Co-evolving Hydroclimatic Signatures and Diarrheal Disease Dynamics in Bangladesh: Implications for Water Management and Public Health

Abstract:

The Bengal Delta region in South Asia is well-known for its endemicity to diarrheal diseases and high population vulnerability to natural calamities and diarrheal and other water-related disease epidemics. The diarrheal disease outbreaks in the coastal and inland floodplains, such as cholera, rotavirus, and dysentery, show distinct seasonal peaks and spatial signatures in their origin and progression. The last three decades of surveillance data also shows a drastic increase of diarrheal incidence in both urban and peri-urban areas, even after correcting for population trends. Recent research has shown increased roles of hydroclimatic events such as droughts and floods on the seasonal to interannual characteristics, as well as the coastal and inland progression patterns of disease outbreaks. However, the mechanisms behind these phenomena, especially how the changes in the regional climatic and hydrologic processes contributed to the spatio-temporal trends of disease outbreaks are not fully understood.

Here, we analyze the last 30-years of diarrheal incidence in Dhaka and regional surveillance centers with changes in climatic or anthropogenic forcings: regional hydrology, flooding, water usage, population growth and density in urban settlements, as well as shifting climate patterns and frequency of natural disasters. We use a set of CMIP5 (Coupled Model Intercomparison Project Phase 5) model projections of regional precipitation and temperature patterns in Bengal Delta to develop scenarios of diarrheal disease projections with spatial (coastal and inland) and temporal (dry vs wet) comparisons. Our preliminary results shows that growing water scarcity in the dry season, increasing salinity in coastal areas, and lack of sustainable water and sanitation infrastructure for urban settlements have increased endemicity of cholera outbreaks in spring, while record flood events, limited stormwater drainage and sanitation, and more intensive monsoon has contributed to increased epidemic outbreaks. However, a number of future projections suggest that spring will be drier and fall will be wetter in upcoming years especially in the southwestern parts of the Bengal delta, which eventually will make the inhabitants more vulnerable to diarrheal outbreaks.