The Impact of Water, Sanitation, and Hygiene (WaSH) in the Presence of Suboptimal Adherence and Complex Interdependencies Open Access

Garn, Joshua (2015)

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The health and educational impacts of school-based water, sanitation, and hygiene (WaSH) are not well established. Suboptimal adherence to WaSH - either to individual technologies and behaviors, or to complementary WaSH combinations - adds complexity to estimating these effects. We performed three studies, each relating to WaSH access and adherence. In our first two studies, we characterize the effects of WaSH in school settings where there was suboptimal adherence and complex adherence patterns. We hypothesized that increased adherence to relevant WaSH combinations would be associated with prevention of infectious diseases. For our final study we sought to understand factors associated with suboptimal adherence, specifically the sanitation component of WaSH.

Our first study used data from a cluster randomized trial that took place in 185 Kenyan schools. There was sub-optimal implementation of WaSH at many schools (i.e. poor school-level adherence), which may have led to intention-to-treat results that were different from what might have been observed under hypothetical conditions of good adherence. We used an instrumental variable analysis to estimate the effects of school-level WaSH adherence on diarrheal illness and on soil-transmitted helminth (STH) infection. We observed that for several outcomes, the preventive effects of WaSH were stronger among schools with better adherence.

For our second study, we characterized the associations between A. lumbricoides reinfection and children's WaSH exposures at school and home, for pupils attending 51 Kenyan schools. There was evidence that some WaSH exposures are independently associated with A. lumbricoides reinfection, but that others depended upon adherence to combinations of WaSH. Estimates were sometimes more pronounced with adherence at both school and home. Counterintuitively, increased access to school latrines was associated with higher reinfection.

In our final study, we used data from 60 Kenyan schools, and characterized the associations between school sanitation conditions and pupils' use of sanitation facilities. A variety of school sanitation conditions were associated with pupils' toilet use, including pupil to toilet ratio, toilet type, toilet age, the number of toilets in a block, and facility cleanliness.

Taken together, these three studies help to characterize the complex role of WaSH adherence in improving child health.

Table of Contents

CHAPTER 1: Overview of WaSH, health, and three studies 1

CHAPTER 2: Methods to deal with non-adherence in trials 12

CHAPTER 3: Using structural nested models to estimate the effect of school WaSH on pupil diarrhea and STH infection 31

CHAPTER 4: Pupils' school and home water, sanitation, and hygiene exposures on Ascaris lumbricoides reinfection 53

CHAPTER 5: Factors associated with pupil toilet use in Kenyan primary schools 79

CHAPTER 6: Conclusions and future directions 102



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