatica internal 18S rRNA primers were also designed and used as a negative control to prove that the eggs in faeces came from D. dendriticum and not from F. hepatica. A molecular tool able to detect a minimum of about 40 D. dendriticum eggs in one of the definitive host faeces has been developed for the first time and could provide a useful molecular tool to improve the conventional coprological diagnosis for detecting D. dendriticum eggs.