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. 2021 Apr 12;104(6):2251-2263.
doi: 10.4269/ajtmh.20-1189.

Statistical Regression Model of Water, Sanitation, and Hygiene; Treatment Coverage; and Environmental Influences on School-Level Soil-Transmitted Helminths and Schistosome Prevalence in Kenya: Secondary Analysis of the National Deworming Program Data

Collins Okoyo  1   2 , Suzy J Campbell  3 , Chrispin Owaga  4 , Nelson Onyango  2 , Graham Medley  5 , Charles Mwandawiro  1
Affiliations

Statistical Regression Model of Water, Sanitation, and Hygiene; Treatment Coverage; and Environmental Influences on School-Level Soil-Transmitted Helminths and Schistosome Prevalence in Kenya: Secondary Analysis of the National Deworming Program Data

Collins Okoyo et al. Am J Trop Med Hyg. .

Abstract

According to the Kenya National School-Based Deworming program launched in 2012 and implemented for the first 5 years (2012-2017), the prevalence of soil-transmitted helminths (STH) and schistosomiasis substantially reduced over the mentioned period among the surveyed schools. However, this reduction is heterogeneous. In this study, we aimed to determine the factors associated with the 5-year school-level infection prevalence and relative reduction (RR) in prevalence in Kenya following the implementation of the program. Multiple variables related to treatment, water, sanitation, and hygiene (WASH) and environmental factors were assembled and included in mixed-effects linear regression models to identify key determinants of the school location STH and schistosomiasis prevalence and RR. Reduced prevalence of Ascaris lumbricoides was associated with low (< 1%) baseline prevalence, seven rounds of treatment, high (50-75%) self-reported coverage of household handwashing facility equipped with water and soap, high (20-25°C) land surface temperature, and community population density of 5-10 people per 100 m2. Reduced hookworm prevalence was associated with low (< 1%) baseline prevalence and the presence of a school feeding program. Reduced Trichuris trichiura prevalence was associated with low (< 1%) baseline prevalence. Reduced Schistosoma mansoni prevalence was associated with low (< 1%) baseline prevalence, three treatment rounds, and high (> 75%) reported coverage of a household improved water source. Reduced Schistosoma haematobium was associated with high aridity index. Analysis indicated that a combination of factors, including the number of treatment rounds, multiple related program interventions, community- and school-level WASH, and several environmental factors had a major influence on the school-level infection transmission and reduction.

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Conflict of interest statement

Disclosure: All the relevant data supporting the conclusions of this manuscript are provided within the article. The raw datasets analyzed were from the respective programs and can be directly requested from them. This article was published with the permission of the director general, KEMRI. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Ethical approval for the original M&E study protocol was obtained from the Kenya Medical Research Institute (KEMRI)’s Scientific and Ethics Review Unit (SSC Number 2206). At the county level, approval was provided by the respective county health and education authorities. At school, parental consent was obtained based on passive opt-out consent rather than written opt-in consent because of the routine and low risk nature of the study procedure. In addition, individual assent was obtained from each child before participation in the study. Furthermore, the datasets for this additional analysis were requested from and approved by the KEMRI’s M&E program and Evidence Action. All data used were anonymized.

Figures

Figure 1.
Figure 1.
Comparison of year 1 and year 5 infection prevalence for soil-transmitted helminths (STH) and schistosome species among the 199 schools included in the analysis. The prevalence together with the associated 95% CI was estimated using binomial regression model while accounting for school clusters.
See this image and copyright information in PMC

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