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Oncomelania hupensis Distribution and Schistosomiasis Transmission Risk in Different Environments under Field Conditions

The goal of schistosomiasis prevention and control in China is shifting from transmission interruption to elimination. However, the area inhabited by the intermediate host, the snail Oncomelania hupensis, has not changed much in recent years. Different environmental types have different impacts on s...

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Autores principales: Li, Yinlong, Guo, Suying, Dang, Hui, Zhang, Lijuan, Xu, Jing, Li, Shizhu
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10220953/
https://www.ncbi.nlm.nih.gov/pubmed/37235290
http://dx.doi.org/10.3390/tropicalmed8050242
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author Li, Yinlong
Guo, Suying
Dang, Hui
Zhang, Lijuan
Xu, Jing
Li, Shizhu
author_facet Li, Yinlong
Guo, Suying
Dang, Hui
Zhang, Lijuan
Xu, Jing
Li, Shizhu
author_sort Li, Yinlong
collection PubMed
description The goal of schistosomiasis prevention and control in China is shifting from transmission interruption to elimination. However, the area inhabited by the intermediate host, the snail Oncomelania hupensis, has not changed much in recent years. Different environmental types have different impacts on snail breeding, and understanding these differences is conducive to improving the efficiency of snail monitoring and control and to saving resources. Based on previous epidemiological data, we selected 199 villages in 2020 and 269 villages in 2021 from transmission control, transmission interruption, and elimination areas of snail breeding. Snail surveys were conducted in selected villages using systematic sampling and/or environmental sampling methods in six types of snail-breeding environments (canals, ponds, paddy fields, dry lands, bottomlands, and undefined environments). All live snails collected from the field were evaluated for Schistosoma japonicum infection using the microscopic dissection method, and a subsample of snails was subjected to loop-mediated isothermal amplification (LAMP) to assess the presence of S. japonicum infection. Snail distribution data and infection rate and nucleic acid positive rate of schistosomes in snails were calculated and analyzed. The 2-year survey covered 29,493 ha of the environment, in which 12,313 ha of snail habitats were detected. In total, 51.16 ha of new snail habitats and 107.76 ha of re-emergent snail habitats were identified during the survey. The occurrence rate of snails in canals (10.04%, 95% CI: 9.88–10.20%) and undefined environments (20.66%, 95% CI: 19.64–21.67%) was relatively high in 2020, and the density of snails in bottomlands (0.39, 95% CI: 0.28–0.50) and undefined environments (0.43, 95% CI: 0.14–1.60) was relatively high in 2021. Of the 227,355 live snails collected in this study, none were S. japonicum-positive as determined by microscopy. Of the 20,131 pooled samples, however, 5 were S. japonicum-positive based on LAMP analysis, and they were distributed in three environmental types: 3 in bottomland, 1 in dry land, and 1 in a canal. The bottomland environment has a high risk of schistosomiasis transmission because it contains a large area of newly emerging and re-emerging snail habitats, and it also had the most breeding snails infected with S. japonicum. Thus, this habitat type should be the key target for snail monitoring and early warning and for the prevention and control of schistosomiasis.
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spelling pubmed-102209532023-05-28 Oncomelania hupensis Distribution and Schistosomiasis Transmission Risk in Different Environments under Field Conditions Li, Yinlong Guo, Suying Dang, Hui Zhang, Lijuan Xu, Jing Li, Shizhu Trop Med Infect Dis Article The goal of schistosomiasis prevention and control in China is shifting from transmission interruption to elimination. However, the area inhabited by the intermediate host, the snail Oncomelania hupensis, has not changed much in recent years. Different environmental types have different impacts on snail breeding, and understanding these differences is conducive to improving the efficiency of snail monitoring and control and to saving resources. Based on previous epidemiological data, we selected 199 villages in 2020 and 269 villages in 2021 from transmission control, transmission interruption, and elimination areas of snail breeding. Snail surveys were conducted in selected villages using systematic sampling and/or environmental sampling methods in six types of snail-breeding environments (canals, ponds, paddy fields, dry lands, bottomlands, and undefined environments). All live snails collected from the field were evaluated for Schistosoma japonicum infection using the microscopic dissection method, and a subsample of snails was subjected to loop-mediated isothermal amplification (LAMP) to assess the presence of S. japonicum infection. Snail distribution data and infection rate and nucleic acid positive rate of schistosomes in snails were calculated and analyzed. The 2-year survey covered 29,493 ha of the environment, in which 12,313 ha of snail habitats were detected. In total, 51.16 ha of new snail habitats and 107.76 ha of re-emergent snail habitats were identified during the survey. The occurrence rate of snails in canals (10.04%, 95% CI: 9.88–10.20%) and undefined environments (20.66%, 95% CI: 19.64–21.67%) was relatively high in 2020, and the density of snails in bottomlands (0.39, 95% CI: 0.28–0.50) and undefined environments (0.43, 95% CI: 0.14–1.60) was relatively high in 2021. Of the 227,355 live snails collected in this study, none were S. japonicum-positive as determined by microscopy. Of the 20,131 pooled samples, however, 5 were S. japonicum-positive based on LAMP analysis, and they were distributed in three environmental types: 3 in bottomland, 1 in dry land, and 1 in a canal. The bottomland environment has a high risk of schistosomiasis transmission because it contains a large area of newly emerging and re-emerging snail habitats, and it also had the most breeding snails infected with S. japonicum. Thus, this habitat type should be the key target for snail monitoring and early warning and for the prevention and control of schistosomiasis. MDPI 2023-04-23 /pmc/articles/PMC10220953/ /pubmed/37235290 http://dx.doi.org/10.3390/tropicalmed8050242 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Li, Yinlong
Guo, Suying
Dang, Hui
Zhang, Lijuan
Xu, Jing
Li, Shizhu
Oncomelania hupensis Distribution and Schistosomiasis Transmission Risk in Different Environments under Field Conditions
title Oncomelania hupensis Distribution and Schistosomiasis Transmission Risk in Different Environments under Field Conditions
title_full Oncomelania hupensis Distribution and Schistosomiasis Transmission Risk in Different Environments under Field Conditions
title_fullStr Oncomelania hupensis Distribution and Schistosomiasis Transmission Risk in Different Environments under Field Conditions
title_full_unstemmed Oncomelania hupensis Distribution and Schistosomiasis Transmission Risk in Different Environments under Field Conditions
title_short Oncomelania hupensis Distribution and Schistosomiasis Transmission Risk in Different Environments under Field Conditions
title_sort oncomelania hupensis distribution and schistosomiasis transmission risk in different environments under field conditions
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10220953/
https://www.ncbi.nlm.nih.gov/pubmed/37235290
http://dx.doi.org/10.3390/tropicalmed8050242
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