title: The joint effects of water and sanitation on diarrhoeal disease: a multicountry analysis of the Demographic and Health Surveys.
abstract: OBJECTIVE
  To assess whether the joint effects of water and sanitation infrastructure, are acting antagonistically (redundant services preventing the same cases of diarrhoeal disease), independently, or synergistically; and to assess how these effects vary by country and over time.
  
  
  METHODS
  We used data from 217 Demographic and Health Surveys conducted in 74 countries between 1986 and 2013. We used modified Poisson regression to assess the impact of water and sanitation infrastructure on the prevalence of diarrhoea among children under 5.
  
  
  RESULTS
  The impact of water and sanitation varied across surveys, and adjusting for socio-economic status drove these estimates towards the null. Sanitation had a greater effect than water infrastructure when all 217 surveys were pooled; however, the impact of sanitation diminished over time. Based on survey data from the past 10 years, we saw no evidence for benefits in improving drinking water or sanitation alone, but we estimated a 6% reduction of both combined (prevalence ratio = 0.94, 95% confidence limit 0.91-0.98).
  
  
  CONCLUSIONS
  Water and sanitation interventions should be combined to maximise the number of cases of diarrhoeal disease prevented in children under 5. Further research should identify the sources of variability seen between countries and across time. These national surveys likely include substantial measurement error in the categorisation of water and sanitation, making it difficult to interpret the roles of other pathways.
authors.affiliation: Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, USA.
authors.forename: James A
authors.initials: JA
authors.lastname: Fuller
authors.forename: Joslyn A
authors.initials: JA
authors.lastname: Westphal
authors.forename: Brooke
authors.initials: B
authors.lastname: Kenney
authors.forename: Joseph N S
authors.initials: JN
authors.lastname: Eisenberg
mesh_terms: D003967:Diarrhea / Q000453:epidemiology*; D005260:Female; D014943:Global Health; D006306:Health Surveys; D006801:Humans; D007223:Infant; D008297:Male; D015995:Prevalence; D012044:Regression Analysis; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data; D012499:Sanitation / Q000592:standards*; D012959:Socioeconomic Factors; D014505:Urban Population / Q000706:statistics & numerical data; D014881:Water Supply / Q000592:standards*
keywords: Agua; Censo demográfico y sanitario; Demographic and Health Surveys; Diarrea; Interacción; Saneamiento; analyse transversale; assainissement; cross-sectional analysis; diarrhoea; diarrhée; eau; enquêtes démographiques et de santé; estudio croseccional; interaction; sanitation; water