Abstract
Though the health risks associated with poor access to water, sanitation, and hygiene (WASH) are well established, recent large-scale WASH trials have found limited impact on enteric disease. The aims of this study were to: 1. estimate the prevalence of enteropathogens among children <5, school-aged children, and adults; 2. model associations between WASH transmission pathways and enteropathogen infections; and 3. quantify clustering of enteropathogen infections at the household- and village-level. We conducted a cross-sectional survey in 50 villages in Saravane Province, Lao People’s Democratic Republic. From 297 households, we collected 891 fecal samples from one child <5, one school-aged child, and one adult living in the same household, and collected survey and observational data on household demographics, WASH access, and animal ownership. Fecal samples were analyzed for 25 enteropathogens using a qRT-PCR assay. We observed near universal infection with at least one enteropathogen (98.3%). Few household or village-level WASH covariates were statistically associated with enteropathogen infection. Concordant household infection was higher than expected under the independence assumption for 14 of the 21 pathogens for which we had sufficient data, indicating strong household correlation for many infections. Median odds ratios (MORs), a measure of cluster-level (e.g. village and household) influence on an individual’s odds of infection, were elevated at the village level, particularly for viruses (MOR: 3.89; 95% confidence interval [CI]: 2.64, 6.69), protozoa (MOR: 2.07; 95% CI: 1.59, 3.10), and soil-transmitted helminths (MOR: 2.46; 95% CI: 1.89, 3.56), indicating strong village-level differences in individuals' odds of enteric infections. WASH access, as hypothesized, is associated with fewer enteroinfections, but WASH access as currently defined does not reveal a measurably protective association with infection for many etiologies. Household- and community-level factors beyond WASH access, such as intra-household pathogen transmission, exposure to animal feces, and contextual factors in the public domain may be important risk factors for enteric infections.Trial registrationclinicaltrials.gov (NCT02342860).
Highlights
The health risks associated with inadequate access to water, sanitation, and hygiene (WASH) are well documented [1,2,3]
Interventions to improve water, sanitation, and hygiene are associated with 33%, 25%, and 30% reductions in risk of childhood diarrhea, respectively [4], and improved WASH is associated with reductions in Giardia [5] and neglected tropical diseases (NTDs) such as soil-transmitted helminths (STHs), trachoma, and schistosomiasis [6,7,8,9]
These important findings point to the need to consider transmission within the household, even among those whom are frequently considered lower priority household members less at risk of morbidities and mortality due to diarrhea
Summary
The health risks associated with inadequate access to water, sanitation, and hygiene (WASH) are well documented [1,2,3]. Interventions to improve water, sanitation, and hygiene are associated with 33%, 25%, and 30% reductions in risk of childhood diarrhea, respectively [4], and improved WASH is associated with reductions in Giardia [5] and neglected tropical diseases (NTDs) such as soil-transmitted helminths (STHs), trachoma, and schistosomiasis [6,7,8,9]. [24], one of the leading causes of moderate-to-severe diarrhea among young children [25] Another hypothesis is that many WASH trials are designed to prevent exposure to human feces and do not adequately address exposure to animal feces [26, 27]. Animal feces present a substantial risk to human health, as animals may be the leading driver of pathogen diversity in the environment [21] and many enteropathogens that cause moderate to severe diarrhea are of animal origin [26]
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