Epidemiology and Ecology of Cholera in Africa

项目摘要 该项目将描述两个“热点”地区霍乱的不同流行病学和生态模式。 坦桑尼亚和喀麦隆的五大湖附近地区，以了解霍乱出现的性质， 在非洲这些地区传播。 我们的小组描述了孟加拉国霍乱的流行病学和生态学， 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，这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 这是引发和/或加速这些疾病爆发的主要决定因素。 与孟加拉国的这种一贯模式相反，非洲霍乱疫情的可预测性要低得多， 不同国家的情况不同。霍乱“热点”发生在坦桑尼亚和喀麦隆的五大湖周围。 例如，在喀麦隆，每隔几年就会发生一次严重的疫情，病死率很高， 在中间的贫期间未检测到。同样，坦桑尼亚也零星爆发疫情。会同 坦桑尼亚卫生部，使用最近爆发的分子方法，我们可以区分局部 与其他传播更广的暴发有关的暴发，这些暴发与持续传播有关。 同样，在喀麦隆，一个地区的疫情可以追溯到乍得湖地区。 本研究将对可培养和不可培养的霍乱弧菌进行临床和环境监测 坦桑尼亚的两个地区（达累斯萨拉姆及周边地区和基戈马农村）和 喀麦隆.我们将描述来自霍乱患者的霍乱弧菌分离株和溶菌噬菌体的特征， 在医院和社区接触者中进行护理，以比较指示病例与附近病例的菌株 水源和邻居。这些菌株也将与非洲其他地区的菌株进行比较。生态 监测将用于将传播与溶解性弧菌噬菌体的存在、天气模式联系起来; 水的特性。 因此，本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，以提高我们对非洲大片地区霍乱传播模式的认识， 包括限制传播的因素。这项研究将评估霍乱爆发的情况， 传播有限的局部暴发，或者由广泛传播的传入引起 跨越国界。通过提供对包括噬菌体在内的因素的更完整的理解， 霍乱的出现成为流行病，以及他们的崩溃，该项目将指导发展， 在非洲控制霍乱。

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.