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

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.

Sensitivity Analysis of a Transmission Interruption Model for the Soil-Transmitted Helminth Infections in Kenya

“…This finding is supported by previous epidemiological studies that have shown high STH (especially Ascaris lumbricoides) burden among pre-school children (75). This high worm burden in these younger children is attributable to their frequent interaction with the contaminated environment especially when they are playing with the soil, eating soil (geophagy), or practicing open defecation (75,76). Therefore, changes in the mortality rate of the infectious materials in the environment will certainly influence the level of worm burdens in the PSAC owing to their high interaction with the environment.…”

Epidemiology of soil-transmitted helminthiasis among school-aged children in pastoralist communities of Kenya: A cross-sectional study

“…trichiura . It has been shown that infection transmission and reduction of STHs can be influenced by environmental conditions, household WASH factors and population density factors [ 19 ].…”

“…More often than not access to water, sanitation and hygiene is linked to socio-economic status. Moreover, factors associated with high prevalence of STHs among SAC have been documented [ 16 , 19 , 20 ]. Currently there is limited data on the prevalence of STHs and the associated risk factors in pastoral communities.…”

Model-based geostatistical design and analysis of prevalence for soil-transmitted helminths in Kenya: Results from ten-years of the Kenya national school-based deworming programme

“…Out of the 27 counties surveyed, 19 counties have attained EPHP while 8 counties which include Bungoma (8.1 %), Nyamira (4.8 %), Kisii (4.5 %), Narok (2.5 %), Kakamega (2.5 %), Nandi (2.4 %), Siaya (2.3 %) and Kericho (2.0 %), have not attained the threshold and shows relatively high disease burden. Previous surveys have documented challenges in the same counties related to transmission drivers including poor sanitation and hygiene conditions, slightly low treatment coverage, suitable environmental conditions for parasite persistence and economic activities that expose individuals to parasite interactions, among other factors [ 26 ]. Improved interventions targeting attainment of EPHP in these counties should be explored as well as research studies to document reasons of persistence of STH in these areas.…”