Hosts Of Trematodes Research Articles

Helminth Fauna of Bats of the Rostov Region: Review. 2. Trematoda

Introduction. The class of Trematoda includes two subclasses — Aspidogastrea and Digenea. Representatives of the former do not parasitize in bats. The definitive hosts for digenetic trematodes (Digenea) are vertebrates, including bats, in which the sexual generation (maritae) parasitizes. Gastropods or bivalves are the intermediate hosts. Supplementary hosts for the trematodes of bats are larvae and imagos of flying insects. Since in most cases the development of parthenites and cercariae of trematodes is related to water environment, the supplementary hosts are the groups of insects whose larvae live in the water. The list of bat species living in the Rostov region has been compiled in the previous research. In the present article the authors investigate the trematode fauna parasitizing in bats of the region under study. The aim of this review is to analyse the current state of knowledge on the species composition of the helminth parasitizing in chiropterans of the Rostov region.Materials and Methods. The research materials have been obtained from the libraries and open access resources: PubMed (pubmed.ncbi.nlm.nih.gov), CyberLeninka (cyberleninka.ru), Google Scholar (scholar.google.com), BHL (www.biodiversitylibrary.org), JSTOR (www.jstor.org). Some data has been provided by the colleagues.Results. 42 trematode species from 10 genera, 5 families and 1 order can parasitize in 15 bat species living in the Rostov region. The Lecithodendriidae family (24 species) and the genus Paralecithodendrium (9 species) are represented by a large number of species. Of the listed trematodes, 33 species used to be recorded on the territory of Russia.Discussion and Conclusion. The results of the conducted systematic review have revealed that the largest number of trematode species parasitizes in two bat species living in the Rostov region: the common noctule (27 species) and the serotine bat (24 species). The smallest number of species (4 per each) is found in the giant noctule and the soprano pipistrelle bat. Two species (Plagiorchis elegans and Plagiorchis vespertilionis) have been found in the companion cats and dogs includingly, wheras a case of the latter parazitising in humans has also been recorded. The presence of bats in the urban environment enables the full life cycle of these trematodes. There exists possibility of the companion animals and people to get infected through incidental ingestion of the infested insects.

Population genetic structure of Indoplanorbis exustus (Gastropoda: Planorbidae) in Thailand and its infection with trematode cercariae.

Indoplanorbis exustus is a freshwater gastropod belonging to the family Planorbidae. This snail is widely distributed across the tropics and plays an important role as the intermediate host for trematodes. However, relatively little is understood regarding the genetic relationship between I. exustus and trematodes. The goals of this study were to investigate the current transmission status of trematode cercariae in I. exustus in Thailand and to examine the genetic diversity, genetic structure, and demographic history of I. exustus. We collected 575 I. exustus from 21 provinces across six regions of Thailand and investigated cercarial infections by using the shedding method. I. exustus from two provinces were infected with cercarial trematodes, and two types of cercarial stages were molecularly identified as furcocercous cercaria and xiphidiocercariae. Phylogenetic tree analysis based on 28S rDNA and ITS2 sequences demonstrated that furcocercous cercaria and xiphidiocercariae were closely clustered with a clade of Euclinostomum sp. and Xiphidiocercariae sp., respectively. Phylogenetic and network analyses of I. exustus haplotypes based on the COI, 16S rDNA, and ITS1 genes demonstrated four main clades. Only snails in clade A were distributed in all regions of Thailand and harbored trematode cercariae. The level of genetic diversity of I. exustus was relatively high, but most populations were not genetically different, thus suggesting the appearance of gene flow within the I. exustus populations. Overall, the haplotype network was star-shaped, thus suggesting the recent demographic expansion of populations. This result was also supported by the unimodal mode of the mismatch distribution graph and the large negative values of the neutrality tests. Therefore, the I. exustus snail was likely another freshwater snail of the invasive species in Thailand. This information will aid in monitoring the spread of the parasitic trematodes carried by I. exustus from different populations.

Assessing the microbiota of the snail intermediate host of trematodes, Galba truncatula

BackgroundThe microbiome is known to play key roles in health and disease, including host susceptibility to parasite infections. The freshwater snail Galba truncatula is the intermediate host for many trematode species, including the liver and rumen flukes Fasciola hepatica and Calicophoron daubneyi, respectively. The snail-parasite system has previously been investigated. However, the specific interaction between the snail-associated microbiota and intra-snail developmental stages of trematodes has yet to be explored.MethodsGalba truncatula snails were collected from farms in Northern Ireland and trematode infection was diagnosed using PCR. High-throughput sequencing analysis of the bacterial 16S ribosomal DNA V3-V4 hypervariable regions was subsequently applied to characterise the microbiota of both uninfected and infected snails.Results We first showed that the snail harboured microbiota that was distinct for its environment. The microbiota of infected snails was found to differ significantly from that of uninfected snails. In particular, the bacterial genera Mycoplasma and Methylotenera were significantly more abundant in infected snails, while genera Sphingomonas and Nocardioides were predominantly associated with uninfected snails. ConclusionThese findings pave the way to future studies on the functional roles of bacteria in host-parasite relationships.Graphical

An integrative taxonomy study reveals a rare new species of the genus Creptotrema (Trematoda: Allocreadiidae) in an endangered frog in South America.

During an ecological study with a near-endangered anuran in Brazil, the Schmidt's Spinythumb frog, Crossodactylus schmidti Gallardo, 1961, we were given a chance to analyze the gastrointestinal tract of a few individuals for parasites. In this paper, we describe a new species of an allocreadiid trematode of the genus Creptotrema Travassos, Artigas & Pereira, 1928, which possesses a unique trait among allocreadiids (i.e., a bivalve shell-like muscular structure at the opening of the ventral sucker); the new species represents the fourth species of allocreadiid trematode parasitizing amphibians. Besides, the new species is distinguished from other congeners by the combination of characters such as the body size, ventral sucker size, cirrus-sac size, and by having small eggs. DNA sequences through the 28S rDNA and COI mtDNA further corroborated the distinction of the new species. Phylogenetic analyses placed the newly generated sequences in a monophyletic clade together with all other sequenced species of Creptotrema. Genetic divergences between the new species and other Creptotrema spp. varied from 2.0 to 4.2% for 28S rDNA, and 15.1 to 16.8% for COI mtDNA, providing robust validation for the recognition of the new species. Even though allocreadiids are mainly parasites of freshwater fishes, our results confirm anurans as hosts of trematodes of this family. Additionally, we propose the reallocation of Auriculostoma ocloya Liquin, Gilardoni, Cremonte, Saravia, Cristóbal & Davies, 2022 to the genus Creptotrema. This study increases the known diversity of allocreadiids and contributes to our understanding of their evolutionary relationships, host-parasite relationships, and biogeographic history.

Helminth fauna of saffron cod <i>Eleginus gracilis</i> in the coastal waters of the Magadan Region (northern coast of the Okhotsk Sea)

Results of parasitological investigation of saffron cod Eleginus gracilis Tilesius, 1810 are presented. The fish samples were collected in 6 distanced marine areas at the coast of Magadan Region, generally corresponded with local stocks or herds of this species. In total, 29 helminth species are identified, including 8 cestodes, 11 trematodes, 5 nematodes, and 5 acanthocephalans. The highest species diversity of helminths is detected for the saffron cod from the Odyan Bay (24 species) and the lowest – for the saffron cod from the Amakhton Bay (16 species). Occurrence and intensity of infestation is the highest for trematodes Hemiurus levinseni, Podocotyle reflexa, and Brachyphallus crenatus, nematodes Ascarophis pacifica, and acanthocephalans Echinorhynchus gadi and Corynosoma strumosum. The number of detected worm species is close to the total number of these parasites recorded for saffron cod in the Far-Eastern Seas and adjacent Pacific – 33 species (excluding monogeneans). Cestodes Diplocotyle olrikii, trematodes Bucephaloides iskaensis, and acanthocephalans Bolbosoma caenoforme are registered for the first time for saffron cod in the Okhotsk Sea. There is found for the first time in the studied area that saffron cod is a definitive host for trematodes Steganoderma formosum and a paratenic host for acanthocephalans Andracantha mergi. Eight species dangerous from medical and (or) veterinary point are detected: Nybelinia surmenicola, Diphyllobothrium sp., Pyramicocephalus phocarum, Anisakis simplex, Pseudoterranova decipiens, Bolbosoma caenoforme, Corynosoma semerme, and C. strumosum. The data on helminth infestation are not useful for differentiation of the saffron cod sub-populations in the northern Okhotsk Sea because of almost permanent partial mixing of these groups.

The impact of climate change and pollution on trematode-bivalve dynamics

Coastal ecosystems and their marine populations are increasingly threatened by global environmental changes. Bivalves have emerged as crucial bioindicators within these ecosystems, offering valuable insights into biodiversity and overall ecosystem health. In particular, bivalves serve as hosts to trematode parasites, making them a focal point of study. Trematodes, with their life cycles intricately linked to external factors, provide excellent indicators of environmental changes and exhibit a unique ability to accumulate pollutants beyond ambient levels. Thus, they act as living sentinels, reflecting the ecological condition of their habitats. This paper presents a comprehensive review of recent research on the use of bivalve species as hosts for trematodes, examining the interactions between these organisms. The study also investigates the combined impact of trematode infections and other pollutants on bivalve molluscs. Trematode infections have multifaceted consequences for bivalve species, influencing various aspects of their physiology and behavior, including population-wide mortality. Furthermore, the coexistence of trematode infections and other sources of pollution compromises host resistance, disrupts parasite transmission, and reduces the abundance of intermediate hosts for complex-living parasites. The accumulation process of these parasites is influenced not only by external factors but also by host physiology. Consequently, the implications of climate change and environmental factors, such as temperature, salinity, and ocean acidification, are critical considerations. In summary, the intricate relationship between bivalves, trematode parasites, and their surrounding environment provides valuable insights into the health and sustainability of coastal ecosystems. A comprehensive understanding of these interactions, along with the influence of climate change and environmental parameters, is essential for effective management and conservation strategies aimed at preserving these delicate ecosystems and the diverse array of species that rely on them.

Effect of predation risk on parasite transmission from first to second intermediate trematode hosts.

Predators can affect parasite-host interactions when directly preying on hosts or their parasites. However, predators may also have non-consumptive indirect effects on parasite-host interactions when hosts adjust their behaviour or physiology in response to predator presence. In this study, we examined how chemical cues from a predatory marine crab affect the transmission of a parasitic trematode from its first (periwinkle) to its second (mussel) intermediate host. Laboratory experiments revealed that chemical cues from crabs lead to a threefold increase in the release of trematode cercariae from periwinkles as a result of increased periwinkle activity. This positive effect on transmission was contrasted by a 10-fold reduction in cercarial infection rates in the second intermediate host when we experimentally exposed mussels to cercariae and predator cues. The low infection rates were caused by a substantial reduction in mussel filtration activity in the presence of predator cues, preventing cercariae from entering the mussels. To assess the combined net effect of both processes, we conducted a transmission experiment between infected periwinkles and uninfected mussels. Infection levels of mussels in the treatments with crab cues were sevenfold lower than in mussels without crab chemical cues. This suggests that predation risk effects on mussel susceptibility can counteract the elevated parasite release from first intermediate hosts, with negative net effects on parasite transmission. These experiments highlight that predation risk effects on parasite transmission can have opposing directions at different stages of the parasite's life cycle. Such complex non-consumptive predation risk effects on parasite transmission may constitute an important indirect mechanism affecting prevalence and distribution patterns of parasites in different hosts across their life cycle.

Molluscicidal activities of green-synthesized Alstonia congensis silver nanoparticles

Objective: To evaluate the efficacy of Alstonia congensis green-synthesized nanoparticles as a molluscicide against snail hosts of trematodes. Methods: The ethanolic leaf extract of Alstonia congensis was used to synthesize silver nanoparticles. The formulation was characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, and scanning electron microscope/energy-dispersed X-ray. The ovicidal and molluscicidal activities of the Alstonia congensis extract and its nanoparticles were tested against Physa acuta and Bulinus forskalii at different concentrations. Results: The green-synthesized nanoparticles inhibited embryonic development within the egg masses of the two snails in all the tested concentrations. Alstonia congensis extract did not show molluscicidal properties against adult Physa acuta but showed a very weak activity against Bulinus forskalii. Moreover, the synthesized nanoparticles showed significantly high molluscicidal activity against adult snails within 5-40 min of exposure in a concentration-dependent manner (P<0.05). Conclusions: The Alstonia congensis-based nanoparticles show molluscicidal activities against adults and embryos of Physa acuta and Bulinus forskalii, and can be further explored as a potent molluscicide for the control of intermediate host of trematode parasites.

Type of cercaria in freshwater snails at Tunggu Pampang Reservoir, Makassar City, Indonesia

The Tunggu Pampang Reservoir is one of the reservoirs located in the city of Makassar. The functions of the reservoir area was tourist attractions and fish farming locations so that the local community uses them for swimming, fishing, selling, and gardening. The existence of various types of freshwater snails in the reservoir has the potential to act as intermediate hosts for trematodes in animals and humans. This study aimed to analyze the type of cercariae in freshwater snails. This research is a descriptive survey to determine the distribution of trematode larvae. The stages of this research began with the snails were collected from Tunggu Pampang Reservoir, Makassar City. Freshwater snails were collected at several points in the reservoir. Freswater snail collection using hand collecting method. The snails were put into a plastic bag with different types of snails and site of collection. The collected samples and cercariae were examined in the Tropical Disease Laboratory of the Study Program of DIII Medical Laboratory Technology, Megarezky University, South Sulawesi, Indonesia. Freshwater snails are placed on a petri dish and their shells were gently crushed with a stamper. Dropped with aquadest on the crushed snail shell. The next step was observed using a microscope to determine the presence of cercariae. Cercariae found then identified according to morphological classification as previously study. A total number of 500 freshwater snail were collected in Tunggu Pampang Reservoir. The results showed that overall snails infected with cercariae was 33,4%. The highest prevalence of cercariae in Indoplanorbis exustus was 94.3%. Total of Echinostoma cercariae found (n = 224) compared to furcocercous cercariae (n = 5). Cercariae of Echinostoma sp., Fasciola gigantica, Fasciolopsis buski living in Tungu Pampang Reservoir can cause diseases in humans and animals. Larval trematodes can be controlled in snails using reducing parasite contamination, monitoring surveillance, information dissemination, and preventive education.

Detection of Trematodes from the Host Exotic Aquatic Snail Melanoides tuberculata in an Urban Stormwater System

The red-rimmed melania or Malaysian Trumpet Snail, Melanoides tuberculata, is a common exotic freshwater snail that has been invading an increasing number of water bodies in North America. As a well-known host for trematodes causing human and animal diseases, the pattern of invasion and parasitic infection for this species is of great concern. Snail specimens were collected from an urban stream in Los Angeles that drains into a fragile, protected wetland ecosystem. Molecular analysis identified four trematode species: Haplorchis pumilio, Fasciola jacksoni, Parorchis sp. TH-2019, and an unclassified trematode species, Trematoda distomecercaria WN-2016. H. pumilio is responsible for haplorchiasis infections, previously considered endemic to Asia. F. jacksoni infection is a significant cause of mortality in Asian elephants. This study represents the first occurrence of F. jacksoni in North America and a novel occurrence of that trematode in association with M. tuberculata. This study also represents new occurrences of Parorchis sp. TH-2019 and an unclassified trematode species, Trematoda distomecercaria WN-2016, within California and North America. Parorchis sp. TH-2019 has previously only been documented in a marine whelk. This identification of these trematodes in association with M. tuberculata further exemplifies the need for ongoing monitoring and detection, especially considering the significance of H. pumilio and haplorchiasis to public health.

Bithyniid Abundance in the South of Western Siberia Water-Courses and Water Reservoirs (Russia)

Gastropoda are an important component of the freshwater benthic communities of Western Siberia and participate in a number of trophic relationships and as the intermediate hosts of trematodes. The purpose of this study is defining the ratio of Bithyniidae mollusks between other gastropods with regard to species diversity, and to compile all information about the abundance of bithyniid snails that we examined over 27 years in four major basins situated in the Novosibirsk region. Analyzing the data diversity and abundance of gastropod communities from freshwater ecosystems south of Western Siberia, we found that 22% of the water bodies contained bithyniid snails. In total, 201 samples that were abundant with bithyniid snails of reproductive age were collected in 34 localities in 25 water bodies. While these freshwater snails are not abundant in most of the inspected reservoirs (fewer than 10 mollusks per square meter), two of the water bodies accommodated a great number of Bithyniidae (more than 100 ind.·m−2). Bithyniid snail abundance may vary tenfold in different years in the same water body. This and the study of seasonal dynamics show that the abundance of bithyniid snails of reproductive age decreased from June to August in all years. The results of this study can be used to identify and predict the natural foci of opisthorchiasis in the south of Western Siberia.

Current knowledge of trematodes (Platyhelminthes: Digenea, Aspidogastrea) in Chile

The aim of the present review was to evaluate the state of knowledge of trematodes (Platyhelminthes: Trematoda) in Chile, covering taxonomy, biology, geographic distribution, and a checklist of all taxa reported in the country. A total of 277 articles published between 1849 and December 2020, have been analyzed. A total of 215 taxa belonging to the subclasses Digenea and Aspidosgastrea have been reported from Chile, 119 of them identified to species level and only three species with completely described life cycles. Trematodes from Chile were found parasitizing both native and exotic species, however, no records from insects and most crustacean classes exist. Overall, 159 out of 3989 potential host native species were reported as hosts for trematodes. Molecular tools were used in more recent taxonomic studies. Although research on trematodes in Chile is on the rise, there is a clear need for more detailed taxonomic studies to include integrative taxonomy approach, deposition of helminths in collections and the training of new generation of parasitologists to better understand the diversity, ecology and evolutionary relationships of trematodes in the region.

Complete mitochondrial genome of the freshwater snail Tarebia granifera (Lamarck, 1816) (Gastropoda: Cerithioidea: Thiaridae)

The freshwater gastropod Tarebia granifera (Lamarck, 1816) is found in Taiwan, Hainan, and Guangdong provinces in China, and is one of the main intermediate hosts of trematodes that infect humans. The taxonomic positions of some cerithioidean families are still unclear, and whole mitochondrial genome studies are scarce in the Thiaridae. In this study, we describe the complete mitogenome of Tarebia granifera (Lamarck, 1816). The mitogenome is 15,555 bp in length, with a total of 37 genes, including 13 protein-coding genes, 2 rRNA genes, and 22 tRNA genes. It is consistent with the essential features of previously studied mitochondrial genomes of species belonging to the superfamily Cerithioidea. Our study demonstrates the usefulness of mitogenomic data for resolving phylogenetic relationships of families within Cerithioidea and may also contribute to the prevention and control of the parasitic diseases caused by trematodes, which use T. granifera as an intermediate host.

Molecular and morphological characterisation of the metacercariae of two species of Cardiocephaloides (Digenea: Strigeidae) infecting endemic South African klipfish (Perciformes: Clinidae).

South African clinids are a major component of the temperate intertidal regions that are also known to participate in life cycles and transmission of several groups of parasites. However, the knowledge of trematode diversity of these fishes is incomplete. In this study, two species of Clinus Cuvier, the super klipfish Clinus superciliosus (Linnaeus) and the bluntnose klipfish Clinus cottoides Valenciennes, were collected from six localities along the South African coast and examined for the presence of trematodes. Metacercariae of Cardiocephaloides Sudarikov, 1959 were found in the eye vitreous humour and brain of C. superciliosus and in the eye vitreous humour of C. cottoides. Detailed analyses integrating morphological and molecular sequence data (28S rDNA, ITS2 rDNA-region, and COI mtDNA) revealed that these belong to two species, Cardiocephaloides physalis (Lutz, 1926) and an unknown species of Cardiocephaloides. This study provides the first report of clinid fishes serving as intermediate hosts for trematodes, reveals that the diversity of Cardiocephaloides in South Africa is higher than previously recorded, and highlights the need for further research to elucidate the life cycles of these trematode species. The broad geographical distribution of Cardiocephaloides spp. was confirmed in the present study based on molecular sequence data. The host-parasite interactions between clinid fishes and metacercariae of Cardiocephaloides are yet to be explored.

Parasitism and host behavior in the context of a changing environment: The Holocene record of the commercially important bivalve Chamelea gallina, northern Italy.

Rapid warming and sea-level rise are predicted to be major driving forces in shaping coastal ecosystems and their services in the next century. Though forecasts of the multiple and complex effects of temperature and sea-level rise on ecological interactions suggest negative impacts on parasite diversity, the effect of long term climate change on parasite dynamics is complex and unresolved. Digenean trematodes are complex life cycle parasites that can induce characteristic traces on their bivalve hosts and hold potential to infer parasite host-dynamics through time and space. Previous work has demonstrated a consistent association between sea level rise and increasing prevalence of trematode traces, but a number of fundamental questions remain unanswered about this paleoecological proxy. Here we examine the relationships of host size, shape, and functional morphology with parasite prevalence and abundance, how parasites are distributed across hosts, and how all of these relationships vary through time, using the bivalve Chamelea gallina from a Holocene shallow marine succession in the Po coastal plain. Trematode prevalence increased and decreased in association with the transition from a wave-influenced estuarine system to a wave-dominated deltaic setting. Prevalence and abundance of trematode pits are associated with large host body size, reflecting ontogenetic accumulation of parasites, but temporal trends in median host size do not explain prevalence trends. Ongoing work will test the roles of temperature, salinity, and nutrient availability on trematode parasitism. Parasitized bivalves in one sample were shallower burrowers than their non-parasitized counterparts, suggesting that hosts of trematodes can be more susceptible to their predators, though the effect is ephemeral. Like in living parasite-host systems, trematode-induced malformations are strongly aggregated among hosts, wherein most host individuals harbor very few parasites while a few hosts have many. We interpret trace aggregation to support the assumption that traces are a reliable proxy for trematode parasitism in the fossil record.

Moluscos e larvas de trematódeos em área não endêmica para a esquistossomose mansoni

RESUMO: A esquistossomose é uma relevante doença para a saúde pública do Brasil e de Alagoas, sendo importante a investigação da presença da doença em áreas endêmicas e não endêmicas para o progresso de erradicação desse agravo. Assim, o objetivo do estudo foi realizar uma investigação dos moluscos e das larvas de trematódeos em uma área não endêmica para a esquistossomose mansoni. O estudo foi realizado em Santana do Ipanema, Alagoas, por meio da captura dos caramujos no riacho Camoxinga e análise da positividade para larvas de trematódeos, incluindo larvas do Schistosoma mansoni, agente etiológico da esquistossomose mansoni. Além disso, foi realizada a análise da constância de captura das espécies e da influência dos períodos de estiagem e de chuva e da precipitação média mensal sobre a abundância das espécies de caramujos, para o período de agosto de 2018 a julho de 2019. Em todo período, foram capturados 2.431 caramujos, estando 443 (18,2%) mortos. Os animais capturados vivos (1.988) pertenciam às espécies Biomphalaria straminea (Dunker, 1848) (Planorbidae) (989; 40%), Melanoides tuberculatus (Müller, 1774) (Thiaridae) (792; 32%), Pomacea lineata (Spix, 1827) (Ampullariidae) (133; 5,4%), Drepanotrema depressissimun (Moricand, 1839) (53; 2,18%), Physa marmorata (Guilding, 1828) (19; 0,78%) e Cyanocyclas brasiliana (Deshayes, 1854) (2; 0,03%). Além disso, B. straminea e M. tuberculatus foram as espécies constantemente coletadas e que apresentaram status de abundantes para a área de estudo. Em relação as duas espécies de maior constância e abundância na área de estudo, B. straminea e M. tuberculatus não foi possível estabelecer relação entre a abundância dos animais e o período de coleta (chuvoso ou seco, p = 0.2336). O maior número de animais foi capturado nos meses de junho e julho de 2019 para B. straminea e M. tuberculatus, respectivamente. O aumento no número de animais coletados começou a ocorrer com o aumento dos índices pluviométricos janeiro a abril de 2019 com uma redução das chuvas e da abundância dos animais em maio de 2019 seguida de uma posterior elevação nos dois parâmetros, até o fim do período estudado. Constatou-se uma relação linear entre a pluviosidade e a abundância dos caramujos da espécie B. straminea. A análise da infecção dos animais coletados por larvas de trematódeos mostrou que nenhum animal da espécie B. straminea estava infectado por larvas do Schistosoma mansoni. Por outro lado, foi diagnosticado caramujos das espécies B. straminea, D. depressissimun e M. tuberculatus eliminando cercárias das espécies Longifurcate pharyngeate distome – Estregeocercária, Echinocercária sp. e Xiphidiocercaria que foram liberadas do molusco M. tuberculatus, D. depressissimum e B. straminea. Esta pesquisa notifica a distribuição de diferentes espécies de caramujos sendo o primeiro relato da presença dos moluscos M. tuberculatus, D. depressissimum, Physa marmorata, Pomacea insularum, Cyanocyclas brasiliana no Riacho Camoxinga, demonstrando a importância de estudos da malacofauna em área não endêmicas para a esquistossomose para assim promover a prevenção e controle desses animais de importância médica, uma vez que estes invertebrados podem atuar como hospedeiros intermediários de trematódeos.
 PALAVRAS-CHAVE: Malacofauna, Schistosoma mansoni, Doenças parasitárias.

How costly are metacercarial infections in a bivalve host? Effects of two trematode species on biochemical performance of cockles

Bivalve stocks have been decreasing in the last decades largely due to emergent diseases and consequent mass mortality episodes. Cerastoderma edule (the edible cockle) is one of the most exploited bivalves in Europe and is among the most common hosts for trematodes, the most prevalent macroparasites in coastal waters but yet poorly studied. Therefore, in the present study, this bivalve species was used as host model to determine if trematode infection exerts a negative effect on bivalve energy metabolism and balance and if the tissues targeted by different trematodes influence the metabolic cost, with physiological and biochemical consequences. Cockles were experimentally infected with two trematode species, Himasthla elongata and Renicola roscovitus, that infect the foot and palps, respectively. Trematode infection exerted a negative effect on the metabolism of C. edule, the second intermediate host, by reduction of oxygen consumption. A different host biochemical response was found depending on trematode species, especially in regard to the level of oxygen consumption decrease and the preferential accumulation of lipids and glycogen. This study represents a step towards the understanding of host-trematode relationships that can be used to better predict potential conservation threats to bivalve populations and to maximize the success of stock and disease management.

Morphology, biology and parasite fauna of the least cisco (Coregonus sardinella) of the Yenisei River

In the present study, we present an analysis of the morphological and ecological characteristics of the “turukhanskaja” form of the Siberian least cisco of the Yenisei River, including the characters of the size-age, sexual composition of the population, fecundity and growth. The variability of 34 morphological characters was studied. Significant differences were noted between males and females of the least cisco of the Yenisei River for 11 morphometric characters (head length, maximum body depth, caudal peduncle length, antepectoral distance, dorsal fin base length and dorsal fin depth, anal fin base length, pectoral fin length, head width, head (at nape), interorbital width). Significant differences in meristic characters were revealed in comparison of the least cisco from the Yenisei River with populations of Siberian least cisco from other water bodies. It was shown that the Yenisei least cisco is close to the European vendace Coregonus albula Linnaeus, 1758 not only according to cluster hierarchical analysis for some meristic and morphometric features but also in terms of growth and fecundity. In general, the Yenisei least cisco, as well as other populations of least cisco of the Taimyr, is characterized by heterogeneity in the structure of populations. The parasite fauna of Yenisei’s Siberian cisco, captured in the area of Dudinka town, consists of 17 species of parasites from seven systematic groups. It is dominated by Diphyllobothrium ditremum (Creplin, 1825) and Discocotyle sagittata (Leuckart, 1842). The feature of the parasite fauna of least cisco from Yenisei River in comparison with the Ob River (neighbouring water basin) is a low infection with trematodes and a high species diversity of Acanthocephala. The reason for the low infection with trematodes may be differences in the hydrological conditions of the water bodies, which in the Yenisei are unfavourable for the development of intermediate hosts of trematodes. Siberian cisco from the Yenisei River is a carrier of Diphyllobothrium dendriticum (Nitzsh, 1824), a species that can cause human disease.

Potamopyrgus antipodarum (Gray, 1843) in Polish waters − its mitochondrial haplotype and role as intermediate host for trematodes

The New Zealand mud snail (Potamopyrgus antipodarum (Gray, 1843)) is on the list of one hundred worst invasive species. Researchers point out that genetic variation between populations of P. antipodarum manifested in differences in life-history traits. The main objective of our investigation was to gain pioneer knowledge about mitochondrial haplotypes of P. antipodarum in Polish waters on the background of these haplotypes recorded in the world and confirmation of the main role of P. antipodarum in the life cycle of digenean trematodes. We examined 1000 individuals of P. antipodarum from five water bodies in three different parts of Poland for the presence of larval stages of digenean trematodes. For several randomly selected individuals we carried out DNA sequencing of the 16S ribosomal RNA gene as marker of this non-indigenous mollusk. Only one 16S rRNA haplotype of P. antipodarum was recorded in Polish waters, defined in this study as haplotype 1 which turned out to be the most widespread in Europe. Potamopyrgus antipodarum is a source of trematode metacercariae belonging mainly to the family Echinostomatidae. As a result, we can demonstrate that it plays a role as the second intermediate host of digenean trematodes in European waters.

WATERBODY FLOWAGE AND ITS EFFECTION ON MOLLUSKS CONTAMINATION UNDER THE CONDITIONS OF UKRAINIAN POLISSYA STREAMFLOWS

The research results on the effect of water flowage of different current speed on the mollusks contamination have been presented in the paper. There is limited data in literature as to the effect of current speed on mollusks contamination under contemporary conditions of Ukrainian Polissya. The presented information broadens and complements the data. The current speed proved to indirectly affect the level of mollusks contamination by larvae stage of trematodes. It was stated that in streamflows with oligotype (0 – 0,1m/s) and mesotype (0,1 – 1m/s) current speeds the infection extensity of some mollusks species by parthenita and trematodes larvae may vary in wide range. It should be noted, that there were no rivers of polytype current speed in the studied waterbody. The high infection extensity indices by parthenita and trematodes larvae were revealed in Bithynia tentaculata mollusks (Linnaeus, 1758), Viviparus (Viviparus) viviparus (Linnaeus, 1758) in the Uzh, the Revna, the Seim under oligotype and mesotype current speed. This testifies to the fact, that contamination of the above mollusks types does not essentially depend on the current speed. We consider it is caused by high density of their population and the number of definite hosts. The above mentioned mollusks are the bridging hosts of trematodes which complete their development mainly in birds and fishes. The current speed is determinative as to contamination of widely distributed mollusks species as Lymnaea stagnalis (Linnaeus, 1758) and Planorbarius corneus (Linnaeus, 1758) which are stagnophiles. The comparison of infection extensity of joint river mollusks selection with oligotype and mesotype current speeds has been conducted.