Echinostoma chankensis nom. nov., other Echinostoma spp. and Isthmiophora hortensis in East Asia: morphology, molecular data and phylogeny within Echinostomatidae.

Life cycles, and morphological and molecular data were obtained for Echinostoma chankensis nom. nov., Echinostoma cinetorchis, Echinostoma miyagawai and Isthmiophora hortensis from East Asia. It was established that, based on both life cycle and morphology data, one of the trematodes is identical to the worms designated as Euparyphium amurensis. Genetic data showed that this trematode belongs to Echinostoma. The complex data on biological, morphological and genetic characterizations establish that the distribution of the morphologically similar species, I. hortensis and Isthmiophora melis, in the Old World are limited by the East Asian and European regions, respectively. Data on mature worms of East Asian E. miyagawai revealed morphological and genetic identity with E. miyagawai from Europe. However, E. miyagawai from Europe differs from E. miyagawai from the type locality (East Asia) in terms of reaching maturity and the morphology of cercariae. These data indicate that the European worm, designated E. miyagawai, does not belong to this species. An analysis of the phylogenetic relationships of Echinostomatidae was conducted based on the 28S, ITS2 and nad1 markers. Analysis using the nad1 gene for the known representatives of Echinostomatidae is carried out for the first time, showing that nuclear markers are ineffective separate from mitochondrial ones.

Echinostoma miyagawai Ishii, 1932 (Echinostomatidae) from Ducks in Aceh Province, Indonesia with Special Reference to Its Synonymy with Echinostoma robustum Yamaguti, 1935.

Adult echinostomes having 37 collar spines collected from the intestine of Pitalah ducks in Aceh Province, Indonesia in 2018 were morphologically and molecularly determined to be Echinostoma miyagawai Ishii, 1932 (Digenea: Echinostomatidae). Among 20 ducks examined, 7 (35.0%) were found to be infected with this echinostome, and the number of flukes collected was 48 in total with average 6.9 (1-17) worms per duck. The adult flukes were 7.2 (6.1-8.5) mm in length and 1.2 (1.0-1.4) mm in width (pre-ovarian or testicular level) and characterized by having a head collar armed with 37 collar spines (dorsal spines arranged in 2 alternating rows), including 5 end group spines, and variable morphology of the testes, irregularly or deeply lobed (3-5 lobes) at times with horizontal extension. The eggs within the worm uterus were 93 (79-105) µm long and 62 (56-70) µm wide. These morphological features were consistent with both E. miyagawai and Echinostoma robustum, for which synonymy to each other has been raised. Sequencing of 2 mitochondrial genes, cox1 and nad1, revealed high homology with E. miyagawai (98.6-100% for cox1 and 99.0-99.8% for nad1) and also with E. robustum (99.3-99.8% for nad1) deposited in GenBank. We accepted the synonymy between the 2 species and diagnosed our flukes as E. miyagawai (syn. E. robustum) with redescription of its morphology. Further studies are required to determine the biological characteristics of E. miyagawai in Aceh Province, Indonesia, including the intermediate host and larval stage information.

Comparative mitogenomics of the zoonotic parasite Echinostoma revolutum resolves taxonomic relationships within the 'E. revolutum' species group and the Echinostomata (Platyhelminthes: Digenea).

The complete mitochondrial sequence of 17,030 bp was obtained from Echinostoma revolutum and characterized with those of previously reported members of the superfamily Echinostomatoidea, i.e. six echinostomatids, one echinochasmid, five fasciolids, one himasthlid, and two cyclocoelids. Relationship within suborders and between superfamilies, such as Echinostomata, Pronocephalata, Troglotremata, Opisthorchiata, and Xiphiditata, are also considered. It contained 12 protein-coding, two ribosomal RNA, 22 transfer RNA genes and a tandem repetitive consisting non-coding region (NCR). The gene order, one way-positive transcription, the absence of atp8 and the overlapped region by 40 bp between nad4L and nad4 genes were similar as in common trematodes. The NCR located between tRNAGlu (trnE) and cox3 contained 11 long (LRUs) and short repeat units (SRUs) (seven LRUs of 317 bp, four SRUs of 207 bp each), and an internal spacer sequence between LRU7 and SRU4 specifying high-level polymorphism. Special DHU-arm missing tRNAs for Serine were found for both tRNAS1(AGN) and tRNAS2(UCN). Echinostoma revolutum indicated the lowest divergence rate to E. miyagawai and the highest to Tracheophilus cymbius and Echinochasmus japonicus. The usage of ATG/GTG start and TAG/TAA stop codons, the AT composition bias, the negative AT-skewness, and the most for Phe/Leu/Val and the least for Arg/Asn/Asp codons were noted. Topology indicated the monophyletic position of E. revolutum to E. miyagawai. Monophyly of Echinostomatidae and Fasciolidae was clearly solved with respect to Echinochasmidae, Himasthlidae, and Cyclocoelidae which were rendered paraphyletic in the suborder Echinostomata.

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.

Infections of Two Isthmiophora Species (Digenea: Echinostomatidae) in Wild Mammals from Republic of Korea with Their Morphological Descriptions.

Isthmiophora hortensis (Digenea: Echinostomatidae) is a dominant echinostome in animal reservoir hosts and humans in the Republic of Korea (Korea). We intended to investigate the infection status with this echinostome species in the several species of wild animals and describe the morphological characteristics in the faunistic view point. A total of 175 animal carcasses belonging to 3 families, i.e., Canidae, Felidae and Mustelidae, were collected from the southern regions of Korea from March 2010 to July 2017. Isthmiophora spp. worms were recovered from the small intestines of each animal under a stereomicroscope after washing of intestinal contents. Isthmiophora hortensis was recovered from 4 species of wild carnivores, i.e., Nyctereutes procyonoides (3/107: 2.8%), Mustela sibirica (11/31: 35.5%), Meles lucurus (2/3: 33.3%) and Martes flavigula (1/2: 50%). The other 3 carnivores comprising stray dogs, cat and leopard cat were negative for I. hortensis infection (0/2, 0/10 and 0/12, respectively). Specimens obtained from the Lutra lutra (6/8: 75%) were identified as a distinct species, I. inermis, by morphological comparison. Isthmiophora inermis has thinner body, elongate testes and different anterior limits of vitelline fields. Detailed morphological descriptions and comparisons with the morphological characteristics are provided. Conclusively, it was confirmed for the first time that 3 species of mustelid mammals, i.e., M. sibirica, M. lucurus, and M. flavigula, are to be the new definitive hosts of I. hortensis in Korea. Additionally, I. inermis is to be newly added in the Korean echinostome fauna.

Multilocus phylogenetic analysis and morphological data reveal a new species composition of the genus Drepanocephalus Dietz, 1909 (Digenea: Echinostomatidae), parasites of fish-eating birds in the Americas.

Members of the genus Drepanocephalus are endoparasites of fish-eating birds of the families Phalacrocoracidae and Sulidae distributed across the Americas. Currently, Drepanocephalus contains three species, i.e. D. spathans (type species), D. olivaceus and D. auritus. Two additional species, D. parvicephalus and D. mexicanus were transferred to the genus Petasiger. In the current study, available DNA sequences of D. spathans, D. auritus and Drepanocephalus sp., were aligned with newly generated sequences of D. spathans and Petasiger mexicanus. Phylogenetic analyses inferred with three nuclear (LSU, SSU and ITS1, 5.8S, ITS2) and two mitochondrial (cox1, nad1) molecular markers showed that the sequences of D. spathans and D. auritus are nested together in a single clade with very low genetic divergence, with Petasiger mexicanus as its sister species. Additionally, P. mexicanus was not a close relative of other members of the genus Petasiger, showing that P. mexicanus actually belongs to the genus Drepanocephalus, suggesting the need to re-allocate Petasiger mexicanus back into the genus Drepanocephalus, as D. mexicanus. Morphological observations of the newly sampled individuals of D. spathans showed that the position of the testes is variable and testes might be contiguous or widely separated, which is one of the main diagnostic traits for D. auritus. Our results suggest that D. auritus might be considered a synonym of D. spathans and, as a result, the latter represents a species with a wide geographic range across the Americas, parasitizing both the Neotropical and the double-crested cormorant in Argentina, Brazil, Paraguay, Venezuela, Colombia, Mexico, USA and Canada.

New Definitive Hosts and Differential Body Indices of Isthmiophora hortensis (Digenea: Echinostomatidae).

The present study was performed to record new definitive hosts of Isthmiophora hortensis, and to describe morphological characteristics derived from a variety of worm samples for clarification of its taxonomic validity. Morphological characteristics with dimensions were observed in worm samples (n=21) from naturally infected wild animals, including a raccoon dog Nyctereutes procyonoides from Gimhae-si (City), Gyeongsangnam-do, stray cats and a striped field mouse from several localities, and a wild boar Sus scrofa, from Gurye-gun (County), Jeollanam-do. In addition, adult flukes (n=45) recovered in albino rats experimentally infected with the metacercariae from a freshwater fish species were also subjected to morphological studies. The mean ratios of the body length (BL) to body width (BW) were 5.86 and 5.76 in worms from wild animals and experimental rats, respectively. Those of the ventral sucker to oral sucker were 2.92 and 3.01 in worms from 2 groups. The mean percentages of the hindbody length (HBL) to BL were 42.1 and 41.2 in 2 groups. Those of uterine fields to BL were 9.8 and 12.2 in the 2 worm groups. By the present study, the 2 species of wild animals, the raccoon dog and wild boar, have been added as new definitive hosts for I. hortensis. The morphological characteristics of adult flukes derived from a variety of host source were redescribed to support the taxonomic validity of this echinostome species.

Molecular characterisation of four echinostomes (Digenea: Echinostomatidae) from birds in New Zealand, with descriptions of Echinostoma novaezealandense n. sp. and Echinoparyphium poulini n. sp.

Morphological and molecular characterisation of echinostome specimens (Digenea: Echinostomatidae) recovered in one Anas platyrhynchos L. and one Cygnus atratus (Latham) (Anseriformes: Anatidae) from New Zealand revealed the presence of two known species, Echinostoma miyagawai Ishii, 1932 and Echinoparyphium ellisi (Johnston & Simpson, 1944) and two species new to science. Comparative morphological and phylogenetic analyses supported the distinct species status of Echinostoma novaezealandense n. sp. ex Branta canadensis (L.), A. platyrhynchos and C. atratus, and Echinoparyphium poulini n. sp. ex C. atratus. Echinostoma novaezealandense n. sp., a species of the "revolutum" species complex characterised by the possession of a head collar armed with 37 spines, keyed down to E. revolutum but was distinguished from the latter in having a much narrower body with almost parallel margins, longer oesophagus, wider cirrus-sac, larger seminal vesicle, much smaller ventral sucker, ovary, Mehlis' gland and testes, more anteriorly located ovary and testes, and distinctly smaller eggs (81-87 × 42-53 vs 106-136 × 55-70 µm). This new species appears similar to Echinostoma acuticauda Nicoll, 1914 described in Australia but differs in having a longer forebody, more posteriorly located ovary and testes, and much smaller eggs (81-87 × 42-53 vs 112-126 × 63-75 µm). Echinoparyphium poulini n. sp. is differentiated from the four species of Echinoparyphium possessing 37 collar spines considered valid as follows: from E. chinensis Ku, Li & Chu, 1964 in having a much smaller body, four (vs five) angle spines and simple seminal vesicle (vs bipartite); from E. schulzi Matevosyan, 1951 in having a less robust body at a comparable body length, much smaller ventral sucker, ovary and testes, and longer but narrower eggs (87-109 × 50-59 vs 70-85 × 60-84 µm); and from the two smaller forms, E. serratum Howell, 1968 and E. aconiatum Dietz, 1909, in a number of additional metrical features correlated with body size and especially in the possession of much larger collar spines. Partial fragments of the mitochondrial nad1 and 28S rRNA genes were amplified for representative isolates of the four species and analysed together with sequences for Echinostoma spp. and Echinoparyphium spp. available on GenBank. Phylogenetic analyses based on the mitochondrial nad1 gene revealed congruence between the molecular data and species identification/delineation based on morphology; this was corroborated by the 28S rDNA sequence data.

Genomic diversity of cercarial clones of Himasthla elongata (Trematoda, Echinostomatidae) determined with AFLP technique.

The aim of this study was to reveal genomic diversity formed during parthenogenetic reproduction of rediae of the trematode Himasthla elongata in its molluskan host Littorina littorea. We applied amplification fragment length polymorphism (AFLP) to determine the genomic diversity of individual cercariae within the clone, that is, the infrapopulation of parthenogenetic progeny in a single molluskan host. The level of genomic diversity of particular cercariae isolates from a single clone, detected with EcoR1/Mse1 AFLP reaction, was significantly lower than the variability of cercariae from different clones. The presence of intraclonal genomic diversity indicates a nonsexual shuffle of alleles during parthenogenesis in the rediae of H. elongata. The obtained polymorphic AFLP fragments were long enough to detect the sequences that may be responsible for clonal genomic variability. Based on this, AFLP can be recommended as a tool for the study of genetic mechanisms of this variability.

Biomphalaria straminea (Mollusca: Planorbidae) as an intermediate host of Drepanocephalus spp. (Trematoda: Echinostomatidae) in Brazil: a morphological and molecular study.

Species of trematodes belonging to the genus Drepanocephalus are intestinal parasites of piscivorous birds, primarily cormorants (Phalachrocorax spp.), and are widely reported in the Americas. During a 4-year malacological study conducted on an urban lake in Brazil, 27-collar-spined echinostome cercariae were found in 1665/15,459 (10.7 %) specimens of Biomphalaria straminea collected. The cercariae were identified as Drepanocephalus spp. by sequencing the 18S (SSU) rDNA, ITS1/5.8S rDNA/ITS2 (ITS), 28S (LSU) rDNA region, cytochrome oxidase subunit 1 (CO1), and nicotinamide adenine dinucleotide dehydrogenase subunit 1 (ND1) markers. In experimental life cycle studies, metacercariae developed in laboratory-reared guppies (Poecilia reticulata); however, attempts to infect birds and rodents were unsuccessful. Two closely related morphotypes of cercariae were characterized. One species, identified by molecular markers as a genetic variant of Drepanocephalus auritus (99.9 % similarity at SSU, ITS, LSU; 97.2 % at CO1; 95.8 % at ND1), differs slightly from an archived North American isolate of this species also sequenced as part of this study. A second species, putatively identified as Drepanocephalus sp., has smaller cercariae and demonstrates significant differences from D. auritus at the CO1 (11.0 %) and ND1 (13.6 %) markers. Aspects related to the morphological taxonomic identification of 27-collar-spined echinostome metacercariae are briefly discussed. This is the first report of the involvement of molluscs of the genus Biomphalaria in the transmission of Drepanocephalus and the first report of D. auritus in South America.

Two Echinostome Species, Pegosomum bubulcum and Nephrostomum ramosum (Digenea: Echinostomatidae), from an Eastern Cattle Egret, Bubulcus ibis coromandus, in Republic of Korea.

We describe 2 echinostome species recovered from an Eastern cattle egret, Bubulcus ibis coromandus, from Cheongju-si (city), Chungcheongbuk-do (province), Korea. Total 72 Pegosomum bubulcum specimens were recovered from the bile duct. They were 7,566×2,938 µm in average size and had 27 collar spines with vitelline extension from anterior 1/3 level of the esophagus to mid-level of the posterior testis as characteristic features. Total 9 specimens of Nephrostomum ramosum were recovered in the small intestines of the bird. They were ribbon-shaped, 11,378×2,124 µm in average size, and morphologically variable in some organs, i.e., the number of collar spines (47-50), the shape of ovary and testes, and the extension of vitelline follicles. These morphological variations observed in a single host indicated that these features are not critical for the classification of Nephrostomum species and thus were reconsidered taxonomically as synonym of N. ramosum. This study is the first report documenting and describing both flukes and their associated genera in Korea.

A Case of Chaunocephalosis by Chaunocephalus ferox (Digenea: Echinostomatidae) in an Oriental White Stork, Ciconia boyciana, in Korea.

We intended to describe a case of chaunocephalosis and morphological characteristics of its causative agent, Chaunocephalus ferox, recovered from an oriental white stork, Ciconia boyciana, in the Republic of Korea. An oriental white stork was referred to the Wildlife Center of Chungbuk in Korea in February 2014 for severe depression with cachexia and it died the next day. At necropsy, the stomach was severely expanded and 7 thick-walled nodules were observed in the upper part of the intestine. Although the stomach was filled with full of foreign materials, the intestine was almost empty. The nodules were globular and total 9 flukes were recovered. They were 8,030-8,091 µm in length and 3,318-3,333 µm in maximum width. Because the flukes had bulbous forebody with short narrow subcylindrical hindbody, 27 collar spines, and vitelline follicles not reaching to the posterior end, the specimens were identified as being C. ferox. The cyst formation induced thickening of the intestinal wall with narrowing of the lumen that could have contributed to the gastric impaction to the death of the host. This is the first described case of chaunocephalosis and its causative agent C. ferox found from an oriental white stork in Korea.

A new species of Drepanocephalus Dietz, 1909 (Digenea: Echinostomatidae) from the double-crested cormorant Phalacrocorax auritus (Lesson) (Aves: Phalacrocoracidae) in North America.

Drepanocephalus auritus n. sp. is described based on specimens from the double-crested cormorant Phalacrocorax auritus (Lesson) in North America. The new species differs from its congeners in its very narrow, elongate body, long uterine field and widely separated testes. Sequences of the nuclear rRNA gene cluster, spanning the 3' end of the nuclear ribosomal 18S rRNA gene, internal transcribed spacer region (ITS1+5.8S gene+ITS2) and partial 28S gene (2,345 bp), were identical in specimens collected from North Dakota, Minnesota and Mississippi, USA. Sequences of the 651 bp long fragment of the mitochondrial cox1 gene exhibited very low intraspecific variability (< 1%). Comparisons of the newly-generated sequences with those available in the GenBank indicate that the sequences from North America published under the name D. spathans Dietz, 1909 in fact represent D. auritus n. sp.

Redescription and phylogenetic relationships of Euparyphium capitaneum Dietz, 1909, the type-species of Euparyphium Dietz, 1909 (Digenea: Echinostomatidae).

Euparyphium capitaneum Dietz, 1909, the type-species of the genus Euparyphium Dietz, 1909, is described on the basis of material collected from the type-host Anhinga anhinga (L.) from Pascagoula River, which drains into the northern coast of the Gulf of Mexico. Combination of light and scanning electron microscopy observations of freshly collected and properly fixed specimens in our study has allowed us to provide novel information on the morphology and topology of the reproductive systems and other morphological features of the species. A Bayesian inference analysis based on the newly-obtained partial sequence of the nuclear 28S rRNA gene for E. capitaneum and 24 previously published sequences from the superfamily Echinostomatoidea Looss, 1899 provided evidence supporting the distinct status of the genera Euparyphium and Isthmiophora Lühe, 1909.

Description of rare echinostomatid fluke Echinodollfusia longiuscula n. sp. (Trematoda: Echinostomatidae) parasitizing white stork with an amended diagnosis of the genus Echinodollfusia.

A new species of digenean, Echinodollfusia longiuscula n. sp. (Trematoda: Echinostomatidae), is described and illustrated based on specimens collected from the intestine of the white stork Ciconia ciconia (L.) (Aves: Ciconiidae) from eastern Slovakia and dissected soon after its spring arrival from African wintering. The new species differs from the two existing congeners Echinodollfusia stenon (Dollfus, 1950) and Echinodollfusia bulgarica Vassilev (Sofia 6:327-338, 1958) clearly by the oesophagus bearing diverticula, the bipartite seminal vesicle and gonads situated entirely in anterior body half. The new species E. longiuscula n. sp. can also be distinguished by possessing the following combination of features: a slender body of 12.85-21.06-mm long and maximum of 581-855-µm wide; head collar with 43-47 small collar spines, dorsal in double row; oral sucker more than half the size as ventral sucker, small pharynx, oval and in tandem testes situated pre-equatorial, small ovary at the boundary of anterior third of the body and anteriormost extent of the vitelline fields just reaching the level of posterior margin of the ventral sucker. An amended generic diagnosis of little-known Echinodollfusia Skrjabin et Bashkirova (Osnovy Trematodologii 12:51-930, 1956) is also given here.

Morphological and molecular data for larval stages of four species of Petasiger Dietz, 1909 (Digenea: Echinostomatidae) with an updated key to the known cercariae from the Palaearctic.

Large-tailed echinostomatid cercariae of the genus Petasiger Dietz, 1909 (Digenea: Echinostomatidae) from the planorbid snails Gyraulus albus (Müller) and Planorbis planorbis (L.) collected in Germany and the Czech Republic and metacercariae from Gasterosteus aculeatus L. (Gasterosteiformes: Gasterosteidae) collected in Canada are characterised morphologically and molecularly. The rediae, cercariae and metacercariae are described in detail and compared with the existing data on the larval stages of Petasiger spp. Comparative molecular analyses using 28S rDNA and nad1 mitochondrial sequences supported the distinct status of four species of Petasiger. Molecular and morphological evidence for their distinction and an updated key to the known large-tailed cercariae of Petasiger from the Palaearctic are provided.

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.

Genetic differentiation of Artyfechinostomum malayanum and A. sufrartyfex (Trematoda: Echinostomatidae) based on internal transcribed spacer sequences.

Genetic differentiation between two synonymous echinostomes species, Artyfechinostomum malayanum and Artyfechinostomum sufrartyfex was determined by using the first and second internal transcribed spacers (ITS1 and ITS2), the non-coding region of rDNA as genetic makers. Of the 699 bp of combined ITS1 and ITS2 sequences examined, 18 variable nucleotide positions (2.58 %) were observed. Of these, 17 positions could be used as diagnostic position between these two sibling species, whereas the other one variation was intraspecific variation of A. malayanum. A clade of A. malayanum was closely aligned with A. sufrartyfex and clearly distance from the cluster of other echinostomes. Our results may sufficiently suggest that the current synonymy of these species is not valid.

Zoonotic echinostome infections in free-grazing ducks in Thailand.

Free-grazing ducks play a major role in the rural economy of Eastern Asia in the form of egg and meat production. In Thailand, the geographical location, tropical climate conditions and wetland areas of the country are suitable for their husbandry. These environmental factors also favor growth, multiplication, development, survival, and spread of duck parasites. In this study, a total of 90 free-grazing ducks from northern, central, and northeastern regions of Thailand were examined for intestinal helminth parasites, with special emphasis on zoonotic echinostomes. Of these, 51 (56.7%) were infected by one or more species of zoonotic echinostomes, Echinostoma revolutum, Echinoparyphium recurvatum, and Hypoderaeum conoideum. Echinostomes found were identified using morphological criteria when possible. ITS2 sequences were used to identify juvenile and incomplete worms. The prevalence of infection was relatively high in each region, namely, north, central, and northeast region was 63.2%, 54.5%, and 55.3%, respectively. The intensity of infection ranged up to 49 worms/infected duck. Free-grazing ducks clearly play an important role in the life cycle maintenance, spread, and transmission of these medically important echinostomes in Thailand.

Echinostome flukes receovered from humans in Khammouane Province, Lao PDR.

Echinostome eggs were detected in 22 (1.1%) of 2,074 people residing in riparian villages along the Mekong River in Khammouane Province, Lao PDR. In order to recover the adult flukes, 9 persons were treated with praziquantel and purged with magnesium salts. A total of 55 echinostome specimens (4 species) were recovered from the 9 persons. Echinostoma revolutum (8 specimens) was recovered from 3 persons, Artyfechinostomum malayanum (8 specimens) was from 2 persons, Echinochasmus japonicus (33 specimens) was from 7 persons, and Euparyphium sp. (6 specimens) was from 1 person. In Lao PDR, only human infections with E. japonicus were previously known. Therefore, the present study describes human infections with E. revolutum, A. malayanum, and Euparyphium sp. for the first time in Lao PDR. These results indicate that the surveyed villages of Khammouane Province, Lao PDR are low-grade endemic foci of echinostomiasis.