Impacts of an urban sanitation intervention on fecal indicators and the prevalence of human fecal contamination in Mozambique

Abstract

Fecal source tracking (FST) may be useful to assess pathways of fecal contamination in domestic environments and to estimate the impacts of water, sanitation, and hygiene (WASH) interventions in low-income settings. We measured two non-specific and two human-associated fecal indicators in water, soil, and surfaces before and after a shared latrine intervention from low-income households in Maputo, Mozambique participating in the Maputo Sanitation (MapSan) trial. Up to a quarter of households were impacted by human fecal contamination, but trends were unaffected by improvements to shared sanitation facilities. The intervention reduced E. coli gene concentrations in soil but did not impact culturable E. coli or the prevalence of human FST markers in a difference-in-differences analysis. Using a novel Bayesian hierarchical modeling approach, we revealed a high amount of uncertainty associated with the FST marker measurements. Diagnostic accuracy-corrected intervention effect estimates were near the null and were imprecise. The field of microbial source tracking would benefit from adding measures of diagnostic accuracy to better interpret findings, particularly when FST analyses convey insufficient information for robust inference. With improved measures, FST could help identify dominant pathways of human and animal fecal contamination in communities and guide implementation of effective interventions to safeguard health.

Long-term impacts of an urban sanitation intervention on enteric pathogens in children in Maputo city, Mozambique: study protocol for a cross-sectional follow-up to the Maputo Sanitation (MapSan) trial five years post-intervention

“…We are sampling environmental compartments at a randomly selected subset of 100 intervention and 100 control compounds to represent compound- and household-level exposures [37]. At the entrance to the compound latrine we collect soil, flies, and a large volume air sample, as well as fecal sludge from the latrine or septic tank and any animal feces observed in the shared outdoor space [49, 50, 56, 57]. One household is selected at random among the households in the compound with children enrolled in the child health study, from which we collect swabs of flooring at the household entrance, flies in cooking area, prepared child’s food, stored drinking water, and water from the household’s primary source [52, 58, 59].…”

“…Furthermore, overall pathogen prevalence, pathogen counts, E. coli gene copy density, and the individual prevalence of Ascaris and pathogenic E. coli were all significantly reduced in soil at the intervention latrine entrance [49, 50], suggesting the intervention effectively contained human excreta. While animals have been implicated as major sources of pathogen exposure in other settings [51], only companion animals were frequently present at study households and a locally validated indicator of poultry fecal contamination (the most commonly observed non-companion animal type) was rarely detected in household environments [52].…”

“…While animals have been implicated as major sources of pathogen exposure in other settings [51], only companion animals were frequently present at study households and a locally validated indicator of poultry fecal contamination (the most commonly observed non-companion animal type) was rarely detected in household environments [52]. Conversely, indicators of human fecal contamination were widespread [50] and the two pathogens most impacted by the intervention— Shigella and Trichuris —are considered anthroponotic [53], suggesting that human excreta was a primary source of enteric pathogens in our dense, urban setting and that human-associated pathogens were impacted by sustained exposure to the intervention.…”

Shigellosis: A Potential Missed Diarrhea among Patients Attending Kashere General Hospital

“…In many rural areas, people rely on untreated water sources such as rivers, streams, and ponds for drinking, cooking, and cleaning [10]. These water sources are often contaminated with fecal matter, which can lead to the spread of diarrheal diseases [11]. Some of the pathogenic bacteria reportedly implicated are Shigella spp., Campylobacter spp., Escherichia coli, Vibrio cholerae, Clostridium botulinum, and Salmonella spp., [12, 13 and 14].…”