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1. The Potential for Aquaculture to Reduce Poverty and Control Schistosomiasis in Côte d’Ivoire (Ivory Coast) during an Era of Climate Change: A Systematic Review

   https://doi.org/10.1080/23308249.2022.2039096  

   Ozretich, Reed W.; Wood, Chelsea L.; Allan, Fiona; Koumi, Ahou Rachel; Norman, Rachel; Brierley, Andrew S.; De Leo, Giulio A.; Little, David C. (February 2022, Reviews in Fisheries Science & Aquaculture)

   The development of water management infrastructures, such as dams and canals, are important components of society’s response to feed a growing human population and to fight climate change. Yet, these changes in land use can also increase the transmission risk for waterborne diseases. Transmission risk associated with artificial reservoirs has been extensively documented for schistosomiasis, a parasitic disease of poverty that infects more than 240 million people worldwide. Over 90% of these cases are in sub-Saharan Africa, a region that is being steadily reshaped by climate change. Controlling the parasite’s obligate intermediate host snail is key to reducing transmission of this disease. Using commercial aquaculture to farm marketable species which predate upon these snails in vulnerable regions can have multiple positive effects, including the improved socioeconomic and nutritional health of surrounding communities. Here the authors assessed the viability of using the aquaculture of snail predators to simultaneously control schistosomiasis infection rates while alleviating economic and/or nutritional poverty in endemic regions of sub-Saharan Africa. A PRISMA-based 6-step systematic methodology was used to explore the primary literature using the case study of Côte d’Ivoire and two native species of snail predator to make evidence-based conclusions on the viability of this method for controlling schistosomiasis. This detailed thematic examination of the literature concluded that using specific approaches and species, aquaculture could be effective in reducing economic poverty and chronic malnourishment along with high levels of schistosomiasis infection. More current species-specific aquaculture data and consumer survey data are, however, needed to determine the economic and logistical effectiveness of farming native snail predators in-country. These and other opportunities for future research are highlighted. 

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2. Human Schistosoma exposure risk in rice fields and an exploration of fish species for snail and schistosomiasis biocontrol

   https://doi.org/10.1371/journal.pgph.0004726  

   Sack, Alexandra; Selland, Emily; Bakhoum, Sidy; Seck, Momy; Jouanard, Nicolas; Magblenou, Louis Dossou; Rohr, Jason R (June 2025, PLOS Global Public Health)

   Broadhurst, Mara Jana (Ed.)

   Schistosomiasis is a devastating parasitic disease in which the infectious stage to humans is released by intermediate host snails. The Senegal River Basin (SRB) is a high-risk area for both urogenital and fecal human schistosomiasis and has extensive rice cultivation. However, occupational risk of schistosomiasis to people working in irrigated rice fields is not well established. We performed intermediate host snail surveys from 2022-2023 in rice fields and irrigation canals throughout the SRB. We discovered human schistosome-shedding snails in rice fields and adjacent irrigation canals during the rice growing and non-growing seasons, establishing a clear occupational exposure risk to rice farmers. Relative to the non-growing season, this risk was higher in the rice growing and harvest season when more people are in the rice fields. Rice-fish co-culturing might reduce this occupational risk to rice farmers if local fish species consume enough snail intermediate hosts to reduceSchistosomatransmission. Our predation trials revealed that localHeterotis niloticusandHemichromisspp. fish consumed significant numbers ofBiomphalaria pfeifferiandBulinusspp. snails, and separate trials revealed that these same snail species exhibited only moderate avoidance and refuge use responses to fish chemical cues. These results indicate that there is exposure toSchistosomaparasites in rice fields in the SRB and introducing local fish to rice fields has promise for reducing this exposure as well as providing a protein source to rice farming families. We encourage future studies to more fully explore the benefits of rice-fish co-culturing in the West Africa. 

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3. Variability of biological traits of Bulinus truncatus and Biomphalaria pfeifferi, the intermediate host snails of schistosomiasis, from three climatic zones of Côte d’Ivoire

   https://doi.org/10.3389/fenvs.2023.1193239  

   Diakité, Nana R; Koffi, Patricia B; Konan, Cyrille K; Bassa, Fidèle K; Chamberlin, Andrew J; Ouattara, Mamadou; De_Leo, Giulio A; N’Goran, Eliezer K (December 2023, Frontiers in Environmental Science)

   Background:Schistosomiasis is endemic throughout all regions of Côte d’Ivoire, however, species of the intermediate snail host vary across bioclimatic zones. Hence, a deeper knowledge of the influence of climatic on the life history traits of the intermediate snail host is crucial to understand the environmental determinants of schistosomiasis in a rapidly changing climate. The aim of this study was to run a common garden experiment to assess differences in survival, somatic growth and fecundity of bothBulinus truncatusandBiomphalaria pfeifferisnails collected in three different bioclimatic areas. Methods:A cross-sectional malacological survey was conducted in February 2021 in the south, center and north of Côte d’Ivoire. We sampled two populations ofB. truncatus, the intermediate host snail ofSchistosoma haematobium, from northern and central Côte d’Ivoire, and two populations ofBi.pfeifferi, the intermediate host snail forSchistosoma mansoni, from the southern and central regions. Snails collected at the human-water contact sites were brought in the laboratory where they reproduced. The first generation snails (G₁) for each population were reared under the same laboratory conditions, i.e., at 24°C–26°C, during 63 days (9 weeks), to estimate survival, growth, and fecundity. Results:We found that G₁Bulinussnails from the north population showed higher survival and growth rates during our study and higher number of eggs at first reproduction, compared to the ones from the central region. ForBi.pfeifferi, no significant difference in survival rate was observed between G₁snails from the southern and central populations, whereas those from the south exhibited higher growth rates and higher number of eggs per individual at first reproduction than G₁snails from the central population. Conclusion:Our study provides evidence for heterogeneity in snails’ life-history traits in response to temperature among the populations from the three climatic regions. Further experiments from multiple populations are needed to confirm that snails express traits under optimal conditions, can lead to expansion of their geographical range and hence an increase in the risk of schistosomiasis transmission. Transplantation experiments will be required to assess implications of the changing climate on snails persistence, distribution and abundance. 

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4. Identification of Snails and Schistosoma of Medical Importance via Convolutional Neural Networks: A Proof-of-Concept Application for Human Schistosomiasis

   https://doi.org/10.3389/fpubh.2021.642895  

   Tallam, Krti; Liu, Zac Yung-Chun; Chamberlin, Andrew J.; Jones, Isabel J.; Shome, Pretom; Riveau, Gilles; Ndione, Raphael A.; Bandagny, Lydie; Jouanard, Nicolas; Eck, Paul Van; et al (July 2021, Frontiers in Public Health)

   null (Ed.)

   In recent decades, computer vision has proven remarkably effective in addressing diverse issues in public health, from determining the diagnosis, prognosis, and treatment of diseases in humans to predicting infectious disease outbreaks. Here, we investigate whether convolutional neural networks (CNNs) can also demonstrate effectiveness in classifying the environmental stages of parasites of public health importance and their invertebrate hosts. We used schistosomiasis as a reference model. Schistosomiasis is a debilitating parasitic disease transmitted to humans via snail intermediate hosts. The parasite affects more than 200 million people in tropical and subtropical regions. We trained our CNN, a feed-forward neural network, on a limited dataset of 5,500 images of snails and 5,100 images of cercariae obtained from schistosomiasis transmission sites in the Senegal River Basin, a region in western Africa that is hyper-endemic for the disease. The image set included both images of two snail genera that are relevant to schistosomiasis transmission – that is, Bulinus spp. and Biomphalaria pfeifferi – as well as snail images that are non-component hosts for human schistosomiasis. Cercariae shed from Bi. pfeifferi and Bulinus spp. snails were classified into 11 categories, of which only two, S. haematobium and S. mansoni , are major etiological agents of human schistosomiasis. The algorithms, trained on 80% of the snail and parasite dataset, achieved 99% and 91% accuracy for snail and parasite classification, respectively, when used on the hold-out validation dataset – a performance comparable to that of experienced parasitologists. The promising results of this proof-of-concept study suggests that this CNN model, and potentially similar replicable models, have the potential to support the classification of snails and parasite of medical importance. In remote field settings where machine learning algorithms can be deployed on cost-effective and widely used mobile devices, such as smartphones, these models can be a valuable complement to laboratory identification by trained technicians. Future efforts must be dedicated to increasing dataset sizes for model training and validation, as well as testing these algorithms in diverse transmission settings and geographies. 

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5. Temperature affects predation of schistosome-competent snails by a novel invader, the marbled crayfish Procambarus virginalis

   https://doi.org/10.1371/journal.pone.0290615  

   Faiad, Sara M.; Williams, Maureen A.; Goodman, Maurice; Sokolow, Susanne; Olden, Julian D.; Mitchell, Kaitlyn; Andriantsoa, Ranja; Gordon Jones, Julia Patricia; Andriamaro, Luciano; Ravoniarimbinina, Pascaline; et al (September 2023, PLOS ONE)

   Mancinelli, Giorgio (Ed.)

   The human burden of environmentally transmitted infectious diseases can depend strongly on ecological factors, including the presence or absence of natural enemies. The marbled crayfish (Procambarus virginalis) is a novel invasive species that can tolerate a wide range of ecological conditions and colonize diverse habitats. Marbled crayfish first appeared in Madagascar in 2005 and quickly spread across the country, overlapping with the distribution of freshwater snails that serve as the intermediate host of schistosomiasis–a parasitic disease of poverty with human prevalence ranging up to 94% in Madagascar. It has been hypothesized that the marbled crayfish may serve as a predator of schistosome-competent snails in areas where native predators cannot and yet no systematic study to date has been conducted to estimate its predation rate on snails. Here, we experimentally assessed marbled crayfish consumption of uninfected and infected schistosome-competent snails (Biomphalaria glabrataandBulinus truncatus) across a range of temperatures, reflective of the habitat range of the marbled crayfish in Madagascar. We found that the relationship between crayfish consumption and temperature is unimodal with a peak at ~27.5°C. Per-capita consumption increased with body size and was not affected either by snail species or their infectious status. We detected a possible satiation effect, i.e., a small but significant reduction in per-capita consumption rate over the 72-hour duration of the predation experiment. Our results suggest that ecological parameters, such as temperature and crayfish weight, influence rates of consumption and, in turn, the potential impact of the marbled crayfish invasion on snail host populations. 

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