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Pomacea canaliculata is a highly successful invasive snail that shapes freshwater communities in both native and invaded habitats. We studied its digenean parasites from three freshwater bodies in its native distribution area in Buenos Aires Province, Argentina. An integrated approach was used to determine and describe the larval stages of digenean, including morphological, molecular, and histopathology analyses. We provide the first record of P. canaliculata as the first intermediate host of Stomylotrema vicarium (Stomylotrematidae), two species of the family Phaneropsolidae, and one species of the family Cyclocoelidae. This is also the first record of a species of the family Cyclocoelidae parasitizing snails of the genus Pomacea, with the apple snail acting as both the first and second intermediate host. The digestive gland was identified as the target organ of infection for all species. Stomylotrema vicarium and Phaneropsolidae gen. et sp. 2 alter the structure of the gonads, causing indirect parasitic castration, and, through mechanical compression, destroying also the digestive gland. Adequate knowledge of the identity and dynamics of the parasites affecting P. canaliculata in its native range and the damage they cause is key to explaining the success of this invasive species. The lack of parasite records in invaded areas supports the "enemy release" hypothesis, which could explain the apple snail's success in these environments. Parasitic castration reduces the reproductive potential of hosts, limiting the expansion and competition of invasive species, making it crucial to understand these impacts for their conservation and control., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier Inc. All rights reserved.)

Metal pollution is a major global issue in aquatic environments, affecting environmental quality and potentially altering host-parasite dynamics. This study evaluates the buffering role of a larval trematode Himasthla sp. under experimental conditions to test the effect of copper (Cu) exposure on the survival of the marine snail Echinolittorina peruviana. Snails were collected from intertidal rocky pools over a two-month period from Coloso (23°45'S, 70°28'W), northern Chile, and identified as parasitized or unparasitized. Both groups were then exposed to Cu concentrations (3 and 6 mg/L). Kaplan-Meier curves were used to determine the percentage of survival over time and the respective confidence intervals (CI). A nested ANOVA was conducted to assess whether rediae abundance per snail varied by experiment time, snail status, and Cu concentration. Snail survival was affected by both Cu-concentrations, but the effect was greater at 6 mg/L. At 3 mg/L, 57% (CI: 49.9-66.6%) of unparasitized snails were alive at 192 h, while 56% (CI: 46.6-67.4%) of parasitized snails survived at 216 h. At 6 mg/L, 42% (CI:35-51%) of unparasitized snails survived at 192 h, while 48% of parasitized snails survived at 216 h (CI:39-59%). Regardless of Cu concentration, after 240 h, all unparasitized snails had died, while 15% of parasitized snails remained alive. Dead snails harboured 125±53 rediae, while survivors had 194±73 rediae, with no significant differences between treatments. Our results show that parasitized snails survived longer than unparasitized snails, suggesting a trade-off between parasitism and host survival in polluted environments.

Iceland is an isolated, sub-Arctic, oceanic island of volcanic origin in the northern North Atlantic. With a limited faunal diversity and being the most northern point in the distributional range for some species, it is an intriguing model region to study parasite biodiversity and biogeography. Since 2006, there has been a history of intense biodiversity discoveries of freshwater trematodes (Trematoda, Digenea), thanks to the use of integrative taxonomic methods. The majority of digeneans (28 out of 41 known) were characterised with molecular genetic methods and morphological analyses, with some of their life-cycle stages and geographical distribution assessed. A surprising diversity has been discovered, comprising species of the families Allocreadiidae, Cyclocoeliidae, Diplostomidae, Echinostomatidae, Gorgoderidae, Plagiorchiidae, Notocotylidae, Schistosomatidae, and Strigeidae. Many of the recorded species complete their life cycles within Iceland, with three snail species ( Ampullaceana balthica , Gyraulus parvus , Physa acuta ) known as intermediate hosts. No trematodes endemic for Iceland were found; they appear to be generalists with wide geographical ranges dispersed mainly by migratory birds. Interestingly, fish trematodes recorded in Iceland were found in mainland Europe, indicating that they might be dispersed by anadromous fishes, by human activity, or by migratory birds carrying intermediate hosts. The trematode fauna is mainly Palaearctic, with few species recorded in North America. We highlight the ongoing need for precise species identification via integrative taxonomic methods, which is a baseline for any further ecological studies and adequate epidemiological and conservation measures. Also, there is still a need of obtaining well-preserved vouchers of adults for definite species delimitation.

Background: Asian schistosomiasis is projected to be eliminated by 2030 according to World Health Organization road map for neglected tropical diseases 2021-2030. Snail control is an important measure but has not yet been systematically evaluated at a country scale. Here, we report the findings from a nationwide survey to demonstrate the dynamics of Oncomelania and its potential role in transmission interruption of schistisomiasis in the People's Republic of China (P.R. China)., Methods: Between March 2016 and December 2017, we conducted a nationwide census on Oncomelania snail habitats in P.R. China. All historically recorded snail habitats were identified and reviewed. Information on habitat attributes, including the infestation of snails, was collected. The shape of habitats was determined using global positioning system and geographical information system technologies. The relationship between snail control and schistosomiasis elimination was established in 378 endemic counties. The comparison of accumulated snail-infested range (ASR) and the median ratio of eliminated ASR between the transmission-interrupted and endemic counties was tested by a non-parametric test (Mann-Whitney) with a significance level of 0.05., Results: Overall, 15,377.7 million m 2 of potential snail habitats with a total of 356,550 snail habitats were identified in P.R. China. The ASR amounted to 86.0% of the total area. Most of the ASR (94.9%) and habitats (68.5%) were distributed in the middle and lower reaches of the Yangtze River. Snail habitats were found up to an altitude of 2859 m above the mean sea level. By 2017, 85.1% of habitats (73.0% of the ASR) had been eliminated with almost half of them eliminated between 1965 and 1982. The elimination of snail habitats promoted transmission interruption of schistosomiasis, but showed variable patterns in different landscapes. The ratio of eliminated ASR was 99.6 and 91.4% in water network and hilly areas, respectively, while it was only 64.8% in marshland areas, particularly in Hunan and Jiangxi where the two largest freshwater lakes of P.R. China are located. Marshland habitats were seen as the most difficult for transmission interruption, which calls for additional control measures in these settings., Conclusions: Our results support recent recommendations by the World Health Organization to implement snail control and demonstrate that schistosomiasis elimination can be achieved. The nationwide, high-resolution map of Oncomelania snail habitats in P.R. China will support further efforts to eliminate schistosomiasis., Competing Interests: Declarations. Ethics approval and consent to participate: The survey was approved by the National Health Commission (Division of Endemic and Parasitic Diseases [2016] 30) and the study did not involve endangered or protected species. The collectors wore gloves and rubber boots in the field survey in order to avoid infection by S. japonicum. All collectors were listed as the co-authors or in the acknowledgements and fully aware of the research. Consent for publication: Not applicable. Competing interests: Xiao-Nong Zhou is the Editor-in-Chief of the journal Infectious Diseases of Poverty. Jürg Utzinger is the deputy Editor-in-Chief of the journal Infectious Diseases of Poverty. They are not involved in the peer-review or handling of the manuscript. The other authors have no other competing interests to disclose., (© 2025. The Author(s).)

In China, health education served as the primary method for controlling schistosomiasis and had significantly contributed to the management of schistosomiasis epidemics. In contrast, university students who lived/studied in schistosomiasis-endemic areas were often in the risk zone for schistosomiasis infection as part of their social practice and leisure activities. Thus, the risk of schistosomiasis transmission remained widespread and chronic. This study will conduct a survey and analyzed schistosomiasis awareness among university students in colleges and universities in endemic areas. The aim was to optimize intervention strategies once transmission had been interrupted. Students from two colleges and universities in the city of Gongqingcheng on Lake Poyang were selected and asked to complete a questionnaire via the online platform Questionnaire Star- The survey assessed exposure to snail-infested water, knowledge about schistosomiasis, and preferences for health education methods among students who had traveled to snail breeding areas. The survey took place from April 2 to April 4, 2024. The survey results showed that of the 4,847 respondents (49% male, 51% female), 53.8% reported exposure to snail-infested environments near their schools, and 38.4% had direct contact with snail-infested water. Of these, with those who dug for wild vegetables exposed significantly more nonendemic than endemic students to snail water (13.93% vs. 8.42%, χ2 = 16.681, P = 0.000). Awareness of schistosomiasis was low (31.08%), with limited knowledge about transmission (30.58%) and symptoms (42.91%). Of these, students from endemic areas were significantly more aware of transmission and symptoms than those from nonendemic areas (36.52% vs. 27.22%, χ2 = 7.623, P = 0.006 & 50.17% vs. 38.80%, χ2 = 9.872, P = 0.002). Preferred education methods included mobile multimedia (72.75%), brochures (68.68%), and physical promotional items (66.58%). In general, the overall awareness of schistosomiasis among university students remained low. There was a need to enhance health education in schools to improve disease prevention awareness within this population., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2025 Zhang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The effect of reservoir construction on medically important parasites is well known worldwide but lacks information in Vietnam. With 385 active hydropower plants and numerous water reservoirs, Vietnam provides an ideal setting for studying this issue. This study investigated trematode infection in snail first intermediate hosts from three hydropower reservoirs: Hoa Binh, Son La, and Thac Ba. In total, 25,299 snails representing 16 species were examined, with 959 individuals (8 species) shedding identifiable cercariae. Infection prevalence was highest in thiarid snails (5.4%-15.4%), followed by bithynid snails (2.9%-5.8%). Other snail species showed infection prevalence ranging from 0.3% to 2.9%. Infection prevalence varied significantly across regions, with the highest prevalence in Son La, followed by Hoa Binh and Thac Ba reservoirs. However, no significant differences were observed between snails collected from reservoirs versus canals and paddy fields. Morphological identification resulted in nine cercarial morphotypes, with pleurolophocercaria, xiphidiocercariae, and echinostome being the most common types, accounting for 89.2% of all cercarial infections. Echinostome cercariae were found in seven snail species, while the other cercarial morphotypes were shed by two to five species. Gabbia fuchsiana , Parafossarulus manchouricus , and Melanoides tuberculata were the most common hosts, each harboring five cercarial morphotypes, while Radix auricularia only released echinostome type. In conclusion, our findings highlight the endemic presence of trematodes in hydropower reservoirs and emphasize the need to consider the human-environment interaction around these reservoirs for a better understanding of disease transmission risks.

Background: The detection of Angiostrongylus spp. larvae in intermediate host snails is a critical epidemiological investigation, essential for the effective control of disease outbreaks. Compared to molecular biological detection methods, lung microscopy, a traditional pathogen morphological detection approach, is susceptible to oversights and exhibits relatively lower sensitivity. However, we posit that lung microscopy offers irreplaceable advantages in the context of large-scale field surveys and can serve as a vital foundation for use in conjunction with other diagnostic technologies., Methods: In this study, 348 Achatina fulica samples were examined using lung microscopy, PCR, and AcanITS1 qPCR. Statistical analysis was conducted to compare detection rates and sensitivities among these methods. DNA from a snail confirmed positive by lung microscopy was diluted and tested using PCR and AcanITS1 qPCR to assess the diagnostic efficacy of the molecular assays. Finally, we combined the highly sensitive AcanITS1 qPCR with lung microscopy for identifying Angiostrongylus spp. larvae in Achatina fulica for the first time to our knowledge and compared its diagnostic efficacy with that of individual testing methods., Results: The lung microscopy, PCR, AcanITS1 qPCR, and combined test yielded detection rates of 29.31%, 32.18%, 38.22%, and 38.51%, respectively. These differences were statistically significant (X 2  = 9.565, p < 0.05). Notably, AcanITS1 qPCR demonstrated superior sensitivity with a detection threshold of 10 pg/μl, outperforming the PCR with a threshold of 10 ng/μl. When PCR was utilized as the gold standard, the sensitivities for lung microscopy, AcanITS1 qPCR, and the combined test were determined to be 88.39%, 97.32%, and 98.21%, respectively. Correspondingly, the specificities were 98.73%, 89.83%, and 89.83%, respectively., Conclusions: This novel straregy, the combined test for the detection of Angiostrongylus spp. larvae in Achatina fulica exhibited superior positive detection rates and sensitivity compared to each of the three individual methods. We believe that this novel strategy is not only applicable to large-scale field investigations of Achatina fulica and Pomacea canaliculata but also has potential application value for monitoring the infection of these snails sold at the local farmers' markets with Angiostrongylus spp. larvae. Of course, while qPCR is exceptionally sensitive, the potential for false negatives remains a consideration. Repeated experimentation is also essential to maximize the reliability and accuracy of the outcomes., Competing Interests: Declarations. Ethics approval and consent to participate: The experiment was approved by the Ethics Review Committee of the Dali Institute of Schistosomiasis Control (Ethics Approval No. DALI Lun Zi (2022) 01). This study did not involve patients who provided informed consent. Consent for publication: The authors of this article agree to publish both the paper version and the online version at the same time. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

Bithyniids are freshwater snails that play a crucial role in the transmission of various parasitic trematodes of medical and veterinary importance. In this study, we explored the prevalence of cercarial trematode infections in bithyniid snails from Thailand and examined the species diversity of both the intermediate snail hosts and parasite larvae. A total of 688 bithyniid snails were collected from diverse natural habitats at 24 locations in 16 provinces across 5 regions of Thailand. The presence of larval trematode infections was examined using the cercarial shedding method. Both the collected snails and the emerging cercariae were identified at the species level using a combination of morphological and molecular techniques. The mitochondrial COI and 16S rDNA sequences of bithyniid snails, along with the ITS2 sequences of cercariae, were obtained via PCR amplification and sequencing. Three species of bithyniid snails were identified in this study: Bithynia funiculata, Bithynia siamensis siamensis, and Hydrobioides nassa. Among these species, B. s. siamensis exhibited the highest population density, followed by B. funiculata and H. nassa. The overall rate of cercarial infection in the bithyniid snails was relatively low, at 1.45%. H. nassa snails had the highest infection prevalence, at 11.11%, while B. s. siamensis had a prevalence of 1.39%. Only the morphological type of the xiphidiocercariae was detected. BLASTn searches in GenBank and phylogenetic trees based on xiphidiocercariae were used to classify the samples into four different families spanning two superfamilies of digenean trematodes. The genera Plagiorchis, Prosthogonimus, Paralecithodendrium, and cercaria of Renicolidae are reported for the first time in B. s. siamensis. Plagiorchis and Paralecithodendrium are significant genera of zoonotic trematodes. These findings indicate that B. s. siamensis and H. nassa can act as the first intermediate hosts for various parasitic trematodes in Thailand., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2025 Dumidae et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: The nematode Angiostrongylus cantonensis, which is endemic to Southeast Asia and adjacent Pacific Islands, has already been recorded in more than 30 countries, including Brazil and other South American nations. It is one of the principal etiological agents of the zoonosis Eosinophilic Meningitis (EoM), which has a number of different species of terrestrial gastropods that act as its intermediate hosts., Objective: The present study investigated the occurrence of the larvae of this nematode in specimens of terrestrial molluscs collected in half of the municipalities of the Brazilian State of Rio de Janeiro., Methods: The study is based on the surveillance of this nematode in the Brazilian State of Rio de Janeiro, where terrestrial snails and slugs were collected in more than half of the state's municipalities (46 in all), and examined for parasitological infections. The nematode larvae retrieved from these specimens were identified based on their morphology and cytochrome oxidase I (COI) mitochondrial DNA sequences., Findings: Angiostrongylid larvae were found in 230 (8.8%) of the 2,600 terrestrial molluscs examined, collected from 26 municipalities. Overall, 14 terrestrial gastropod species were identified, including both native and exotic taxa, and six were found to be infected naturally by A. cantonensis. The natural infection rates by Angiostrongylus in the different terrestrial molluscs species were 12.5% in Angustipes erinaceus, 9.7% in Achatina fulica, 6.8% in Bradybaena similaris, 6.3% in Sarasinula linguaeformis, 3.9% in Leptinaria unilamellata, and 4.6% in Subulina octona. A. fulica was the most frequent and extensively distributed species, with infected snails being found in 22 municipalities., Main Conclusions: The data from this first comprehensive survey of A. cantonensis in Rio de Janeiro highlights the potential epidemiological risk of human infection in this state. Mapping the spread of infected molluscs will also provide essential information for the evaluation of the risk of human infection, and should help local health authorities to provide a faster and more accurate diagnosis whenever neuroangiostrongyliasis is suspected.

Schistosomiasis is a parasitic disease affecting more than 250 million people worldwide. Schistosomes infect humans by cercariae penetrating the skin in a freshwater environment. Findings obtained more than 100 years prior showed that miracidium develops into cercaria in freshwater snails, though detailed development dynamics have not been elucidated. Although results of histological analyses of development of schistosomes in snails were presented in our previous studies, findings obtained with dynamic imaging have yet to be reported. In the present study, imaging of schistosome infection and dynamics in snails occuring within a short period was performed using fluorescent labeling agents. Labeling of S. mansoni cercariae with carboxyfluorescein succinimidyl ester (CFSE) caused no toxicity, and allowed for monitoring of schistosome dynamics in snails for up to 10 days and release of infective cercariae without fluorescence in 40 days following infection., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to declare., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The complex life cycle of the rumen fluke Calicophoron daubneyi is similar to that of the liver fluke Fasciola hepatica. Interestingly, C. daubneyi and F. hepatica share the same intermediate host, Galba truncatula. However, in contrast to its relative, experimental production of metacercariae is a major challenge for C. daubneyi, hampering a detailed analysis of its life cycle, especially in the definitive host. G. truncatula snails collected from natural habitats were bred in glass Petri dishes and fed dried organic lettuce leaves. C. daubneyi eggs were obtained from feces of naturally infected cattle and incubated until miracidia were hatching. Subsequently, these miracidia were allowed to infect snails, which were kept under specific laboratory conditions to monitor the shedding of metacercariae. In total, 177 G. truncatula snails were exposed to C. daubneyi miracidia during eleven snail infection trials. Sixty-eight of these snails survived for longer than 30 days post-infection (p.i.). From day 35 p.i., seven snails from five trials started shedding an average number of 106 metacercariae (range: 38-186) per snail. Three ewe lambs (aged 7-10 months) were inoculated orally with 150 metacercariae each. A different batch of metacercariae (obtained from three different snail trials) was used for each lamb. Another two lambs served as controls. All animals were regularly examined clinically, hematologically and coproscopically, using sedimentation techniques for the detection of trematode eggs. Low numbers of C. daubneyi eggs were detected in fecal samples of two of the three inoculated lambs on day 86 post-inoculation (yielding ≤ 2 epg), but only one lamb continued to shed eggs (up to 6 epg) until the end of the experiment (day 104 post-inoculation). None of the animals showed any abnormal clinical findings or blood parameters throughout the course of the study. Production of C. daubneyi metacercariae under laboratory conditions is reported, followed by experimental infection of the definitive host, thus completing the full life cycle of this parasite under experimental conditions. However, neither the survival rate of the snails nor the amount of metacercariae produced were comparable to previously published experiments using F. hepatica, necessitating further optimization of the laboratory protocols. Nevertheless, the results can serve as a starting point for more in-depth studies of this increasingly important trematode., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 The Authors. Published by Elsevier B.V. All rights reserved.)

Fasciolosis is a food-borne parasitic disease, caused by the large liver fluke, Fasciola. Humans acquire infection by ingesting fresh or undercooked water plants, on which infective metacercaria encyst. In spite of the rarity of the disease in Japan, we encountered four successive fasciolosis patients within a short period, who were all living in the same area. The patients were 70-82 years old, three females and the husband of one of the female patients. They started complaining of non-specific symptoms, such as fever, general fatigue, appetite loss, and abdominal pain, almost at the same time. All patients showed prominent peripheral blood eosinophilia, and the medical imaging indicated multiple hepatic lesions. No parasite eggs or worms were detected in any of the patients. Diagnosis was made serologically and they were treated with praziquantel and/or triclabendazole. No cattle or sheep were farmed in the area, but the wild sika deer, Cervus nippon, inhabited adjacent to the residential area. The intermediate host snail, Austropeplea ollula, were found near the residence of the patients, and one of the collected snails was positive for F. hepatica/gigantica hybrid type rediae. Our report should alarm the medical professionals for this rare and unfamiliar parasitic disease., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest associated with this manuscript., (Copyright © 2024 Japanese Society of Chemotherapy, Japanese Association for Infectious Diseases, and Japanese Society for Infection Prevention and Control. Published by Elsevier Ltd. All rights reserved.)

Digeneans of the family Notocotylidae differ from other digeneans in their peculiar eggs. The eggs feature a pair of long filaments extending from their poles, and their contents differ significantly from what we expect to observe in the eggs of digeneans. Instead of a ciliated miracidium larva, the notocotylid egg contains a tiny few-celled mother sporocyst. This sporocyst infects a snail host following accidental ingestion of the egg. Previous transmission electron microscope studies elucidated the structure of the sporocyst and proposed a mechanism of the injection relying on the structure called the opercular cord, but the data were insufficient to describe certain details. Here, we present ultrastructural data on the egg of Paramonostomum, clarifying the nature of the injection apparatus and providing the missing details of the in-egg mother sporocyst structure. We found the opercular cord to be part of the eggshell associated with the vitelline membrane. We also elucidated the intertwining connection between the germ cells and the sporocyst's tegument and explored 'nuage' granules present in the cytoplasm of the germ cells, providing evidence for identification of these cells as the germ ones. We discuss our findings in the context of transition of miracidia to a passive strategy of snail infection., Competing Interests: Declarations. Ethical approval: Not applicable. Animal welfare: Not applicable. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

The Northern Bolivian Altiplano is the fascioliasis endemic area where the highest prevalences and intensities in humans have been recorded. In this hyperendemic area of human fascioliasis, the disease is caused only by Fasciola hepatica and transmitted by Galba truncatula, the sole lymnaeid species present in the area. When analysing the link between global warning and the recently reported geographical spread of lymnaeid populations to out-border localities, a marked heterogeneous climatic change was found throughout the endemic area. The aim of the present study was to analyse the physiographical heterogeneity of the fascioliasis hyperendemic area in the Northern Bolivian Altiplano, in order to assess its repercussions in the implementation of a One Health action. We applied multivariate linear mixed models to analyse the influence of a number of physiographical features on the long-term variation of climate and of the risk of transmission. Despite its apparent physiographic homogeneity, the findings of this study revealed markedly heterogeneous climate characteristics throughout the endemic area. This irregular pattern is influenced by physiographical features such as altitude, inner hills, closeness to Lake Titicaca, and El Niño-Southern Oscillation. This is the broadest study ever performed in a human fascioliasis endemic area about the influence of physiography on climate. It highlights the importance of considering physiographical features, an aspect usually not considered in studies dealing with the influences of climate and climate change on human and animal fascioliasis. Moreover, it shows that an endemic area may climatically evolve differently in its various inner zones and emphasizes the need for continuous monitoring to assess whether control measures should be modified accordingly., Competing Interests: The authors declare that no competing interests exist., (Copyright: © 2025 Cuervo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Purpose: A comprehensive survey was conducted to assess the prevalence of Schistosoma japonicum infection in humans, water buffaloes, and snails in the two endemic municipalities of Talibon and Trinidad in Bohol, Philippines, which are nearing elimination., Methods and Results: Human stool and blood samples were collected from barangays with snail breeding sites, and results showed higher positivity rates using the rSjTPx-1-ELISA compared to the Kato-Katz technique. Human stool examination for showed a 0.57% positivity rate for S. japonicum in San Vicente, Trinidad, while no cases were found in San Roque, Talibon. On the other hand, 3.43% of human serum samples from San Vicente, Trinidad, and 46.20% from San Roque, Talibon tested seropositive. Similarly, water buffalo samples revealed 16.95% seropositivity in Talibon and 10% in Trinidad. Additionally, snail infection was determined microscopically from collected Oncomelania hupensis quadrasi snails in Talibon, but no schistosome parasites were detected in the crushed snail tissues., Conclusion: These findings highlight that despite progress towards elimination, schistosomiasis transmission persists in these areas, emphasizing the need for continued surveillance and targeted interventions., Competing Interests: Declarations. Ethical approval: This study was done following the ethical guidelines for the epidemiological study using human (UPM-REB 2020-761-01) and animal samples (IACUC 2021-004) provided by the University of the Philippines Manila. Consents for sample collection, participation in the study and publication of the results were obtained from human participants and owners of the water buffaloes. Conflict of interest: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Schistosomiasis is a neglected tropical disease caused by digenetic trematode from Schistosoma genus, as an etiological agent that uses snails as an intermediate host. In mollusc-trematode relationships, the miracidia attract in the aquatic media to a specific snail as an intermediate hosts, then penetrate its integument in the sporocyst form thereafter, the invasive sporocysts produce secreted/excreted products in order to survive and avoid the snails' immune system. The next larval stage is the cercariae that developed by sporocysts. Subsequently, the snail intermediate host suffers from biological, physiological, biochemical and immunological changes during the development of these parasite larval stages within their tissues. Snails and their parasites engage in an interactive innate and putative adaptive immune response that involves many immune mechanisms, such as the production of nitric oxide, lysozymes, phagocytosis, lectin formation and phenol oxidase activity. Schistosomes have developed a variety of strategies to evade and counteract these deliberate host reactions. These strategies include the secretion of many strong proteases, the use of an immune-resistant outer tegument, the molecular mimicry of host antigens, and the controlled release of certain immunomodulatory substances that influence immune cell activities. This review aims to characterize these important immune evasion mechanisms in order to comprehend the many immunological molecular determinants in the snail/schistosome interaction and to develop alternate management measures for schistosomiasis control., Competing Interests: Declaration of competing interest I am declaring that this is an original article, the manuscript or parts of it have not been published elsewhere, and that the paper is not under consideration elsewhere., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The lifecycle of schistosomes must be continuously maintained to clarify and understand this parasite in various aspects in laboratory settings. In the previous studies by other researchers, preservation of schistosome larvae or eggs was attempted by freezing with liquid nitrogen or organic chemicals, but frozen schistosomes were substantially impaired. The present study was conducted to determine whether schistosome eggs can be preserved under a non-frozen condition. The results showed that Schistosoma mansoni eggs could be maintained in phosphate-buffered saline at 4 °C, with a high level of infectivity of miracidia to freshwater snails thereafter. Furthermore, the egg hatchability was maintained for up to 12 weeks with weekly exchanges of the medium. The cercariae derived from snails infected with miracidia from preserved eggs were highly infective to mice. This simple schistosome egg preservation method allow researchers to maintain the schistosome lifecycle without freezing or other special procedures., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to declare., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Schistosomiasis is the second most important tropical disease in terms of socio-economic and public health impact among human parasitic diseases. In China, Oncomelania hupensis is the only intermediate host of Schistosoma japonicum. Despite the significant progress made, the wide distribution of O. hupensis habitats remains a major challenge to eliminating S. japonicum across China. Therefore, it is important to understand the population genetics of O. hupensis in given environment in order to guide local snail control. In this study, O. hupensis snails were collected from five snail habitats/sites (i.e., DT, JC, XG, XP and YH) in Jiaxing city in Zhejiang province of China between 2022 and 2023, and population genetic analyses were conducted based on nine microsatellites. Results showed that four O. hupensis snail populations (i.e., JC, XP and YHs) from two proximity geographically distant districts clustered together, indicating genetic exchange. Snails collected in XG and YH showed significant temporal genetic variation between two years. However, bottleneck effects were only observed in snails from two sites (JC and YH). Although the hypothesis that snail control would greatly reduce the effective population size was not completely supported by our evidence, completely eradicating snails from XG site is possible. These findings will aid in the development of more practical guidelines for local snail monitoring and control., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Infectious disease can reduce labor productivity and incomes, trapping subpopulations in a vicious cycle of ill health and poverty. Efforts to boost African farmers' agricultural production through fertilizer use can inadvertently promote the growth of aquatic vegetation that hosts disease vectors. Recent trials established that removing aquatic vegetation habitat for snail intermediate hosts reduces schistosomiasis infection rates in children, while converting the harvested vegetation into compost boosts agricultural productivity and incomes. We develop a bioeconomic model that interacts an analytical microeconomic model of agricultural households' behavior, health status, and incomes over time with a dynamic model of schistosomiasis disease ecology. We calibrate the model with field data from northern Senegal. We show analytically and via simulation that local conversion of invasive aquatic vegetation to compost changes the feedback among interlinked disease, aquatic, and agricultural systems, reducing schistosomiasis infection and increasing incomes relative to the current status quo, in which villagers rarely remove aquatic vegetation. Aquatic vegetation removal disrupts the poverty-disease trap by reducing habitat for snails that vector the infectious helminth and by promoting the production of compost that returns to agricultural soils nutrients that currently leach into surface water from on-farm fertilizer applications. The result is healthier people, more productive labor, cleaner water, more productive agriculture, and higher incomes. Our model illustrates how this ecological intervention changes the feedback between the human and natural systems, potentially freeing rural households from poverty-disease traps., Competing Interests: Competing interests statement:The authors declare no competing interest.

Schistosomiasis is a neglected tropical disease of public health significance. In view of its elimination as a public health problem by 2030, adopting a One Health approach is necessary, considering its multidimensional nature. Animal reservoirs, in particular, pose a significant threat to schistosomiasis control in Africa and beyond. In this study, we conducted a spatio-temporal survey of Schistosoma infections in small mammal communities and intermediate snail hosts in the vicinity of Lake Guiers in northern Senegal. Sampling campaigns were undertaken four times between April 2021 and August 2022 around eight villages. A total of 534 small mammals of four species, primarily Hubert's multimammate mice Mastomys huberti, were captured. Out of 498 individuals examined, only 18 rodents (17 M. huberti and 1 Arvicanthis niloticus) were infected with schistosomes. The infection rates in M. huberti varied over time (prevalence range: 2.4% to 9.3%, intensity range: 4 to 132), and space (prevalence range: 3.1% to 40%, intensity range: 2 to 110) and were higher in adult hosts captured during or just after the rainy season, a time when older individuals dominate in rodent populations. Using a multi-locus molecular approach (cox1 and ITS) on Schistosoma larvae (cercariae and miracidia) and adult worms, we identified Schistosoma mansoni as the most widespread species. We also detected Schistosoma bovis and Schistosoma haematobium in M. huberti from one locality (Temeye). Although no Schistosoma hybrids were found, the discovery of a male S. mansoni and a female S. bovis pair raises concerns about potential hybridization patterns that could occur in rodents. Finally, three snail species were found infected (25 Biomphalaria pfeifferi, 3 Bulinus truncatus and 1 Bulinus senegalensis) including with S. mansoni, S. bovis, S. haematobium and S. haematobium x S. bovis hybrids. Our findings highlight the spatial-temporal variations of Schistosoma infections in rodents and emphasize the need for fine-scale monitoring over time and space for effective One Health measures and ensuring the sustainability of schistosomiasis control efforts., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Kincaid-Smith et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: The trematode parasite Fasciola hepatica (liver fluke) can infect livestock, wild mammals, and humans, generating serious economic losses worldwide. Aquatic or amphibious snails of the Lymnaeidae family are the intermediate host of this parasite. Both snail population dynamics and parasite development are closely associated with temperature, although most field studies have recorded air temperature rather than water temperature. Our aim was to statistically model the population dynamics of lymnaeid snails and their infection by F. hepatica under natural environmental conditions in Northwest Andean Patagonia., Methods: For two years, we sampled snails monthly in four bodies of water, while registering water and air temperature hourly, and assessing F. hepatica infection in snails. Hierarchical Bayesian modeling allowed us to estimate the functional relationship between water temperature and population growth, the probability of detecting snails, and infection by F. hepatica ., Results: A total of 1,411 Galba viatrix snails were collected, identified, and analyzed for F. hepatica infection. All sites showed seasonal variation in the number of snails collected and in water temperature as well as sharp variations in snail counts between surveys adjacent in time. The hierarchical model revealed that water temperature acts, at least, at two different time scales: water temperature at the time of sampling determines snail detection probability, whereas the average water temperature between sampling dates affects lymnaeid population growth. We found maximum F. hepatica prevalences in snails of 40% (2/5 and 4/10), followed by 33% (65/197). These are the highest prevalences recorded in G. viatrix populations in Argentina to date. Our modeling evidenced that the positive effects of water temperature on infection probability increases with snail size and prevalence on the previous survey, while previous prevalence strongly enhances the effects of snail size., Conclusions: Our results underscore the high temporal and spatial variability in the population of snails and the prevalence of F. hepatica , as well as the major impact temperature has on detecting snails. Our models provide quantifications of the effects of water temperature on the population growth of G. viatrix , its detection, and infection under natural field conditions. These are crucial steps towards generating mechanistic models of F. hepatica transmission that would facilitate the design and simulation of potential interventions based on treatments and on environmental and livestock management, taking into account the specific characteristics of each region., Competing Interests: The authors declare that they have no competing interests., (© 2024 Soler et al.)

Background: Schistosomiasis is an important snail-borne parasitic disease whose transmission is exacerbated by water resource management activities. In Rwanda, meeting the growing population's demand for food has led to wetlands reclamation for cultivation and increased agrochemical enrichment for crop production. However, the ecological consequences of agrochemical enrichment on schistosomiasis transmission remain unexplored., Methods: A malacological survey was conducted in 71 villages selected from 15 schistosomiasis endemic districts. Snail sampling was done in wetlands used for agriculture, along lake Kivu and at constructed multipurpose water dams. Water physico-chemical parameters were collected at all snail sampling sites. Analysis of collected data was performed using Xgboost (gain) and Random Forest (mean decrease in accuracy), machine learning techniques, to construct models that evaluate and categorize the importance of all physico-chemical properties on the presence and abundance of intermediate host snails (IHS)., Results: Different sets of parameters were relevant for the presence and abundance of Biomphalaria spp. and/or Bulinus spp. snails. Electrical conductivity, elevation, magnesium and lead content were deemed to shape the presence and abundance of Bulinus spp. snails. The impact of phosphate ion concentration, ammonia ions, total nitrogen and total organic carbon levels mirrored their importance towards the presence and abundance of Biomphalaria spp. Factors such as pH, electric conductivity, total nitrogen content and total organic carbon influenced the coexistence of both species. Our study highlights the value of integrating a wide range of predictor variables, enabling effective variable selection to uncover important predictors of snail distribution., Conclusion: The results suggest that agrochemical compounds can enhance the abundance of IHS leading to an increased risk of Schistosoma transmission. Snail surveillance could therefore be integrated into agricultural expansion projects in our match towards schistosomiasis elimination. Recognizing the impact of agrochemicals on IHS is crucial for minimizing schistosomiasis transmission among those working in wetlands while meeting the growing need for food., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Kagabo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Malaysian fire snails (Platymma tweediei) , face threats to their environment, including habitat destruction and the illegal wildlife trade. Captive breeding projects are likely to play a role in the survival of this species; however, mortality in captive populations potentially presents a significant challenge. This paper presents the results of histopathologic examination of tissues from 10 P. tweediei casualties in a captive population at Chester Zoo. In October 2022, a captive breeding program was established with 20 wild-born P. tweediei . All adult founder animals died by July 2023, of which 10 were submitted for necropsy and histopathology of organs. Significant histologic abnormalities were present in all cases, primarily affecting the lung, integument, and heart. Histological analyses indicated a pneumonia-like condition was prevalent in all cases, suggesting potential environmental factors contributed to respiratory infections. A variety of possible etiologic or secondary infectious agents were present in sections including bacteria, fungi, and trematodes. There were some challenges in interpreting the histologic changes, emphasizing the need for more reference material and studies on the normal histologic anatomy of terrestrial gastropods. The findings underline the importance of understanding mortality events in captive populations to improve husbandry and environmental management. Additionally, the study recommends the submission of fresh specimens for necropsy to enhance diagnostic capabilities, such as bacterial culture, and suggests targeted sampling strategies for future research on captive snail species.

Completing parts of trematode life cycles in the laboratory is a useful way to obtain experimentally infected hosts and identify how specific aspects of parasitism influence host ecology and behavior. However, a lack of knowledge about host specificity and other factors that influence prevalence can hamper those efforts. Echinostoma trivolvis lineage c is a genetically distinct member of the E. trivolvis species complex that is known only from DNA sequences from adult and larval stages recovered from naturally infected muskrats (Ondatra zibethicus) and the marsh pondsnail (Ladislavella elodes), respectively. We determined the effect of host species/morphotype, host size, and miracidial dose on the infection success in potential first intermediate hosts. In the laboratory, we exposed 2 freshwater snail species (L. elodes and Planorbella duryi) and a morphological variant of L. elodes (formerly known as Stagnicola reflexa) to 2 miracidia to determine first intermediate host use. Among these 3 snail groups, we also tested the effect of host size on infection success with 3 size classes (1-5 mm, 5-10 mm, and 10-15 mm). Within 1 host species, L. elodes, we compared the effect of 2 doses (2 and 5 miracidia) and 3 size classes on infection success. At a dose of 2 miracidia, rediae and cercariae developed within 1 host species, L. elodes, as well as the S. reflexa morphotype, although infection success varied according to host size. At a dose of 5 miracidia, infection success increased in small and medium-size L. elodes relative to the low dose group. Our results confirm the first intermediate host species observed in nature but indicate that prevalence is influenced by host species morphotype, host size, and parasite dose. To obtain more infected snails, our experiments suggest exposing small and medium-size L. elodes snails to 5 miracidia. This research encourages further use of E. trivolvis lineage c in the laboratory to explore aspects of host-parasite interactions such as parasite-modified behavior., (© American Society of Parasitologists 2024.)

Freshwater snails act as obligate intermediate hosts for trematode parasites that cause trematodiases threatening public and veterinary health, and biodiversity conservation. While interest in snail control for trematodiases has re-emerged, their ecology remains poorly understood. We examined the relationship between ecosystem indicators - such as environmental variables, macroinvertebrates, macrophytes, and land use - and their correlation with snail abundance, diversity, and infection prevalence in 19 man-made ponds in eastern Zimbabwe. In total, 926 freshwater snails from 10 species were collected, with 547 individuals belonging to five schistosome-competent species: Bulinus tropicus, Bulinus truncatus, Bulinus globosus, Bulinus forskalii, and Biomphalaria pfeifferi. The remaining 379 snails comprised Radix natalensis, Gyraulus sp., and the exotic invasive species Melanoides tuberculata, Pseudosuccinea columella, and Physella acuta. Six cercarial types - mammalian schistosomes, avian schistosomes, longifurcate pharyngeates, echinostomes, amphistomes, and xiphidiocercariae - were isolated from 104 out of 926 snails (11.2 %). PCR revealed a significantly higher infection rate, with 70.2 % of snails testing positive for trematodes. Snail taxon diversity and infection rate significantly varied across land use types, with the lowest values observed in the commercial tobacco farm section, highlighting the potential adverse effects of agriculture on biodiversity. Ponds with extensive Lagarosiphon major (oxygen weed) coverage appeared to facilitate the presence and abundance of P. acuta and P. columella. Schistosome-competent snails such as B. truncatus and B. tropicus seemed to favor shallow water depths and more eutrophic sites characterized by high levels of nitrates, phytoplankton biomass, turbidity, and phycocyanin. These ponds were predominantly associated with the emergent macrophyte Cladium mariscus, revealing a potential association with important intermediate snail hosts. In conclusion, our study emphasizes the complex interplay among environmental factors, macrophyte composition, land use, and the abundance, diversity, and infection prevalence of freshwater snails, offering insights into potential strategies for targeted snail control and disease management in man-made waterbodies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In Japan, trematodes of the family Ochetosomatidae are not naturally distributed. However, the introduced ochetosomatid Ochetosoma kansense (Crow, 1913) has been reported from the oral cavity of native snakes in western Japan since 2010s. In this study, trematodes were isolated from the oral cavities of the native Japanese snakes, Elaphe quadrivirgata (Boie, 1826), E. climacophora (Boie, 1826), and Rhabdophis tigrinus (Boie, 1826), in the central Kanto region of eastern Japan. Morphological and molecular analyses of the isolated trematodes revealed that all trematodes were identifiable to a newly introduced ochetosomatid species to Japan, O. elongatum (Pratt, 1903), which originated from North America; Lechriorchis tygarti Talbot, 1933 was synonymized with O. elongatum based on identical molecular data and morphological similarity. To identify first intermediate hosts of O. elongatum, seven freshwater snail species were examined in eastern Japan. Molecular analysis was used to identify O. elongatum sporocysts in the freshwater snail Physella acuta (Draparnaud, 1805), which also originated from North America. The other six species did not host O. elongatum, suggesting that Ph. acuta is the only first intermediate host of O. elongatum in Japan. Although O. elongatum has been detected in Japan, its invasion route and period of introduction are unclear. Frequent imports of freshwater snails and wild snakes from North America, after the 1990s and 2005, respectively, presumably introduced O. elongatum in Japan., Competing Interests: Declaration of competing interest None., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Snails of the genus Bithynia, whose primary habitat is slow-flowing ponds and ditches, serve as the first intermediate hosts of liver fluke. Currently, approximately 200 million individuals worldwide are at risk of liver fluke infection, yet questions still persist regarding the taxonomic identification of Bithynia genus, a crucial player in the transmission of this disease. Accurate taxonomic classification of the Bithynia genus could significantly enhance current understanding of the disease's transmission mechanisms. In this article we comprehensively review the extensive research conducted on Bithynia genus, spanning past inquiries up to the latest findings. The primary emphasis is placed on exploring the taxonomic identification of this genus within various technological settings. We then present a consolidated analysis of the morphological taxonomic identification methods, highlighting their strengths and limitations. We also introduce a novel perspective on the future direction of identification and classification efforts for the members of this genus, emphasizing the crucial role Bithynia plays in the epidemiological cycle of liver fluke transmission. We conclude by urging researchers to prioritize the significance of the members of this genus in the epidemiological cycle of liver fluke transmission and in control measures for disease dissemination, within the context of the vector organisms., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background: The World Health Organization (WHO) has set the goal of eliminating schistosomiasis as a public health problem globally by 2030 and to interrupt transmission in selected areas. Chemical snail control is one important measure to reduce transmission and achieve local elimination. We aimed to assess the impact of several rounds of chemical snail control on the presence and number of the Schistosoma haematobium intermediate snail host (Bulinus spp.) in water bodies (WBs) on Pemba Island, Tanzania, a setting targeted for elimination of urogenital schistosomiasis., Methods: During the three annual intervention periods of the SchistoBreak study implemented in the north of Pemba from 2020 to 2024, malacological surveys were conducted up to four times per period in WBs of hotspot implementation units (IUs). Present freshwater snail species, vegetation, and WB characteristics were recorded. If Bulinus were found, the snails were inspected for Schistosoma infection and snail control with niclosamide was conducted., Results: Across the three intervention periods, a total of 112 WBs were identified in 8 hotspots IUs. The spatial distribution of WBs with Bulinus per IU was heterogeneous, ranging from 0.0% (0/15) of WBs infested in one IU in 2022 to 80.0% (8/10) of WBs infested in one IU in 2021. Bulinus presence was significantly associated with lower pH values in WBs (odds ratio: 0.2, 95% confidence interval 0.1-0.4). A total of 0.2% (6/2360) of collected Bulinus were shedding Schistosoma cercariae. Following snail control, the number of Bulinus decreased or remained absent in 56.7% (38/67) of visits at WBs when compared with the previous visit in 2021, 54.9% (28/51) in 2022, and 33.3% (32/96) in 2023. In a total of 43.1% (22/55) of initially infested WBs, no Bulinus were found in the survey round conducted a few weeks after the first application of niclosamide. However, 25.4% (14/55) of WBs showed a pattern of recurring Bulinus presence., Conclusions: The distribution of WBs containing Bulinus was very heterogeneous. The percentage of Bulinus with patent Schistosoma infection in our study area was extremely low. Repeated niclosamide application reduced the number of Bulinus in WBs, but snails often recurred after one or multiple treatments. While chemical mollusciciding can reduce snail numbers, to fully break the S. haematobium transmission cycle, timely diagnosis and treatment of infected humans, access to clean water, sanitation, and health communication remain of prime importance., Trial Registration: ISRCTN, ISRCTN91431493. Registered 11 February. 2020, https://www.isrctn.com/ISRCTN91431493., Competing Interests: Declarations. Ethics approval and consent to participate: The SchistoBreak study protocol was waived by the ethics committee in Switzerland (Ethikkommission Nordwest- und Zentralschweiz; EKNZ) on 23 October 2019 (Req-2019-00951). It subsequently received annual ethical approval by the Zanzibar Health Research Institute (ZAHRI). The first approval was given on 13 December 2019 (ZAHREC/03/PR/December/2019/12), and the latest approval was given on 31 March 2023 (ZAHREC/04/AMEND/MARCH/2023/03). The study was registered prospectively at ISRCTN (ISCRCTN91431493). At the beginning of each annual intervention period, the leaders of the IUs (shehas) were invited to meetings at the PHL-IdC. In the meetings, updates on the SchistoBreak study results were presented. Moreover, challenges of surveys and interventions were discussed and concerns addressed, and the shehas were invited to support the project by announcing the forthcoming activities in their communities. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Objective: Oncomelania hupensis robertsoni is the only intermediate host of Schistosoma japonicum in hilly regions of south-west China, which plays a key role during the transmission of Schistosomiasis. This study aimed to sequence the complete mitochondrial genome of Oncomelania hupensis robertsoni and analyze genetic differentiation of Oncomelania hupensis robertsoni., Methods: Samples were from 13 villages in Yunnan Province of China, with 30 Oncomelania hupensis snails per village, and the complete mitochondrial genome was sequenced. A comprehensive analysis of the genetic differentiation of Oncomelania hupensis robertsoni was conducted by constructing phylogenetic trees, calculating genetic distances, and analyzing identity., Results: A total of 26 complete mitochondrial sequences were determined. The length of genome ranged from 15,181 to 15,187 bp, and the base composition of the genome was A+T (67.5%) and G+C content (32.5%). This genome encoded 37 genes, including 13 protein-coding genes, 2 rRNA genes, and 22 tRNA genes. The phylogenetic trees and identity analysis confirmed that Oncomelania hupensis robertsoni was subdivided into Oncomelania hupensis robertsoni Yunnan strain and Sichuan strain, with a genetic distance of 0.0834. Oncomelania hupensis robertsoni Yunnan strain was further subdivided into two sub-branches, corresponding to "Yunnan North" and "Yunnan South", with a genetic distance of 0.0216, and the samples exhibited over 97% identity., Conclusion: Oncomelania hupensis robertsoni is subdivided into Oncomelania hupensis robertsoni Yunnan strain and Sichuan strain. Oncomelania hupensis robertsoni Yunnan strain exhibits a higher level of genetic identity and clear north-south differentiation. This work reported the first mitochondrial genome of Oncomelania hupensis robertsoni Yunnan strain, which could be used as an important reference genome for Oncomelania hupensis, and also provide the important information for explaining the distribution pattern of Oncomelania hupensis robertsoni and control of Schistosoma japonicum., Competing Interests: The authors declare that no competing interests exist., (Copyright: © 2024 Song et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Schistosoma japonicum, the causative agent of schistosomiasis, heavily relies on its single intermediate host, the Oncomelania hupensis snail, for its life cycle. Controlling these snails effectively plays a pivotal role in curbing the transmission and prevalence of this disease. While prior research has extensively investigated the impact of environmental factors such as temperature and vegetation on snail survival, growth, and reproduction, the contribution of water physicochemical properties has been notably underexplored. This study presents laboratory experiments designed to comprehensively explore the influence of water physicochemical properties on snail survival, offering valuable insights into environmental factors for more precise predictions of snail distribution., Methods: We meticulously conducted laboratory snail survival experiments using water from different sources (river water/tap water), and employed a statistical approach amalgamating principal component analysis with Cox regression to preliminarily investigate the effects of different water physicochemical properties on the survival of snails., Results: Our analysis indicates that after a 6-month laboratory snail survival experiment, the survival rate in the tap water group was significantly higher than that in the river water group for infected snails (χ 2  = 7.74, p = 0.005), while the difference in survival rates for non-infected snails was not statistically significant (χ 2  = 0.61, p = 0.434). The Principal Component-Cox regression analysis revealed that in the infected snail group, total phosphorus, pH value, five-day biochemical oxygen demand, conductivity, and nitrite were protective factors for snail survival, while phosphate and total nitrogen were risk factors. In the non-infected snail group, total phosphorus, pH value, five-day biochemical oxygen demand, conductivity, and nitrite were protective factors for snail survival, and total nitrogen, ammonia nitrogen, phosphate, and nitrate were risk factors., Conclusions: This study underscores the substantial impact of water quality's physicochemical properties on snail survival. The effects of water quality on snails are complex, and maintaining an appropriate level of organic matter content and controlling the pH value at a weak alkalescency level prove beneficial for snail survival. These findings hold significant promise for advancing our understanding of snail-borne diseases and optimizing control strategies., Competing Interests: Declarations Ethics approval and consent to participate Not applicable. Consent for publication Not applicable. Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Oncomelania hupensis snail control by chemical treatment is an important approach for control and elimination of snails, and an appropriate apparatus for spraying chemicals is an important support to molluscicidal effects. Nevertheless, the research and evaluation of molluscicidal apparatuses have not been paid high attention in the schistosomiasis control programme for a long period of time. Currently, agricultural plant-protective apparatuses have been widely used for chemical treatment. This comment provides a short overview of the application of drones in O. hupensis snail control by chemical treatment, and proposes suggestions for solving the problems of use of drones in O. hupensis snail control by chemical treatment in China.

Objective: To investigate the Oncomelania hupensis snails spread and its spatio-temporal clustering characteristics in Suzhou City, Jiangsu Province from 2016 to 2023, so as to provide insights into precision control of O. hupensis snails in the City., Methods: O. hupensis snail surveillance data in Suzhou City from 2016 to 2023 were collected, and the areas of O. hupensis snail spread and areas of emerging and re-emerging snail habitats were retrieved. The spatial distribution characteristics and clustering types and locations of environments with O. hupensis snail spread were investigated using global and local spatial auto correlation analyses with the software ArcGIS 10.7, and the clustering and cluster areas of O. hupensis snail spread were identified in Suzhou City using spatio-temporal scans with the software SaTScan 10.0.2., Results: O. hupensis snail spread covered an area of 677 171 m 2 in Suzhou City from 2016 to 2023, including 376 230 m 2 emerging snail habitats and 300 941 m 2 re-emerging snail habitats. Global spatial autocorrelation analysis showed overall clustering of O. hupensis snail spread in Suzhou City from 2016 to 2023 (Moran's I = 0.066, P = 0.007), and there were spatial clustering of areas with O. hupensis snail spread in 2019 (Moran's I = 0.086, P = 0.001) and 2021 (Moran's I = 0.045, P = 0.003). Local spatial autocorrelation analysis showed clusters of O. hupensis snail spread in Suzhou City from 2016 to 2023, with high-high clusters in Guangfu Township and Dongzhu Street, and the high-high clusters of O. hupensis snail spread were mainly distributed in southwestern Suzhou City. Spatio-temporal scans identified two clusters of areas with O. hupensis snail spread and areas of re-emerging snail habitats in Suzhou City from 2016 to 2023, with large clustering areas found in Guangfu Township, Dongzhu Street, Tong'an Township and Wangting Township [relative risk ( RR ) = 22.34, log likelihood ratio ( LLR ) = 163 295.32, P < 0.001] and small clustering areas in Xukou Township, Mudu Township and Xiangshan Street ( RR = 2.73, LLR = 921.92, P < 0.001)., Conclusions: There was spatial clustering of O. hupensis snail spread in Suzhou City from 2016 to 2023. Improved quality of O. hupensis snail control and intensified management of environments at a high risk of O. hupensis snail spread are recommended in Suzhou City.

Metal pollution is a worldwide problem and one of the greatest threats to ecosystem integrity due to its toxicity, persistence, and bioaccumulation in biological systems. Anthropogenic pollution impacts marine organisms and host-parasite dynamics, with the northern Chilean coast experiencing elevated copper levels in marine waters and sediments due to mining activities. In this study, we assessed the effects of exposure to copper concentrations at low and high-water temperatures on the survival and longevity of the marine parasite Himasthla sp. cercariae (Trematoda: Digenea) using the snail Echinolittorina peruviana as its first intermediate host. Snails were collected from intertidal rocky pools in northern Chile (23°S). To assess parasite survival and longevity, cercariae were collected from a pool of infected snails, and their mortality was recorded every 6 hours until all cercariae were dead. In a preliminary experiment conducted at 19°C, cercariae were exposed to different copper concentrations (0.2, 1.5, 3.0, and 6.0 mg/L) for 78 hours. Cercariae showed tolerance to copper. However, at the higher copper concentration (6 mg/L), survival was negatively impacted (50%) at 54 hours. In contrast, at the lower concentration (0.2 mg/L) and in the control group, cercariae sustained a 73-90% survival rate even after 54 hours. Based on these findings, we conducted subsequent experiments involving two copper treatments (0.2 and 3.0 mg/L) and two temperatures (14 and 22°C). Survival and longevity were significantly higher at lower temperature and copper concentration (14°C and 0.2 mg/L). Conversely, at higher temperature and copper concentration (22°C and 3 mg/L), survival and longevity decreased to only 66 hours. Our results show that Himasthla sp. cercariae tolerated most copper concentrations, with vulnerability observed primarily in high water temperatures, indicating an adverse effect on cercariae performance. This study contributes valuable insights into how parasites respond to environmental pollution, in marine ecosystems influenced by anthropogenic activities., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Leiva et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Schistosomiasis, a chronic parasitic disease, remains a public health issue in tropical and subtropical regions, especially in low and moderate-income countries lacking assured access to safe water and proper sanitation. A national prevalence survey carried out by the Brazilian Ministry of Health from 2011 to 2015 found a decrease in human infection rates to 1%, with 19 out of 26 states still classified as endemic areas. There is a risk of schistosomiasis reemerging as a public health concern in low-endemic regions. This study proposes an integrated landscape-based approach to aid surveillance and control strategies for schistosomiasis in low-endemic areas., Methodology/principal Findings: In the Middle Paranapanema river basin, specific landscapes linked to schistosomiasis were identified using a comprehensive methodology. This approach merged remote sensing, environmental, socioeconomic, epidemiological, and malacological data. A team of experts identified ten distinct landscape categories associated with varying levels of schistosomiasis transmission potential. These categories were used to train a supervised classification machine learning algorithm, resulting in a 92.5% overall accuracy and a 6.5% classification error. Evaluation revealed that 74.6% of collected snails from water collections in five key municipalities within the basin belonged to landscape types with higher potential for S. mansoni infection. Landscape connectivity metrics were also analysed., Conclusions/significance: This study highlights the role of integrated landscape-based analyses in informing strategies for eliminating schistosomiasis. The methodology has produced new schistosomiasis risk maps covering the entire basin. The region's low endemicity can be partly explained by the limited connectivity among grouped landscape-units more prone to triggering schistosomiasis transmission. Nevertheless, changes in social, economic, and environmental landscapes, especially those linked to the rising pace of incomplete urbanization processes in the region, have the potential to increase risk of schistosomiasis transmission. This study will help target interventions to bring the region closer to schistosomiasis elimination., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Ferreira da Silva et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Turtle acanthocephalans in the genus Neoechinorhynchus have complex life cycles and are thought to involve an ostracod intermediate host and a turtle definitive host. For Neoechinorhynchus emydis, an additional snail paratenic host is part of its life cycle. However, how snails become infected and whether other species of Neoechinorhynchus can be found in snails remains unclear. This study was conducted to understand the survival, development, and host use of 4 species of turtle acanthocephalans (Neoechinorhynchus chrysemydis, N. emydis, Neoechinorhynchus emyditoides, and Neoechinorhynchus pseudemydis) in their intermediate, paratenic, and definitive hosts. Using eggs recovered from adult acanthocephalans from naturally infected turtle hosts in Oklahoma, experimental infections were conducted in 2 species of ostracods and 1 species of freshwater snail. Ionomes also were generated for these acanthocephalans and their turtle definitive hosts to better understand resource competition. Upon ingestion by ostracods, eggs of all 4 species of acanthocephalans hatched in both ostracod species. However, no further acanthocephalan development occurred in Cypridopsis sp. ostracods, whereas all 4 acanthocephalan species grew and developed into infective juveniles over 28-32 days in Physocypria sp. ostracods. Of the 4 species of acanthocephalans, N. emydis grew faster early in ostracods and was the only species to survive and establish in snail hosts. This finding was supported by the observation of proboscis remnants in the feces of snails that ingested ostracods infected with N. chrysemydis, N. emyditoides, and N. pseudemydis. In contrast, when snails were exposed to eggs of all 4 acanthocephalan species, eggs were passed in the feces, resulting in no infections. The overall ionomic composition of adult acanthocephalans and their turtle hosts suggested that the hosts and parasites share host resources. However, specific elemental differences indicated that turtle acanthocephalans can accumulate heavy metals at concentrations higher than those in their hosts. Results of this study support previous field observations and hypotheses that (1) Physocypria sp. ostracods serve as intermediate hosts for N. chrysemydis, N. emydis, N. emyditoides, and N. pseudemydis; (2) N. emydis uses snail paratenic hosts, but snails are a non-viable route of transmission to turtles for N. chrysemydis, N. emyditoides, and N. pseudemydis; and (3) as adults, these 4 acanthocephalan species utilize their turtle definitive hosts similarly in terms of ionomic composition. This work challenges the traditional view of the acanthocephalan life cycle and sets the stage for future hypotheses., (© American Society of Parasitologists 2024.)

This study aimed to investigate the infection status and species diversity of trematode cercariae in freshwater snails from canal networks in the Bangkok Metropolitan Region (BMR), Thailand. The snails were collected from 35 sites during 2 cycles of the wet (July-October) and dry (November-June) seasons in 2018-2019. A total of 29,420 snails representing 24 species/subspecies were examined for cercarial infection using shedding and crushing techniques. We found that 1,275 snails from 12 species/subspecies were infected, resulting in an overall prevalence of 4.3%. Infections were significantly higher (p&lt;0.001) during the wet season (5.9%; 970/16,473) than during the dry season (2.4%; 305/12,947). Morphological identification revealed 37 distinct types within 15 morphotypes, with the armatae morphotype showing the highest infection rate (1.8%) and the greatest cercarial diversity (8 distinct types). This study highlights the health risk posed by the Bithynia siamensis siamensis, which was the second most prevalent (8.5%) and hosted the greatest cercarial diversity (11 morphotypes, 15 distinct types). This subspecies also displayed a wide distribution range (31 localities) with a generally high occurrence frequency in the BMR. This study firstly documents a gymnophallid digenean as a freshwater digenean, presenting evidence of a dichotoma cercarial morphotype from 4 species/subspecies (Filopaludina martensi martensi, F. sumatrensis polygramma, B. siamensis siamensis, and Wattebledia siamensis) with a low infection range (0.1-0.4%). A staggering diversity of cercariae was observed in the BMR canal networks with seasonal fluctuations. The B. siamensis siamensis displayed notable epidemiological importance in the BMR flowing-water networks. This study provides quantitative and qualitative morphological descriptions and measurement guidelines for the dichotoma cercaria in Thailand.

The literature about mollusc-parasite interactions is focused on species affecting human health, such as trematodes on freshwater snails as intermediate hosts. Far less attention has been paid to parasite-snail interactions in terrestrial habitats. Here we present the first observation of a sciomyzid larva of Limnia unguicornis, parasitizing a vulnerable, tiny air-breading snail, Vertigo moulinsiana (strictly protected by Polish law). Sciomyzids are almost exclusively malacophagous but their biology and ecology are understudied. Thus, we have reviewed the available information on Limnia species and discussed the results of our research., (© 2024. The Author(s).)

Objective: To investigate the trends in areas of Oncomelania hupensis snail habitats in Anhui Province from 2004 to 2023, so as to provide insights into facilitating the progress of schistosomiasis elimination in the province., Methods: Areas of O. hupensis snail habitats in Anhui Province from 2004 to 2023 were collected, and the trends in and mutations of O. hupensis snail habitats in Anhui Province, and the trends in O. hupensis snail habitats in different types of schistosomiasis-endemic foci and in different cities of Anhui Province from 2004 to 2023 were analyzed using Mann-Kendall test., Results: The areas of O. hupensis snail habitats reduced by 12.62% in Anhui Province in 2023 relative to in 2004. Mann-Kendall trend test showed that the areas of O. hupensis snail habitats appeared a tendency towards a decline in Anhui Province from 2004 to 2023 ( Z = -3.926, P < 0.001, β = -215.66), with an annual average reduction of 215.66 hm 2 . Mann-Kendall mutation test showed that the areas of O. hupensis snail habitats appeared a tendency towards a decline in Anhui Province since 2015 (| Z | > U 0.05 , P < 0.05). The areas of O. hupensis snail habitats appeared a tendency towards a decline in marshland and lake regions ( Z = -4.899, P < 0.001, β = -260.13), and a tendency towards a rise in hilly regions of Anhui Province from 2004 to 2023 ( Z = 2.758, P < 0.01, β = 44.55). Among 9 cities endemic for schistosomiasis in Anhui Province, the areas of O. hupensis snail habitats appeared a tendency towards a decline in 5 cities of Ma'anshan, Tongling, Anqing, Huangshan and Chizhou ( Z = -4.056 to -2.109, all P values < 0.05, β = -92.12 to -0.45). The average constituent ratios of areas of O. hupensis snail habitats were 88.19% and 11.81% in marshland and lake regions and hilly regions of Anhui Province from 2004 to 2023, respectively, and the ratio of areas of O. hupensis snail habitats in marshland and lake regions to areas of snail habitats in hilly regions reduced from 9.23∶1 in 2004 to 5.74∶1 in 2023 in Anhui Province, with the ratio appearing a tendency towards a decline ( Z = -4.477, P < 0.001, β = -0.16)., Conclusions: The areas of O. hupensis snail habitats appeared a tendency towards a decline in Anhui Province from 2004 to 2023, with a reduction in areas of O. hupensis snail habitats in marshland and lake regions and a rise in hilly regions. Targeted O. hupensis snail control interventions are required tailored to real snail status.

Several aquatic ecosystems present favorable conditions for the establishment of freshwater gastropod populations in Maranhão (Brazil). However, research on these snails in this Brazilian state is more focused on Baixada Maranhense, an endemic area for schistosomiasis in Maranhão. Considering the need to expand information on the occurrence of limnic gastropods in Maranhão, a qualitative study was carried out in the Microregion of Lençóis Maranhenses. The capture of freshwater snails was carried out between June 2016 and November 2019. Were obtained 3,244 specimens of freshwater gastropods: 2,372 specimens of Biomphalaria straminea (Dunker, 1848); 17 specimens of Biomphalaria schrammi (Crosse, 1864); 19 specimens of Drepanotrema lucidum (Pfeiffer, 1939); 115 specimens of (Hydrobiidae; Rissooidea); 24 specimens of Physa marmorata Guilding, 1828; 73 specimens of Pomacea maculata (Perry, 1810); 613 specimens of Pomacea sp. (Perry, 1810). Were also found 11 shells of Biomphalaria glabrata (Say, 1818). The greatest richness of snails was observed in Tutóia. The most abundant species during the study was B. straminea (73,45%). Pomacea sp. was the most representative species with constant frequency (57,15%) in the Lençóis Maranhenses Microregion, present in lentic and lotic ecosystems. The forecast maps indicate the possibility of occurrence and establishment of freshwater gastropods species throughout the investigated region. The presence of gastropods that are hosts of parasites represents a risk to human health, especially in the Lençóis Maranhenses area, which is one of Brazil's tourist destinations. Studies on the occurrence and distribution of limnic gastropods are of great relevance for understanding the conservation status of existing species. Furthermore, they are necessary to monitor snails that act as parasite hosts.

While biogeographic patterns of free-living organisms are well documented, the biogeography of parasitic fauna remains largely unclear. Due to morphological similarities, parasites are often difficult to identify without the aid of molecular genetics, further complicating the interpretation of their biogeographic patterns. We investigated trematode parasites infecting the East Asian freshwater snail Semisulcospira libertina to understand their biogeography and to evaluate how molecular approaches influence the interpretation of biogeographic patterns of the trematode fauna. We identified 46 genetically delimited species from 19 morphologically distinguishable trematodes infecting S. libertina and found that their species richness was negatively correlated to latitude. We also found that potential definitive host (fishes) richness and host body size were positively correlated with trematode species richness, suggesting that host attributes are essential factors shaping the biogeographic pattern in trematodes. These trends were observed irrespective of species identification methods, demonstrating that classical morphological identification can also effectively identify the latitudinal gradient pattern in trematodes. We further detected the distance decay of similarity in trematode communities, although this trend was only detectable in the biogeographic dataset based on molecular identification. Our study showed that morphological identification sufficiently reflects the latitudinal richness gradient while molecular identification is essential to estimate accurate local species richness and increase the resolution of the large-scale pattern of population similarities in the trematode communities., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Schistosomiasis, a freshwater-borne neglected tropical disease, disproportionately affects impoverished communities mainly in the tropical regions. Transmission involves humans and intermediate host (IH) snails. This manuscript introduces a mathematical model to probe schistosomiasis dynamics and the role of non-host snail competitors and predators as biological control agents for IH snails. The numerical analyses include investigations into steady-state conditions and reproduction numbers associated with uncontrolled scenarios, as well as scenarios involving non-host snail competitors and/or predators. Sensitivity analysis reveals that increasing snail mortality rates is a key to reducing the IH snail population and control of the transmission. Results show that specific snail competitors and/or predators with strong competition/predation abilities reduce IH snails and the subsequent infectious cercaria populations, reduce the transmission, and possibly eradicate the disease, while those with weaker abilities allow disease persistence. Hence our findings advocate for the effectiveness of snail competitors with suitable competitive pressures and/or predators with appropriate predatory abilities as nature-based solutions for combating schistosomiasis, all while preserving IH snail biodiversity. However, if these strategies are implemented at insignificant levels, IH snails can dominate, and disease persistence may pose challenges. Thus, experimental screening of potential (native) snail competitors and/or predators is crucial to assess the likely behavior of biological agents and determine the optimal biological control measures for IH snails., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

This study aimed to investigate the occurrence of larval trematode infections in bithyniid snails across five provinces in southern Thailand. A total of 1,413 Bithynia siamensis snails were collected between October 2021 and October 2022 using handpicking and scooping methods. Among these, 844 were identified as B. s. siamensis and 569 as B. s. goniomphalos. The snail samples were examined for parasitic infections in the laboratory using shedding and crushing methods. Among the 27 sampling sites, snails from 6 sites were infected with various trematode species (infection rate: 4.95%, 70/1,413). Evaluation of the morphological and internal organ characteristics of the cercariae allowed for the categorization of the trematodes into five species of trematodes (belonging to four families). The identified species included Echinochasmus pelecani (family: Echinostomatidae), Echinostoma revolutum (family: Echinostomatidae), Haematoloechus similis (family: Haematoloechidae), Loxogenoides bicolor (family Lecithodendriidae), and Stictodora tridactyla (family: Heterophyidae), and the infection rates for these species were 3.26% (46/1,413), 0.35% (5/1,413), 0.42% (6/1,413), 0.78% (11/1,413), and 0.14% (2/1,413), respectively. The cercariae from the identified trematode species were studied for DNA analysis. The phylogenetic lineage reveals relationships among the species, confirming the morphological distinctions., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Urogenital schistosomiasis due to Schistosoma haematobium is a major public health problem in Mauritania, but little is known about its epidemiology in many areas of the country, particularly in the lake zones. The objectives of the present parasitological and malacological study were to assess the prevalence and intensity of urogenital schistosomiasis among school children in Kankossa and Oued Rawdha lakes, southern Mauritania, and determine the species of intermediate host snails and the prevalence of snails with schistosome., Methods: A school-based epidemiological survey was conducted in two villages in the lake areas of Kankossa and Oued Rawdha. Urine samples were collected from 450 state primary school children and Koranic school children and examined for the presence of S. haematobium eggs using filtration technique. Water bodies adjacent to human settlement were surveyed for Bulinus and Biomphalaria snails that may potentially be intermediate hosts of S. haematobium. Morphological, molecular, and proteomic (i.e. matrix-assisted laser desorption ionization time-of-flight mass spectrometry [MALDI-TOF MS]) identification of collected snails were conducted, and their infection status was assessed by real-time polymerase chain reaction (RT-PCR) using the highly repetitive DraI gene., Results: The prevalence of urogenital schistosomiasis was 35.6% and 15.8% in Kankossa and Oued Rawdha villages, respectively, corresponding to 'moderate' prevalence (i.e., 10-49% infected schoolchildren). Urogenital schistosomiasis prevalence was higher in boys (30.0%) than in girls (21.2%; P < 0.05), and in Koranic schools pupils (37.1%) than in state schools (20.5%; P < 0.05) pupils. Multiple regression analysis showed that sex (odds ratio [OR]: 1.64; 95% confidence interval [95% CI]: 1.06-2.57; P = 0.03) and Koranic school level (OR: 1.79; 95% CI: 1.06-3.04; P = 0.03) were independently and significantly associated with urogenital schistosomiasis. Based on molecular and proteomic identification, both B. senegalensis and B. umbilicatus colonized the water bodies of Oued Rawdha, whereas both B. forskalii and B. truncatus colonized those of Kankossa. The DraI RT-PCR detected S. haematobium complex DNA in 8 of 66 (12.1%) analysed snails: one B. truncatus and one B. forskalii in Kankossa and five B. senegalensis and one B. umbilicatus in Oued Rawdha., Conclusion: Urogenital schistosomiasis is moderately prevalent in the lake zones of Kankossa and, to a lesser extent, Oued Rawdha, located in southern Mauritania. Mass drug administration campaigns with praziquantel should be conducted to reduce the prevalence of urogenital schistosomiasis among school-aged children in the lake zone of Kankossa and Oued Rawdha village. Further parasitological and malacological studies should be conducted in other villages located in the Mauritanian lakes in the southern Sahelian zones and the northern oasis areas to strengthen our knowledge of the current epidemiological situation and implement appropriate urogenital schistosomiasis control strategies., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Nakatt et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: The transmission cycle of Schistosoma is remarkably complex, including sexual reproduction in human hosts and asexual reproduction in the intermediate host (freshwater snails). Patterns of rapid recrudescence after treatment and stable low transmission are often observed, hampering the achievement of control targets. Current mathematical models commonly assume regulation of transmission to occur at worm level through density-dependent egg production. However, conclusive evidence on this regulating mechanism is weak, especially for S. mansoni. In this study, we explore the interplay of different regulating mechanisms and their ability to explain observed patterns in S. mansoni epidemiology., Methodology/principal Findings: We developed SchiSTOP: a hybrid stochastic agent-based and deterministic modelling framework for S. mansoni transmission in an age-structured human population. We implemented different models with regulating mechanisms at: i) worm-level (density-dependent egg production), ii) human-level (anti-reinfection immunity), and iii) snail-level (density-dependent snail dynamics). Additionally, we considered two functional choices for the age-specific relative exposure to infection. We assessed the ability of each model to reproduce observed epidemiological patterns pre- and post-control, and compared successful models in their predictions of the impact of school-based and community-wide treatment. Simulations confirmed that assuming at least one regulating mechanism is required to reproduce a stable endemic equilibrium. Snail-level regulation was necessary to explain stable low transmission, while models combining snail- and human-level regulation with an age-exposure function informed with water contact data were successful in reproducing a rapid rebound after treatment. However, the predicted probability of reaching the control targets varied largely across models., Conclusions/significance: The choice of regulating mechanisms in schistosomiasis modelling largely determines the expected impact of control interventions. Overall, this work suggests that reaching the control targets solely through mass drug administration may be more challenging than currently thought. We highlight the importance of regulating mechanisms to be included in transmission models used for policy., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Malizia et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Schistosomiasis is a major public health concern in the world, and precision control is crucial to combating this disease. Due to the complex and diverse transmission route of schistosomiasis, conventional statistical models have significant limitations for precision control of schistosomiasis. As an important branch of artificial intelligence, machine learning has shown remarkable advantages in schistosomiasis control and research. It has been shown that machine learning is highly effective for disease prediction and risk assessment, so as to optimize the disease control strategy and resource allocation and achieve the precision control target. This review summarizes the characteristics of machine learning models and their applications in the research of intermediate host snails and schistosomiasis.

Trematodes and their snail hosts have developed intimate parasite-host associations, with snails supporting a diverse and often species-specific trematode fauna. In the faucet snail, Bithynia tentaculata (Caenogastropoda, Littorinimorpha), a unique trematode fauna has been recorded recently. However, knowledge of the exact species identity, phylogenetic relationships, and geographical distribution remains limited as many of the species belong to groups with unclear or controversial taxonomical assignment. To contribute to our knowledge of the trematodes, we investigated the trematode fauna of B. tentaculata by examining a total of 556 snails from lakes in County Galway, Ireland. Using an integrative taxonomic approach including DNA sequence data analyses (28S rRNA gene, ITS1-5.8S-ITS2, ITS2, cox 1, nad 1) and morphological tools (taxonomical drawings and measurements), we identified nine trematode species of seven families, with seven species occurring as cercariae ( Cyathocotyle prussica , Lecithodendrium linstowi , Lecithodendrium sp., Asymphylodora progenetica , Sphaerostoma bramae , Metorchis xanthosomus , and Notocotylus sp.) and three species occurring as metacercariae ( A. progenetica , Parasymphylodora parasquamosa , and Sphaeridiotrema sp.). Except for S. bramae , all are new species records for Ireland and provide the most western distribution of these trematodes in Europe. The trematode species recorded are known to use a wide range of definitive hosts and have a wide geographical distribution; among them are species members of genera that are zoonotic ( Metorchis ) and pathogenic to wildlife ( Cyathocotyle , Sphaeridiotrema , and Notocotylus ). There remains an ongoing need for precise identification of the trematode species to ensure that wider ecological contexts are correctly understood and biodiversity and disease threats can be accurately evaluated.

Objective: To investigate the capability for distinguishing between the morphology of Oncomelania hupensis and Tricula snails and its influencing factors among schistosomiasis control professionals in Yunnan Province, so as to evaluate the interference of Tricula snails with O. hupensis surveys., Methods: O. hupensis and Tricula snails were sampled from 9 schistosomiasis-endemic counties (districts) in Yunnan Province. The capability for distinguishing between O. hupensis and Tricula snails was evaluated using online questionnaire surveys and field blind tests among schistosomiasis control professionals, and the proportions of correct judgment, misjudgment and missed judgment were calculated. Univariate and multivariate logistic regression models were created using the software SPSS 25.0, and factors affecting the proportion of correct judgments of O. hupensis snails were identified among schistosomiasis control professionals., Results: Questionnaire surveys and field blind tests showed that the overall proportions of correct judgments of O. hupensis snails were 56.77% (2 305/4 060) and 68.28% (1 556/2 279) among schistosomiasis control professionals in Yunnan Province, respectively. Univariate logistic regression analysis of online questionnaire surveys identified gender [odds ratio ( OR ) = 1.244, 95% confidential interval ( CI ): (1.073, 1.441), P < 0.05], professional title [ OR = 0.628, 1.741, 95% CI : (0.453, 0.871), (1.109, 2.734), both P < 0.05], working duration [ OR = 0.979, 95% CI : (0.971, 0.987), P < 0.05] and classification of schistosomiasis epidemics in endemic foci [ OR = 1.410, 0.293, 0.523, 95% CI : (1.103, 1.804), (0.237, 0.361), (0.416, 0.657), all P < 0.05] as factors affecting the proportion of correct judgments of O. hupensis snails among schistosomiasis control professionals in Yunnan Province, and multivariate logistic regression analysis after adjustments showed that the proportion of O. hupensis snail misjudgments was 1.179 times higher among male schistosomiasis control professionals than among females [ OR = 1.179, 95% CI : (1.006, 1.382), P < 0.05], and 1.474 times higher among schistosomiasis control professionals in schistosomiasis-elimination areas with snails than in areas without snails [ OR = 1.474, 95% CI : (1.145, 1.898), P < 0.05], and the proportions of missed judgments of O. hupensis snails were 0.284 [ OR = 0.284, 95% CI : (0.225, 0.359), P < 0.05] and 0.523 times [ OR = 0.523, 95% CI : (0.412, 0.664), P < 0.05] higher among schistosomiasis control professionals in transmission-interruption areas with snails and schistosomiasis-elimination areas with snails than in schistosomiasis-elimination areas without snails. Univariate logistic regression analysis of field blind tests showed age [ OR = 2.381, 95% CI : (1.677, 3.381), P < 0.05], professional title [ OR = 1.688, 95% CI : (1.103, 2.582), P < 0.05］, working duration [ OR = 0.970, 95% CI : (0.956, 0.984), P < 0.05] and classification of schistosomiasis epidemics in endemic foci [ OR = 0.262, 0.593, 95% CI : (0.188, 0.364), (0.420, 0.837), both P < 0.05] as factors affecting the proportion of correct judgments of O. hupensis snails among schistosomiasis control professionals in Yunnan Province, and multivariate logistic regression analysis after adjustments showed the proportions of missed judgments of O. hupensis snails were 0.263 [ OR = 0.263, 95% CI : (0.176, 0.394), P < 0.05] and 0.604 times [ OR = 0.604, 95% CI : (0.416, 0.875), P < 0.05] higher among schistosomiasis control professionals in transmission-interruption areas with snails and schistosomiasis-elimination areas with snails than in schistosomiasis-elimination areas without snails., Conclusions: Schistosomiasis control professionals in Yunnan Province have a low accuracy rate for distinguishing between the morphology of O. hupensis and Tricula snails, and gender and classification of schistosomiasis epidemics in endemic foci are factors that affect their ability to distinguish. The presence of Tricula snails causes a high degree of interference with O. hupensis surveys in O. hupensis snail-infested areas of Yunnan Province. Reinforced training for distinguishing between O. hupensis and Tricula snails is required among schistosomiasis control professionals in Yunnan Province.

Background: Combating infectious diseases and halting biodiversity loss are intertwined challenges crucial to ensure global health. Biodiversity can constrain the spread of vector-borne pathogens circulation, necessitating a deeper understanding of ecological mechanisms underlying this pattern. Our study evaluates the relative importance of biodiversity and the abundance of Bulinus truncatus, a major intermediate host for the trematode Schistosoma haematobium on the circulation of this human pathogen at aquatic transmission sites., Methods: We combined mathematical modelling and a molecular based empirical study to specifically assess the effect of co-infections between S. haematobium and other trematodes within their B. truncatus snail hosts; and B. truncatus abundance at transmission sites, on the production of S. haematobium infective cercariae stages released into the aquatic environment., Results: Our modelling approach shows that more competitive trematode species exploiting B. truncatus as an intermediate host at the transmission site level leads to higher co-infection rates within snail hosts, subsequently reducing the production of S. haematobium cercariae. Conversely, an increase in B. truncatus abundance results in lower co-infection rates, and a higher proportion of S. haematobium cercariae released into the environment. Our empirical data from the field support these findings, indicating a significant negative effect of local trematode species richness (P-value = 0.029; AIC = 14.9) and co-infection rates (P-value = 0.02, AIC = 17.4) on the dominance of S. haematobium based on our GLMM models, while B. truncatus abundance positively influences S. haematobium dominance (P-value = 0.047, AIC = 20.1)., Conclusions: Our study highlights the importance of biodiversity in influencing the transmission of S. haematobium through the effect of antagonistic interactions between trematodes within bulinid snail hosts. This effect intensifies when B. truncatus populations are low, promoting co-infections within snails. In line with the One Health concept, our results suggest that maintaining high level of freshwater biodiversity to sustain global trematode diversity at transmission sites can help reducing the circulation of Schistosoma species locally., (© 2024. The Author(s).)

Background: The control of schistosomiasis is particularly difficult in sub-Saharan Africa, which currently harbours 95% of this disease. The target population for preventive chemotherapy (PC) is expanded to all age group at risk of infection, thus increasing the demands of praziquantel (PZQ) tablets according to the new released guideline by World Health Organization. Due to the gap between available PZQ for PC and requirements, alternative approaches to assess endemicity of schistosomiasis in a community, are urgently needed for more quick and precise methods. We aimed to find out to which degree the infection status of snails can be used to guide chemotherapy against schistosomiasis., Methods: We searched literature published from January 1991 to December 2022, that reported on the prevalence rates of Schistosoma mansoni, S. haematobium in the intermediate snails Biomphalaria spp. and Bulinus spp., respectively, and in humans. A random effect model for meta-analyses was used to calculate the pooled prevalence estimate (PPE), with heterogeneity assessed using I-squared statistic (I 2 ), with correlation and regression analysis for the exploration of the relationship between human S. mansoni and S. haematobium infections and that in their specific intermediate hosts., Results: Forty-seven publications comprising 59 field investigations were included. The pooled PPE of schistosomiasis, schistosomiasis mansoni and schistosomiasis haematobium in humans were 27.5% [95% confidence interval (CI): 24.0-31.1%], 25.6% (95% CI: 19.9-31.3%), and 28.8% (95% CI: 23.4-34.3%), respectively. The snails showed an overall infection rate of 8.6% (95% CI: 7.7-9.4%), with 12.1% (95% CI: 9.9-14.2%) in the Biomphalaria spp. snails and 6.9% (95% CI: 5.7-8.1%) in the Bulinus spp. snails. The correlation coefficient was 0.3 (95% CI: 0.01-0.5%, P < 0.05) indicating that the two variables, i.e. all intermediate host snails on the one hand and the human host on the other, were positively correlated., Conclusions: The prevalence rate of S. mansoni and S. haematobium is still high in endemic areas. Given the significant, positive correlation between the prevalence of schistosomes in humans and the intermediate snail hosts, more attention should be paid to programme integration of snail surveillance in future., (© 2024. The Author(s).)

The production demand of edible snails in the Mediterranean area is very high and the attention to snail borne diseases is increasing. Following mass mortality events, we have analyzed 240 samples of Cornu aspersum collected from farms across Italy. Anatomopathological examination showed the presence of alterations of the gastro-intestinal apparatus and of the digestive gland, while histopathological examination revealed the presence of Rickettsia-like organisms (RLOs) in 70% (168/240) of cases and Giemsa positive amoebae in the remaining 30% (72/240) of cases. RLOs were localized mainly at the level of the DG, where regressive changes or nodular inflammation was observed. TEM examination of RLOs samples revealed the presence of many rod-shaped electron dense microorganisms. Amoebal infection occurred in the kidney, intestine, lung, the DG and were associated to regressive events or infiltrative/nodular and encapsulation like inflammation. To date it is still unclear if the pathogens detected could represent a risk for humans and animals, therefore further studies are needed to better elucidate this point., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)