Water bodies as interfaces and pathways for zoonotic and livestock pathogen transmission in Africa and Scotland

钩端螺旋体、分枝杆菌、大肠埃希菌、弯曲杆菌等水媒病原体是引起人畜共患的重要疾病。水可以发挥重要的流行病学作用，它通过流域范围的水流促进疾病在人群或牛群之间的空间传播，和/或通过在作为感染源的动物物种和敏感宿主之间提供传播接口(例如，牲畜向人传播或野生动物向牲畜传播)，发挥重要的流行病学作用。DNA提取方案和定量分子诊断分析的最新进展使解决关键问题的潜力发生了革命性变化，例如，什么类型的淡水生境对传播的风险最大，水道在跨景观传播水媒病原体方面发挥了什么作用，以及水流和水源的物理化学特征的时间变化如何影响病原体的丰度？除了提高我们对流域内水传播病原体流行病学的了解外，环境采样还可以构成更有效的监测战略的基础，因为对水库宿主进行采样可能具有挑战性和昂贵。这项研究将集中在两个全球重要的水传播病原体属--钩端螺旋体属。和分枝杆菌，利用从高风险环境中对水体进行广泛的集水区采样来解决我们在流行病学理解中的关键知识空白。钩端螺旋体病和分枝杆菌感染是牲畜生产力损失和人类疾病的主要原因。钩端螺旋体病每年造成约100万人感染病例和60000人死亡，接触水(职业性或娱乐性)以及洪水1被认为是一个重要的危险因素。分枝杆菌属例如牛分枝杆菌(负责牛结核病)和禽分枝杆菌亚种。副结核(MAP)(导致约翰氏病)是具有经济破坏性的牲畜病原体和潜在的公共卫生威胁2。越来越多的证据表明，水在分枝杆菌的流行病学中可以发挥作用。例如，野生动物-家畜传播牛分枝杆菌更有可能发生在水源，那里的动物聚集和环境条件有利于病原体的生存3，MAP的水道污染已被证明与集水区的距离、降雨量和河流流速4呈正相关。最近的全球审查强调，迫切需要提高我们对环境传播在不同情况下这些病原体的流行病学中所起作用的理解。

Waterborne pathogens, such as Leptospira spp., Mycobacterium spp., E. coli and Campylobacter spp., are responsible for important diseases of human and livestock. Water can play an important epidemiological role by facilitating the spatial spread of disease between populations or herds through catchment-wide water flow, and/or by providing a transmission interface between animal species that act as reservoirs of infection and susceptible hosts (e.g. livestock to human transmission or wildlife to livestock transmission). Recent advances in DNA extraction protocols and quantitative molecular diagnostic assays have revolutionised the potential to address key questions, such as what types of freshwater habitats pose the greatest risk for transmission, what role do water courses play in disseminating waterborne pathogens across landscapes and how do temporal changes to water flows and physico-chemical characteristics of water sources influence the abundance of pathogens? In addition to improving our understanding of the epidemiology of waterborne pathogens within catchments, environmental sampling could form the basis of more effective surveillance strategies, as sampling of reservoir hosts can be challenging and expensive.This study will focus on two globally important waterborne pathogen genera, Leptospira spp. and Mycobacterium spp., using catchment wide sampling of water bodies from high risk settings to address key knowledge gaps in our epidemiological understanding. Leptospirosis and mycobacterial infections are key causes of livestock productivity loss and human disease. Leptospirosis is responsible for an estimated 1 million human cases and 60000 deaths annually and contact with water (occupational or recreational) is recognised as a significant risk factor, along with flooding1. Mycobacterium spp. such as M. bovis (responsible for bovine tuberculosis) and M. avium subsp. paratuberculosis (Map) (responsible for Johne's disease) are economically devastating livestock pathogens and potential public health threats2. Evidence is increasing of the role that water can play in the epidemiology of Mycobacterium spp. For example, wildlife-livestock transmission of M. bovis is more likely to occur at water sources, where animals aggregate and environmental conditions favour the survival of the pathogen3, and water course contamination with Map has been shown to be positively associated with distance down a catchment, rainfall and river flow rate4. Recent global reviews have emphasised the urgent need to improve our understanding of the role that environmental transmission plays in the epidemiology of these pathogens under different contexts1,2.