Enteropathogen infections in areas with poor access to water, sanitation, and hygiene: environmental drivers, co-infections, and potential interventions Open Access

Chard, Anna N. (Spring 2019)

Permanent URL: https://etd.library.emory.edu/concern/etds/0k225b97p?locale=en


Enteric disease­ — including diarrheal illness and soil-transmitted helminth (STH) infections ­— is common in low-resource settings and primarily driven by inadequate access to water, sanitation, and hygiene (WASH). To better understand the potential for environmental improvements to mitigate enteric infection, we designed and conducted a series of studies in rural Lao People’s Democratic Republic to measure the prevalence of enteropathogens, elucidate how enteropathogens interact with each other, and quantify the role of WASH in schools as a potential environmental mediator of infection in school children.   

We conducted a longitudinal cluster-randomized controlled trial (RCT) to evaluate the impact of a comprehensive WASH in schools (WinS) evaluation on pupil absence and health among 100 randomly selected primary schools (50 intervention and 50 control). Within this study, we conducted a cross-sectional sub-study to examine the underlying drivers of enteropathogen infections and co-infection among households in the RCT school-hosting communities. We utilized a household survey to measure demographics and WASH access, and collected stool samples from three household members (child <5, school-aged child, and their parent). Stool samples (n=891) were analyzed for 25 enteropathogens using a quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay.

Enteropathogen infection was nearly universal; 98.3% of participants had at least one infection (mean=4.3 infections, standard deviation=2.0). Associations between household- and village-level WASH transmission pathways and infection were heterogenous across taxa and specific pathogens. STH infection was associated with lower odds of concurrent viral infections (odds ratio [OR]: 0.48, 95% confidence interval [CI]: 0.28, 0.83), but higher odds of concurrent bacterial infections (OR: 1.81, 95% CI: 1.06, 3.07) and concurrent protozoal infections (OR: 1.50, 95% CI: 0.95, 2.37). In the parent trial, we found no impact of the WinS intervention on any primary (pupil absence) or secondary (enrollment, dropout, grade progression, diarrhea, respiratory infection, conjunctivitis, STH) impacts. Results highlight the challenges and complexities of mitigating enteric disease due to a diverse range of pathogens, multiple transmission routes, within-host interactions, and human-environment interactions. 

Table of Contents

Table of Contents

Introduction   1

Dissertation Aims      7

Study Setting 7

Study Design  8

Additional Research  10

References     13

Chapter 1. Environmental and spatial determinants of enteric pathogen infection in rural Lao People’s Democratic Republic: A cross-sectional study  21

Abstract         22

Introduction   23

Methods         26

Results 31

Discussion      38

Conclusions    45

Acknowledgments     46

References     47

Figures 56

Chapter 2. Associations between soil-transmitted helminthiasis and viral, bacterial, and protozoal enteroinfections: A cross-sectional study in rural Laos       58

Abstract         59

Introduction   61

Materials and Methods         63

Results 70

Discussion      72

Conclusions    78

List of abbreviations  78

Declarations   79

References     82

Tables 89

Supplementary Material       92

Chapter 3. Impact of a school-based water, sanitation, and hygiene intervention on school absence, diarrhea, respiratory infection, and soil-transmitted helminths: Results from the WASH HELPS cluster-randomized trial    95

Abstract         96

Introduction   98

Methods         100

Results 109

Discussion      111

Conclusions    116

Declarations   116

References     119

Figures 123

Tables 125

Discussion      128

Strengths and limitations      130

Policy and program recommendations         136

Recommendations for future research         137

References     140

Appendices of articles published during PhD 145

Appendix 1. Design, Intervention Fidelity, and Behavioral Outcomes of a School-Based Water, Sanitation, and Hygiene Cluster-Randomized Trial in Laos 146

Appendix 2. The impact of school water, sanitation, and hygiene improvements on infectious disease using serum antibody detection           180

Appendix 3. The impact of water consumption on hydration and cognition among schoolchildren: Methods and results from a crossover trial in rural Mali       210

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