Microscale Dynamics of Escherichia coli in Rivers of Northern Coastal Ecuador Open Access

Abstract

Background: Diarrheal disease is a leading cause of mortality and morbidity around the world, killing approximately 1.5 million children and resulting in 2 billion cases every year. The use of contaminated water continues to be a pressing issue, with approximately 1.1 billion people who lack access to improved water sources in the world. In northern coastal Ecuador many communities rely heavily on untreated surface water as their primary source of drinking water. These villages routinely access the river for water for drinking, cooking, bathing, washing, navigation, and recreation, and through these interactions the streams become contaminated.

Methods: We undertook a study to explore how specific water collection locations and microscale river hydrodynamics affect microbial water quality on three rivers with varying stream velocity and turbidity profiles (Rio Santiago, Rio Onzole, Rio Cayapas).

We carried out this research in six villages in the Esmeraldas Province of northern coastal Ecuador during June-July, 2012. Our study focused on the following questions: (1) How does distance from river shore affect microbial contamination levels; and (2) How do physicochemical water quality variables affect microbial contamination levels in the river. We collected a total of 355 water samples and tested for E. coli concentrations using the IDEXX Quantitray method. We established 2-3 transects in each village at sites where villagers washed clothes and dishes, and collected water. Each transect consisted of six point samples to cover locations both within and outside of the river eddy.

Results: We found a significant association between proximity to shore and E. coli concentrations. Higher E. coli concentrations were also significantly associated with increased turbidity and decreased dissolved oxygen levels.

Conclusion: The results of this study can help inform community members about the safest locations to collect drinking water and can also provide information to characterize and differentiate rivers based on localized contamination of microbial contaminants and water quality parameters.

Table of Contents

INTRODUCTION............................................................................................................. 1

METHODS........................................................................................................................ 5

Study Region..................................................................................................................... 5

Study Design..................................................................................................................... 6

Sampling Methods............................................................................................................ 7

Laboratory Methods....................................................................................................... 12

Data Analysis Methods................................................................................................. 13

Data entry and cleaning........................................................................................................ 13

RESULTS........................................................................................................................ 19

Summary Statistics......................................................................................................... 19

DISCUSSION................................................................................................................. 28

CONCLUSION............................................................................................................... 30

REFERENCES................................................................................................................. 31

About this Master's Thesis

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School	Rollins School of Public Health
Department	Environmental Health
Degree	MPH
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health
Keyword	E. coli Ecuador River
Committee Chair / Thesis Advisor	Levy, Karen, Emory University
Partnering Agencies	Emory University schools, faculty or affiliated programs University, college or educational institution (other than Emory)

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