The Changing Cholera-Climate Relationship in the Bengal Delta over the Past Century

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 how and if this relationship has changed over time. Results: In this study, we analyse the changing relationship between climate and cholera over a recent (1999-2019) and historical (1897-1941) time interval using wavelet analysis to measure signal coherence. Significant and non-stationary coherence levels with cholera were observed in both time intervals for both climate oscillations. While a notable weakening of the relationship with ENSO over time was evident, the relationship with IOD remained strong. Our results suggest that temperature, and not rainfall or SST, is the mediating factor behind the association between cholera and both climate oscillations. Conclusions: Despite consistent improvements to WASH infrastructure, the link between cholera and climate remains strong. Climate-change induced warming and strengthening of the IOD are likely to increase vulnerability to cholera in the region in the future.