Soil epidemiology: a new tool for environmental surveillance of soil-transmitted helminth infections in endemic settings.

项目摘要 土壤传播蠕虫（STH）感染（肠道蠕虫）影响15亿人 在全球最近的试验和模型研究证据表明， 驱虫药物给药（cMDA），覆盖率和依从性充分 可以消除STH传播。然而，在持续环境传播的环境中， 网络卫生覆盖率低，STH卵的持久环境水库 导致高再感染率，阻碍消灭疟疾的进展。 STH控制计划使用基于人类粪便的方法来评估STH患病率， 在地方性环境中的强度。然而，个人粪便取样是昂贵的和后勤 很难，特别是在人类感染率较低的情况下。如果收集和分析 人类活动频繁的社区内的位置（例如，家庭入口，集水点， 学校）被建立为与人类粪便诊断同等或更敏感，这 这种方法可能是一种侵入性更小、更具成本效益的MDA监测工具 方案监测和评价。 本研究将利用一项多国随机分组对照试验， 贝宁和印度为期三年的两年期cMDA（DeWorm3）。试验将收集和分析 通过qPCR，在最后一轮cMDA后24个月（总共n = 80，000）的人粪便样品， 这将在研究区域产生高度准确的人类STH感染流行率估计。 通过在印度和贝宁的广泛实验室研究和现场测试，我们的团队 建立了一种灵敏、特异的STH环境DNA检测方法 （eDNA）在大量的土壤中。我们将在同一时间点在试验范围内进行巢土采样 一年后，具体目标是：1）量化 每年两次的cMDA干预土壤STH水库; 2）确定土壤STH eDNA是否 水平可以预测社区水平的人类STH感染流行率; 3）制定最佳的 土壤取样策略，并将成本与基于人类粪便的监测进行比较。 将土壤STH eDNA评估与人类感染流行率数据配对 DeWorm3试验收集的数据是一个独特的、时间敏感的机会，可以验证和 测试环境STH监测的效用。我们的发现也将有助于 了解MDA计划与改善卫生设施相结合的条件 需要采取干预措施，以实现持续降低性病感染率。

PROJECT SUMMARY Soil-transmitted helminth (STH) infections (intestinal worms) affect 1.5 billion individuals globally. Recent evidence from trials and modeling studies suggests that community-wide mass drug administration (cMDA) of deworming medication with sufficient coverage and adherence can eliminate STH transmission. However, in settings with ongoing environmental transmission and low coverage of networked sanitation, persistent environmental reservoirs of STH eggs result in high reinfection rates, and hinder progress towards elimination. STH control programs use human stool-based methods to assess STH prevalence and intensity in endemic settings. However, individual stool sampling is expensive and logistically difficult, particularly when human infection prevalence is low. If collecting and analyzing soil from locations in communities with high human activity (e.g. home entrances, water collection points, schools) were established to be equally or more sensitive than human stool diagnostics, this approach may represent a less invasive and more cost-effective surveillance tool for MDA program monitoring and evaluation. This study will leverage a multi-country cluster-randomized controlled trial delivering three-years of biannual cMDA in Benin and India (DeWorm3). The trial will collect and analyze by qPCR, human stool samples 24 months (n=80,000 in total) after the final round of cMDA, which will yield highly accurate human STH infection prevalence estimates in the study areas. Through extensive laboratory studies and field testing in India and Benin, our team has developed a sensitive and specific molecular method for detecting STH environmental DNA (eDNA) in large volumes of soil. We will nest soil sampling within the trial at the same time point as human stool collection and one year later with the specific aims to: 1) Quantify the effect of a biannual cMDA intervention on the soil STH reservoir; 2) Determine whether soil STH eDNA levels can predict community-level human STH infection prevalence; and 3) Develop the optimal soil sampling strategy and compare costs to human stool-based surveillance. Pairing soil STH eDNA assessments with human infection prevalence data already being collected by the DeWorm3 trial is a unique and time sensitive opportunity to validate and test the utility of environmental STH surveillance. Our findings will also contribute to understanding the conditions under which MDA program integration with improved sanitation interventions is needed for achieving sustained reductions in STH infection prevalence.