Effects of functional latrine density on household drinking water contamination, soil-transmitted helminth infection, and diarrhea: a spatial analysis 公开

Abstract

Background: India accounts for 60% of the 2.4 billion people practicing open defecation worldwide. The Government of India's Total Sanitation Campaign (TSC) aimed to increase sanitation coverage. A large cluster-randomized trial (CRT) in Orissa found that coverage across intervention villages varied greatly, and found no village-level health benefits. Latrine use remained low due to poor construction/sociocultural barriers. Given the transmission pathways of sanitation-related illnesses, transmission may often occur on a fine spatial scale. This spatial analysis assesses environmental health impacts of functional latrine coverage, as a proxy of latrine use, within various distances from a household.

Methods: This is a secondary analysis of geospatial data from households in 50 intervention villages in Clasen's CRT. The density of latrines and functional latrines within 25m, 50m, 100m, and 200m was calculated using a multiple ring buffer analysis in ArcGIS. The number and proportions of all latrines and functional latrines were assessed as predictors of household drinking water contamination (N=1,009), soil-transmitted helminthiasis (N=822), diarrhea among all ages (N=1,275) and among children <5 (N=1,017) in univariate and multivariate regressions adjusted for village-level clustering with Generalized Estimating Equations.

Results (of multivariate regressions, unless otherwise stated):Increased latrine coverage, regardless of functionality, was associated with decreased levels of thermotolerant coliform (TTC) in household drinking water at 200m. Increasing the number of functional latrines within 25m yielded the greatest reduction of TTC (28 cfu per 100 mL for each additional functional latrine), though the estimate was not statistically significant (p=0.165). For every additional 10 latrines within 25m, regardless of functionality, household longitudinal diarrhea prevalence (all ages) increased by 2.13 days per 1,000 person days (p=0.044). In univariate models, a 10% increase in the proportion of functional latrines within 200m was associated with about one fewer days of diarrhea per 1,000 person days (p=0.006). The presence of a functional latrine within the household was associated with up to 8 fewer days of childhood diarrhea per 1,000 person days (p<0.05).

Conclusion: Ensuring 100% sanitation coverage and functionality within the immediate surroundings of the home is critical for reducing exposure to pathogenic feces that cause diarrheal diseases.

Table of Contents

I. Literature Review

a.Global sanitation………………………………………………...1

b.Disease burden……………………………………………………2

c.Transmission pathways…………………………………………3

d.Evidence for health benefits of interventions………........5

e.Sanitation coverage………………………………………………8

f.Latrine use & other routes of exposure……………….......12

g.Spatial analyses in WASH……………………………………..14

II. Current Study

a.Rationale………………………………………………………….16

b.Research questions……………………………………………..17

III. Methods

a.Study population…………………………………………………18

b.Latrine functionality……………………………………………19

c.Latrine density……………………………………………………19

d.Fecal contamination in drinking water………………........21

e.Health outcomes…………………………………………………22

f.Statistical analysis……………………………………………….23

IV. Results

a.Observations included in analysis…………………………..25

b.Potential confounding factors………………………………..25

c.Latrine functionality and density…………………………...26

d.Fecal contamination in drinking water…………………....29

e.Soil-transmitted helminthiasis………………………………35

f.Diarrhea among all household members……………….....41

g.Diarrhea among children under five………………………..47

V. Discussion ……………………………………………………...53

VI. Conclusions & Recommendations ………………….......58

VII. References…………………………………………………….59

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 Environmental Health
关键词	environmental exposure water quality rural sanitation soil-transmitted helminth diarrhea open defecation India water, sanitation and hygiene
Committee Chair / Thesis Advisor	Clasen, Thomas, Emory University
Committee Members	Tolbert, Paige, Emory University
Partnering Agencies	Emory University schools, faculty or affiliated programs

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