Precision mapping of snail habitat provides a powerful indicator of human schistosomiasis transmission
Precision mapping of snail habitat provides a powerful indicator of human schistosomiasis transmission
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DOI：
10.1073/pnas.1903698116
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发表时间：
2019-11-12
影响因子：
11.1
通讯作者：
De Leo, Giulio A.
中科院分区：
文献类型：
--
作者：
Wood, Chelsea L.;Sokolow, Susanne H.;De Leo, Giulio A.
最近，世界卫生组织认识到，通过大规模给药来阻断血吸虫病传播的努力在一些区域收效甚微；他们推荐的全球血吸虫病控制新策略之一强调以传播血吸虫寄生虫的淡水蜗牛为目标。我们试图确定能够精确定位这些蜗牛的可靠指标。在世界上有记录的最大血吸虫病流行地点——塞内加尔的下塞内加尔河流域，密集抽样显示中间寄主蜗牛（丰度、密度和流行率）与人类泌尿生殖系统血吸虫病再感染（服药后学童的流行率和强度）之间存在正相关关系。然而，我们也发现蜗牛的分布在空间和时间上是如此的不均匀，以至于获得有用的数据所需要的努力超出了标准监测和控制活动的可行性。相反，我们确定了几个比蜗牛变量更有效的环境变量来预测人类感染：适合蜗牛栖息地覆盖的面积（即漂浮的、非紧急植被），适合蜗牛栖息地覆盖的百分比，以及水接触面积的大小。与蜗牛调查不同，每个地点需要数百人小时的时间来进行，栖息地覆盖范围和地点面积可以通过无人机或卫星图像快速估计。反过来，这使得对人类泌尿生殖血吸虫病风险进行大规模、高分辨率的估计成为可能，以支持大规模药物给药和蜗牛控制工作的目标。
Recently, the World Health Organization recognized that efforts to interrupt schistosomiasis transmission through mass drug administration have been ineffective in some regions; one of their new recommended strategies for global schistosomiasis control emphasizes targeting the freshwater snails that transmit schistosome parasites. We sought to identify robust indicators that would enable precision targeting of these snails. At the site of the world's largest recorded schistosomiasis epidemic-the Lower Senegal River Basin in Senegal-intensive sampling revealed positive relationships between intermediate host snails (abundance, density, and prevalence) and human urogenital schistosomiasis reinfection (prevalence and intensity in schoolchildren after drug administration). However, we also found that snail distributions were so patchy in space and time that obtaining useful data required effort that exceeds what is feasible in standard monitoring and control campaigns. Instead, we identified several environmental proxies that were more effective than snail variables for predicting human infection: the area covered by suitable snail habitat (i.e., floating, nonemergent vegetation), the percent cover by suitable snail habitat, and size of the water contact area. Unlike snail surveys, which require hundreds of person-hours per site to conduct, habitat coverage and site area can be quickly estimated with drone or satellite imagery. This, in turn, makes possible large-scale, high-resolution estimation of human urogenital schistosomiasis risk to support targeting of both mass drug administration and snail control efforts.