The changing relationship between Cholera and interannual climate variables in Kolkata over the past century

Debbie Shackleton; Fayyaz Ali Memon; Albert Chen; Shanta Dutta; Suman Kanungo; Alok Deb

doi:10.1186/s13099-023-00565-w

The changing relationship between Cholera and interannual climate variables in Kolkata over the past century

Gut Pathog. 2023 Sep 13;15(1):42. doi: 10.1186/s13099-023-00565-w.

Authors

Debbie Shackleton¹, Fayyaz Ali Memon², Albert Chen², Shanta Dutta³, Suman Kanungo³, Alok Deb³

Affiliations

¹ Centre for Water Systems, Department of Engineering, University of Exeter, EX4 4QF, Exeter, UK. dmshackleton@gmail.com.
² Centre for Water Systems, Department of Engineering, University of Exeter, EX4 4QF, Exeter, UK.
³ National Institute of Cholera and Enteric Diseases, Kolkata, India.

Abstract

Background: In the Bengal Delta, research has shown that climate and cholera are linked. One demonstration of this is the relationship between interannual ocean-atmospheric oscillations such as the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD). What remains unclear in the present literature is the nature of this relationship in the specific context of Kolkata, and how this relationship may have changed over time.

Results: In this study, we analyse the changing relationship between ENSO and IOD with cholera in Kolkata over recent (1999-2019) and historical (1897-1941) time intervals. Wavelet coherence analysis revealed significant non-stationary association at 2-4 year and 4-8 year periods between cholera and both interannual timeseries during both time intervals. However, coherence was notably weakened in the recent interval, particularly with regards to ENSO, a result supported by a complementary SARIMA analysis. Similar coherence patterns with temperature indicate it could be an important mediating factor in the relationship between cholera and oscillating climate phenomena in Kolkata.

Conclusions: This study reveals a shifting relationship between cholera and climate variables (ENSO and IOD) in Kolkata, suggesting a decoupling between environmental influences and cholera transmission in recent years. Our results therefore do not suggest that an intensification of ENSO is likely to significantly influence cholera in the region. We also find that the relationship between cholera and interannual climate variables is distinct to Kolkata, highlighting the spatial heterogeneity of the climate-cholera relationship even within the Bengal Delta.

Keywords: Cholera; Climate; ENSO; IOD; Wavelet Analysis.

Grants and funding

WISE CDT; EP/L016214/1/EPSRC