Medical Research Council Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom.
Department of Clinical Science, Liverpool School of Tropical Medicine, Liverpool, United Kingdom.
PLoS Negl Trop Dis. 2024 Sep 27;18(9):e0012518. doi: 10.1371/journal.pntd.0012518. eCollection 2024 Sep.
Environmental surveillance for Salmonella Typhi may provide information on the community-level dynamics of typhoid fever in resource poor regions experiencing high disease burden. Many knowledge gaps concerning the feasibility of ES remain, especially in areas lacking formal sewage systems. We implemented protocols for S. Typhi ES, including site selection and catchment population estimation, sample concentration and testing using qPCR for S. Typhi specific gene targets. Between May 2021 and May 2022, we collected grab samples and Moore swabs from 43 sites in Blantyre, Malawi. Catchment characteristics, water quality, and human faecal contamination (qPCR for Bacteroides HF183) were also recorded. Their association with S. Typhi detection was investigated using a logistic mixed-effects regression analysis. Prevalence of S. Typhi in ES samples was 2.1% (1.1-4.0%) and 3.9% (1.9-7.9%) for grab and Moore swab samples, respectively. HF183 was associated S. Typhi positivity, with a unit increase in log genome copies/microlitre increasing the odds of detection of S. Typhi by 1.56 (95% CI: 1.29-1.89) and 1.33 (1.10-1.61) in Moore swabs and grab samples, respectively. The location and timing of S. Typhi detection through ES was not associated with the incidence of typhoid fever reported in associated catchment populations. During this period of relatively low typhoid fever incidence, wastewater surveillance continued to detect S. Typhi in human sewage and wastewater suggesting that ES using natural river systems can be a sensitive indicator of transmission.
环境监测沙门氏菌 Typhi 可能为资源匮乏地区的伤寒社区级动态提供信息，这些地区的伤寒负担高。关于 ES 的许多可行性知识空白仍然存在，特别是在缺乏正规污水系统的地区。我们实施了用于环境监测沙门氏菌 Typhi 的方案，包括地点选择和集水区人口估计、使用 qPCR 对伤寒特异性基因靶标进行样本浓缩和检测。2021 年 5 月至 2022 年 5 月，我们从马拉维布兰太尔的 43 个地点收集了 grab 样本和 Moore 拭子。还记录了集水区特征、水质和人类粪便污染（qPCR 用于双歧杆菌 HF183）。使用逻辑混合效应回归分析调查了它们与伤寒 Typhi 检测的关联。环境监测样本中伤寒 Typhi 的流行率分别为 2.1%（1.1-4.0%）和 3.9%（1.9-7.9%），用于 grab 和 Moore 拭子样本。HF183 与伤寒 Typhi 阳性相关，每增加一个对数基因组拷贝/微升，Moore 拭子和 grab 样本中伤寒 Typhi 的检测几率分别增加 1.56（95%CI：1.29-1.89）和 1.33（1.10-1.61）。通过环境监测检测到伤寒 Typhi 的位置和时间与相关集水区人口报告的伤寒发病率无关。在这个相对较低的伤寒发病率期间，废水监测继续在人类污水和废水中检测到伤寒 Typhi，这表明使用自然河流系统的环境监测可以作为传播的敏感指标。
