Abstract
BackgroundMost of the studies conducted in Brazil assessing the relationship between water, sanitation and hygiene (WASH) and Soil-transmitted helminth (STH) infections, have focused on cases, reflecting the reality of small areas and not of a countrywide situation. In order to fill this gap, the current paper presents an epidemiological study exploring the association between water and sanitation and STHs prevalence in students from 7 to 17 years old, in all 27 Brazilian Federation Units.MethodsThree ecological studies were carried out considering the prevalence of ascariasis, trichuriasis, and hookworm as outcome variables. The sample consisted of 197,567 students aged 7–17 years old living in 521 Brazilian municipalities. Data were retrieved from the National Survey on the Prevalence of Schistosomiasis mansoni and Soil-transmitted helminth infections (2011–2015). The Generalized Linear Model with the negative binomial distribution was used to evaluate the statistical association between outcomes and explanatory variables. Univariate and Multivariate analyses were conducted with 25 and 5 % significance levels, respectively. Data were aggregated considering municipalities as the geographical unit for analysis.ResultsProtective association was found between access to filtered water and adequate sanitation in schools with ascariasis (RR 0.989, CI 95 % 0.983–0.996; RR 0.988, CI 95 % 0.977–0.998), access to filtered water in schools with trichuriasis (RR 0.986, CI 95 % 0.979–0.993) and adequate sanitation at home with hookworm ((RR 0.989, CI 95 % 0.982–0.996). The percentage of population served with Bolsa Família Program, used as a proxy for poverty, was the only significant variable common to all models.ConclusionsOur findings support that WASH, both in schools and homes, are essential to schoolchildren health with regard to STHs. However, sanitary interventions will not be fully effective in preventing STH infections without promoting access to quality public services, particularly for people living in poverty, the most vulnerable group.
Highlights
Most of the studies conducted in Brazil assessing the relationship between water, sanitation and hygiene (WASH) and Soil-transmitted helminth (STH) infections, have focused on cases, reflecting the reality of small areas and not of a countrywide situation
The reduction of STHs prevalences along the past decades in Brazil and the current disparities in prevalence among municipalities raise questions on the determinants of the control of these diseases. Since they are conditioned by a multiplicity of factors, a key hypothesis for this new epidemiological profile would be the role of environmental determinants, the access to water and sanitation services
Several studies already showed that water, sanitation and hygiene (WASH) play important role in the interruption of the transmission cycle of these parasites [4, 7, 8], empirical evidence that links WASH improvements to reduction in STH infections is still scarce [8, 9]
Summary
Most of the studies conducted in Brazil assessing the relationship between water, sanitation and hygiene (WASH) and Soil-transmitted helminth (STH) infections, have focused on cases, reflecting the reality of small areas and not of a countrywide situation. The prevalence and distribution of STHs are the result of the interdependence of human factors (social, economic and cultural), environmental conditions (temperature, humidity, soil, etc.) and biological aspects of the helminths [2]. In spite of their low mortality rates, these diseases constitute a serious public health problem due to the long-term effects on malnutrition, on compromising children’s physical and intellectual development, and on the reduction of adult work productivity [2]. Nationwide surveys can contribute to a more accurate picture of diseases spread and their distribution within Brazilian territory [6]
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