Linkages Between Extreme Precipitation, Water Quality, and Gastrointestinal Illness.

Abstract

Background: The frequency, intensity, and duration of extreme weather events are expected to increase based on current climate model projections. Such changes, particularly those associated with extreme precipitation, will likely threaten water quality and exacerbate global health disparities. Vulnerable subpopulations include children, the elderly, and the poor.

Objectives: This dissertation evaluates the association between extreme precipitation and hospital admissions among: 1) a population in Chennai, India during 2004-2007, 2) the elderly in the Great Lakes Region in relation to beach closures during 2000-2006, and 3) the elderly in 132 U.S. cities during 1992-2006.

Methods: Daily hospital admissions were merged with daily meteorological data. Hospital admissions were examined for seasonal trends. Poisson regression and case-crossover models were fit to evaluate the association between extreme precipitation and daily hospital admissions. Season and age were explored as potential effect modifiers.

Results: In India, extreme precipitation (greater than or equal to the 90th percentile) was positively associated with hospital admissions related to gastrointestinal illness (GI). The cumulative risk, estimated over a 15-day lag period, was 1.61 (95% confidence interval (CI): 1.29, 2.00) and was elevated among the young 2.65 (95% CI: 1.21, 5.80) and the old 1.68 (95% CI: 1.01, 2.80). Risk varied across seasons, peaking during pre-monsoon 1.58 (95% CI: 1.24, 1.90). In the Great Lakes Region, beaches were closed 10% of summer days. Precipitation above the 90th percentile at lag 1 significantly predicted (p <0.05) beach closures in 8 of the 12 cities. No consistent associations between beach closures and hospital admissions were seen when pooled across the 12 cities, 0.98 (95% CI: 0.94, 1.01). In 132 U.S. cities, nearly 1 million GI-related hospital admissions occurred. Overall, no positive associations between extreme precipitation and GI-related hospital admissions were observed. The overall national pooled estimate for risk of GI-related hospital admission at lag 15 was 1.01 (95% CI: 1.00, 1.02).

Conclusions: This work highlights the potential impacts of climate change on waterborne disease in the U.S. and India. The threat of more extreme weather events necessitates further study of how climate and weather are associated with hospital admissions and overall health.