Environmental transmission of cholera in Tanzania: Building resilience in rural communities

这个跨学科项目利用物理科学的不同方面，在了解和预测霍乱环境传播方面取得重大进展。该项目成果将用于改进对霍乱宿主霍乱弧菌的地点和人群暴露风险的预测。该项目建立在之前通过矿物颗粒内的发光信号耦合沉积物运动和环境光暴露的发展基础上（McGuire和Rhodes 2015a， b； Gray等人，2015），并基于EPSRC的三个核心主题：物理科学、医疗保健技术和生活与环境变化。该项目将制定改善人类健康和了解水媒疾病传播的解决办法，并对水安全的重大挑战作出贡献。尽管科学取得了重大进展，但随着我们正在经历第七次霍乱大流行，霍乱继续破坏全球南方的生命和生计（Mpazi & Mnyika， 2005年），全球每年报告约290万例病例，约9.5万人死亡（世卫组织，2018年）。仅在非洲，就有4000万人生活在霍乱易发地区（Anderson, 2020）。自1974年以来，坦桑尼亚一直是非洲大陆霍乱报告最多的国家之一，截至2018年，有超过25万例病例和13078例死亡（Lessler等人，2018年）。在坦桑尼亚，霍乱爆发的背景是，由于物价波动和世界银行实施的偿债政策，卫生系统受到影响，农村穷人尤其感受到这些政策的不利影响。（Baker et al., 2013; Mamdani & Bangser, 2004）。此外，在COVID-19期间，卫生系统不堪重负，国家承受着越来越大的财政负担（Saleh， 2020年）。最近的气候模拟工作表明，东非将经历更短、更强烈的雨季，随后是严重干旱，预计这将导致非洲霍乱负担向该大陆东部的重大转移（Colwell, 1996； Traeup等人，2011）。水资源短缺迫使人们使用不安全的水源，而洪水导致饮用水受到粪便污染（Moore et al. 2017）。这突出表明需要准确预测农村地区的霍乱疫情，以便及时分配资源（Akanda等人，2011年；Azman等人，2019年；Emch等人，2008年），并最大限度地提高支撑坦桑尼亚卫生保健系统的投资价值。细菌可以作为生物膜附着在矿物表面。霍乱弧菌能够在不利于其生存和生长的条件下形成保护机制并进入休眠状态，并在条件改善时恢复毒力（Lutz et al., 2013）。在河流和湖泊细粒度沉积物储存中，霍乱弧菌已被记录为这种非毒性状态，在那里它会持续存在，直到暴雨等干扰事件发生，然后引起爆发（Abia等人，2017；Perkins等人，2014）。因此，河流和湖泊沉积物（活跃河道和湖泊系统中的泥质物质）中的霍乱弧菌储存对公众健康构成重大威胁。了解这些储存库在哪里，以及沉积物在高流量期间是如何运输的，对预测霍乱爆发具有很大的潜力。发光技术的新应用将用于构建优化的方法和设备，以监测和测量河流和湖泊系统内的水文过程，并将这些应用于解决上述公共卫生威胁。发光利用石英和长石晶粒晶格内的电荷。当谷物被埋在地下并受到自然电离辐射时，电荷会增加，而当谷物暴露在热或光下时，电荷会减少。这可以作为发光信号来测量，通过加热或将颗粒暴露在光下刺激

This interdisciplinary project uses different aspects of physical science to make significant advances in understanding and predicting environmental cholera transmission. The project outcomes will be used to improve prediction of location and exposure risk of populations to Vibrio cholerae, the bacterium that hosts cholera. The project builds on previous developments in the coupling of sediment movement and ambient light exposure via luminescence signals within mineral grains (McGuire and Rhodes 2015a, b; Gray et al., 2015), and is based within three core EPSRC themes: Physical Science, Healthcare Technologies, and Living with Environmental Change. This project will devise solutions to improve human health and understanding of water-borne disease transmission, and represents a contribution to the grand challenges of water security. Despite significant scientific advances, cholera continues to destroy lives and livelihoods in the global south as we live through the seventh cholera pandemic (Mpazi & Mnyika, 2005), with global reports of ~2.9 million cases and ~95,000 deaths annually (WHO, 2018). In Africa alone, 40 million people live in cholera-prone areas (Anderson, 2020). Since 1974, Tanzania has remained one of the top cholera-reporting counties on the continent, with over 250,000 cases and 13,078 deaths, up to 2018 (Lessler et al. 2018). In Tanzania, cholera outbreaks occur against a backdrop of a health system suffering in the wake of volatile prices and debt-servicing policies imposed by the World Bank, the adverse effects of which are disproportionately felt by the rural poor. (Baker et al., 2013; Mamdani & Bangser, 2004). Furthermore, in times of COVID-19 health systems are overwhelmed and the country is under increasing financial burden (Saleh, 2020). Recent climate modelling efforts suggest East Africa will experience shorter, more intense wet seasons, followed by severe drought, which is projected to cause a significant shift in the african cholera burden towards the east of the continent (Colwell, 1996; Traeup et al. 2011). Water scarcity forces people to use unsafe water sources, whereas flooding causes fecal contamination of drinking water (Moore et al. 2017). This highlights the need for accurate prediction of cholera outbreaks in rural areas, to enable the timely allocation of resources (Akanda et al. 2011; Azman et al. 2019; Emch et al. 2008), and maximise the value of investment that underpins the Tanzanian healthcare system. Bacteria can attach to mineral surfaces as biofilms. Vibrio cholerae are able to develop protective mechanisms and enter a state of dormancy in conditions unfavourable for its survival and growth, and 2 can return to virulence when conditions improve (Lutz et al., 2013). Vibrio cholerae have been recorded in this non-virulent state in fluvial and lacustrine fine-grained sediment stores, where it persists until the onset of a disturbance event, such as heavy rainfall, and then causes an outbreak (Abia et al., 2017; Perkins et al., 2014). Thus, stores of Vibrio cholerae in fluvial and lacustrine sediment, which is muddy material within active river channels and lake systems, pose a major public health risk. Understanding where these stores are, and how sediment is transported during periods of high flow, holds great potential for predicting cholera outbreaks. Novel application of luminescence techniques will be used to construct optimised approaches and equipment to monitor and measure hydrological processes within fluvial and lacustrine systems, and apply these to tackle the public health threat described above. Luminescence exploits the charge trapped within the crystal lattice of quartz and feldspar grains. Charge is built up when grains are buried and subject to natural ionising radiation, and reduces when grains are exposed to heat or light. This can be measured as a luminescence signal, stimulated by heating or exposing the grains to light