BACKGROUND: The relationship between poor sanitation and the @entity281 @entity2040 is well-known, but still rarely investigated directly and quantitatively. In a Brazilian village we correlated the spatial concentration of @entity1 fecal contamination of its main river and the prevalence of @entity2040 . METHODS: We validated three bacterial markers of contamination in this population by high throughput sequencing of the 16S rRNA gene and qPCR of feces from local residents. The qPCR of genetic markers from the 16S rRNA gene of Bacteroides-Prevotella group, Bacteroides HF8 cluster, and Lachnospiraceae Lachno2 cluster as well as sequencing was performed on georeferenced samples of river water. Ninety-six percent of residents were examined for @entity2040 . FINDINGS: Sequence of 16S rRNA DNA from stool samples validated the relative @entity1 specificity of the HF8 and Lachno 2 fecal indicators compared to animals. The concentration of fecal contamination increased markedly along the river as it passed an increasing proportion of the population on its way downstream as did the sequence reads from bacterial families associated with @entity1 feces. Lachnospiraceae provided the most robust signal of @entity1 fecal contamination. The prevalence of @entity2040 likewise increased downstream. Using a linear regression model, a significant correlation was demonstrated between the prevalence of @entity383 infection and local concentration of @entity1 fecal contamination based on the Lachnospiraceae Lachno2 cluster (r2 0.53) as compared to the correlation with the general fecal marker @entity526 (r2 0.28). INTERPRETATION: Fecal contamination in rivers has a downstream cumulative effect. The transmission of @entity2040 correlates with very local factors probably resulting from the distribution of @entity1 fecal contamination, the limited movement of snails, and the frequency of water contact near the home. In endemic regions, the combined use of @entity1 associated bacterial markers and GIS analysis can quantitatively identify areas with risk for @entity2040 as well as assess the efficacy of sanitation and environmental interventions for prevention.

Sources and distribution of surface water fecal contamination and prevalence of XXXX in a brazilian village.

@entity1 :: ('9606', 'Species') :: ['human'] @entity383 :: ('99802', 'Species') :: ['S. mansoni'] @entity281 :: ('MESH:D007239', 'Disease') :: ['parasitic infection'] @entity2040 :: ('MESH:D012552', 'Disease') :: ['schistosomiasis'] @entity526 :: ('562', 'Species') :: ['E. coli']
@entity2040 :: (MESH:D012552,Disease) :: ['schistosomiasis']
