Search Results (107)

Urogenital schistosomiasis, caused by Schistosoma haematobium and transmitted by Bulinus snails, affects approximately 190 million individuals globally and remains a major public health concern. Effective surveillance of snail vectors is critical for disease control, but traditional identification methods are time-intensive and require specialized expertise. Environmental DNA (eDNA) detection using qPCR has emerged as a promising alternative for large-scale vector surveillance. To prevent eDNA degradation, benzalkonium chloride (BAC) has been proposed as a preservative, though its efficacy with schistosomiasis snail vectors has not been evaluated. This study tested the impact of BAC (0.01%) on the stability of Bulinus truncatus eDNA under simulated field conditions. Water samples from aquaria with varying snail densities (0.5–30 snails/L) were stored up to 42 days with BAC. eDNA detection via qPCR and multivariable linear mixed regression analysis revealed that BAC enhanced eDNA stability. eDNA was detectable up to 42 days in samples with ≥1 snail/L and up to 35 days at 0.5 snails/L. Additionally, a positive correlation between snail density and eDNA concentration was observed. These findings support the development of robust eDNA sampling protocols for field surveillance, enabling effective monitoring in remote areas and potentially distinguishing between low- and high-risk schistosomiasis transmission zones. Full article

In the freshwater snail L. stagnalis, two hours of shallow water crawling exercise are accompanied by the formation of memory, metabolic, neuronal, and behavioral changes, such as faster orientation in a novel environment. Interestingly, rest following exercise enhances serotonin and dopamine metabolism linked to the formation of memory and adaptation to novel conditions. However, the underlying transcriptional responses are not characterized. In this paper, we show that, while two hours of forced crawling exercise in L. stagnalis produce significant changes in nervous system gene expression, the subsequent rest induces a completely distinct transcriptional program. Chromatin-modifying, vesicle transport, and cell cycle genes were induced, whereas neurodevelopmental, behavioral, synaptic, and hormone response genes were preferentially repressed immediately after two hours of exercise. These changes were normalized after two hours of the subsequent rest. In turn, rest induced the expression of genes functioning in neuron differentiation and synapse structure/activity, while mitotic, translational, and protein degradation genes were repressed. Our findings are likely relevant to the physiology of exercise, rest, and learning in other species. For example, chronic voluntary exercise training in mice affects the expression of many homologous genes in the hippocampus. Moreover, in humans, homologous genes are pivotal for normal development and complex neurological functions, and their mutations are associated with behavioral, learning, and neurodevelopmental abnormalities. Full article

Glufosinate-ammonium (GLA) is a broad-spectrum herbicide widely used for weed control. However, its potential toxic effects on non-target aquatic organisms, especially in freshwater ecosystems, are of growing concern. This study investigates the toxic effects of GLA on Biomphalaria glabrata, a freshwater snail highly sensitive to environmental pollutants and commonly used as a model organism in toxicological studies. Acute toxicity tests revealed that the 96-h LC50 of GLA for adult snails was 3.77 mg/L, indicating moderate toxicity, while the LC50 for embryos was 0.01576 mg/L, indicating extremely high toxicity. Chronic exposure experiments further showed that at high concentrations (0.5 mg/L), the shell diameter and body weight of the snails not only failed to increase but also decreased, and they ceased to lay eggs. Moreover, their hepatopancreas and gonads suffered significant damage. Even at an environmentally relevant concentration of 0.05 mg/L, the body length, body weight, and reproductive capacity of the snails were inhibited, and damage to the hepatopancreas and gonads was observed. These findings provide important data for assessing the potential risks of GLA to aquatic ecosystems and offer a scientific basis for formulating environmental protection policies and optimizing herbicide usage standards. Full article

African swine fever virus (ASFV), a highly contagious and lethal virus affecting domestic and wild pigs, has raised global concerns due to its continued spread across Europe and Asia. While traditional transmission pathways involve suids and soft ticks, this study investigates the potential role of freshwater gastropods as environmental reservoirs capable of sustaining ASFV. We analysed ASFV survival in ten gastropod species after long-term co-incubation with the virus. Viral transcriptional activity, particularly of the late gene B646L and members of the multigene family MGF505, was evaluated in snail faeces up to nine weeks post-infection. Results revealed that several gastropods, including Melanoides tuberculata, Tarebia granifera, Physa fontinalis, and Pomacea bridgesii, support long-term persistence of ASFV, accompanied by increased MGF505 gene expression. Notably, the simultaneous activation of MGF5052R and MGF50511R significantly correlated with higher B646L expression and extended viral survival, suggesting a functional role in ASFV maintenance. Conversely, antiviral (AV) activity assays showed that some gastropod faeces reduced replication of the unrelated Influenza virus, hinting at induced host defences. A negative correlation was observed between AV activity and the expression of MGF505 2R/11R, implying that ASFV may suppress antiviral responses to facilitate persistence. These findings suggest that certain gastropods may serve as overlooked environmental hosts, contributing to ASFV epidemiology via long term viral shedding. Further research is needed to clarify the mechanisms underlying ASFV–host interactions and to assess the ecological and epidemiological implications of gastropods in ASFV transmission cycles. Full article

Schistosomiasis, a neglected tropical disease caused by parasitic worms of the genus Schistosoma and transmitted through freshwater snails, affects over 200 million people worldwide. Climate change, through rising temperatures, altered rainfall patterns, and extreme weather events, is influencing the distribution and transmission dynamics of schistosomiasis. This scoping review examines the impact of climate change on schistosomiasis transmission and its implications for disease control. This review aims to synthesize current knowledge on the influence of climate variables (temperature, rainfall, water bodies) on snail populations, transmission dynamics, and the shifting geographic range of schistosomiasis. It also explores the potential effects of climate adaptation policies on disease control. The review follows the Arksey and O’Malley framework and PRISMA-ScR guidelines, including studies published from 2000 to 2024. Eligible studies were selected based on empirical data on climate change, schistosomiasis transmission, and snail dynamics. A two-stage study selection process was followed: title/abstract screening and full-text review. Data were extracted on environmental factors, snail population dynamics, transmission patterns, and climate adaptation strategies. Climate change is expected to increase schistosomiasis transmission in endemic regions like Sub-Saharan Africa, Southeast Asia, and South America, while some areas, such as parts of West Africa, may see reduced risk. Emerging hotspots were identified in regions not currently endemic. Climate adaptation policies, such as improved water management and early warning systems, were found effective in reducing transmission. Integrating climate adaptation strategies into schistosomiasis control programs is critical to mitigating the disease’s spread, particularly in emerging hotspots and shifting endemic areas. Full article

This study investigated the encapsulation of snail protein hydrolysates (SPHs) using carrageenan as a microencapsulating agent at concentrations of 1%, 2%, and 3%. SPHs were prepared from the soft tissue of freshwater snails (Bellamya bengalensis) through enzymatic hydrolysis using bromelain, resulting in a degree of hydrolysis of 48.05%. The encapsulation process was carried out using the spray-drying technique. Encapsulation with 3% carrageenan enhanced the yield, encapsulation efficiency (up to 84.96%), colloidal stability (up to −33.8 mV), and thermal stability (up to 75 °C). The particle size increased as the carrageenan concentration increased, reaching 206.9 nm at 3%, and the uniform polydispersity index (0.26) indicated stable encapsulation. While encapsulation reduces solubility and antioxidant activity (DPPH, FRAP, ABTS, and HRSA), it effectively protects SPH from environmental factors such as hygroscopicity and storage stability, thus maintaining high scavenging activity. Fourier transform infrared spectroscopy confirmed that carrageenan and SPH strongly interact. Scanning electron microscopy revealed that the particles had better shapes and smooth, cohesive surfaces. This study demonstrates the effectiveness of carrageenan as an encapsulating agent for SPH, enhancing its stability and bioactivity for potential applications in the food and nutraceutical industries as a bioactive additive and offering an alternative to conventional coating materials. Full article

The aim of this paper is to describe and analyse the present Swedish fauna of freshwater snails, based on material in museum collections, the literature, records in conservation reports and in databases. The Swedish fauna comprises 50 species (42 indigenous and 8 introduced). Moreover, 31 out of 50 species belong to the superorder Hygrophila. The species’ zoogeography, ecology and conservation status are highlighted. The species distributions can roughly be classified according to four different geographical groups of patterns. 23 species have their northern limit within or close to the limes norrlandicus, an important biogeographical transition zone in Central Sweden. The history of the exploration of the fauna and groups/species with taxonomical/determination problems are discussed. The six species, which are present in the Swedish National Red List, are discussed in detail. Main threats include the exploitation of Swedish rivers and the changing of insolation in small water bodies due to vegetation alteration, eutrophication and drainage. The threat status of the species in the national Swedish list and the general European list are compared and show a high degree of agreement. Full article

Physella acuta is an invasive freshwater snail with a global distribution and a recognized role as an intermediate host for various trematodes, including Echinostoma spp. and Trichobilharzia physellae. In Portugal, P. acuta is commonly found in freshwater bodies such as Lake Alqueva, the largest artificial reservoir in Europe. The lake’s creation has altered local ecosystems, influencing freshwater snail populations and migratory bird activity, which may contribute to the dispersal of trematode parasites. While P. acuta is present in the region, its role in trematode transmission remains unclear. This study investigated P. acuta as a potential intermediate host for trematodes in Lake Alqueva. Freshwater snails were collected from 18 sites, with cercarial shedding induced under artificial light. Infected snails were found in 2 of the 18 snail populations surveyed. A sequence analysis of the amplified ITS2 rDNA region confirmed the presence of Posthodiplostomum sp., implicating, for the first time, P. acuta as an intermediate host for this parasite in Portugal. This study highlights the need for further research on P. acuta’s role in trematode transmission and potential impact on local ecosystems to assess parasitic risks to veterinary and public health. Full article

Introduction: Freshwater snails, particularly snails from the genus Biomphalaria, play a key role in the transmission of schistosomiasis, a parasitic disease prevalent in tropical regions. Schistosomiasis poses a significant public health challenge in these regions, leading to chronic illness, reduced productivity, and impaired childhood development, particularly in communities with limited access to healthcare and sanitation. Understanding the seasonal and spatial variations in snail populations and infection rates is crucial for controlling schistosomiasis, especially in areas like Southwest Ethiopia, where the disease burden is high. Methods: This study was conducted in Mizan Aman, Southwest Ethiopia, across two seasons, dry and wet. A total of 1150 snail samples were collected from 20 freshwater sites, and their species, abundance, and infection status were assessed. Environmental parameters, including temperature, pH, salinity, and conductivity, were measured to analyze their impact on snail populations. Results: Four snail species were identified, Biomphalaria pfeifferi, Biomphalaria sudanica, Lymnaea natalensis, and Bulinus globosus, with B. pfeifferi and B. sudanica being the most prevalent. Snail abundance varied by site and season, with 598 in the dry season and 552 in the wet season. Snail abundance and species composition showed significant spatial variation, with higher counts in sites like Sasin and Agu 1, while some sites had no snails. Biomphalaria snails, particularly B. pfeifferi, are the principal intermediate host for Schistosoma mansoni. The overall prevalence of Biomphalaria snails exceeded 85% in both seasons, and their average infection rate in Mizan Aman was 13.5%. This infection rate showed a strong correlation (r = 0.733, p < 0.001) with the incidence of schistosomiasis cases in the community. Seasonal variation in environmental factors, such as temperature and pH, had no significant effect on snail abundance; however, water salinity showed to be correlated with snail abundance during the dry season. Furthermore, community-led vegetation clearance at selected sites significantly reduced snail abundance. Conclusions: This study highlights the seasonal and spatial dynamics of freshwater snails, particularly Biomphalaria species, in relation to schistosomiasis transmission in Mizan Aman, Southwest Ethiopia. The findings confirm that B. pfeifferi species is the predominant intermediate host for schistosoma in this region and that schistosomiasis infection rates among snails significantly correlate with human cases in the community. While environmental factors such as temperature and pH showed no significant influence on snail abundance, water salinity had an impact during the dry season. Additionally, community-led vegetation clearance was an effective intervention in reducing snail populations. These results emphasize the need for targeted, site-specific control measures integrating ecological and community-based interventions to sustainably reduce schistosomiasis transmission. Full article

Clinostomum is a genus of parasitic trematodes found worldwide, infecting a wide range of hosts, including freshwater fishes, snails, birds and occasionally humans. In this study, clinostomid metacercariae were collected from Nile tilapia raised in fish farms in the Upper Tana River region, Kenya. The prevalence of infection was 17.2%, with metacercariae infecting the skin, gills and buccal cavity of the fish. Using light microscopy, scanning electron microscopy (SEM) and molecular methods targeting both nuclear ribosomal (ITS1, 5.8S, ITS2) and mitochondrial (COI) regions, the metacercariae were identified as C. cutaneum, C. phalacrocoracis, C. tilapiae and Euclinostomum heterostomum. The three species of Clinostomum have previously been reported to infect fish or piscivorous birds in Kenya, while this is the first report of E. heterostomum in this country. SEM analysis revealed new ultrastructural features of C. cutaneum, including an excretory pore surrounded by minute spiny papillae, an everted cirrus and dome-shaped papillae on the tegumental area around the genital pore. The cirrus lacked basal papillae, showing morphological variation between the adult and metacercarial stages. Our study, therefore, provides new insights into the phenotypic identification of flukes that may be pathogenic to fishes and humans and, therefore, of scientific and practical importance. Full article

Fungi play vital roles in ecosystems through parasitism, commensalism, and mutualism. Additionally, they are widely used in industry as bioactive compound producers and biological control agents. Biomphalaria glabrata is a freshwater snail often controlled with chemical molluscicides. However, developing effective alternatives to these chemical treatments is essential. This study evaluated the molluscicidal potential of culture supernatant from Hypocreales fungi isolated from a cave in the Brazilian Cerrado against the B. glabrata. The isolates were identified based on morphological features and ITS rDNA sequences. Fifteen filtrates of Hypocreales fungi were obtained and tested both pure and in different dilutions (10% and 50%) against newly hatched snails during 96 h of exposure. The fungal isolates were identified as belonging to the genera of Clonostachys (1), Cylindrocladiella (1), Fusarium (1), Gliocladiopsis (1), Keithomyces (1), Marquandomyces (1), Ovicillium (1), Pochonia (1), Purpureocillium (1), Sarcopodium (1), Sarocladium (1), Trichoderma (3), and Volutella (1). The results showed 93.33% (14) of the fungal filtrates induced significant mortality, indicating their molluscicidal activity, with Pochonia chlamydosporia FCCUFG 100 and Volutella aeria FCCUFG 107 causing 100% mortality in all dilutions. These results reveal the potential of Hypocreales fungi from a Brazilian Cerrado cave as a promising approach for snail control. Full article

Lake Issyk-Kul, situated in the Republic of Kyrgyzstan, is one of the largest lakes in Central Asia. Though this brackish-water basin holds only a species-poor fauna of molluscs, the number of species inhabiting Issyk-Kul and their true taxonomic position remain unsatisfactorily studied. Most nominal species of Mollusca reported from Issyk-Kul are known from empty shells only and have never been studied molecularly. This study reports the results of a revision of the genus Radix (Gastropoda:Hygrophila:Lymnaeidae) based on the integrated approach. We revealed that only two species of this genus inhabit Issyk-Kul Lake: Radix auricularia (Linnaeus, 1758) and R. obliquata (von Martens, 1864). The former species is widespread in the Palearctic and has an enormous range, whereas the latter is considered here to be endemic to Issyk-Kul Lake. All records of R. obliquata from waterbodies other than Issyk-Kul Lake are, most probably, based on misidentification. To date, no molecular evidence of the presence of R. obliquata outside Issyk-Kyl is available. The third species of Radix discussed in this paper, R. subdisjuncta (Nevill, 1878) sensu Kruglov and Starobogatov, 1993, is identical to R. obliquata and represents, most probably, an ecological morph (“race”) of the latter. The paper provides a review of Radix species recorded in other ancient tectonic lakes of the world (Baikal, Victoria, Ohrid, etc.). Though the lymnaeid snails are generally scarce in such lakes, the genus Radix represents an exception, with several species being endemics of various tectonic lakes (Issyk-Kul, Lugu, Skadar, Trichonis, and Biwa). Full article

(1) Background: Nanoplastics are emerging environmental pollutants with potential toxic effects on aquatic organisms. This study investigates the toxicity of NPs in Biomphalaria glabrata, a freshwater snail species widely used as a bioindicator species in ecotoxicology studies.; (2) Methods: We exposed three generations (F0–F2) of B. glabrata snail embryos to different sizes of polystyrene nanoparticles and assessed responses.; (3) Results: We observed severe effects on F0 to F2 B. glabrata embryos, including size-dependent (30 to 500 nm) increases in mortality rates, size and dosage-dependent (1 to 100 ppm) effects on hatching rates with concentration-dependent toxicity in the 30 nm exposure group. The F2 generation embryos appear to be most responsive to detoxification (CYP450) and pollutant metabolism (HSP70) at 48-h-post-treatment (HPT), while our developmental marker (MATN1) was highly upregulated at 96-HPT. We also report a particle-size-dependent correlation in HSP70 and CYP450 mRNA expression, as well as enhanced upregulation in the offspring of exposed snails. We also observed significant reductions in hatching rates for F2.; (4) Conclusions: These findings indicate that F2 generation embryos appear to exhibit increased stress from toxic substances inherited from their parents and grandparents (F1 and F0). This study provides valuable insights into the impact of plastic particulate pollution on multiple generations and highlights the importance of monitoring and mitigating plastic waste. Full article

Cadmium (Cd) pollution poses an important problem, but limited information is available about the toxicology effects of Cd on freshwater invertebrates. We investigated the accumulation, oxidative stress, microbial community changes, and transcriptomic alterations in apple snails (Pomacea canaliculata) under Cd stress. The snails were exposed to the 10 μg/L Cd solution for 16 days, followed by a 16-day elimination period. Our results showed that the liver accumulated the highest Cd concentration (17.41 μg/g), followed by the kidneys (8.00 μg/g) and intestine-stomach (6.68 μg/g), highlighting these tissues as primary targets for Cd accumulation. During the elimination period, Cd concentrations decreased in all tissues, with the head-foot and shell exhibiting over 30% elimination rates. Cd stress also resulted in reduced activities of superoxide dismutase (SOD), catalase (CAT), and glutathione transferase (GST) compared to the control group. Notably, even after 16 days of depuration, the enzyme activities did not return to normal levels, indicating persistent toxicological effects. Cd exposure significantly reduced the diversity of gut microbiota in P. canaliculata. Moreover, transcriptome analysis identified differentially expressed genes (DEGs) primarily associated with lysosome function, motor proteins, protein processing in the endoplasmic reticulum, drug metabolism via cytochrome P450 (CYP450), arachidonic acid metabolism, and ECM–receptor interactions. These findings suggest that Cd stress predominantly disrupts cellular transport and metabolic processes. Overall, our study provides comprehensive insights into the toxicological impact of Cd on P. canaliculata and emphasizes the importance of understanding the mechanisms underlying Cd toxicity in aquatic organisms. Full article

Urinary schistosomiasis is caused by the blood fluke Schistosoma haematobium, which is predominantly found in Africa. The freshwater snail Bulinus globosus is its main intermediate host. The species that make up the B. globosus group are genetically complex, and their taxonomic status remains controversial. Genetic variation, heterozygosity, and DNA recombination in B. globosus were examined using the mitochondrial cytochrome c oxidase subunit 1 (COI) and the intron 3 region of the arginine kinase gene (AkInt3). A total of 81 B. globosus snails were collected from three different localities in Kwale County, Kenya. Genomic diversity, heterozygosity, DNA recombination, and haplotype network were calculated using AkInt3 sequences. Low polymorphism in the COI sequence divided B. globosus into six haplotypes (C1–C6). However, AkInt3 sequencing studies showed high polymorphisms, classifying 81 B. globosus snails into 44 haplotypes (H1–H44). These haplotypes were separated into three haplogroups (I–III). AkInt3 sequence heterozygosity was also found. DNA recombination haplotypes between haplogroups were commonly found in heterozygous samples. AkInt3 sequence studies showed high levels of genetic polymorphism and heterozygosity, supporting its use as a genetic marker for elucidating the population genetics of B. globosus. Furthermore, our study showed that B. globosus populations in Kenya form a “species complex”. Full article