Epidemiology and Ecology of Cholera in Africa

项目总结 该项目将描述两个“热点”不同的霍乱流行病学和生态模式。 坦桑尼亚和喀麦隆五大湖附近地区了解霍乱出现的性质和 在非洲这些地区的传播。 我们小组描述了孟加拉国霍乱的流行病学和生态，那里的霍乱遵循着 可预测的年度时间表。霍乱弧菌，可培养和不可培养的形式都可以在 孟加拉国的池塘，表明来自环境水库的弧菌直接感染人类，导致 粪口传播和季节性暴发。孟加拉国的季节性表明气候因素是 引发和/或加速这些疫情的主要决定因素。 与孟加拉国的这种一贯模式形成对比的是，非洲霍乱疫情的可预测性要低得多，而且 它们在不同的国家有所不同。霍乱“热点”出现在坦桑尼亚和喀麦隆的五大湖周围。 例如，在喀麦隆，每隔几年就会发生严重的疫情，病死率很高，但病例很少。 在中间的瘦肉期没有被检测到。同样，坦桑尼亚也有零星的疫情。使用 坦桑尼亚卫生部，使用分子方法从最近的疫情中，我们可以区分局部 与持续传播有关的其他更广泛传播的疫情。 同样，在喀麦隆，一个地区的疫情在转移到乍得湖地区时可以追踪到。 这项研究将对可培养和不可培养霍乱弧菌进行临床和环境监测。 坦桑尼亚的两个地区(达累斯萨拉姆及其周边地区和基戈马农村)和#年的远北地区 喀麦隆。我们将对霍乱弧菌分离株和霍乱患者的裂解噬菌体进行鉴定 在医院和社区接触者中提供护理，以比较指示病例和附近病例的毒株 水源和邻居。这些毒株还将与来自非洲其他地区的毒株进行比较。生态 监测将用于将传播与裂解噬菌体的存在、天气模式联系起来； 和水的特性。 因此，这项提案将描述坦桑尼亚霍乱的分子流行病学和生态学。 喀麦隆为提高我们对霍乱在非洲大片地区传播模式的了解， 包括限制传播的因素。这项研究将评估霍乱作为一种 传播有限的局部性暴发，或者是广泛传播的引入造成的 跨越国界。通过提供对包括噬菌体在内的因素的更全面的了解，导致 霍乱的流行以及霍乱的消亡，该项目将指导制定 控制非洲霍乱的干预措施。

PROJECT SUMMARY This project will describe the differing epidemiological and ecological patterns of cholera in two “hotspot” regions near the great lakes of Tanzania and Cameroon to understand the nature of cholera emergence and transmission in these areas of Africa. Our group has described cholera’s epidemiology and ecology in Bangladesh where cholera follows a predictable annual schedule. V. cholerae, both culturable and non-culturable forms can be detected in the ponds of Bangladesh, suggesting that vibrios from environmental reservoirs directly infect humans, leading to fecal-oral transmission and seasonal outbreaks. The seasonality in Bangladesh indicates climatic factors to be a major determinant for initiating and / or accelerating these outbreaks. In contrast to this consistent pattern in Bangladesh, African cholera outbreaks are much less predictable and they differ between countries. Cholera “hotspots” occur around the great lakes of Tanzania and Cameroon. For example, in Cameroon, severe outbreaks occur every few years with high case fatality rates, but cases are not detected during intervening lean periods. Similarly, Tanzania has outbreaks sporadically. Working with the Tanzanian Health Ministry, using molecular methods from recent outbreaks, we could differentiate localized outbreaks from other more widely disseminated outbreaks which were associated with continued spread. Similarly, in Cameroon, an outbreak in one region could be traced as it moved to the Lake Chad region. The study will conduct clinical and environmental surveillance for culturable and non-culturable V. cholerae in two regions of Tanzania (Dar es Salaam and surrounding areas and rural Kigoma) and the Far North Region of Cameroon. We will characterize the V. cholerae isolates and lytic vibriophage from cholera patients seeking care at hospital as well as community contacts to compare strains from index cases with those from nearby water sources and neighbors. These will also be compared to strains from other areas in Africa. Ecological surveillance will be used to associate transmission with the presence of lytic vibriophage, weather patterns; and water characteristics. Thus, this proposal will describe the molecular epidemiology and ecology of cholera in Tanzania and Cameroon to improve our understanding of transmission patterns of cholera across large areas of Africa, including factors that limit transmission. The research will evaluate outbreaks in which cholera emerges as a localized outbreak with limited transmission, or alternatively, results from widely transmitted introductions across borders. By providing a more complete understanding of factors, including vibriophage, leading to cholera’s emergence into epidemics, as well as their collapse, the project will guide the development of interventions to control cholera in Africa.