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

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  • 1 Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya;
  • 2 School of Mathematics, College of Biological and Physical Sciences, University of Nairobi, Nairobi, Kenya;
  • 3 Deworm the World, Evidence Action, Washington, District of Columbia;
  • 4 Deworm the World, Evidence Action, Nairobi, Kenya;
  • 5 Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, United Kingdom

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.

Author Notes

Address correspondence to Collins Okoyo, Eastern and Southern Africa Centre of International Parasite Control (ESACIPAC), Kenya Medical Research Institute (KEMRI), P.O. Box 54840-00200, Nairobi, Kenya. E-mails: comondi@kemri.org or collinsomondiokoyo@gmail.com

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.

Financial support: The financial support for this study was provided by the END Fund, GiveWell, and Epic Foundation via Evidence Action.

Authors’ addresses: Collins Okoyo, Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya, and School of Mathematics, College of Biological and Physical Sciences, University of Nairobi, Nairobi, Kenya, E-mail: comondi@kemri.org. Suzy J. Campbell, Deworm the World, Evidence Action, Washington, DC, E-mail: suzy.campbell@rocketmail.com. Chrispin Owaga, Deworm the World, Evidence Action, Nairobi, Kenya, E-mail: chrispin.owaga@evidenceaction.org. Nelson Owuor, School of Mathematics, College of Biological and Physical Sciences, University of Nairobi, Nairobi, Kenya, E-mail: onyango@uonbi.ac.ke. Graham Medley, Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, United Kingdom, E-mail: graham.medley@lshtm.ac.uk. Charles Mwandawiro, Charles Mwandawiro, Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya, E-mail: mwandawirocharles@gmail.com.

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