Assessing effect of sanitation and water supply coverage thresholds on STH parasitology Open Access

Prentice-Mott, Graeme (Spring 2019)

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Based on current evidence, it may be challenging to eliminate soil-transmitted helminths (STH) through preventative chemotherapy (PC) alone. There is reason to believe combining water, sanitation, and hygiene (WASH) interventions with PC may be the next step towards STH elimination. We conducted secondary analysis of impact evaluation data collected by the Kenya Medical Research Institute (KEMRI) from January to May 2018 in schools participating in a national PC program (N = 9,400 students from 100 schools). Stool samples were analyzed using the Kato-Katz technique and household WASH conditions were recorded based on student reports. We used mixed-effects log-binomial and negative binominal hurdle models to assess associations between STH prevalence/infection intensity and WASH access in school-clusters. We found increased infection intensity for hookworms for those with a private household latrine (IRR 2.00; 95% CI: 1.05, 3.81). Prevalence of STH was also highest in students for whom 60-79.9% of classmates had access to a private household latrine (PR 5.59; 95% CI: 2.13, 14.68). While estimates were imprecise, among students with a private household latrine, having at least 80% of classmates who also had a private household latrine was associated with lower infection intensity for T. trichiuria and hookworms (IRRtrichuris 0.15; 95% CI: <0.01, 4.78 – IRRhookworms 0.23; 95% CI: 0.02, 2.68). We also found prevalence of A. lumbricoides was lower for students if at least 67% of classmates had household water access (PR 0.05; 95% CI: 0.02, 0.19). Our findings indicate that STH reductions following PC might not be observed in communities with increased latrine access, however the study may have limitations.

Table of Contents

Table of Contents

Introduction. 1

Methods. 5

Study Design. 5

Outcomes. 6

Predictors. 6

Community Coverage Assessment 7

Control Variables. 8

Data Analysis. 9

Results. 13

Descriptive Statistics for STH, sanitation, and water. 13

Figure 1. 14

Table 1. 14

Table 2. 15

Multivariable Analyses. 15

Table 3. 16

Table 4. 17

Figure 2. 18

Table 5. 19

Figure 3. 20

Discussion. 20

Strengths. 23

Limitations. 24

Conclusion. 25

Works Cited. 27

Appendix. 31

A1. 31

A2. 31

A3. 32

A4. 32

A5. 32

A6. 33

A7. 33


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