International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), 68 Shaheed Tajuddin Ahmed Sarani, Mohakhali, Dhaka 1212, Bangladesh.
International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), 68 Shaheed Tajuddin Ahmed Sarani, Mohakhali, Dhaka 1212, Bangladesh.
Vaccine. 2020 Feb 29;38 Suppl 1:A52-A62. doi: 10.1016/j.vaccine.2019.06.033. Epub 2019 Jul 5.
The environmental reservoir of Vibrio cholerae, the causative agent of cholera, has been a topic of scientific investigation ever since the discovery of the bacterium itself. While the bacteria can be isolated from both clinical and environmental sources during epidemics, it evades isolation by conventional culture techniques during the period between successive epidemics. The problem is identifying the location and mode of survival and multiplication of V. cholerae during this inter-epidemic period. This information is crucial not only for epidemiological reasons, but also because the seasonality of cholera epidemics is plausibly mediated by the climate-regulated activity of the reservoir. This article focuses on the epidemiological importance of the environmental reservoir of V. cholerae, considering several investigations made on different types of aquatic fauna (zooplanktons, crustaceans, etc.) and flora (macrophytes and microphytes). After evaluating different lines of evidence, we make the case that certain species of cyanobacteria (Anabaena variabilis, Microcystis aeruginosa) can act as inter-epidemic reservoirs of V. cholerae. Physiological and functional aspects of this association are also discussed. We then present a hypothesis, expanding upon a previously published conceptual model, of how the climate-regulated seasonality of cholera epidemics is mediated by the effect of climatic factors on algal bloom and other local abiotic variables in the water, using Bangladesh as a model. Finally, another aspect of the climate-dependence of disease patterns is briefly explored: large-scale environmental signatures associated with cholera, and recent modelling efforts to predict cholera outbreaks based on coastal phytoplankton. The review, therefore, serves not only as a study of the identity of the inter-epidemic reservoir of V. cholerae, but also explores different ways in which the reservoir and the pathogen behaviour is affected by the climate, and the possible consequences it may have on disease pattern.
霍乱弧菌的环境储库一直是科学研究的主题，自从发现该细菌以来，它一直是科学研究的主题。虽然在流行期间可以从临床和环境来源中分离出细菌，但在连续流行之间的时期，它会逃避常规培养技术的分离。问题是确定 V. cholerae 在这一流行间期的位置和生存方式。这一信息不仅具有流行病学意义，而且还因为霍乱流行的季节性可能是由储库的气候调节活动介导的。本文重点关注 V. cholerae 的环境储库的流行病学重要性，考虑了对不同类型水生动物（浮游动物、甲壳类动物等）和植物（大型植物和小型植物）进行的几项调查。在评估了不同的证据后，我们提出了一个案例，即某些蓝藻物种（变异性 Anabaena variabilis、铜绿微囊藻 Microcystis aeruginosa）可以作为 V. cholerae 的流行间期储库。还讨论了这种关联的生理和功能方面。然后，我们提出了一个假设，扩展了以前发表的概念模型，即气候对藻类水华和水中其他局部非生物变量的影响如何通过气候因素来调节霍乱流行的季节性，以孟加拉国为例。最后，简要探讨了疾病模式对气候的依赖的另一个方面：与霍乱相关的大规模环境特征，以及最近基于沿海浮游植物预测霍乱爆发的建模工作。因此，该综述不仅研究了 V. cholerae 的流行间期储库的身份，还探讨了储库和病原体行为受气候影响的不同方式，以及这可能对疾病模式产生的可能后果。
