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Fascioliasis is a worldwide emerging snail-borne zoonotic trematodiasis with a great spreading capacity linked to animal and human movements, climate change, and anthropogenic modifications of freshwater environments. South America is the continent with more human endemic areas caused by Fasciola hepatica, mainly in high altitude areas of Andean regions. The Peruvian Cajamarca area presents the highest human prevalences reported, only lower than those in the Bolivian Altiplano. Sequencing of the complete rDNA ITS-2 allowed for the specific and haplotype classification of lymnaeid snails collected in seasonal field surveys along a transect including 2007–3473 m altitudes. The species Galba truncatula (one haplotype preferentially in higher altitudes) and Pseudosuccinea columella (one haplotype in an isolated population), and the non-transmitting species Lymnaea schirazensis (two haplotypes mainly in lower altitudes) were found. Climatic seasonality proved to influence G. truncatula populations in temporarily dried habitats, whereas L. schirazensis appeared to be more climatologically independent due to its extreme amphibious ecology. Along the southeastern transect from Cajamarca city, G. truncatula and L. schirazensis shared the same site in 7 localities (46.7% of the water collections studied). The detection of G. truncatula in 11 new foci (73.3%), predominantly in northern localities closer to the city, demonstrate that the Cajamarca transmission risk area is markedly wider than previously considered. Lymnaea schirazensis progressively increases its presence when moving away from the city. Results highlight the usefulness of lymnaeid surveys to assess borders of the endemic area and inner distribution of transmission foci. Similar lymnaeid surveys are still in need to be performed in the wide northern and western zones of the Cajamarca city. The coexistence of more than one lymnaeid transmitting species, together with a morphologically indistinguishable non-transmitting species and livestock movements inside the area, conform a complex scenario which poses difficulties for the needed One Health control intervention., Graphical abstract Unlabelled Image, Highlights • Lymnaeid surveys by rDNA ITS-2 in Cajamarca human fascioliasis hyperendemic area • New foci with Galba truncatula and Lymnaea schirazensis at 2007–3473 m altitudes • Only one Pseudosuccinae columella population found in a seasonal survey • Seasonal lymnaeid surveys useful to assess endemic area distribution and borders • Geographical distribution of Cajamarca endemic markedly wider than previously considered

Background Humans impose a significant pressure on large herbivore populations, such as hippopotami, through hunting, poaching, and habitat destruction. Anthropogenic pressures can also occur indirectly, such as artificial lake creation and the subsequent introduction of invasive species that alter the ecosystem. These events can lead to drastic changes in parasite diversity and transmission, but generally receive little scientific attention. Results In order to document and identify trematode parasites of the common hippopotamus (Hippopotamus amphibius) in artificial water systems of Zimbabwe, we applied an integrative taxonomic approach, combining molecular diagnostics and morphometrics on archived and new samples. In doing so, we provide DNA reference sequences of the hippopotamus liver fluke Fasciola nyanzae, enabling us to construct the first complete Fasciola phylogeny. We describe parasite spillback of F. nyanzae by the invasive freshwater snail Pseudosuccinea columella, as a consequence of a cascade of biological invasions in Lake Kariba, one of the biggest artificial lakes in the world. Additionally, we report an unknown stomach fluke of the hippopotamus transmitted by the non-endemic snail Radix aff. plicatula, an Asian snail species that has not been found in Africa before, and the stomach fluke Carmyerius cruciformis transmitted by the native snail Bulinus truncatus. Finally, Biomphalaria pfeifferi and two Bulinus species were found as new snail hosts for the poorly documented hippopotamus blood fluke Schistosoma edwardiense. Conclusions Our findings indicate that artificial lakes are breeding grounds for endemic and non-endemic snails that transmit trematode parasites of the common hippopotamus. This has important implications, as existing research links trematode parasite infections combined with other stressors to declining wild herbivore populations. Therefore, we argue that monitoring the anthropogenic impact on parasite transmission should become an integral part of wildlife conservation efforts. Graphical abstract

Despite the epidemiological importance of the Lymnaeidae family regarding transmission of Fasciola hepatica, knowledge about the diversity and distribution of these molluscs and the role of each species in the expansion of fasciolosis remains sparse. Classical morphological (n=10) identification was performed in lymneids from Lagoa Santa, a municipality in the state of Minas Gerais, Brazil, along with molecular and phylogenetic analysis (n=05) based on the partial nucleotide sequences of the mitochondrial cytochrome c oxidase subunit I gene (COI mtDNA) and ribosomal internal transcribed spacer II (ITS-2 rDNA). The shell morphology made it possible to distinguish the lymneids of Lagoa Santa from Pseudosuccinea columella. Differences found in the penile complex and prostate shape allowed this species to be distinguished from Galba truncatula. However, the homogeneity of reproductive tract characteristics among Lymnaea (Galba) cubensis, L. viator and L. neotropica confirmed that these characteristics show low taxonomic reliability for identifying cryptic species. Genetic divergence analysis for the COI mtDNA gene and ITS-2 region of rDNA revealed greater similarity to Lymnaea (Galba) cubensis. Thus, correct species differentiation is important for monitoring the epidemiological risk of fasciolosis in the state of Minas Gerais, where cases of the disease have increased over recent years. Resumo Apesar da importância epidemiológica da família Lymnaeidae na transmissão de Fasciola hepatica, o conhecimento sobre a diversidade e a distribuição desses moluscos e o papel de cada espécie, na expansão da fasciolose, ainda é escasso. Realizou-se a identificação morfológica clássica (n=10) em limneídeos de Lagoa Santa, município do estado de Minas Gerais, Brasil, juntamente com a análise molecular e filogenética (n=05), baseada nas sequências parciais de nucleotídeos do gene mitocondrial da subunidade I do citocromo c oxidase (COI mtDNA) e espaçador interno, transcrito do DNA ribossomal II (ITS-2 rDNA). A morfologia da concha possibilitou distinguir os limneídeos de Lagoa Santa de Pseudosuccinea columella. As diferenças encontradas no complexo peniano e na forma da próstata permitiram que essa espécie fosse distinta de Galba truncatula. No entanto, a homogeneidade das características do trato reprodutivo entre Lymnaea (Galba) cubensis, L. viator e L. neotropica confirmou que essas características apresentam baixa confiabilidade taxonômica para a identificação de espécies crípticas. A análise da divergência genética para o gene COI mtDNA e região ITS-2 do rDNA revelou maior similaridade entre os limneídeos de Lagoa Santa com Lymnaea (Galba) cubensis.

The snail Pseudosuccinea columella participates in the distribution of Fasciola hepatica in the environment by acting as its intermediate host. Therefore, the control of this lymnaeid is one of the ways to prevent hepatic fascioliasis. The objective of this study was to evaluate the susceptibility of P. columella to infective juveniles (IJs) of the entomopathogenic nematode (EPN) Heterorhabditis baujardi in laboratory conditions, as well as to investigate aspects related to the biochemistry and histopathology of snails exposed or not to the EPNs during three weeks. The EPN exposure induced significant reductions in the concentrations of glucose, total proteins and glycogen (gonad-digestive gland complex) in the snails during the onset of the infection, with the levels being restored as the infection progresses. These alterations were accompanied by increased hemolymph activities of aminotransferases and lactate dehydrogenase, as well as the concentrations of uric acid after the first and second weeks of the experiment. The histopathological analyses of the exposed snails revealed cell necrosis at the end of the first week, tissue inflammatory reactions one and two weeks after exposure, and degeneration three weeks afterward in comparison with the unexposed snails. Finally, scanning electronic microscopy revealed proliferation of fibrous connective tissue three weeks after exposure. The results indicate that P. columella is susceptible to H. baujardi. The exposure favored the establishment of a negative energy balance, increased the activity of enzymes related to tissue damages and promoted accumulation of nitrogen compounds in the host snails. Additionally, was observed in P. columella exposed to the EPNs, significant tissue lesions, and demonstrated the strong pathogenic potential of H. baujardi, indicating its possible application for biological control of this snail.

El objetivo fundamental fue identificar el riesgo epidemiológico y zoonótico de la malacofauna fluvial y terrestre en el Área de Salud Roberto Fleites, perteneciente al municipio Santa Clara, provincia Villa Clara, Cuba. Los caracoles fueron muestreados mensualmente durante el 2011- 2012. Las especies de moluscos con mayor frecuencia y distribución fueron: Praticolella griseola, Tarebia granifera y Pseudosuccinea columella. Las especies con mayor interés médico fueron: P. griseola, P. columella, Subulina octona, Physella acuta, Pomacea poeyana y Galba cubensis que son hospederos intermediarios y transmisores de enfermedades parasitarias helmínticas. Se observó una mayor abundancia de moluscos en huertos-organopónicos en relación a los cuerpos de agua muestreados; sin embargo, se obtuvo mayor riqueza de especies de moluscos en los cuerpos de agua que en los huertos-organopónicos. Existe mayor riesgo epidemiológico en huertos-organopónicos, donde el 96,49 % de los moluscos son capaces de transmitir enfermedades al hombre y los animales, mientras que en los cuerpos de agua, solo el 8,32 % de los moluscos son capaces de transmitir enfermedades al hombre y animales. Se evidenció una relación significativa entre las poblaciones de moluscos y la humedad relativa máxima y la precipitación.

Fasciolosis is a worldwide spread parasitosis mainly caused by the trematode Fasciola hepatica. This disease is particularly important for public health in tropical regions, but it can also affect the economies of many developed countries due to large infections in domestic animals. Although several studies have tried to understand the transmission by studying the prevalence of different host species, only a few have used population genetic approaches to understand the links between domestic and wildlife infections. Here, we present the results of such genetic approach combined with classical parasitological data (prevalence and intensity) by studying domestic and wild definitive hosts from Camargue (southern France) where fasciolosis is considered as a problem. We found 60% of domestic hosts (cattle) infected with F. hepatica but lower values in wild hosts (nutria, 19%; wild boars, 4.5%). We explored nine variable microsatellite loci for 1,148 adult flukes recovered from four different populations (non-treated cattle, treated cattle, nutria and wild boars). Populations from the four groups differed, though we found a number of migrants particularly non-treated cattle and nutria. Overall, we detected 729 different multilocus genotypes (from 783 completely genotyped individuals) and only 46 genotypes repeated across samples. Finally, we experimentally infected native and introduced intermediate snail hosts to explore their compatibility with F. hepatica and assess the risks of fasciolosis expansion in the region. The introduced species Galba truncatula and Pseudosuccinea columella attained the higher values of overall compatibility in relation to the European species. However, concerning the origin, sympatric combinations of G. truncatula were more compatible (higher prevalence, intensity and survival) than the allopatric tested. According to our results, we should note that the assessment of epidemiological risks cannot be limited to a single host–parasite system, but should focus on understanding the diversity of hosts in the heterogeneous environment through space and time. Fil: Vázquez, Antonio A.. Instituto de Medicina Tropical “Pedro Kourí”; Cuba. Université Montpellier II; Francia. Centre National de la Recherche Scientifique; Francia Fil: Sabourin, Emeline. Centre National de la Recherche Scientifique; Francia. Université Montpellier II; Francia Fil: Alda, Maria del Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados I; Argentina. Centre National de la Recherche Scientifique; Francia. Université Montpellier II; Francia Fil: Leroy, Clémentine. Centre National de la Recherche Scientifique; Francia. Université Montpellier II; Francia Fil: Leray, Carole. Institut de Recherche de la Tour du Valat; Francia Fil: Carron, Eric. Centre National de la Recherche Scientifique; Francia. Université Montpellier II; Francia Fil: Mulero, Stephen. Centre National de la Recherche Scientifique; Francia. Université Montpellier II; Francia. Université de Perpignan Via Domitia; Francia Fil: Caty, Céline. Institut de Recherche de la Tour du Valat; Francia Fil: Hasfia, Sarah. Centre National de la Recherche Scientifique; Francia. Université Montpellier II; Francia Fil: Boisseau, Michel. Centre National de la Recherche Scientifique; Francia. Université Montpellier II; Francia Fil: Saugné, Lucas. Centre National de la Recherche Scientifique; Francia. Université Montpellier II; Francia Fil: Pineau, Olivier. Institut de Recherche de la Tour du Valat; Francia Fil: Blanchon, Thomas. Institut de Recherche de la Tour du Valat; Francia Fil: Alba, Annia. Instituto de Medicina Tropical “Pedro Kourí”; Cuba. Università di Corsica Pasquale Paoli; Francia Fil: Faugère, Dominique. Centre National de la Recherche Scientifique; Francia. Université Montpellier II; Francia Fil: Vittecoq, Marion. Centre National de la Recherche Scientifique; Francia. Université Montpellier II; Francia. Institut de Recherche de la Tour du Valat; Francia Fil: Hurtrez Boussès, Sylvie. Centre National de la Recherche Scientifique; Francia. Université Montpellier II; Francia

International audience; The Fasciola hepatica/Pseudosuccinea columella interaction in Cuba involves a unique pattern of phenotypes; while most snails are susceptible, some field populations are naturally resistant to infection and parasites are encapsulated by snail hemocytes. Thus, we investigated the hemocytes of resistant (R) and susceptible (S) P. columella, in particular morphology, abundance, proliferation and in vitro encapsulation activity following exposure to F. hepatica. Compared to susceptible P. columella, hemocytes from exposed resistant snails showed increased levels of spreading and aggregation (large adherent cells), proliferation of circulating blast-like cells and encapsulation activity of the hemocytes, along with a higher expression of the cytokine granulin. By contrast , there was evidence of a putative F. hepatica-driven inhibition of host immunity, only in susceptible snails. Additionally, (pre-)incubation of naïve hemocytes from P. columella (R and S) with different monosaccharides was associated with lower encapsulation activity of F. hepatica larvae. This suggests the involvement in this host-parasite interaction of lectins and lectins receptors (particularly related to mannose and fucose sensing) in association with hemocyte activation and/or binding to F. hepatica.

A systematic review was conducted focusing on the distribution ofFasciolaspecies and their snail intermediate hosts (IHs) in East and Southern Africa. The reviewed literature showed that bothFasciola hepaticaandF. giganticaare present in East and Southern Africa, and infect a wide range of domestic and wild ruminants.Fasciola giganticawas reported in six East African and five Southern African countries, whereRadix natalensis(found in low altitudes) was reported to be the main IH.Fasciola hepaticawas reported in Tanzania and Ethiopia (East Africa), and in South Africa and Zimbabwe (Southern Africa), whereGalba truncatula(found in high altitudes) was documented as the IH in all countries except in Zimbabwe. BothFasciolaspecies were documented in Tanzania, Ethiopia, Zimbabwe and South Africa. An overlap of the two was observed in areas with an intermediate altitude in Ethiopia and South Africa, wherePseudosuccinea columellawas widespread and assumed to transmit both species.Pseudosuccinea columellahas been reported in South Africa and Namibia, and proven to transmitF. giganticain South Africa; its role in Namibia in the transmission ofFasciolaspecies has not been reported. Other lymnaeid species such asR. rubiginosawere reported in South Africa, andR. auriculariain South Africa and Botswana; their role in the transmission ofFasciolaspecies has not been proven. Future studies should aim to determine the role ofP. columellain the geographical spread of the two species in East and Southern African countries.

The main intermediate host ofFasciola giganticain sub-Saharan Africa isLymnaea(Radix)natalensis.Lymnaea(Pseudosuccinea)columellais capable of transmitting bothF. giganticaandF. hepaticaand has been reported to be present in South Africa. To date, no natural infection withF. giganticahas been reported despite the wide distribution of the snail. The aim of this study was to confirm whetherL.(P.)columellawas transmittingF. giganticaand/orF. hepaticain selected locations of KwaZulu-Natal and Eastern Cape provinces of South Africa.Lymnaea(Pseudosuccinea)columellasnails were collected from two locations in two provinces of South Africa and screened for cercariae shedding. This was followed by humanely sacrificing the screened snails, and whole tissue of each individual snail was homogenized and amplified using primers designed to amplify the ITS-1 region ofFasciolaspp. No cercariae were shed from the screened snails and molecular analysis showed that snails from the two locations were infected withF. gigantica. This study confirms natural infection ofL.(P.)columellawithF. giganticain South Africa, whereF. giganticaandF. hepaticahave already been reported to coexist. AlthoughL.(P.)columellais able to transmit the two species, surprisingly no infection withF. hepaticawas detected from the screened snails. The natural intermediate host ofF. giganticain southern Africa, including South Africa, isLymnaea(Radix)natalensisand comparative studies are needed to determine the competence of the two snail species in the transmission ofF. gigantica.

Snails of the species Pseudosuccinea columella are considered intermediate hosts of Fasciola hepatica, a digenetic trematode that infects bile ducts of ruminants and humans, causing economic damage and serious problems for public health. These gastropods inhabit ponds, have high reproductive capacity, and lay their egg masses in submerged substrates on pond edges where they are exposed to desiccation and microbes, including fungi, that may exert pathogenic effects on the snail and its embryos. This information is relevant for control of the intermediate host and therefore of fasciolosis. With the objective of evaluating ovicidal potential of Pochonia chlamydosporia (Pc-10 isolate), a nematophagous fungus used as antagonistic agent for a wide variety of helminths of medical and veterinary importance, on egg masses of P. columella, we compared a treated group, where the egg masses were exposed to Pc-10 for a period of 25 days, and a control group, in which there was no exposure to the fungus. The results indicated that the embryogenesis process was significantly inhibited (93.15%) by Pc-10, suggesting its applicability in biological control programs of lymnaeid snails. In addition, ultrastructure showed the occurrence of different types of interactions between the egg masses with the mycelia of Pc-10: type 1, biochemical effects by the adherence of hyphae; type 2, morphological alterations, but without hyphal penetration; and type 3, lytic effect, morphological damage caused by penetration of hyphae by the fungus, resulting in some important structural modifications, thus compromising the viability of the eggs. The results demonstrate the susceptibility of P. columella egg masses to an isolate of P. chlamydosporia under laboratory conditions, providing valuable information for the biological control of this intermediate host.

Aquatic insects that oviposit on rocks may evolve strategies to mitigate loss of eggs to opportunistic predation by common native grazers, but such strategies may be ineffective against non-native grazers. We tested whether the eggs of common New Zealand caddisfly families (Hydrobiosidae and Hydropsychidae) that oviposit on rocks were more susceptible to predation by native or non-native snails. The native snail Potamopyrgus antipodarum (Grey, 1843) and non-native snails Physa acuta Draparnaud, 1805 and Pseudosuccinea columella (Say, 1817) were presented with caddisfly egg masses and the number of individual eggs consumed was recorded after 24 and 48 hours. The larger Pseudosuccinea readily consumed the eggs, especially spumaline-encapsulated Hydrobiosidae eggs. Physa consumed very few Hydrobiosidae eggs and no Hydropsychidae eggs, whereas Potamopyrgus did not consume eggs of either family. The trichopteran egg masses tested did not succumb to predation by the native Potamopyrgus but are highly vu...

The freshwater snail Pseudosuccinea columella was recorded for the first time in Argentina more than 60 years ago. Since then its distribution in the wild has been restricted to the northeastern provinces. Here we record the presence of P. columella in southern Pampas for the first time, extending its distribution more than 500 km southwards. The climatic suitability of this and other areas of South America for its establishment and spread was analysed using habitat modelling software. Hitherto its spread within and between watercourses in southern Pampas has been very limited, probably through a combination of low climatic suitability, recent introduction and low connectivity of the drainage basins. The suitability of other areas where it has been recently recorded indicates a moderate risk of further spread in central and northwestern Argentina and in coastal areas of the Pacific rim of South America (southern Peru and northern Chile). The recent spread of P. columella in the wild in Argentina m...

Experimental co-infections of juvenile and pre-adult Pseudosuccinea columella with Calicophoron daubneyi and Fasciola hepatica (five miracidia of each digenean per snail) were carried out to determine the aptitude of this lymnaeid to ensure complete larval development of the former parasite, the latter or both. Snails infected with F. hepatica were found in the two groups of juveniles, i.e. 1 and 2 mm at exposure, and the four groups of pre-adults, i.e. 3–6 mm. The highest frequency of F. hepatica, i.e. 37.3%, was noted in the 4 mm group. Low frequencies were noted for C. daubneyi and co-infections of both digeneans in the 3, 4 and 5 mm groups. Two other groups of P. columella, measuring 3 and 4 mm at exposure, were also constituted to study the characteristics of these co-infections. Compared to controls infected only with F. hepatica, the frequency of this digenean infection and the mean number of metacercariae were significantly lower in co-infected snails, while the patent period was significantly shorter. In snails harbouring C. daubneyi only or both digeneans, lower values were noted for prevalence, the patent period and the number of metacercariae. Pre-adult P. columella (3–5 mm in shell height at exposure) were able to sustain larval development of C. daubneyi if they were co-infected with the sequence C. daubneyi +F. hepatica. Low values noted for the prevalence of C. daubneyi infection and the number of metacercariae would be in favour of a still incomplete adaptation between the snail population and the miracidial isolate.

Pseudosuccinea columella and Radix natalensis live in the same habitat in Egypt and are important intermediate hosts of Fasciola hepatica and F. gigantica. Our study aimed to characterise both snail species using molecular analysis and shell measurements. The ranges of morphometric parameters overlapped in the two lymnaeids, indicating that they do not clearly differentiate the two species. PCR-sequence analysis of the nuclear ribosomal small subunit rRNA and the polymorphic mitochondrial cytochrome oxidase subunit 1 (CO1) genes were used to determine the genetic identity and the potential diversity of the snails. Little intrasequence variations were detected in the sequences of both gene loci, indicating the potential homogeneity of lymnaeid populations in Egypt. Generated sequences of the mitochondrial CO1 gene locus for R. natalensis showed obvious heterogeneity compared to other sequences in GenBank. Molecular characterisation of these lymnaeids might help to understand the snails’ biodiversit...

International audience; The snail Pseudosuccinea columella is one of the main vectors of the medically-important trematode Fasciola hepatica. In Cuba, the existence of natural P. columella populations that are either susceptible or resistant to F. hepatica infection offers a unique snail-parasite for study of parasite-host compatibility and immune function in gastropods. Here, we review all previous literature on this system and present new "omic" data that provide a molecular baseline of both P. columella phenotypes from naïve snails. Comparison of whole snail transcriptomes (RNAseq) and the proteomes of the albumen gland (2D-electrophoresis, MS) revealed that resistant and susceptible strains differed mainly in an enrichment of particular biological processes/functions and a greater abundance of proteins/transcripts associated with immune defense/stress response in resistant snails. These results indicate a differential allocation of molecular resources to self-maintenance and survival in resistant P. columella that may cause enhanced responsiveness to stressors (i.e. F. hepatica infection or tolerance to variations in environmental pH/total water hardness), possibly as trade-off against reproduction and the ecological cost of resistance previously suggested in resistant populations of P.

Fasciolosis is an important food-borne parasitic disease affecting over two million people worldwide with economic losses related to cattle production of up to US$ 3 billion annually. Despite the long known presence of Fasciola hepatica in the Caribbean islands its transmission is not well known. This study reviews historical and recent data on fasciolosis in the West Indies, revealing for the first time the outcomes of sympatric and allopatric fluke/snail interactions in the area by exploring the susceptibility of four lymnaeid species after exposure to F. hepatica isolates from Cuba, the Dominican Republic and France. Overall, Galba cubensis showed a mean prevalence of 71.8% and appears to be the most suitable intermediate host species irrespective of the isolate used. Sympatric combinations (snail and parasite from the same country) were generally more compatible (higher susceptibility, parasite intensity and snail survival post-exposure) and only the allopatric interaction of French G. truncatula/Cuban F. hepatica attained 100% prevalence and mean intensity over 33 rediae/snail. However, certain Dominican populations of Pseudosuccinea columella showed high parasite intensities (>30 rediae/snail) when infected with Cuban flukes, highlighting the potential risks of biological introductions. Overall, high compatibility in most sympatric combinations compared to low or moderate compatibility in allopatric ones, suggests the existence of local adaptation from a long sustained interaction that has led to high rates of transmission. Interestingly, attempts to infect G. schirazensis with sympatric and allopatric flukes failed and coupled with the lowest survival rates which supposes a low risk of fasciolosis transmission in areas where this is the only snail species. Although there are significant gaps in the actual status of fasciolosis transmission from several islands in the West Indies these results show a permanent risk. We conclude that fasciolosis transmission is high in areas where the local snail, G. cubensis, occurs, and will be even higher in the presence of the invasive P. columella. Fil: Vázquez, Antonio A.. Centre National de la Recherche Scientifique; Francia. Institute of Tropical Medicine Pedro Kourí. Laboratory of Malacology; Cuba Fil: de Vargas, Mercedes. Instituto Tecnológico de Santo Domingo; República Dominicana Fil: Alba, Annia. Institute of Tropical Medicine Pedro Kourí. Laboratory of Malacology; Cuba Fil: Sánchez, Jorge. Institute of Tropical Medicine Pedro Kourí. Laboratory of Malacology; Cuba Fil: Alda, Maria del Pilar. Centre National de la Recherche Scientifique; Francia. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina Fil: Sabourin, Emeline. Centre National de la Recherche Scientifique; Francia. Institut de recherche de la Tour du Valat; Francia Fil: Vittecoq, Marion. Centre National de la Recherche Scientifique; Francia. Institut de recherche de la Tour du Valat; Francia Fil: Alarcón Elbal, Pedro M.. Universidad Iberoamericana, Santo Domingo; Fil: Pointier, Jean Pierre. Université de Perpignan; Francia Fil: Hurtrez Boussès, Sylvie. Centre National de la Recherche Scientifique; Francia. Université Montpellier II; Francia

International audience; The Lymnaeidae constitute a family of freshwater gastropod molluscs whose diversity and ecology have been infrequently studied throughout Colombia. Some lymnaeid species act as intermediate hosts of trematode parasites, which are of great importance in both the veterinary and medical fields. Among trematode parasites, Fasciola hepatica is best known for being an important parasite of sheep and cattle for decades and causes significant economic losses in these livestock species. The main objective of this work is to identify the various species of lymnaeids that occupy different geographical regions of Santander and its bordering departments within Colombia. This will expand the knowledge of lymnaeid diversity in Colombia and provide further insight into their role in the transmission of F. hepatica. A total of 118 georeferenced sites between 126 m.a.s.l. and 3870 m.a.s.l. were sampled in Santander, Boyacá, Norte de Santander and Cundinamarca, respectively. Lymnaeid snails were identified according to the morphology of their shells and by several characteristics of their reproductive systems. Species identification was confirmed using DNA barcoding. Four lymnaeid species are reported in the study area: the native Galba cousini and three exotic species, Pseudosuccinea columella, G. truncatula and G. schirazensis. The four species were examined for natural infection with F. hepatica. Infected variants of the main snail host, G. cousini, were found in the Onzaga, Encino and Vetas municipalities of Santander, as well as in the Belén municipality of Boyacá. A second species, G. truncatula was also found naturally infected in Mutiscua municipality of Norte de Santander. The two other species, P. columella and G. schirazensis were found free of infection.

Objective. Identify the natural infection of freshwater snails as an intermediate host of Fasciola hepatica in Guatemala. Materials and methods. Freshwater snails were collected in a high-altitude village (3.000 mamsl) from Huehuetenango department, where fasciolasis is endemic. The identification of the snail species was based on the morphological characteristics observed under the stereoscope using an identification key. The trematode phases were searched externally by visual inspection using a light source, and internally by dissection and visual inspection of the tissues under a stereoscope and microscope. Results. 260 snails were found and identified as Pseudosuccinea columella. Two of them were found naturally infected with larval phases of F. hepatica. Conclusions. This is the first report of P. columella carrying phases of F. hepatica in the highlands of Guatemala. It is necessary to increase the research of the ecology of this parasite in other understudied areas in Guatemala and Central America, due to the latent risk of infection for populations of herbivorous animals and humans., Objetivo. Identificar la infección natural de caracoles de agua dulce con Fasciola hepatica en una localidad del altiplano de Guatemala. Materiales y métodos. Se colectaron caracoles de agua dulce en una aldea endémica de fascioliasis, en la localidad de Paquix, en el departamento de Huehuetenango, ubicado a ~3.300 msnm. La identificación de la especie de caracol se basó en las características morfológicas observadas por estereoscopio usando una clave de identificación. La búsqueda de fases del trematodo se realizó mediante la inspección visual externa con fuente de luz y la disección e inspección visual dentro del molusco bajo estereoscopio y microscopio. Resultados. 260 caracoles fueron encontrados e identificados como Pseudosuccinea columella. Se examinaron los especímenes colectados y se encontraron dos caracoles infectados de forma natural con fases larvarias de F. hepatica. Conclusiones. Este es el primer reporte de este hospedero intermediario portando formas de F. hepatica en Guatemala. Es necesario aumentar los reportes de este parásito y de sus interacciones ecológicas en otras áreas no estudiadas de Guatemala y Centro América, debido al riesgo latente de infección para poblaciones de animales herbívoros y humanos.

The characteristics of parasitic infections are often tied to host behavior. Although most studies have investigated definitive hosts, intermediate hosts can also play a role in shaping the distribution and accumulation of parasites. This is particularly relevant in larval stages, where intermediate host's behavior could potentially interfere in the molecules secreted by the parasite into the next host during infection. To investigate this hypothesis, we used a proteomic approach to analyze excretion/secretion products (ESP) from Fasciola hepatica newly excysted juveniles (NEJ) derived from two intermediate host species, Lymnaea viatrix and Pseudosuccinea columella. The two analyzed proteomes showed differences in identity, abundance, and functional classification of the proteins. This observation could be due to differences in the biological cycle of the parasite in the host, environmental aspects, and/or host-dependent factors. Categories such as protein modification machinery, protease inhibitors, signal transduction, and cysteine-rich proteins showed different abundance between samples. More specifically, differences in abundance of individual proteins such as peptidyl-prolyl cis-trans isomerase, thioredoxin, cathepsin B, cathepsin L, and Kunitz-type inhibitors were identified. Based on the differences identified between NEJ ESP samples, we can conclude that the intermediate host is a factor influencing the proteomic profile of ESP in F. hepatica.

Background Pseudosuccinea columella is one of the most widespread vectors of Fasciola hepatica, a globally distributed trematode that affects humans, livestock and wildlife. The exclusive occurrence in Cuba of susceptible and naturally-resistant populations to F. hepatica within this snail species, offers a fascinating model for evolutionary biology, health sciences and vector control strategies. In particular, resistance in P. columella is characterized by the encapsulation of the parasite by host’s immune cells and has been experimentally tested using different Cuban F. hepatica isolates with no records of successful infection. Here, we aimed to explore for the first time, the effect of different parasite doses, successive exposures and different parasite origins on the infection outcomes of the two phenotypes of P. columella occurring in Cuba. Methods To increase the chances for F. hepatica to establish, we challenged Cuban P. columella with increasing single parasite doses of 5, 15 or 30 miracidia and serial exposures (three-times) of 5 miracidia using a sympatric F. hepatica isolate from Cuba, previously characterized by microsatellite markers. Additionally, we exposed the snails to F. hepatica from different geographical origins (i.e. Dominican Republic and France). Parasite prevalence, redial burden and survival of snails were recorded at 25 days post-exposure. Results No parasite development was noted in snails from the resistant populations independent of the experimental approach. Contrastingly, an overall increase in prevalence and redial burden was observed in susceptible snails when infected with high miracidia doses and after serial exposures. Significant differences in redial burden between single 15 miracidia and serial 3 × 5 miracidia infected snails suggest that immune priming potentially occurs in susceptible P. columella. Compatibility differences of allopatric (Caribbean vs European) F. hepatica with susceptible snails were related to the geographical scale of the combinations. Conclusions Here, the effectiveness of P. columella resistance to F. hepatica does not decline with increasing parasite doses, successive infection or different geographical origins of parasite isolates, while presenting new evidence for specificity for infection in susceptible P. columella snails. Understanding the peculiarities of the P. columella-F. hepatica interaction and the extent of the resistant phenotype is crucial for an effective parasite control and for developing alternatives to tackle fasciolosis transmission.

Parasite spillback, the infection of a non-indigenous organism by a native parasite, is a highly important although understudied component of ecological invasion dynamics. Here, through the first analysis of the parasite fauna of lymnaeid gastropods of Lake Kariba (Zimbabwe). We illustrate how the creation of an artificial lake may lead to a cascade of biological invasions in which an invasive aquatic plant promotes the proliferation of invasive gastropods, which in turn alters the epidemiology of trematodiases of potential medical and veterinary importance. Using a new multiplex Rapid Diagnostic PCR assay, we assessed the prevalence of Fasciola sp. infections in the gastropod populations. Both gastropod hosts and trematode parasites were identified using DNA barcoding. We provide the first record of the invasive North-American gastropod Pseudosuccinea columella in Lake Kariba. This species was found at 14 out of 16 sampled sites and its abundance was strongly positively correlated with the abundance of the invasive South-American water hyacinth (Eichhornia crassipes). About 65% of the P. columella specimens analysed were infected with a hitherto unknown Fasciola species. Phylogenetic analyses indicate close affinity to Fasciola hepatica and F. gigantica, which cause fasciolosis, an important liver disease affecting both ruminants and humans. In addition, another non-native Lymnaeid species was found: a Radix sp. that clustered closely with a Vietnamese Radix species. Radix sp. hosted both amphistome and Fasciola trematodes. By linking an invasion cascade and parasite spillback, this study shows how both processes can act in combination to lead to potentially important epidemiological changes.

Lymnaeidae snail species are known to be intermediate hosts of human and livestock helminths parasites, especially Fasciola species. Identification of these species and their geographical distribution is important to better understand the epidemiology of the disease. Significant diversity has been observed in the shell morphology of snails from the Lymnaeidae family and the systematics within this family is still unclear, especially when the anatomical traits among various species have been found to be homogeneous. Although there are records of lymnaeid species of southern Africa based on shell morphology and controversial anatomical traits, there is paucity of information on the molecular identification and phylogenetic relationships of the different taxa. Therefore, this study aimed at identifying populations of Lymnaeidae snails from selected sites of the Okavango Delta (OKD) in Botswana, and sites located in the KwaZulu-Natal (KZN) and Mpumalanga (MP) provinces of South Africa using molecular techniques. Lymnaeidae snails were collected from 8 locations from the Okavango delta in Botswana, 9 from KZN and one from MP provinces and were identified based on phylogenetic analysis of the internal transcribed spacer (ITS-2). Analyses based on the ITS-2 marker identified the presence of a well-supported Radix clade containing Radix auricularia, R. natalensis and R. rubiginosa, which were not well resolved. Experimental samples from the OKD and KZN present in this clade were referable to these species. An unidentified experimental taxon from the OKD formed a well-supported sister clade to the Radix clade, although it was not possible to identify it. Galba truncatula was well supported in a sister relationship to a well-supported Pseudosuccinea columella clade which included samples from MP and KZN provinces of South Africa. We observed that P. columella shared the same habitats with R. natalensis and R. auricularia in KZN. Our study contributes new knowledge on the Lymnaeidae species present in Southern Africa and their phylogenetic relationships. The study further identifies the species which are likely to co-exist in the same environment and this information will be of use to those designing control programs for fasciolosis. This is the first study reporting the presence of R. auricularia in the OKD of Botswana and KZN province of South Africa.

Des échantillons de Pseudosuccinea columella adultes ont été introduits expéri-mentalement dans huit fossés colonisés par Galba truncatula ou par Omphiscola glabra afin de suivre la distribution et la densité de ces espèces de mai 2014 à mai 2016. Les mêmes paramètres ont été étudiés dans quatre habitats témoins, colonisés seulement par G. truncatula ou O. glabra. La même expérience a, également, été réalisée dans les conditions du labora-toire. Sur le terrain, la colonisation des fossés par P. columella est plus rapide dans les habitats colonisés par G. truncatula que dans ceux avec O. glabra. De la même façon, la présence de P. columella induit une diminution dans le nombre des limnées transhivernantes et celle-ci est également plus rapide pour G. truncatula que pour O. glabra. Ce dernier résultat a été aussi noté dans les conditions du laboratoire. La colonisation des habitats à G. truncatula ou à O. glabra par P. columella sur les sols acides est donc possible et se traduit par une chute dans les effectifs des deux limnées locales, suivie de leur disparition pour l'une d'entre elles., Samples of adult Pseudosuccinea columella were experimentally introduced into eight ditches colonized by Galba truncatula and Omphiscola glabra to follow the distribution and density of these snail species from May 2014 to May 2016. The same parameters were also studied in four control ditches only colonized by G. truncatula or by O. glabra. The same experiment was also carried under laboratory conditions. In the field, the colonization of lymnaeid habitats by P. columella was quicker for G. truncatula than for O. glabra. Similarly, the presence of P. columella led to a decrease in the number of overwintering lymnaeids and this decrease was also quicker for G. truncatula than for the other lymnaeid. This last finding was also noted in laboratory conditions. The colonization of G. truncatula or O. glabra habitats by P. columella on acidic soils was thus feasible and induced a fall in the numbers of local lymnaeids, followed by their disappearance for one of these species., Annales Scientifiques du Limousin, Tome 26 | 2016

The lymnaeids are important in the epidemiology of Fasciola hepatica, a neglected and endemic zoonosis. The interaction between the internal defense system of Pseudosuccinea columella and F. hepatica has been little studied. In the present study the effect of infection by F. hepatica on P. columella circulating haemocytes was investigated. Changes in the average number of total circulating haemocytes have been observed at 30 minutes post-infection and 1, 7, 10, 14, 21, 28 and 50 days post-infection (dpi). Miracidia were observed head-foot and mantle at 30 minutes post-infection. Miracidia/Sporocysts in the mantle skirt 1 dpi, and fully formed sporocysts were observed in the head-foot at 7 dpi. Rediae became evident at 10 dpi and were located between the haemocoel and the muscles from 14 dpi; 50 dpi, the rediae in the digestive gland contained cercariae. The statistical analysis of the total haemocytes of P. columella infected by F. hepatica showed significant differences on the 30 minutes post-infection and 1, 14, 21, and 28 dpi in comparison to uninfected molluscs (0 dpi). Therefore, the interference observed on the internal defence system of P. columella may have direct association with the development of F. hepatica. Resumo Os limnaeideos são importantes na epidemiologia de Fasciola hepatica, uma zoonose negligenciada e endêmica. A interação entre o sistema interno de defesa de Pseudosuccinea columella e F. hepatica tem sido pouco estudada. No presente estudo, investigou-se o efeito da infecção por F. hepatica nos hemócitos circulantes de P. columella. Alterações no número médio de hemócitos circulantes foram observadas aos 30 minutos e 1, 7, 10, 14, 21, 28 e 50 dias após a infecção (dpi). Miracídios foram observados na região cefalopodal e manto aos 30 minutos após a infecção. Miracídio/esporocistos foram observados no colar do manto ao 1 dpi, e esporocistos totalmente formados na região cefalopodal aos 7 dpi. Rédias tornam-se evidentes aos 10 dpi entre a hemocele e músculos a partir de 14 dpi; e rédias com cercárias próximas a glândula digestiva aos 50 dpi. A análise estatística dos hemócitos totais de P. columella infectados por F. hepatica demonstrou diferenças significativas nos 30 minutos pós-infecção e 1, 14, 21 e 28 dpi em comparação aos moluscos não infectados (0 dpi). Portanto, a interferência observada no sistema de defesa interna de P. columella pode ter associação direta com o desenvolvimento de F. hepatica.