Snail-borne parasitic diseases:an update on global epidemiological distribution,transmission interruption and control methods

Background:Snail-borne parasitic diseases,such as angiostrongyliasis,clonorchiasis,fascioliasis,fasciolopsiasis,opisthorchiasis,paragonimiasis and schistosomiasis,pose risks to human health and cause major socioeconomic problems in many tropical and sub-tropical countries.In this review we summarize the core roles of snails in the life cycles of the parasites they host,their clinical manifestations and disease distributions,as well as snail control methods.Main body:Snails have four roles in the life cycles of the parasites they host:as an intermediate host infected by the first-stage larvae,as the only intermediate host infected by miracidia,as the first intermediate host that ingests the parasite eggs are ingested,and as the first intermediate host penetrated by miracidia with or without the second intermediate host being an aquatic animal.Snail-borne parasitic diseases target many organs,such as the lungs,liver,biliary tract,intestines,brain and kidneys,leading to overactive immune responses,cancers,organ failure,infertility and even death.Developing countries in Africa,Asia and Latin America have the highest incidences of these diseases,while some endemic parasites have developed into worldwide epidemics through the global spread of snails.Physical,chemical and biological methods have been introduced to control the host snail populations to prevent disease.Conclusions:In this review,we summarize the roles of snails in the life cycles of the parasites they host,the worldwide distribution of parasite-transmitting snails,the epidemiology and pathogenesis of snail-transmitted parasitic diseases,and the existing snail control measures,which will contribute to further understanding the snail-parasite relationship and new strategies for controlling snail-borne parasitic diseases.

Gut microbiota in parasite-transmitting gastropods

Background Gastropoda,the largest class within the phylum Mollusca,houses diverse gut microbiota,and some gastropods serve as intermediate hosts for parasites.Studies have revealed that gut bacteria in gastropods are associated with various biological aspects,such as growth,immunity and host-parasite interactions.Here,we summarize our current knowledge of gastropod gut microbiomes and highlight future research priorities and perspectives.Methods A literature search was undertaken using PubMed,Web of Science and CNKI for the articles on the gut microbiota of gastropods until December 31,2022.We retrieved a total of 166 articles and identified 73 eligible articles for inclusion in this review based on the inclusion and exclusion criteria.Results Our analysis encompassed freshwater,seawater and land snails,with a specific focus on parasite-transmitting gastropods.We found that most studies on gastropod gut microbiota have primarily utilized 16S rRNA gene sequencing to analyze microbial composition,rather than employing metagenomic,metatranscriptomic,or metabolomic approaches.This comprehensive review provided an overview of the parasites carried by snail species in the context of gut microbiota studies.We presented the gut microbial trends,a comprehensive summary of the diversity and composition,influencing factors,and potential functions of gastropod gut microbiota.Additionally,we discussed the potential applications,research gaps and future perspectives of gut microbiomes in parasite-transmitting gastropods.Furthermore,several strategies for enhancing our comprehension of gut microbiomes in snails were also discussed.Conclusions This review comprehensively summarizes the current knowledge on the composition,potential function,influencing factors,potential applications,limitations,and challenges of gut microbiomes in gastropods,with a specific emphasis on parasite-transmitting gastropods.These findings provide important insights for future studies aiming to understand the potential role of gastropod gut microbiota in controlling snail populations and snail-borne diseases.

Climate change and epidemiology of human parasitoses in Saudi Arabia:A review

Climate change is an emerging global problem.It has hazardous effects that vary across different geographic regions and populations.It is anticipated to have significant effects in Saudi Arabia.The present work reviews the future of human parasitoses in Saudi Arabia in response to the expected climate change.The key projections are increased precipitations,flash floods,unstable temperatures,sea-level rise and shoreline retreat.Such environmental changes could strongly influence the epidemiology of fly-borne,mosquito-borne,snail-borne and water-borne human parasitoses in the country.