Gobioecetes biwaensis n. g., n. sp. (Monogenea: Dactylogyridae) from the gills of a freshwater gobiid fish, Rhinogobius sp. BW Takahashi & Okazaki, 2002, with a redescription of Parancyrocephaloides daicoci Yamaguti, 1938

A description is given of Gobioecetes biwaensis n. g., n. sp. (Monogenea: Dactylogyridae) on the gills of a freshwater gobiid fish, Rhinogobius sp. BW Takahashi & Okazaki, 2002 from Lake Biwa, Shiga Prefecture and Rhinogobius sp. from Sento Imperial Palace, Kyoto Prefecture, Japan. This monogenean is most similar to Parancyrocephaloides rhinogobius Ling, 1973, proposed here as Gobioecetes rhinogobius n. comb., collected from the gills of Rhinogobius giurinus (Rutter, 1897) in Hupei Province, China, but can be differentiated from it in that ventral hamuli of G. biwaensis are larger than those of G. rhinogobius and in that in G. biwaensis, ventral hamuli are larger than dorsal ones, but in G. rhinogobius, ventral and dorsal hamuli are almost equal in size. The new genus is characterized by the absence of a bar supporting dorsal hamuli. Parancyrocephaloides daicoci Yamaguti, 1938, the type species of the genus, is redescribed based on newly collected specimens from a marine dactylopterid, Dactyloptena peterseni (Nyström, 1887) and the type specimens, revealing that it has a pair of vestigial bars supporting dorsal hamuli. The generic diagnoses of Gobioecetes n. g. and Parancyrocephaloides are given and systematic position of these genera in Dactylogyridae is discussed in this paper.

Development of quantitative PCR assay for detection of the trematode parasite Proctoeces maculatus in the blue mussel Mytilus edulis

The digenean trematode Proctoeces maculatus is an important parasite of the blue mussel Mytilus edulis. The parasite reduces mussel quality and yield, negatively impacting mussel aquaculture efforts. Typically, the trematode is detected by visual observation. To provide a better diagnostic tool able to detect this parasite at any life stage and at low intensities, we designed a species-specific molecular assay to detect P. maculatus in M. edulis tissue. Primers targeting the 18S nuclear ribosomal DNA (rDNA) from P. maculatus were used to develop an end-point polymerase chain reaction assay and a quantitative polymerase chain reaction (qPCR) assay. Analytical specificity of the assays was demonstrated using DNA from 4 other digenean trematodes. The qPCR assay was linear from 6.79 × 102 to 6.79 × 107 copies of the cloned target DNA and had a conservative detection limit of 68 copies. The qPCR assay detected single cercariae, and the number of isolated cercariae was linearly correlated with the threshold cycle (CT). Diagnostic sensitivity of the PCR-based methods was 100%. The assays also detected the parasite in 6 additional samples from the 57 tested through microscopy. We used the assays to verify the presence of encapsulated sporocysts in the mantle and to document infected mussels from Dover, New Hampshire, extending the previously described northern range of the species. Thus, this work has important implications for detection of the parasite in aquaculture and in monitoring its potential spread with climate change.

Developmental stages of fish blood flukes, Cardicola forsteri and Cardicola opisthorchis (Trematoda: Aporocotylidae), in their polychaete intermediate hosts collected at Pacific bluefin tuna culture sites in Japan

Farming of Pacific bluefin tuna (PBT), Thunnus orientalis, is a rapidly growing industry in Japan. Aporocotylid blood flukes of the genus Cardicola comprising C. orientalis, C. opisthorchis and C. forsteri are parasites of economic importance for PBT farming. Recently, terebellid polychaetes have been identified as the intermediate hosts for all these parasites. We collected infected polychaetes, Terebella sp., the intermediate host of C. opisthorchis, from ropes and floats attached to tuna cages in Tsushima, Nagasaki Prefecture, Japan. Also, Neoamphitrite vigintipes (formerly as Amphitrite sp. sensu Shirakashi et al., 2016), the intermediate host of C. forsteri, were collected from culture cages in Kushimoto, Wakayama Prefecture, Japan. The terebellid intermediate hosts harbored the sporocysts and cercariae in their body cavity. Developmental stages of these blood flukes were molecularly identified using species specific PCR primers. In this paper, we describe the cercaria and sporocyst stages of C. opisthorchis and C. forsteri and compare their morphological characteristics among three Cardicola blood flukes infecting PBT. We also discuss phylogenetic relations of the six genera of the terebellid intermediate hosts (Artacama, Lanassa, Longicarpus, Terebella, Nicolea and Neoamphitrite) of blood flukes infecting marine fishes, based on their morphological characters.

Emergence of the Zoonotic Biliary Trematode Pseudamphistomum truncatum in Grey Seals (Halichoerus grypus) in the Baltic Sea

The biliary trematode Pseudamphistomum truncatum parasitizes a wide range of fish-eating mammals, including humans. Here we report the emergence of this parasite in grey seals (Halichoerus grypus) in the Baltic Sea. One hundred eighty-three of 1 554 grey seals (11.9%) examined from 2002-2013 had detectable hepatobiliary trematode infection. Parasite identification was confirmed as P. truncatum by sequencing the ITS2 region of a pool of five to 10 trematodes from each of ten seals collected off the coast of seven different Swedish counties. The proportion of seals parasitized by P. truncatum increased significantly over time and with increasing age of seals. Males were 3.1 times more likely to be parasitized than females and animals killed in fishery interactions were less likely to be parasitized than animals found dead or hunted. There was no significant difference in parasitism of seals examined from the Gulf of Bothnia versus those examined from the Baltic Proper. Although the majority of infections were mild, P. truncatum can cause severe hepatobiliary disease and resulted in liver failure in at least one seal. Because cyprinid fish are the second intermediate host for opisthorchiid trematodes, diets of grey seals from the Baltic Sea were analysed regarding presence of cyprinids. The proportion of gastrointestinal tracts containing cyprinid remains was ten times higher in seals examined from 2008 to 2013 (12.2%) than those examined from 2002 to 2007 (1.2%) and coincided with a general increase of trematode parasitism in the host population. The emergence and relatively common occurrence of P. truncatum in grey seals signals the presence of this parasite in the Baltic Sea ecosystem and demonstrates how aquatic mammals can serve as excellent sentinels of marine ecosystem change. Investigation of drivers behind P. truncatum emergence and infection risk for other mammals, including humans, is highly warranted.

Trematode Fluke Procerovum varium as Cause of Ocular Inflammation in Children, South India

Larvae of this fluke are novel causes of granulomatous eye disease in children.

Trematodes are recognized as a group of emerging parasites in tropical countries. We identified a trematode as a cause of ocular granulomas that developed in children who bathed in ponds or rivers in South India. DNA was isolated from patients’ surgically excised granulomas and from the trematode cercariae (larvae) released by the snail Melanoidestuberculata in water in which the children bathed. Real-time and conventional PCRs were performed that targeted ribosomal DNA regions spanning the internal transcribed spacer 2 and 28S sequences of this trematode. The PCR-amplified products were subjected to bidirectional sequencing. Analysis of sequences for the granuloma samples and the trematode cercariae showed maximum sequence similarity with Procerovumvarium (family Heterophyidae). Our results confirmed the etiology of the ocular infection, implicating snail vectors as environmental risk factors for ocular parasitosis.

A new species of Hemipera Nicoll, 1913 (Digenea: Derogenidae) from fishes of the intertidal rocky zone of Chile

A new species, Hemipera cribbi sp. nov., is described. This trematode was found in three intertidal fish species: Scartichthys viridis (Valenciennes) (Blenniidae), Gobiesox marmoratus Jenyns (Gobiesocidae) and Myxodes viridis Valenciennes (Clinidae) from the central and southern coast of Chile. Of 233 individuals of S. viridis from the central coast examined, 19 were infected. From the southern coast, nine individuals of S. viridis (one infected), five individuals of G. marmoratus (four infected), and 16 individuals of M. viridis (one fish infected) were examined. Hemipera cribbi sp. nov. is distinguished from the five other congeneric species mainly in the body size, being the smallest and narrowest species in the genus, reaching five times longer than wide. This is the first species of the genus described for the South Pacific Ocean off South America. ITS2 rDNA sequences of Hemipera cribbi sp. nov. from each host and locality were identified.

Redescription of Proctophantastes gillissi (Overstreet et Pritchard, 1977) (Trematoda: Zoogonidae) with discussion on the systematic position of the genus Proctophantastes Odhner, 1911

The redescription of Proctophantastes gillissi (Overstreet et Pritchard, 1977) (Trematoda: Zoogonidae) was made on specimens collected from Muraenolepis marmorata Günther, 1880 (Gadiformes) caught in the Ross Sea and the Amundsen Sea (Antarctic). The fish is a new host of this parasite. Phylogenetic relations of P. gillissi were inferred by Maximum Likelihood and Bayesian inference analysis of partial sequences from 28S rDNA. The findings from analysis of the molecular data are not consistent with the traditional point of view about the position of the genus Proctophantastes Odhner, 1911 in the subfamily Lepidophyllinae. The taxonomical position of the genus needs further revision.

New larval trematodes in Biomphalaria species (Planorbidae) from Northeastern Argentina

Larval trematodes infecting Biomphalaria tenagophila and B. occidentalis were surveyed in a suburban and semipermanent pond of Corrientes province, Northeastern Argentina. A total of 1,409 snails were examined between spring 2011 to winter 2013, and 8 different larval trematodes were studied morphologically. Three of these species-Echinocercaria sp. IV, Ribeiroia sp. and Echinocercaria sp. XIV-have been previously found in Corrientes province. Six other trematodes belonging to Strigeidae (Furcocercaria sp. III), Clinostomidae (Cercaria Clinostomidae sp.), Spirorchiidae (Cercaria Spirorchiidae sp.) and Echinostomatidae (Echinocercaria sp. 1, Echinocercaria sp. 2, Echinocercaria sp. 3) are new species parasitizing Biomphalaria snails. Cercaria Spirorchiidae sp. is the third larval trematode related to Spirorchiidae recorded in South America and the first one for Argentina. Cercaria Clinostomidae sp. is the first one related to Clinostomidae in northeastern Argentina. The prevalence of larval trematodes infecting B. tenagophila and B. occidentalis in the environment studied was low (<5%) with the echinostome group better represented in terms of prevalence and species richness. Drought periods could affect the dynamics of parasitic transmission due to the absence of trematodes in the autumn and winter of the first seasonal cycle. However, in humid periods parasite transmission can occur throughout the year due to the presence of larvae in all seasons of the second seasonal cycle, although the less-warm seasons showed higher prevalence than the summer period probably related to the subtropical climate of Corrientes province.

Description of three species of Isorchis (Digenea: Atractotrematidae) from Australia

Three species of Isorchis Durio and Manter, 1969 are described from Australian waters. Isorchis megas sp. nov. is described from the spotbanded scat, Selenotoca multifasciata (Richardson), off Western Australia (WA) and Northern Territory (NT); Isorchis currani sp. nov. is described from S. multifasciata off NT; and Isorchis anomalus sp. nov. is described from the milkfish, Chanos chanos Forsskål, off WA. Isorchis megas sp. nov. can be differentiated from the other species of Isorchis by possessing a single, large egg that is greater than 20% of the body length; having a shorter body (the largest specimen is less than 500 μm); and utilizing a scatophagid rather than a chanid host. Isorchis currani sp. nov. can be differentiated from species of Isorchis other than I. megas sp. nov. by utilizing a scatophagid rather than a chanid host; it is differentiated from I. megas sp. nov. in having eggs that are 11-15% of the body length. Isorchis anomalus sp. nov. can be differentiated from all other species of Isorchis in possessing an irregular shaped genital pore rather than one that is circular to oblong. A Bayesian inference analysis of partial 28S rDNA sequences of the three new species of Isorchis and 30 other haploporoids revealed 1) the monophyly of the Atractotrematidae Yamaguti, 1939, 2) the two species of Isorchis infecting S. multifasciata were each other's closest relative, and 3) that Isorchis was most closely related to Pseudomegasolena Machida and Komiya, 1976 rather than Atractotrema Goto and Ozaki, 1929 although sequence data are not yet available for a member of Pseudisorchis Ahmad, 1985.

Parasite fauna of Antarctic Macrourus whitsoni (Gadiformes: Macrouridae) in comparison with closely related macrourids

BACKGROUND

The extreme, isolated environment within the Antarctic Convergence has fuelled the evolution of a highly endemic fauna with unique adaptations. One species known from this area is the Whitson's grenadier Macrourus whitsoni (Regan, 1913). While closely related species occurring in the Northern Hemisphere were targets of a variety of studies, knowledge on M. whitsoni is scarce, including not only its ecology but also its parasite fauna. Parasites, an often overlooked but important component of every ecosystem, can provide important insights into host ecology, including feeding habits, food web interactions and distribution patterns. The aim of our study was to increase the currently limited knowledge on the ecology of M. whitsoni and its parasite life-cycles.

METHODS

In this study, parasite fauna and stomach content of 50 specimens of M. whitsoni were sampled off Elephant and King George Islands. Fish samples were morphological, food ecological and parasitological examined and parasites morphological and partly molecular identified. To evaluate the findings, results were compared with other macrourid species.

RESULTS

The parasite fauna of M. whitsoni revealed 9 genera and 17 species. Stomach content analysis indicated Amphipoda and Mysida as the primary food source. Considering the parasites of M. whitsoni, the highest diversity was found within the Digenea, while prevalence was highest for the Acanthocephala and Nematoda. The diverse parasite fauna of M. whitsoni together with the stomach content analysis, suggests a benthopelagic mode of life. Furthermore, an extensive evaluation of the parasite fauna of species of the Macrourinae was conducted, which is probably the most thorough one yet, to compare the findings with closely related host fish species. A similarity analysis revealed a strong connection between the parasite fauna composition and geographical distribution, with a clear separation between the parasite faunas in fishes sampled in the Pacific and the Atlantic Oceans.

CONCLUSIONS

Due to the isolated habitat within the Antarctic Conversion, the parasite fauna of M. whitsoni differs clearly from those of closely related and closely occurring species of the genus Macrourus. Our study revealed an endemically dominated parasite fauna, with parasites often host-specific to M. whitsoni. The comparison with the faunas of other species of the Macrourinae revealed a largely endemic parasite fauna, which emphasizes again the isolated character of the Antarctic shelf regions.

The first record of Centrocestus formosanus (Nishigori, 1924) (Digenea: Heterophyidae) in Egypt

The life cycle of Centrocestus formosanus (Digenea: Heterophyidae) was to be successfully completed in the laboratory in the present study. Hundreds of the thiarid snail, Melanoides tuberculata, were collected from the main water course Mansouriya Canal, Giza Governorate, Egypt. The snails were individually exposed to artificial light to determine possible infection with trematode larvae. Fifteen snails were found infected with opthalmopleurolophocercous cercariae (infection index of 1.97). These opthalmopleurolophocercous cercariae shedded from snails were collected and placed in an aquarium with fish intermediate host, Gambusia affinis, to obtain metacercariae encysted in the gills. The gills with metacercariae were fed to albino rats, Rattus norvegicus, to obtain the adult worms. Adult worms were recovered in the small intestine of rats at 7 days after infection and they were identified as Centrocestus formosanus based on the morphological characteristics and the comparison with the previous descriptions in the literature. They were small, 518 × 324 μm in average size and had characteristic 32 circumoral spines around the oral sucker. The morphological characteristics of the developmental stages, from cercariae to adults, of this heterophyid fluke were given here. Therefore, the presence of this fluke is to be confirmed for the first time in Egypt by the present study.

Descriptions of diplostomid metacercariae (Digenea: Diplostomidae) from freshwater fishes in the Tshwane area

The metacercarial (larval) stages of diplostomid digeneans are known to inhabit freshwater fish, causing tissue damage in the process. Due to their widespread diversity, little is known about their life cycle. The classification of these parasitic stages to the species level using only the morphology is very challenging due to the lack of genitalia; they are regarded to be the most important structures in the identification of these organisms. In this study, additional morphological information through light and scanning electron microscopy is given for two different diplostomids found in the cranial cavity of Clarias gariepinus and the vitreous chambers of Tilapia sparrmanii and Pseudocrenilabrus philander. The diplostomid metacercaria inhabiting the cranial cavity of Clarias gariepinus was morphologically identified as Diplostomulum (Tylodelphys) mashonense and an unknown metacercaria of the genus Diplostomum was found in the vitreous chambers of Pseudocrenilabrus philander and Tilapia sparrmanii. Both parasitic species' 28S recombinant deoxyribonucleic acid genomic regions were successfully amplified using Dig 125/1500R primer pairs. The assay yielded a product of approximately 1300 base pairs as seen on the gel images. There were 14 nucleotide differences over the entire analysed sequences resulting in a 1.1% (14/1273) nucleotide difference. In line with the morphological characteristics of these parasites, there seemed to be a slight difference in their genetic make-up. The application of molecular techniques on digenetic trematodes seems very promising and may yield great potential in future descriptions of morphologically similar parasitic species.

[EXTERNAL QUALITY ASSESSMENT FOR THE LABORATORY IDENTIFICATION OF THE PATHOGENS OF PARASITIC DISEASES AS AN ELEMENT FOR IMPROVING THE POSTGRADUATE TRAINING OF SPECIALISTS]

Within the framework of the Federal External Quality Assessment (EQA) System and in the context of postgraduate training improvement for health workers in 2010-2014, specialists from the laboratories of the therapeutic-prophylactic organizations and institutions of the Russian Federal Service for Supervision of Consumer Rights Protection and Human Welfare were examined for their professional competence in microscopically identifying the pathogens of parasitic diseases in feces. The virtual remote educational computer technology tools that included different combinations of 16 helminthic species, 5 intestinal protozoan species, and a number of artefacts, were used. The specialists from 984 laboratories of multidisciplinary therapeutic-prophylactic organizations and hygiene and epidemiology centers in all Federal Districts of the Russian Federation were covered. A total of 8245 replies were analyzed. The detection rate for helminths was 64.0%, including those by a taxonomic group (nematodes, 65.0%; cestodes, 72.0%; trematodes, 55.1%). There was a dynamic decrease in the above indicators. There were low detection rates for trematodes parasitizing the small intestine (Metagonimus, 10.2%; Nanophyetus, 26.2%) and hepatobiliary organs (Fasciola, 59.6%; Clonorchis, 34.9%). The similar trend was seen in the detection rates for the pathogens of geohelminthisms (ascariasis, trichocephaliasis, etc.) and contagious helminthisms (enterobiasis, hymenolepiasis). The level of competence in detecting and identifying intestinal protozoa was much lower than the similar rates for helminthism pathogens. EQA for the laboratory diagnosis of the pathogens of parasitic diseases, by using the virtual tools is a leading element of the postgraduate training system for laboratory specialists. The results of EQA for the laboratory diagnosis of the pathogens of parasitic diseases are a basic material for the development, and improvement of training modernization programs, by applying a modular approach.

[FINDING OF PARALECITHODENDRIUM CHILOSTOMUM (TREMATODA: LECITHODENDRIIDAE) IN A ROUNDLEAF BAT AND IN THE AFRICAN SHARPTOOTH CATFISH FROM ETHIOPIA]

Adult trematodes Paralecithodendrium chilostomum (Mehlis, 1831) were detected in the roundleaf bat Hipposideros sp. and in the African sharptooth catfish Clarias gariepinus from Tana Lake, Ethiopia. The catfish is an accidental host for P. chilostomum. This is the first record of P. chilostomum from Ethiopia. The description and figures of P. chilostomum from both host species, Hipposideros sp. and Clarias gariepinus are given.

[Investigation of natural foci of Metorchis taiwanensis in Wuhu area]

OBJECTIVE

To explore the existence of natural foci of Metorchis taiwanensis in Wuhu area.

METHODS

The ecological environment and daily living habits of residents were investigated; the eggs of M. taiwanensis in the dung of ducks in local region were collected by the sedimentation method; the Parafossarulus striatulus were disposed by the tabletting method and examined with a microscope to isolate the rediae and cercariae; the metacercariae in Pseudorasbora parve were isolated by using the homogenation. The duckling were fed directively by metacercaria of M. taiwanensis or by P. parve infected with metacercaria of M. taiwanensis for artificial infection, and M. taiwanensis were separated from ducks by dissecting the gallbladder and bile ducts.

RESULTS

The survey revealed that there were staggered lake river, rich vegetation, overgrown shrubs, aquatic plants, rich variety of freshwater snails and fish resources in Wuhu area, and it was home to a variety of waterfowl and duck. The average detection rate of eggs of M. tanwanensis in stool of ducks was 33.33% (10/30); that of rediae and cercarriae in P. striatulus was 1.17%(7/600); and that of encysted metacercaria in P. parve was 13.33% (8/60); the number of M. taiwanensis detected in the infected ducklings in 3 groups were 31, 8 and 0, respectively, the natural M. tanwanensis infection rate of ducks was 23.33% (7/30).

CONCLUSION

We have confirmed the existence of natural foci of M. tanwanensis in Wuhu area.

Annulotrema (Monogenea: Dactylogyridae) from the gills of African tetras (Characiformes: Alestidae) in Lake Turkana, Kenya, with descriptions of four new species and a redescription of A. elongata Paperna and Thurston, 1969

Four new and four previously described species of Annulotrema were collected from the gills of four species (three genera, i.e. Alestes, Hydrocynus and Brycinus) of African tetras from Lake Turkana, Kenya: Annulotrema alestesnursi Paperna, 1973 from Brycinus nurse; Annulotrema ansatum n. sp., Annulotrema besalis Řehulková, Musilová and Gelnar, 2014, Annulotrema bipatens n. sp., Annulotrema cucullatum n. sp., Annulotrema nili Paperna, 1973, and Annulotrema pontile n. sp. from Hydrocynus forskahlii; and Annulotrema elongata Paperna and Thurston, 1969 from Alestes baremoze and Alestes dentex. A. elongata is re-described on the basis of new material from A. baremoze. The sclerotized structures of the haptor and male copulatory organ of A. alestesnursi and A. elongata are illustrated from their type material. H. forskahlii is a new host record for A. besalis. The findings of A. besalis and A. elongata in Kenya represent a new locality records for these helminths. Three Annulotrema spp., namely A. besalis, A. elongata and A. pontile n. sp., share the same type of male copulatory organ, which may indicate a close relationship among these species.

Eye fluke infection status in Baltic cod, Gadus morhua, after three decades and their use as ecological indicators

Eye flukes of the genus Diplostomum were recorded with a prevalence of 7.4% and a mean intensity of 11.9 (range 1-75) parasites per fish in eye lenses of a total of 188 Atlantic cod, Gadus morhua, sampled in the Southeastern Baltic Sea from March 2013 to February 2014. A slight decrease of infection level, among the fish with body length ranging from 30 to 89.5 cm, was found when data were compared to a corresponding survey in the 1980s. Due to imprecise species identification of eye flukes based on morphometric analyses we present, as a baseline for further studies, rDNA sequences from a subsample of 19 eye flukes based on sequencing of a part of 18S, ITS-1, 5.8S, ITS-2 and part of 28S. We discuss the use of eye fluke recordings in Baltic cod as an environmental indicator due to the dependence of the parasite's life cycle on biotic (occurrence of snail and bird hosts) and abiotic (temperature and salinity) parameters.

Molecular characterization of muscle-parasitizing didymozoid from a chub mackerel, Scomber japonicus

Didymozoids found in the muscles of marine fish are almost always damaged because they are usually found after being sliced. Therefore, identifying muscle-parasitizing didymozoids is difficult because of the difficulty in collecting non-damaged worms and observing their organs as key points for morphological identification. Moreover, muscle-parasitizing didymozoids are not easily found because they parasitize at the trunk muscles. Therefore, muscle-parasitizing didymozoid classification has not progressed because there are few opportunities to detect them. Our recent report was the first to describe the usefulness of sequencing analysis for discrimination among muscle-parasitizing didymozoids. Recently, we found a didymozoid in the trunk muscle of a chub mackerel Scomber japonicus. The present study genetically compares the present isolate with other muscle-parasitizing didymozoids. The present isolate differs markedly from the previously unidentified didymozoid from an Atlantic mackerel S. scombrus by phylogenetic analysis of 18S rDNA. It also differs from other muscle-parasitizing didymozoids from other host species based on phylogenetic analyses of 18S, 28S rDNAs, and coxI loci. These results suggest that sequencing analysis is useful for the discrimination of muscle-parasitizing didymozoids. Combining the present data with earlier data for sequencing analysis, muscle-parasitizing didymozoids from seven marine fish species were classified as seven species. We proposed appellations for six distinct muscle-parasitizing didymozoids for future analysis: sweetlips fish type from Diagramma pictum and Plectorhinchus cinctus, red sea bream type from Pagrus major, flying fish type from Cypselurus heterurus, Atlantic mackerel type from Scomber scombrus, chub mackerel type from S. japonicus, and purple rockcod type from Epinephelus cyanopodus.

Diversity, specificity and speciation in larval Diplostomidae (Platyhelminthes: Digenea) in the eyes of freshwater fish, as revealed by DNA barcodes

Larvae (metacercariae) in some species of Diplostomidae (Platyhelminthes: Digenea) inhabit fish eyes and are difficult to identify to species based on morphology. DNA barcoding has clarified the diversity and life cycles of diplostomids in North America, Europe and Africa, but has seldom been used in parasites sampled in large numbers or at large spatial scales. Here, distance-based analysis of cytochrome c oxidase 1 barcodes and, in some specimens, internal transcribed spacer (ITS-1, 5.8S, ITS-2) sequences was performed for over 2000 diplostomids from Africa, the Middle East, Europe, Asia and the Americas. Fifty-two species of Diplostomum, Tylodelphys and Austrodiplostomum (Digenea: Diplostomidae) were distinguished. The 52 species comprise 12 identified species, six species in two species complexes and 34 putative species, and 33/52 had been delineated in previous studies. Most (23/40) of the unidentified, putative species distinguished by cytochrome c oxidase 1 distances were supported by at least one additional line of evidence. As the intensity of sampling of the 52 species increased, variation in cytochrome c oxidase 1 decreased between and increased within species, while the spatial scale at which species were sampled had no effect. Nonetheless, variation between species always exceeded variation within species. New life-cycle linkages, geographic and host records, and genetic data were recorded in several species, including Tylodelphys jenynsiae, Tylodelphys immer and Diplostomum ardeae. Species of Diplostomum inhabiting the lens are less host-specific and less numerous than those infecting other tissues, suggesting that reduced immune activity in the lens has influenced rates of speciation.

Heterophyid trematodes recovered from people residing along the Boseong River, South Korea

We conducted an epidemiological survey to determine the status of heterophyid fluke infections among people residing along the Boseong River, Gokseong-gun, South Korea (= Korea) from October 2011 to February 2012. Fecal specimens were collected from 115 (male 51, female 64) people and examined for intestinal helminth eggs using the Kato-Katz thick smear technique. The eggs of Metagonimus yokogawai together with other Metagonimus spp. were detected in 28 (24.3%) cases. Eleven egg positive people were treated with 10mg/kg praziquantel followed by MgSO4 purging in order to recover the adult flukes. Whole consecutive diarrheic stools were collected individually 4-5 times. Adult flukes recovered were 66,499 specimens (6045.4/positive case) of M. yokogawai, 343 (38.1) of Metagonimus miyatai, 3293 (299.4) of Metagonimus takahashii, 81 (20.3) of Heterophyes nocens, 6 (3.0) of Heterophyopsis continua, and 1 (1.0) of Stictodora fuscata. The results indicated that the surveyed area is a highly endemic area of metagonimiasis (three Metagonimus species) with low-grade mixed infections of 3 other heterophyid flukes. The infected people experienced variable degrees of gastrointestinal discomfort and indigestion. They consumed raw freshwater and brackish water fish, including sweetfish and mullets. It is strongly recommended that people residing in the survey area avoid eating raw fish to prevent M. yokogawai and other heterophyid infections.

Phyllodistomum spinopapillatum sp. nov. (Digenea: Gorgoderidae), from the Oaxaca killifish Profundulus balsanus (Osteichthyes: Profundulidae) in Mexico, with new host and locality records of P. inecoli: Morphology, ultrastructure and molecular evidence

Phyllodistomum spinopapillatum sp. nov. is described from the urinary bladder of the Oaxaca killifish, Profundulus balsanus Ahl (Profundulidae) in Rio Pueblo Viejo and Rio Santa Cruz, Oaxaca, southwestern Mexico. The new species is described based on evidence gathered from morphology, scanning electron microscopy (SEM), and partial sequences of the 28S rRNA gene. Diagnostic characters of the new species of Phyllodistomum Braun 1899 are the presence of spines on the entire body surface and having a ventral sucker almost half the size of oral sucker. The new species possess a large number of dome-like papillae on the body surface with scattered distribution along the hindbody, and these papillae are characteristically spinulated. Phyllodistomum spinopapillatum sp. nov. most closely resembles P. inecoli Razo-Mendivil, Perez-Ponce de Leon and Rubio- Godoy, 2013, a parasite of the twospot livebearer Pseudoxiphophorus bimaculatus (Heckel) from Veracruz, in the Atlantic slope of Mexico. In addition to the new species, specimens of P. inecoli were also found parasitising the urinary bladder of cyprinodontiforms such as the Mexican molly Poecilia sphenops Valencienes in a pond at Santa Maria Coyotepec, and in Profundulus sp. in Rio Templo, both in Oaxaca, and in the Porthole livebearer Poeciliopsis gracilis (Heckel) in Rio San Juan, as well as in Profundulus punctatus (Gunter) from Rio Nueva Francia, both in Chiapas. The distribution and host range of P. inecoli is extended to freshwaters of the Pacific slope of Mexico, and to other cyprynodontiforms.

[Metorchis orientalis founded in basin of Wuhu City, Anhui Province]

OBJECTIVE

To investigate the epidemic situation of Metorchis orientalis in Wuhu City, Anhui Province.

METHODS

Three lakes (Fengming, Longwo and Kui lakes) were selected in Wuhu City, and the poultries around the lakes and freshwater fishes in the lakes were captured to test the infection of M. orientalis, and the infection rates were calculated.

RESULTS

The adult worms of M. orientalis were found in gall bladder and hepatic duct of domestic ducks with infection rate of 16.7%. The metacercariae of M. orientalis were discovered in the muscle of Pseudorasbora parva and Pseudogobio rivularis with infection rates of 7.13% and 3.38% respectively.

CONCLUSION

M. orientalis is endemic in Wuhu City, which should be paid enough attention to the animal husbandry, aquaculture and medicine.

Description of a new species of Podocotyle Dujardin, 1845 (Digenea: Opecoelidae: Plagioporinae) from the cusk-eel, Luciobrotula corethromycter Cohen, 1964 (Ophidiiformes: Ophidiidae), from the Gulf of Mexico and Caribbean Sea

Podocotyle bathyhelminthos n. sp. (Opecoelidae: Plagioporinae) is described from the cusk-eel, Luciobrotula corethromycter Cohen, 1964 (Ophidiiformes: Ophidiidae), collected at depths of 622-1,280 m in the northern Gulf of Mexico and Caribbean Sea off Colombia. The new species is distinguished by possessing a combination of the following features: an elongate oval body shape, a sucker width ratio of 1:1.4-1.9, deeply lobed and irregularly-shaped testes, a cirrus-sac that extends just in to the hindbody, a trilobed ovary and vitellarium that extend to the ventral sucker level. Several unique features in P. bathyhelminthos n. sp. were not present in all, or almost all, recognized species of Podocotyle including a conspicuous deep cleft at the posterior end of the worm, a small transverse ridge on the ventral surface immediately anterior to the ventral sucker, uterine loops extending ventral to the caeca and, at times, lateral to the caeca, a thick-walled metraterm extending 1/3 to 1/2 the length of the cirrus-sac and P. bathyhelminthos n. sp. parasitizes a deep water piscine host. Podocotyle etheostomae Aliff, 1973 is declared a nomen nudum. A brief discussion of Podocotyle Dujardin, 1845 in deep waters is presented, and a gastropod, caridean shrimp and cusk-eel are hypothesized as hosts in the life cycle of P. bathyhelminthos n. sp. in the deep sea.

Development and application of an eDNA method to detect and quantify a pathogenic parasite in aquatic ecosystems

Approaches based on organismal DNA found in the environment (eDNA) have become increasingly utilized for ecological studies and biodiversity inventories as an alternative to traditional field survey methods. Such DNA-based techniques have largely been used to establish the presence of free-living organisms, but have much potential for detecting and quantifying infectious agents in the environment, which is necessary to evaluate disease risk. We developed an eDNA method to examine the distribution and abundance of the trematode Ribeiroia ondatrae, a pathogenic parasite known to cause malformations in North American amphibians. In addition to comparing this eDNA approach to classical host necropsy, we examined the detectability of R. ondatrae in water samples subject to different degradation conditions (time and temperature). Our test exhibited high specificity and sensitivity to R. ondatrae, capable of detecting as little as 14 fg (femtograms) of this parasite's DNA (1/2500th of a single infectious stage) from field water samples. Compared to our results from amphibian host necropsy, quantitative PCR was -90% concordant with respect to R. ondatrae detection from 15 field sites and was also a significant predictor of host infection abundance. DNA was still detectable in lab samples after 21 days at 25°C, indicating that our method is robust to field conditions. By comparing the advantages and disadvantages of eDNA vs. traditional survey methods for determining pathogen presence and abundance in the field, we found that the lower cost and effort associated with eDNA approaches provide many advantages. The development of alternative tools is critical for disease ecology, as wildlife management and conservation efforts require reliable establishment and monitoring of pathogens.

TREMATODE INFECTION OF FRESHWATER SNAIL, FAMILY BITHYNIIDAE IN THAILAND

Opisthorchis viverrini is restricted to and requires for its aquatic life cycle only Bithynia snail as first intermediate host but many species of cyprinid fish as second intermediate hosts. A survey in Thailand of trematode infection in freshwater snails of the family Bithyniidae carried out during October 2008 - July 2009 found a total of 5,492 snails, classified into ten species distributed in various geographic areas. Bithyniafuniculata and Gabbia pygmaea were localized to the north, B. s. goniomphalos, Wattebledia siamensis and W. crosseana to northeast and B. s. siamensis, Hydrobioides nassa and G. wykoffi to central region. W. baschi and G. erawanensis was found only in the south and Erawan waterfall, Kanchanaburi Province, respectively. Trematode infection rate was 3.15%. Cercariae were identified as belonging to six types, namely, amartae , monostome, mutabile, O. viverrini, virgulate, and unknown. The prevalence of cercarial infection in B. s. goniomphalos of amartae, mutabile, O. viverrini, virgulate, and unknown type cercaria was 0.55%, 0.74%, 1.07%, 2.87%, and 0.37%, respectively, and in B. s. siamensis monostome (1.10%) and virgulate (0.55%). Only virgulate cercariae were shed from W. crosseana (3.85%) and W. siamensis (5.19%). Cercariae of the unknown type were found in G. wykoffi (1.69%). No infection of O. viverrini cercariae was detected in the other species.