The Association between Heavy Rainfall Events and Diarrheal Disease: The Influence of Urban and Rural Geography Open Access

Deshpande, Ani (2016)

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Climate change is expected to impact health outcomes in the 21st century. Changes in precipitation are projected, with greater contrasts between wet and dry periods and increases in extreme weather events. Heavy rainfall events (HRE) have been shown to be associated with diarrheal diseases and waterborne disease outbreaks. Diarrhea remains an important cause of mortality amongst children under five years of age, causing over 700,000 deaths per year, and is also associated with long term health outcomes such as stunting. Differences in urban and rural settings could play an important role in driving the relationship between precipitation and diarrhea due to underlying differences in infrastructure and social factors. In this study we examine how urban versus rural contexts affects the relationship between HRE and diarrheal disease, using a dataset of daily case counts of diarrhea in all public hospitals and clinics from all 68 parishes in the Esmeraldas province of northwestern Ecuador from 2013-14. Our rainfall exposure measurements were taken from average daily precipitation estimates from the TRMM 3B42 satellite platform. HRE was defined as daily rainfall higher than the 90th percentile for the entire period, and antecedent rainfall conditions were defined as wet or dry depending on 8-week total prior rainfall. We carried out mixed effects Poisson regression on daily case count data, with heavy rainfall estimates and antecedent conditions lagged from 0 to 14 days. In rural areas, we found a positive association between HRE and daily case counts of diarrhea during the dry season, whereas a protective effect was observed in the wet season. In urban areas the expected counts of diarrhea were higher in all environmental conditions analyzed when compared to rural areas, and there was no protective effect in the wet season. Factors associated with urbanization, such as crowding or infrastructure, seem to dominate over climate related factors. Despite this, dry conditions appear to be highly associated with increased diarrhea in all areas. This study provides interesting insights into differences in mechanistic differences in how rainfall is associated with diarrhea in urban and rural areas.

Table of Contents

1. Chapter I: Manuscript

A. Title, Authors, Abstract

B. Introduction

C. Methods

D. Results

E. Discussion

F. References

G. Tables

H. Figures with Legends

2. Chapter II: Summary

3. Appendices

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