Seasonality of cholera in Kolkata and the influence of climate
Abstract 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 variati...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2023-09-01
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| Series: | BMC Infectious Diseases |
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| Online Access: | https://doi.org/10.1186/s12879-023-08532-1 |
| _version_ | 1797453749196685312 |
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| author | Debbie Shackleton Theo Economou Fayyaz Ali Memon Albert Chen Shanta Dutta Suman Kanungo Alok Deb |
| author_facet | Debbie Shackleton Theo Economou Fayyaz Ali Memon Albert Chen Shanta Dutta Suman Kanungo Alok Deb |
| author_sort | Debbie Shackleton |
| collection | DOAJ |
| description | Abstract 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. |
| first_indexed | 2024-03-09T15:27:22Z |
| format | Article |
| id | doaj.art-88a775a8bc5443ccaf78ca366d7b69ae |
| institution | Directory Open Access Journal |
| issn | 1471-2334 |
| language | English |
| last_indexed | 2024-03-09T15:27:22Z |
| publishDate | 2023-09-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Infectious Diseases |
| spelling | doaj.art-88a775a8bc5443ccaf78ca366d7b69ae2023-11-26T12:27:47ZengBMCBMC Infectious Diseases1471-23342023-09-0123111110.1186/s12879-023-08532-1Seasonality of cholera in Kolkata and the influence of climateDebbie Shackleton0Theo Economou1Fayyaz Ali Memon2Albert Chen3Shanta Dutta4Suman Kanungo5Alok Deb6College of Engineering, Mathematics, and Physical Sciences, University of ExeterDepartment of Mathematics, University of ExeterCollege of Engineering, Mathematics, and Physical Sciences, University of ExeterCollege of Engineering, Mathematics, and Physical Sciences, University of ExeterNational Institute of Cholera and Enteric DiseasesNational Institute of Cholera and Enteric DiseasesNational Institute of Cholera and Enteric DiseasesAbstract 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.https://doi.org/10.1186/s12879-023-08532-1Generalized additive modellingClimateCholeraCross-correlation lag analysisIndia |
| spellingShingle | Debbie Shackleton Theo Economou Fayyaz Ali Memon Albert Chen Shanta Dutta Suman Kanungo Alok Deb Seasonality of cholera in Kolkata and the influence of climate BMC Infectious Diseases Generalized additive modelling Climate Cholera Cross-correlation lag analysis India |
| 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 | Generalized additive modelling Climate Cholera Cross-correlation lag analysis India |
| url | https://doi.org/10.1186/s12879-023-08532-1 |
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