Environmental Risk Factors during the Zimbabwe Cholera Outbreak, 2008-2009 Open Access

Abstract

Environmental Risk Factors during the Zimbabwe Cholera Outbreak, 2008-2009
By David Berendes
Cholera is a waterborne disease that causes outbreaks worldwide. Despite advances in
safe water distribution networks in the developing world, cholera and other waterborne
diseases persist in the environment. In Zimbabwe, gradual economic collapse over the
last 10 years culminated in the creation of a complex humanitarian emergency state in
2008, with massive loss of health and water infrastructure. This situation put the country
at risk for one of the largest and most severe cholera outbreaks in the past 10 years. The
goal of this study was to assess the effect of safe water use, particularly borehole use, at
the village level in preventing cholera spread and lowering cholera attack rates in the
Chivi and Gokwe North districts during the outbreak. Safe water use, and borehole use
in particular, was associated with reduced attack rates and fewer outbreak-affected
villages when compared with unsafe water use by villages. Both the reductions seen in
attack rates and those seen in cholera prevalence across villages were borderline
significant. Missing data was an issue in the analysis, and imputation methods were
compared and contrasted in the development of final logistic and multiple linear
regression models. Despite the limited availability of timely point-of-use water treatment
in the Zimbabwean cholera outbreak, a characteristic inherent to many response efforts,
there was suggestive but inconclusive evidence that water quality at the source may
reduce cholera morbidity by itself. This paper has important implications not only for
field outbreak data methodology, but for water and sanitation promotion as well. While
simple imputation methods seem to be the norm in outbreaks in the field, there was value
in multiple imputation methods for improving the validity and precision of the model
estimates.

Environmental Factors in Boreholes Use Affecting the Cholera Outbreak in Zimbabwe
By
David Berendes
B.S., Duke University, 2009
Thesis Committee Chair: Juan Leon PhD, MPH
A thesis submitted to the Faculty of the
Rollins School of Public Health of Emory University
in partial fulfillment of the requirements for the degree of
Master of Science in Public Health
in Global Epidemiology
2011

Table of Contents

Table of Contents

Literature Review: 1
Cholera Surveillance 2
Cholera Types and Environmental Features 3
Clinical Features of Cholera: 4
Treatment of Cholera and Mortality: 5
Cholera Transmission 6
Cholera Outbreaks: 7
Safe Water: 7
Cholera in Africa: 11
Complex Humanitarian Emergencies: 12
Zimbabwe: 16
District-Level Water Access: 17
Goals and Aims: 18
Significance: 19
Materials and Methods: 20
Analysis: 23
Results: 26
Water: 26
Cholera and Water Source Analysis in Study Villages: 28
Cholera Modeling: 29
Discussion: 33
Future Directions and Public Health Implications: 41
Tables and Figures: 43
Table 1: Village Demographics and Attack Rate by District 43
Table 2: Main source of pre-outbreak drinking water and cholera distribution for all villages 44
Table 3: Borehole Functionality and Distribution Across Districts 45
Table 4: Cholera Spread and Attack Rate Analysis by Village Main Water Source Type 46
Table 5: Logistic Regression Model Cholera Distribution by Village on Safe/Unsafe Water Use 47
Table 6: Logistic Regression Model Cholera Distribution by Village on Borehole/Unsafe Water Use 48
Table 7: Risk Factors Associated with Cholera Attack Rate by Village 49
Appendix A: IRB Clearance 50
References: 51

About this Master's Thesis

Rights statement

• Permission granted by the author to include this thesis or dissertation in this repository. All rights reserved by the author. Please contact the author for information regarding the reproduction and use of this thesis or dissertation.

School	Rollins School of Public Health
Department	Epidemiology
Subfield / Discipline	Global Epidemiology - MPH & MSPH
Degree	MSPH
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health Health Sciences, Epidemiology
Keyword	cholera Zimbabwe safe water
Committee Chair / Thesis Advisor	Leon, Juan, Emory University
Committee Members	Handzel, Thomas Richard, Emory University Morof, Diane, CDC
Partnering Agencies	CDC

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