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Seasonality of cholera in Kolkata and the influence of climate

BACKGROUND: Cholera in Kolkata remains endemic and the Indian city is burdened with a high number of annual cases. Climate change is widely considered to exacerbate cholera, however the precise relationship between climate and cholera is highly heterogeneous in space and considerable variation can b...

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Autores principales: Shackleton, Debbie, Economou, Theo, Memon, Fayyaz Ali, Chen, Albert, Dutta, Shanta, Kanungo, Suman, Deb, Alok
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10474634/
https://www.ncbi.nlm.nih.gov/pubmed/37660078
http://dx.doi.org/10.1186/s12879-023-08532-1
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author Shackleton, Debbie
Economou, Theo
Memon, Fayyaz Ali
Chen, Albert
Dutta, Shanta
Kanungo, Suman
Deb, Alok
author_facet Shackleton, Debbie
Economou, Theo
Memon, Fayyaz Ali
Chen, Albert
Dutta, Shanta
Kanungo, Suman
Deb, Alok
author_sort Shackleton, Debbie
collection PubMed
description BACKGROUND: Cholera in Kolkata remains endemic and the Indian city is burdened with a high number of annual cases. Climate change is widely considered to exacerbate cholera, however the precise relationship between climate and cholera is highly heterogeneous in space and considerable variation can be observed even within the Indian subcontinent. To date, relatively few studies have been conducted regarding the influence of climate on cholera in Kolkata. METHODS: We considered 21 years of confirmed cholera cases from the Infectious Disease Hospital in Kolkata during the period of 1999–2019. We used Generalised Additive Modelling (GAM) to extract the non-linear relationship between cholera and different climatic factors; temperature, rainfall and sea surface temperature (SST). Peak associated lag times were identified using cross-correlation lag analysis. RESULTS: Our findings revealed a bi-annual pattern of cholera cases with two peaks coinciding with the increase in temperature in summer and the onset of monsoon rains. Variables selected as explanatory variables in the GAM model were temperature and rainfall. Temperature was the only significant factor associated with summer cholera (mean temperature of 30.3 °C associated with RR of 3.8) while rainfall was found to be the main driver of monsoon cholera (550 mm total monthly rainfall associated with RR of 3.38). Lag time analysis revealed that the association between temperature and cholera cases in the summer had a longer peak lag time compared to that between rainfall and cholera during the monsoon. We propose several mechanisms by which these relationships are mediated. CONCLUSIONS: Kolkata exhibits a dual-peak phenomenon with independent mediating factors. We suggest that the summer peak is due to increased bacterial concentration in urban water bodies, while the monsoon peak is driven by contaminated flood waters. Our results underscore the potential utility of preventative strategies tailored to these seasonal and climatic patterns, including efforts to reduce direct contact with urban water bodies in summer and to protect residents from flood waters during monsoon. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12879-023-08532-1.
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spelling pubmed-104746342023-09-03 Seasonality of cholera in Kolkata and the influence of climate Shackleton, Debbie Economou, Theo Memon, Fayyaz Ali Chen, Albert Dutta, Shanta Kanungo, Suman Deb, Alok BMC Infect Dis Research BACKGROUND: Cholera in Kolkata remains endemic and the Indian city is burdened with a high number of annual cases. Climate change is widely considered to exacerbate cholera, however the precise relationship between climate and cholera is highly heterogeneous in space and considerable variation can be observed even within the Indian subcontinent. To date, relatively few studies have been conducted regarding the influence of climate on cholera in Kolkata. METHODS: We considered 21 years of confirmed cholera cases from the Infectious Disease Hospital in Kolkata during the period of 1999–2019. We used Generalised Additive Modelling (GAM) to extract the non-linear relationship between cholera and different climatic factors; temperature, rainfall and sea surface temperature (SST). Peak associated lag times were identified using cross-correlation lag analysis. RESULTS: Our findings revealed a bi-annual pattern of cholera cases with two peaks coinciding with the increase in temperature in summer and the onset of monsoon rains. Variables selected as explanatory variables in the GAM model were temperature and rainfall. Temperature was the only significant factor associated with summer cholera (mean temperature of 30.3 °C associated with RR of 3.8) while rainfall was found to be the main driver of monsoon cholera (550 mm total monthly rainfall associated with RR of 3.38). Lag time analysis revealed that the association between temperature and cholera cases in the summer had a longer peak lag time compared to that between rainfall and cholera during the monsoon. We propose several mechanisms by which these relationships are mediated. CONCLUSIONS: Kolkata exhibits a dual-peak phenomenon with independent mediating factors. We suggest that the summer peak is due to increased bacterial concentration in urban water bodies, while the monsoon peak is driven by contaminated flood waters. Our results underscore the potential utility of preventative strategies tailored to these seasonal and climatic patterns, including efforts to reduce direct contact with urban water bodies in summer and to protect residents from flood waters during monsoon. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12879-023-08532-1. BioMed Central 2023-09-02 /pmc/articles/PMC10474634/ /pubmed/37660078 http://dx.doi.org/10.1186/s12879-023-08532-1 Text en © The Author(s) 2023 https://creativecommons.org/licenses/by/4.0/Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/ (https://creativecommons.org/publicdomain/zero/1.0/) ) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
spellingShingle Research
Shackleton, Debbie
Economou, Theo
Memon, Fayyaz Ali
Chen, Albert
Dutta, Shanta
Kanungo, Suman
Deb, Alok
Seasonality of cholera in Kolkata and the influence of climate
title Seasonality of cholera in Kolkata and the influence of climate
title_full Seasonality of cholera in Kolkata and the influence of climate
title_fullStr Seasonality of cholera in Kolkata and the influence of climate
title_full_unstemmed Seasonality of cholera in Kolkata and the influence of climate
title_short Seasonality of cholera in Kolkata and the influence of climate
title_sort seasonality of cholera in kolkata and the influence of climate
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10474634/
https://www.ncbi.nlm.nih.gov/pubmed/37660078
http://dx.doi.org/10.1186/s12879-023-08532-1
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