Effects of Climate Change on Cholera Dynamics and Prediction

描述（由申请人提供）：霍乱已重新成为全球杀手，在过去二十年中，世界目睹了霍乱感染和传播的前所未有的上升。霍乱的病原体是霍乱弧菌，它是许多类型水生环境的自然居民，但在沿海生态系统中更为普遍。因此，全球气候变暖，降水模式日益多变，海平面加速上升，很可能对这一传染病的爆发和传播产生广泛影响。大多数这些健康影响可能发生在水文、气候和生态极端情况与人口脆弱性交汇的地方。世界上霍乱易发地区气候条件的可变性和变化的影响还没有得到很好的理解。长期干旱、洪水和大飓风等极端气候事件与重大霍乱疫情有关。这种极端事件也可能在生态系统中造成看不见的变化，并可能影响霍乱细菌。现有文献表明，在将霍乱的蔓延和死灰复燃归因于气候变化方面仍然存在重大的不确定性和知识空白，原因有二：（i）对极端气候和水文条件下的霍乱生态学及其在霍乱流行病学上的表现的认识不完全;以及（ii）缺乏长期数据集，也缺乏能够在一个一致的框架内将气候、水文、生态和霍乱流行病学联系起来的机械模型。三项经验性观察表明，气候变化和变异性与霍乱的生态、水文和微生物学之间可能存在联系：（a）如果目前的变暖趋势继续下去，极端事件可能更加频繁和严重;（B）几乎所有霍乱疫情都起源于沿海地区附近;及（三）极端天气及气候事件可能对霍乱弧菌的爆发及传播有重大影响。综上所述，这三个经验性观察促使我们通过使用综合诊断（第3.2节）和预测（第3.3节）框架调查水文，生态和气候对霍乱流行病学的作用来探索上述两个广泛而复杂的知识差距。在诊断框架内，具体目标是审查气候、水文和生态极端情况与霍乱动态之间的联系，重点是四个相关目标：（1）量化大河流域淡水排放在改变海洋表面温度和浮游植物的关系和季节性方面的作用;（2）定量分析不同地区极端水文气候对霍乱动力学的影响：（3）评价ENSO循环对霍乱动力学的影响;（4）研究海平面变化对河口生态系统和霍乱动力学的影响。为了针对气候变化制定有效的霍乱适应战略，预测框架内的具体目标是为不同的合理情景提供疾病负担和结果的估计。将通过整合现有知识、诊断分析结果和先前开发的三个物理模型（缩小尺度的气候预测、水文模块和生态系统模块），开发霍乱-气候预测模型（CCPM），拟议的CCPM将整合霍乱发生和传播的水文、生态、微生物和海洋决定因素。一个关键的创新是第一次直接应用降尺度气候预测，这些预测来自世界三个不同地区（南亚、撒哈拉以南非洲和拉丁美洲）的霍乱-气候预测模型中的气候模型模拟集合。塔夫茨大学、马里兰州大学和一个国际合作伙伴-孟加拉国水模型研究所-之间的这一合作倡议整合并借鉴了几十年来在霍乱生态学和微生物学、水文学、遥感、气候学、水动力学和生态系统模型方面不断扩大的跨学科经验。一旦经过测试和验证，拟议的霍乱跟踪和预测模型将具有对世界许多地区有用的能力和功能。 公共卫生相关性：气候变化对霍乱动力学和预测的影响 气候变暖可能会对世界不同地区霍乱的爆发和传播产生广泛影响，这些地区的水文、气候和生态极端情况以及人口脆弱性都集中在一起。通过该项目开发的霍乱-气候预测模型将综合霍乱发生和传播的水文、生态、微生物和海洋决定因素。这也许是第一次直接应用降尺度的气候预测，从一个CCPM内的气候模式模拟的集合，为世界上三个不同的霍乱易发地区。一旦经过测试和验证，拟议的CCPM将具备对世界许多地区有用的能力和功能。

DESCRIPTION (provided by applicant): Cholera has reemerged as a global killer with the world witnessing an unprecedented rise in cholera infection and transmission over the past two decades. The causative agent of cholera is Vibrio cholera, a natural inhabitant of many types of aquatic environments but is more prevalent in coastal ecosystems. Thus, a warmer global climate with increasingly variable precipitation patterns and accelerated sea level rise is likely to have wide-ranging effects on the outbreaks and transmission of this infectious disease. Most of these health effects are likely to occur where hydrologic, climatic, and ecological extremes and population vulnerability converge. The impact of variability and changes in climatic conditions in cholera prone regions of the world are not well understood. Extreme climatic events such as prolonged droughts, floods and major cyclones have been implicated with major cholera epidemics. Such extreme events are also likely to create unseen changes in the ecosystem and can potentially impact cholera bacteria. Existing literature suggests that significant uncertainly and knowledge gaps remain in attributing the expansion and resurgence of cholera to climate change for two reasons: (i) incomplete understanding of ecology of cholera within the context of climatic and hydrologic extremes and their manifestations on the epidemiology of cholera; and (ii) lack of long-term data sets as well as absence of mechanistic models that can link climate, hydrology, ecology, and epidemiology of cholera within a consistent framework. Three empirical observations suggest possible connections among climate change and variability with ecology, hydrology and microbiology of cholera: (a) if the current warming trends continue, extreme events are likely to be more frequent and intense; (b) almost all cholera outbreaks originate near the coastal areas; and (c) extreme weather and climate events are likely to have significant effects on the outbreak and transmission of cholera vibrio. Taken together, these three empirical observations motivate us to explore the above two broad and complex knowledge gaps by investigating the role of hydrology, ecology, and climate on the epidemiology of cholera using an integrated diagnostic (Section 3.2) and predictive (Section 3.3) framework. Within the diagnostic framework, the specific aim is to examine linkages among climatic, hydrologic and ecological extremes with cholera dynamics by focusing on four related objectives: (1) Quantify the role of freshwater discharge from the large river basins in altering the relationships and seasonality of sea surface temperature (SST) and phytoplankton; (2) Quantify the effects of hydrologic and climatic extremes on cholera dynamics for different regions; (3) Evaluate the influences of ENSO cycle on cholera dynamics; and (4) Examine the effects of sea-level changes on estuarine ecosystems and cholera dynamics. To develop an effective cholera adaptation strategy for a changing climate, the specific aim within the predictive framework is to provide estimates of disease burden and outcomes for different plausible scenarios. A cholera-climate prediction model (CCPM) will be developed by integrating existing knowledge, results from diagnostic analyses and three previously developed physical models (downscaled climate projections, hydrologic module, and ecosystem module).The proposed CCPM will integrate hydrological, ecological, microbiological and oceanic determinants of cholera occurrences and transmission. A key innovation is the first direct application of downscaled climate projections from an ensemble of climate model simulations within a predictive cholera-climate model for three different regions (South Asia, Sub-Saharan Africa, and Latin America) of the world. This collaborative initiative among Tufts University, University of Maryland, and an international partner - Institute of Water Modeling from Bangladesh -- integrates and builds on several decades of expanding interdisciplinary experience in ecology and microbiology of cholera, hydrology, remote sensing, climatology, hydrodynamic and ecosystem modeling. Once tested and validated, the proposed cholera tracking and prediction model will have the capabilities and functionalities to be useful for many regions of the world. PUBLIC HEALTH RELEVANCE: Effects of Climate Change on Cholera Dynamics and Prediction A warmer climate is likely to have wide-ranging effects on outbreaks and transmission of cholera in different parts of the world where hydrologic, climatic, and ecological extremes and population vulnerability converge. The Cholera-Climate Prediction Model (CCPM) developed through this project will integrate hydrological, ecological, microbiological and oceanic determinants of cholera occurrences and transmission. This is perhaps the first direct application of downscaled climate projections from an ensemble of climate model simulations within a CCPM for three different cholera prone regions of the world. Once tested and validated, the proposed CCPM will have the capabilities and functionalities to be useful for many regions of the world.