Domains of transmission and association of community, school, and household sanitation with soil-transmitted helminth infections among children in coastal Kenya

Abstract

Introduction Few studies have simultaneously examined the role of sanitation conditions at the home, school, and community on soil-transmitted helminth (STH) infection. We examined the contribution of each domain that children inhabit (home, village, and school) to STH infection and estimated the association of STH infection with sanitation in each domain. Methods Using data from 4,104 children from Kwale County, Kenya, who reported attending school, we used logistic regression models with cross-classified random effects to calculate measures of general contextual effects and estimate associations of village sanitation coverage (percentage of households with reported access to sanitation), school sanitation coverage (number of usable toilets per enrolled pupil), and sanitation access at home with STH infection. Findings We found reported use of a sanitation facility by households was associated with reduced prevalence of hookworm infection but not with reduced prevalence of T. trichiura infection. School sanitation coverage > 3 toilets per 100 pupils was associated with lower prevalence of hookworm infection. School sanitation was not associated with T. trichiura infection. Village sanitation coverage > 81% was associated with reduced prevalence of T. trichiura infection, but no protective association was detected for hookworm infection. General contextual effects represented by residual heterogeneity between village and school domains had comparable impact upon likelihood of hookworm and T. trichiura infection as sanitation coverage in either of these domains. Conclusion Findings support the importance of providing good sanitation facilities to support mass drug administration in reducing the burden of STH infection in children.Author summary Infection by the soil-transmitted helminths (STH) whipworm and hookworm results from either ingestion of eggs or larvae or through skin exposure to larvae. These eggs and larvae develop in suitable soils contaminated with openly-deposited human faeces. Safe disposal of faeces should reduce transmission of STH, yet evidence of the impact of sanitation on STH transmission remains limited. A large, community-wide survey was conducted in 2015 to measure prevalence of STH infections in Kwale County, Kenya. Here, we used this data and observations made in schools to examine the relationship between sanitation conditions at home, school, and village and the presence of STH infection among 4,104 children who attend school. We found that sanitation access at home and school sanitation coverage (number of usable toilets per enrolled pupil), but not the overall level of village sanitation coverage (percentage of households with reported access to sanitation), was protective against hookworm infection. In contrast, only high village sanitation coverage, but not home or school sanitation, was protective against whipworm infection. Current STH control strategies emphasise periodic deworming of at-risk populations, including school-age children. Our findings highlight the need for continued efforts, alongside deworming, to extend access to good sanitation facilities at homes, schools, and across communities.