Role of estuarine biogeochemistry on abundance and types of Vibrio cholerae in West Bengal: seasonality and relation with cholera incidence

恒河三角洲可能拥有世界上最大的红树林（孙德尔本斯）。然而，这个水生生态系统的动态与高有机物输入和强大的，经常性的洪水知之甚少，特别是季节性变化和水的地球化学和微生物学的联系。霍乱弧菌是这些沃茨水域的天然居民。虽然这个生态系统自古以来就与地方性霍乱有关，但大多数与水生生态系统有关的证据大多来自内陆池塘或海洋参数。目前还没有系统的研究确定西孟加拉河口的有机、无机营养物和物理化学参数的年度循环与霍乱弧菌的季节动态之间的因果关系，而霍乱弧菌是本项目的主要目标。此外，有待研究的具体假设是：（a）甲壳质微碎屑而不是浮游动物是霍乱弧菌的主要宿主（B）即使在环境浓度下，较高含量的甲壳质、盐、营养物和微生物也有利于致病性水生霍乱弧菌新变种的短期出现。(c)孙德尔本斯地区存在特定霍乱弧菌的小生境，包括致病血清型（非马血清型或混合血清型）。可培养或休眠形式、01、0139、非01和非0139血清型的季节性将有助于了解流行和流行间隔期。这项研究将揭示特定的霍乱弧菌类型是否对河口梯度更具抵抗力，以及旋风造成的沉积物再悬浮如何影响水柱中霍乱弧菌的多样性和丰度。这些数据将与季节性霍乱发病模式有关。

The Ganges delta embraces the likely largest mangroves (Sunderbans) worldwide. Yet, the dynamics of this aquatic ecosystem with high organic matter input and strong, recurrent floods are poorly understood, particularly the seasonal variation and links of water biogeochemistry and microbiology. Vibrio cholerae is a natural inhabitant of these waters. Although this ecosystem has been related since ancient times to endemic cholera, most evidence relating disease incidence to aquatic ecosystems has been mostly obtained from inland ponds or ocean parameters. There are no systematic studies establishing causal links between the yearly cycles of organic, inorganic nutrients and physico-chemical parameters in West Bengal estuaries and the seasonal dynamics of V. cholerae, a main objective of this project. Further, specific hypotheses to be investigated are:(a) Chitinaceous micro-detritus rather than Zooplankton are a main V. cholera reservoir(b) Even at environmental concentrations, higher contents of chitin, salt, nutrients andphages favor short-term emergence of new variants of pathogenic aquatic V. cholerae.(c) There are niches in Sunderbans hosting specific V. cholerae, including pathogenicserogroups ( nonmar or hybrid).The seasonality of cultivable or dormant forms, 01, 0139, non-01 and non-0139 serotypes will help understand epidemic and interepidemic periodicity. The study will reveal if specific V. cholerae types are more resistant to estuarine gradients and how sediment resuspension by cyclones influences V. cholerae diversity and abundance in the water column. These data will be related to seasonal cholera incidence patterns.