Intermediate Hosts Of Parasite Research Articles

Host species of freshwater snails within the same freshwater ecosystem shapes the intestinal microbiome

BackgroundFreshwater snails are not only intermediate hosts for parasites but also an important part of the food chain as they convert plant biomass and humus into animal biomass. However, being widely distributed in freshwater environments, snails are highly affected by human activities, which makes their adaptation to altering environments challenging. The gut microbiome helps animals in their digestion, immune system, growth and adapting to changing environments. The effect of host species on intestinal microbial community has been poorly studied in snails.MethodsIn this study, single-molecule real-time sequencing technology (SMRT) was used to obtain full-length 16S rRNA genes to determine the intestinal microbiomes of three species of freshwater snails (SQ: Sinotaia quadrata, BU: Boreoelona ussuriensis, RP: Radix plicatula) with similar feeding habits in a same water environment.ResultsUnifrac PCoA (P<0.05), hierarchical cluster and Ternary analyses showed distinct and significant segregation of the intestinal microbiomes of the three hosts. The phyla Cyanobacteria, Proteobacteria, Firmicutes and Planctomycetota dominated snail guts, comprising 93.47%, 86.22%, and 94.34% of the total reads in SQ, BU and RP, respectively. Of these, only 25.26% of OTUs were identified up to species level, while 72.07% of OTUs were identified at the genus level. Although 72.94% of the total bacterial species (566) were common to three snails, significant differences were observed in terms of their abundance (P < 0.05). Several genera can help to determine the phenotype of the intestinal microbiota. In this case, Lelliottia contributed mainly to stress tolerance, biofilm formation, potential pathogenicity, mobile elements and facultatively anaerobic phenotypes in RP. Furthermore, Romboutsia and Clostridium_sensu_stricto_1 contributed to the anaerobic phenotype of SQ and RP, while Pirellula contributed to the aerobic phenotype in SQ. Moreover, PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) predicted 68 GH (glycoside hydrolase) genes, with these including monosaccharide-, disaccharide-, polysaccharide-, and starch-digesting enzyme genes as well as enzymes specific to aquatic plants. Many of the identified pathways were related to Infectious diseases and Xenobiotics biodegradation and metabolism, which expanded the resistance of freshwater snails.ConcludesLelliottia, Romboutsia, Clostridium_sensu_stricto_1, and Pirellula play an important role in the intestinal microbiota phenotype of the host snails. In general, the host species affects the structure of the gut microbial community, which in turn helps gastropods improve their environmental adaptability, but further study is still needed.

Infection with acanthocephalans increases tolerance of Gammarus roeselii (Crustacea: Amphipoda) to pyrethroid insecticide deltamethrin

Crustacean amphipods serve as intermediate hosts for parasites and are at the same time sensitive indicators of environmental pollution in aquatic ecosystems. The extent to which interaction with the parasite influences their persistence in polluted ecosystems is poorly understood. Here, we compared infections of Gammarus roeselii with two species of Acanthocephala, Pomphorhynchus laevis, and Polymorphus minutus, along a pollution gradient in the Rhine-Main metropolitan region of Frankfurt am Main, Germany. Prevalence of P. laevis was very low at the unpolluted upstream reaches (P ≤ 3%), while higher prevalence (P ≤ 73%) and intensities of up to 9 individuals were found further downstream—close to an effluent of a large wastewater treatment plant (WWTP). Co-infections of P. minutus and P. laevis occurred in 11 individuals. Highest prevalence of P. minutus was P ≤ 9% and one parasite per amphipod host was the maximum intensity recorded. In order to assess whether the infection affects survival in the polluted habitats, we tested the sensitivity of infected and uninfected amphipods towards the pyrethroide insecticide deltamethrin. We found an infection-dependent difference in sensitivity within the first 72 h, with an effect concentration (24 h EC50) of 49.8 ng/l and 26.6 ng/l for infected and uninfected G. roeselii, respectively. Whereas final host abundance might partially explain the high prevalence of P. laevis in G. roeselii, the results of the acute toxicity test suggest a beneficial effect of acanthocephalan infection for G. roeselii at polluted sites. A strong accumulation of pollutants in the parasite could serve as a sink for pesticide exposure of the host. Due to the lack of a co-evolutionary history between parasite and host and a lack of behavioral manipulation (unlike in co-evolved gammarids), the predation risk by fish remains the same, explaining high local prevalence. Thus, our study exemplifies how organismic interaction can favor the persistence of a species under chemical pollution.

Molecular Phylogenetics of Physa acuta (Pulmonata: Basommatophora): an Invasive species in Central Punjab Pakistan.

Physids belong to Class Gastropoda; belong to Phylum Mollusca and being bioindicators, intermediate hosts of parasites and pests hold a key position in the ecosystem. There are three species of Genus Physa i.e. P. fontinalis, Physa acuta and P. gyrina water bodies of Central Punjab and were characterized on the basis of molecular markers High level of genetic diversity was revealed by polymorphic RAPD, however SSR markers were not amplified. The multivariate analysis revealed polymorphism ranging from 9.09 percent to 50 percent among the three Physid species. Total number of 79 loci were observed for the three species under study and 24 loci were observed to be polymorphic. These RAPD fragment(s) can be developed into co dominant markers (SCAR) by cloning and can be further sequenced for the development of the Physa species specific markers to identify the introduced and native species in Pakistan.

Molecular identifications of land snails (Gastropoda) and determination of its associated parasites

Freshwater snail is known to be an intermediate host for parasites. However, little is known on terrestrial snails whether they can become host for any parasites as well. The identification of the land snails also need confirmation as there are disagreements on the classification result of land snail species. Therefore, this study was conducted to determine the prevalence of snail parasites in livestock and poultry farms from Penang and Kedah, Malaysia. Identification of the snail species was conducted based on the morphological features and mitochondrial cytochrome c oxidase subunit I (COI) gene analysis. Out of 105 individual snails collected, four species were found in this study with the highest prevalence of 47.62% (50/105) snails identified as Physella acuta followed by Macrochlamys sp. with 31.4% (33/105). While 14.3% (15/105) were identified as Physella cubensis and the lowest prevalence was identified as Filopaludina sp. with 6.7% (7/105). Among these four species, only Physella acuta and Macrochlamys sp. were found to be infected with helminth parasites namely trematode and nematode. Macrochlamys sp. recorded the highest prevalence of parasitic infection with the prevalence of 87.9%. Besides, there are 134 of endoparasite and 36 of ectoparasite found in this study namely, Barchylaima fuscatum (helminth), 3 unknown nematode, and 36 Riccardoella limacum or slug mite which was found on the surface and in the mantle cavity of the snails.

Survey of the African giant land snail (Archachatina marginata), intermediate host of intestinal parasites in Akure Metropolis, Ondo State

BackgroundAfrican giant land snails (Archachatina marginata) are hermaphroditic pulmonate nocturnal gastropods of the Achatinidae family. The snail is one of West Africa's largest known terrestrial snails. The majority of land snails live in Nigeria's derived guinea savannah's forest litters, which range from deep tropical high forest to bordering riparian forests. Africa's giant land snails, which are noted for their ravenous feeding habits and extensive food range, are a major reservoir and intermediate host for parasites that can infect humans.ResultsSeventy snail samples were collected from the study site in total. The parasites found is a nematode rat lung worm (Angiostrongylus cantonensis), which have a fragile, narrow, and simple mouth with no lip or buccal cavity and belong to the order Strongylida. The parasite was found to be most prevalent in small snails (52.94%), followed by medium sized snails with a frequency of 29.41%, and the giant-sized snails with the lowest prevalence of infection. The mantle parasite has the largest prevalence (48.6%), while parasites retrieved from the stomach have the highest mean intensity (2.50 ± 0.25).ConclusionThe African giant land snail can serve as a vector for zoonotic diseases, transmitting parasites to humans through raw or undercooked snails, infested vegetation, and contact with contaminated water. As a result, effective control measures for human infection should be established.

Identification of the gastropod snails and shells collected from Ain El-Sokhna region, Red Sea, Egypt

The Red Sea is known for its unique coral reef topography that harbors many marine species making the Red Sea a biodiversity hot spot. The molluscan fauna of the Red Sea has been extensively studied for its ecology, biology and economic importance. In the present study, numerous live specimens and gastropod shells were collected from Ain El-Sokhna area on the western shore of the Red Sea’s Gulf of Suez. Samplings were done during June-October, 2020. The collected species were identified based on published keys for the identification of Red Sea molluscs. A total of 24 gastropod species belonging to 12 families were identified. Among these, the highest abundant species was Thais savignyi (Muricidae) followed by Cellana rota (Nacellidea). Some other species were rarely abundant such as Conomurex fasciatus (Strombidae), the reef-eating snail, Drupella cornus (Muricidae), Nassarius fenistratus, N. castus (Nassariidae), and Polinices pecelephanti (Naticidae). The present findings demonstrate high molluscan biodiversity at Ain El-Sokhna region of the Red Sea and set the platform for further studies and assessments of biological and biomedical importance of identified molluscs species either as intermediate hosts for parasites or sources for bioactive compounds.

Paragonimus westermani ichunensis and paragonimosis in the south of the Russian Far East: yesterday, today and tomorrow

Paragonimosis is a severe parasitic disease, which causative agent (on the territory of Russia, trematode Paragonimus westermani ichunensis Chung, Hsu et Kao, 1978) circulates in the south of the Far East. Two forms of paragonimosis are known: pulmonary and muscular (larval) with clinical manifestations like diseases of a different etiology, mimicking the symptoms of malignant tumors, and in cases of late diagnosis and improper treatment, leading to death. Long-term studies of the ecology and biology of the parasite, as well as monitoring the incidence among residents of the southern Far East of Russia made it possible to analyze the situation with paragonimosis in the designated region. Based on the available data, until the mid-1990s, natural sites of disease were found almost everywhere in the river basins inhabited by mollusks of the genus Parajuga and crayfish of the genus Cambaroides as parasite intermediate hosts. During this period, according to official information, the population invasion rate reached 6%. Then, as a result of the mass extinction of freshwater crayfish, the population of P. westermani ichunensis was on the brink of survival, and from that moment on, the number of diagnosed cases of paragonimosis in the inhabitants of the region began to decline, down to zero in recent years. Currently, the population of crayfish Cambaroides is reviving and a case of P. westermani ichunensis infestation of a tiger cub has been recorded, which indicates the population restoration of the parasite itself. This indicates the functioning resumption of the Paragonimus sp. infection centers in the south of the Russian Far East. It is necessary to be prepared for the possibility of an exponential growth in the number of infected animals with such a developmentтof events. Due to the complexity of the disease diagnosing and the lack of certain knowledge about the parasite biology among the majority of medical workers, it is necessary to be ready to low detection rate among the region population.

Molecular Identification of Oxyspirura Petrowi Intermediate Hosts by Nested PCR Using Internal Transcribed Spacer 1 (ITS1)

Recently, the heteroxenous eyeworm, Oxyspirura petrowi, has gained attention due to its prevalence in the declining game bird, Northern bobwhite (Colinus virginianus), but the intermediate hosts of many nematodes remain unknown. However, identifying the intermediate host of O. petrowi with traditional techniques would be difficult and time-consuming, especially considering there are more than 80 potential orthopteran hosts just in Texas. To screen a large number of samples quickly and effectively, primers for nested PCR (nPCR) were developed using the internal transcribed spacer 1 (ITS1) region. Then the nPCR was used to identify which of the 35 species collected from the Order Orthoptera were potential intermediate hosts of O. petrowi. With this technique, 18 potential intermediate hosts were identified. Later, we collected live specimens of species that tested positive to confirm the presence of larvae, but larvae were not found in the live specimens, nor in the extra tissue of the species that had tested positive for O. petrowi DNA. Despite this, this study demonstrated that nPCR is more sensitive than traditional techniques and can be a valuable tool in determining the intermediate hosts of parasites.

DISTRIBUTION AND DIVERSITY OF FRESHWATER SNAILS OF PUBLIC HEALTH IMPORTANCE IN KUBANNI RESERVOIR AND WEIR/SEDIMENT TRAP, ZARIA, NIGERIA

Due to survival of intermediate hosts of parasites causing schistosomiasis and fascioliasis under changing environmental conditions, this research was conducted to investigate the distribution and diversity of freshwater snails between March and June, 2017. Physico-chemical parameters were analyzed according to the standard operating procedures for examination of water and wastewaters. Snails were sampled using an Ekman grab from different sites in each reservoir, counted and identified using standard identification guide. A total of 108 snails were collected and identified in Kubanni reservoir comprising Biomphalaria sp. (48.15%), Lymnaea sp. (39.81%) and Bulinus sp. (12.04%). While in Weir, 141 snails which comprised Biomphalaria sp. (53.19%), Lymnaea sp. (24.11%) and Bulinus sp. (22.70%) were collected. Shanon-Weiner diversity index for Kubanni and Weir were 0.97 and 1.02 respectively. Variation in physico-chemical parameters between the reservoirs shows no significant difference (P>0.05), except for electrical conductivity (EC; p-0.0015), total dissolved solid (TDS; p-0.0016), biochemical oxygen demand (BOD; p-0.0004) and concentration of phosphate (PO4.-0.026) The three snail species obtained were common to the two reservoirs; however species diversity is higher in Kubanni reservoir than Weir. The presence of these snails in the two reservoirs could pose a serious threat to humans coming in contact with these reservoirs, in their role as intermediate hosts of parasites that causes schistosomiasis and fascioliasis.

Food web structure selects for parasite host range.

Complex life cycle parasites, including helminths, use intermediate hosts for development and definitive hosts for reproduction, with interactions between the two host types governed by food web structure. I study how a parasite's intermediate host range is controlled by the diet breadth of definitive host species and the cost of parasite generalism, a putative fitness cost that assumes host range trades off against fitness derived from a host species. In spite of such costs, a benefit to generalism may occur when the definitive host exhibits a large diet breadth, enhancing transmission of generalist parasites via consumption of a broad array of infected intermediate hosts. I develop a simple theoretical model to demonstrate how different host range infection strategies are differentially selected for across a gradient of definitive host diet breadth according to the cost of generalism. I then use a parasitic helminth-host database in conjunction with a food web database to show that diet breadth of definitive hosts promotes generalist infection strategies at the intermediate host level, indicating relatively low costs of parasite generalism among helminths.

ACANTHOCEPHALUS AND NEMATODES OF FISH IN WATER BODIES OF THE SYRDARYA RIVER MIDSTREAMS

The features of the nematode and acanthocephalus fauna of Cypriniformes and Siluriformes fish, their distribution in the water bodies of the Syrdarya River midstream were studied. In total, 18 helminth species belonging to the classes Nematoda – (14 species) and Acantocephala – (4) are registered in the region. 7 species we marked for the first time for the region of under consideration.Studies were conducted of different types of water bodies of the Syrdarya river in 2016–2019 years. The collection and study of helminths of fish were carried out by known methods in helminthology and ichthyoparasitology. 1239 copies of Cypriniformes fish belonging to 15 species (Cyprinidae – 12 species, Cobitidae – 3) and 12 specimens of Siluriformes fishes from the families (Siluridae and Clariidae) were researched.According to preliminary data, 18 species of helminths belonging to the class Nematoda (14 species) and to the class Acantocephala (4 species) were found in the studied fish orders in the reservoirs of the region. Significant species diversity is characterized by the class Nematoda. We have registered 14 species belonging to 4 orders. The detachment Trichocephalida Skrjabin et Schulz, 1928 is represented by one species – Capillaria tomentosa Dujardin, 1843, which is noted in most Cypriniformes in the natural and artificial reservoirs of the northeast of Uzbekistan. The greatest species diversity is distinguished by the detachment Spirurida Chitwood, 1933. We noted 8 species. The remaining units are represented by 1–2 species – banal fish parasites. The findings of Dioctophyme renale Goeze, 1782 (larvae) in Cypriniformes in the studied region should be noted.The Acanthocephala class is represented by 4 species: Neoechinorhynchus rutileMüller, 1780, Pomphorhynchus laevis Müller, 1776, Acanthocephalus lucii Müller, 1776 and A. anguillae Müller, 1780. Nematodes are dominant. The results suggest that the most optimal conditions for the functioning of the corresponding helminth communities probably exist in the water bodies of the Syrdarya’s midstream. The abundance of a number of invertebrate groups, the inhabitants of aquatic ecosystems, which are intermediate hosts of parasites, the accumulation of waterbirds and mammals contribute to the irreversible circulation of helminths in aquatic cenoses of the study area. All this requires systematic monitoring of fish helminthiasis in order to develop preventive measures.

Severe outbreak of Centrocestus formosanus (Trematoda: Heterophyidae) in farm-raised ornamental platies Xiphophorus maculatus.

This report describes a severe outbreak of the gill fluke Centrocestus formosanus in farm-raised platies Xiphophorus maculatus in Brazil, with mortality rate approaching 95%. Typical clinical signs of infection were observed, with microscopic examinations of fresh gills revealing multiple cysts containing a once-folded metacercaria with an X-shaped excretory bladder. The 18S subunit of the metacercariae (BR1) was amplified by PCR, sequenced and analyzed by BLAST. Subsequent phylogenetic analyses revealed that the BR1 isolate was closely related to C. formosanus from Thailand. This is the first report of C. formosanus in ornamental fish in Brazil. Our observations suggest that platies are highly sensitive to this digenetic parasite. Controlling population densities of the parasite's intermediate host, the snail Melanoides tuberculata, would help to reduce outbreaks.

Helminth fauna of the screaming hairy armadillo Chaetophractus vellerosus from Argentina: the consequence of host isolation on parasite diversity

Chaetophractus vellerosus in Argentina has a north-west and central distribution. An isolated population is located in the east of the Buenos Aires province, separated from the population of central Argentina by about 500 km. We compared the component community of C. vellerosus between the main population in central Argentina and the isolated population, evaluating the impact of the host isolation on parasite diversity. Sixteen species of helminths were found, namely Ancylostoma caninum, Aspidodera fasciata, Aspidodera scoleciformis, Mazzia bialata, Pterygodermatites chaetophracti, Pterygodermatites argentinensis, Strongyloides sp., Trichohelix tuberculata, Cruzia tentaculata, Cyclobulura superinae, Delicata ransomi, Macielia jorgei, Moennigia celinae, Orihelia anticlava (Nematoda), Mathevotaenia sp. (Cestoda) and Travassosia sp. (Acanthocephala). Only the first 8 species, however, were present in both populations. Prevalences and intensities of the shared species were similar. The parasite community of the isolated population, however, was less rich and diverse than that of the main population. The poor parasite community in the isolated population could have several causes: the founding population was composed of few specimens that were only infected with the most prevalent parasite species and intermediate hosts for parasites with indirect cycles were absent. In addition, coexistence with another Chlamyphoridae would have contributed to maintaining a group of species that are usual in armadillos along their distribution.

English

Schistosomiasis is a widespread parasitic infection globally but more so in sub-Saharan Africa which accounts for about 90% of those seeking treatment globally. Fresh water aquatic snails are intermediate hosts of parasites causing the disease. Niclosamide was approved by the World Health Organization to be the main molluscicide used in the control of the snails. However, many plant species could be used as alternative molluscicides as they are environmentally friendly. This study aimed to isolate and characterize the chemicals responsible for the molluscicidal activity in the plants, Phytolacca octandra, Phytolocca dodecandra and Balanites aegyptiaca. Parts of the whole plant (berries, leaves, stems and roots) were collected, air dried to constant weight, macerated to a fine powder and extracted separately using methanol in soxhlet apparatus. After extraction, the crude extracts were isolated and purified. The melting points of the isolated compounds were determined and testing was done for alkaloids, triterpenoids, glycosides and saponins. The tests were positive for triterpenoids, glycosides and saponins but negative for alkaloids. Key words: Schistosomiasis, molluscicide, Phytolacca octandra, Phytolocca dodecandra, Balanites aegyptiaca.

Early evidence for a virus-like agent infecting the pest snail Theba pisana (Gastropoda: Pulmonata) in Southern Italy.

The Mediterranean land snail Theba pisana (Mollusca: Helicidae) is an introduced agricultural pest in many countries around the world, including Australia, Israel, USA and South Africa. In addition, this snail is an intermediate host of parasites of importance in both human and veterinary medicine. In this study, a natural population of T. pisana snails on the Domitian coast of Italy was surveyed following a mass mortality event. By light microscopy, 30% of the collected individuals showed in the calcium cells of the digestive gland the presence of hypertrophied nuclei containing eosinophilic to weakly basophilic inclusion bodies. Ultrastructural examination by transmission electron microscopy (TEM) showed nuclear inclusions constituted by a reticulated stroma into which unenveloped, roundish virus-like particles (38±4nm in diameter) were present. To the best of our knowledge this could be the first evidence for a virus-like agent infecting the gastropod T. pisana, which may open new biocontrol perspectives of the this pest worldwide.

Genetic Evidence of Contemporary Dispersal of the Intermediate Snail Host of Schistosoma japonicum: Movement of an NTD Host Is Facilitated by Land Use and Landscape Connectivity.

BackgroundWhile the dispersal of hosts and vectors—through active or passive movement—is known to facilitate the spread and re-emergence of certain infectious diseases, little is known about the movement ecology of Oncomelania spp., intermediate snail host of the parasite Schistosoma japonicum, and its consequences for the spread of schistosomiasis in East and Southeast Asia. In China, despite intense control programs aimed at preventing schistosomiasis transmission, there is evidence in recent years of re-emergence and persistence of infection in some areas, as well as an increase in the spatial extent of the snail host. A quantitative understanding of the dispersal characteristics of the intermediate host can provide new insights into the spatial dynamics of transmission, and can assist public health officials in limiting the geographic spread of infection.Methodology/Principal findingsOncomelania hupensis robertsoni snails (n = 833) were sampled from 29 sites in Sichuan, China, genotyped, and analyzed using Bayesian assignment to estimate the rate of recent snail migration across sites. Landscape connectivity between each site pair was estimated using the geographic distance distributions derived from nine environmental models: Euclidean, topography, incline, wetness, land use, watershed, stream use, streams and channels, and stream velocity. Among sites, 14.4% to 32.8% of sampled snails were identified as recent migrants, with 20 sites comprising >20% migrants. Migration rates were generally low between sites, but at 8 sites, over 10% of the overall host population originated from one proximal site. Greater landscape connectivity was significantly associated with increased odds of migration, with the minimum path distance (as opposed to median or first quartile) emerging as the strongest predictor across all environmental models. Models accounting for land use explained the largest proportion of the variance in migration rates between sites. A greater number of irrigation channels leading into a site was associated with an increase in the site’s propensity to both attract and retain snails.Conclusions/SignificanceOur findings have important implications for controlling the geographic spread of schistosomiasis in China, through improved understanding of the dispersal capacity of the parasite’s intermediate host.

A Theoretical Analysis of the Geography of Schistosomiasis in Burkina Faso Highlights the Roles of Human Mobility and Water Resources Development in Disease Transmission

We study the geography of schistosomiasis across Burkina Faso by means of a spatially explicit model of water-based disease dynamics. The model quantitatively addresses the geographic stratification of disease burden in a novel framework by explicitly accounting for drivers and controls of the disease, including spatial information on the distributions of population and infrastructure, jointly with a general description of human mobility and climatic/ecological drivers. Spatial patterns of disease are analysed by the extraction and the mapping of suitable eigenvectors of the Jacobian matrix subsuming the stability of the disease-free equilibrium. The relevance of the work lies in the novel mapping of disease burden, a byproduct of the parametrization induced by regional upscaling, by model-guided field validations and in the predictive scenarios allowed by exploiting the range of possible parameters and processes. Human mobility is found to be a primary control at regional scales both for pathogen invasion success and the overall distribution of disease burden. The effects of water resources development highlighted by systematic reviews are accounted for by the average distances of human settlements from water bodies that are habitats for the parasite’s intermediate host. Our results confirm the empirical findings about the role of water resources development on disease spread into regions previously nearly disease-free also by inspection of empirical prevalence patterns. We conclude that while the model still needs refinements based on field and epidemiological evidence, the proposed framework provides a powerful tool for large-scale public health planning and schistosomiasis management.

Cooling water of power plant creates "hot spots" for tropical fishes and parasites.

Thermally altered water bodies can function as "hot spots" where non-native species are establishing self-sustaining populations beyond their tropical and subtropical native regions. Whereas many tropical fish species have been found in these habitats, the introduction of non-native parasites often remains undetected. Here, n = 77 convict cichlids (Amatitlania nigrofasciata) were sampled by electro-fishing at two sites from a thermally altered stream in Germany and examined for parasite fauna and feeding ecology. Stomach content analysis suggests an opportunistic feeding strategy of A. nigrofasciata: while plant material dominated the diet at the warm water inlet (∼30 °C), relative contributions of insects, plants, and crustaceans were balanced 3 km downstream (∼27 °C). The most abundant non-native parasite species was the tropical nematode Camallanus cotti with P = 11.90 % and P = 80.00 % at the inlet and further downstream, respectively. Additionally, nematode larvae of Anguillicoloides crassus and one specimen of the subtropical species Bothriocephalus acheilognathi were isolated. A. nigrofasciata was also highly infected with the native parasite Acanthocephalus anguillae, which could be linked to high numbers of the parasite's intermediate host Asellus aquaticus. The aim of this study was to highlight the risk and consequences of the release and establishment of ornamental fish species for the introduction and spread of non-indigenous metazoan parasites using the convict cichlid as a model species. Furthermore, the spread of non-native parasites into adjacent fish communities needs to be addressed in the future as first evidence of Camallanus cotti in native fish species was also found.

Reduced transmission of human schistosomiasis after restoration of a native river prawn that preys on the snail intermediate host

Eliminating human parasitic disease often requires interrupting complex transmission pathways. Even when drugs to treat people are available, disease control can be difficult if the parasite can persist in nonhuman hosts. Here, we show that restoration of a natural predator of a parasite's intermediate hosts may enhance drug-based schistosomiasis control. Our study site was the Senegal River Basin, where villagers suffered a massive outbreak and persistent epidemic after the 1986 completion of the Diama Dam. The dam blocked the annual migration of native river prawns (Macrobrachium vollenhoveni) that are voracious predators of the snail intermediate hosts for schistosomiasis. We tested schistosomiasis control by reintroduced river prawns in a before-after-control-impact field experiment that tracked parasitism in snails and people at two matched villages after prawns were stocked at one village's river access point. The abundance of infected snails was 80% lower at that village, presumably because prawn predation reduced the abundance and average life span of latently infected snails. As expected from a reduction in infected snails, human schistosomiasis prevalence was 18 ± 5% lower and egg burden was 50 ± 8% lower at the prawn-stocking village compared with the control village. In a mathematical model of the system, stocking prawns, coupled with infrequent mass drug treatment, eliminates schistosomiasis from high-transmission sites. We conclude that restoring river prawns could be a novel contribution to controlling, or eliminating, schistosomiasis.

Seven species of land­snails (Gastropoda) new to the Faroe Islands

Since the investigation performed by Solhøy between 1977 and 1979 (Solhøy, 1981) no organized investigation has been performed on the distribution of land snails in the Faroes. Intense importation of building and gardening materials has since increased the risk of introducing new snail species to the islands. This article is based on material and observations from observers around the islands over several years, who have contacted the first author. This has resulted in the discovery of seven new species to the islands in addition to Solhøy’s twenty species. Four of the new species are snails, while two are slugs. An additional species was introduced for commercial purpose but does not seem to have survived well in the Faroese climate.It is difficult to predict the consequences of the settlement of these new Faroese gastropod species, but they may act as intermediate hosts for parasites, having cats and dogs as final hosts.