Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, CH-8600 Dübendorf, Switzerland; Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, P.O. Box, CH-4003 Basel, Switzerland.
UNESCO-IHE Institute for Water Education, 2601 Delft, The Netherlands; Sri Lanka National Water Supply and Drainage Board, Dehiwala-Mount Lavinia, Sri Lanka.
Sci Total Environ. 2018 Sep 1;635:120-131. doi: 10.1016/j.scitotenv.2018.04.100. Epub 2018 Apr 13.
Infectious disease transmission is frequently mediated by the environment, where people's movements through and interactions with the environment dictate risks of infection and/or illness. Capturing these interactions, and quantifying their importance, offers important insights into effective interventions. In this study, we capture high time-resolution activity data for twenty-five Vietnamese farmers during collection and land application of human excreta for agriculture. Although human excreta use improves productivity, the use increases risks of enteric infections for both farmers and end users. In our study, the activity data are integrated with environmental microbial sampling data into a stochastic-mechanistic simulation of E. coli contamination on hands and E. coli ingested. Results from the study include frequent and variable contact rates for farmers' hands (from 34 to 1344 objects contacted per hour per hand), including highly variable hand-to-mouth contact rates (from 0 to 9 contacts per hour per hand). The frequency of hand-to-mouth contacts was substantially lower than the widely-used frequency previously reported for U.S. Office Workers. Environmental microbial contamination data highlighted ubiquitous E. coli contamination in the environment, including excreta, hands, toilet pit, handheld tools, soils, surfaces, and water. Results from the simulation suggest dynamic changes in E. coli contamination on hands, and wide variation in hand contamination and E. coli ingested amongst the farmers studied. Sensitivity analysis suggests that E. coli contamination on hands and ingested doses are most influenced by contamination of handheld tools, excreta, and the toilet pit as well as by frequency of hand-to-mouth contacts. The study findings are especially relevant given the context: no farmers reported adequate storage time of human excreta, and personal protective mask availability did not prevent hand-to-mouth contacts. Integrating high time-resolution activity data into exposure assessments highlights variation in exposures amongst farmers, and offers greater insight into effective interventions and their potential impacts.
传染病的传播通常是通过环境进行的，人们在环境中的活动和互动决定了感染和/或疾病的风险。捕捉这些相互作用并量化其重要性，为有效的干预措施提供了重要的见解。在这项研究中，我们对二十五名越南农民在收集和土地应用人类粪便用于农业时的高时间分辨率活动数据进行了捕获。尽管人类粪便的使用提高了生产力，但它增加了农民和最终使用者患肠道感染的风险。在我们的研究中，活动数据与环境微生物采样数据相结合，对大肠杆菌在手和大肠杆菌摄入方面的污染进行了随机-机械模拟。研究结果包括农民手部频繁且可变的接触率（每小时每只手接触 34 到 1344 个物体），包括手部到口腔接触率的高度可变（每小时每只手接触 0 到 9 次）。手部到口腔接触的频率明显低于以前广泛报道的美国办公室工作人员的频率。环境微生物污染数据突出显示了环境中普遍存在的大肠杆菌污染，包括粪便、手部、厕所坑、手持工具、土壤、表面和水。模拟结果表明，手部的大肠杆菌污染会发生动态变化，而且研究中的农民手部污染和大肠杆菌摄入存在广泛差异。敏感性分析表明，手部的大肠杆菌污染和摄入剂量受手持工具、粪便和厕所坑的污染以及手部到口腔接触的频率影响最大。鉴于背景，研究结果特别相关：没有农民报告人类粪便有足够的储存时间，个人防护口罩的可用性并不能防止手部到口腔的接触。将高时间分辨率的活动数据纳入暴露评估中，突出了农民之间暴露的差异，并为有效的干预措施及其潜在影响提供了更深入的了解。
