Animal Feces Contribute to Domestic Fecal Contamination: Evidence from E. coli Measured in Water, Hands, Food, Flies, and Soil in Bangladesh

Self Cite

Sanitation improvements have had limited effectiveness in reducing the spread of fecal pathogens into the environment. We conducted environmental measurements within a randomized controlled trial in Bangladesh that implemented individual and combined water treatment, sanitation, handwashing (WSH) and nutrition interventions (WASH Benefits, NCT01590095). Following approximately 4 months of intervention, we enrolled households in the trial’s control, sanitation and combined WSH arms to assess whether sanitation improvements, alone and coupled with water treatment and handwashing, reduce fecal contamination in the domestic environment. We quantified fecal indicator bacteria in samples of drinking and ambient waters, child hands, food given to young children, courtyard soil and flies. In the WSH arm, Escherichia coli prevalence in stored drinking water was reduced by 62% (prevalence ratio = 0.38 (0.32, 0.44)) and E. coli concentration by 1-log (Δlog10 = −0.88 (−1.01, −0.75)). The interventions did not reduce E. coli along other sampled pathways. Ambient contamination remained high among intervention households. Potential reasons include noncommunity-level sanitation coverage, child open defecation, animal fecal sources, or naturalized E. coli in the environment. Future studies should explore potential threshold effects of different levels of community sanitation coverage on environmental contamination.

Section: ■ Backgroundmentioning

confidence: 99%

Do Sanitation Improvements Reduce Fecal Contamination of Water, Hands, Food, Soil, and Flies? Evidence from a Cluster-Randomized Controlled Trial in Rural Bangladesh

Ercümen

Pickering

Kwong

et al. 2018

Self Cite

“…31−33 Domestic soils contaminated by enteric pathogens can pose infection risks beyond incidental 34 and direct 35 soil ingestion: contaminated soil may be transported to hands, food, fomites, or household stored water. 36 For these reasons, soils may be a useful matrix to assess the impact of onsite sanitation interventions.…”

Section: ■ Introductionmentioning

confidence: 99%

“…We accounted for clustering between compounds across the two study phases because the intervention was implemented at the compound level. 67 To generate adjusted estimates, we selected nine covariates from the MapSan baseline and 24 month data sets based on their biological plausibility to impact the transport 57 or persistence 68 of pathogens in the domestic environment and previously reported associations in the literature 36,44 (Table S4). We used the same nine covariates to adjust all DID models: compound population (a 10-person increase in compound population), wealth (one-quartile increase in wealth index 69 ), soil moisture (assessed visually at the time of sampling), sun exposure status (estimated at the time of sampling; full sun, partially shaded, shaded 44 ), the meancentered average air temperature in Fahrenheit for the day of and day preceding sample collection (i.e., two-day average), a binary variable for the presence of cats, a binary variable for the presence of dogs, a binary variable for the presence of chickens or ducks, and a binary variable for the presence of visible animal or human feces in the compound (Table S4).…”

Section: ■ Introductionmentioning

confidence: 99%

Impact of an Urban Sanitation Intervention on Enteric Pathogen Detection in Soils

Capone

Berendes

Cumming

et al. 2021

Environmental fecal contamination is common in many low-income cities, contributing to a high burden of enteric infections and associated negative sequelae. To evaluate the impact of a shared onsite sanitation intervention in Maputo, Mozambique on enteric pathogens in the domestic environment, we collected 179 soil samples at shared latrine entrances from intervention (n = 49) and control (n = 51) compounds during baseline (preintervention) and after 24 months (postintervention) as part of the Maputo Sanitation Trial. We tested soils for the presence of nucleic acids associated with 18 enteric pathogens using a multiplex reverse transcription qPCR platform. We detected at least one pathogenassociated gene target in 91% (163/179) of soils and a median of 3 (IQR = 1, 5) pathogens. Using a difference-in-difference analysis and adjusting for compound population, visibly wet soil, sun exposure, wealth, temperature, animal presence, and visible feces, we estimate the intervention reduced the probability of detecting ≥1 pathogen gene by 15% (adjusted prevalence ratio, aPR = 0.85; 95% CI: 0.70, 1.0) and the total number of pathogens by 35% (aPR = 0.65; 0.44, 0.95) in soil 24 months following the intervention. These results suggest that the intervention reduced the presence of some fecal contamination in the domestic environment, but pathogen detection remained prevalent 24 months following the introduction of new latrines.

“…36,37 An observational analysis within the WASH Benefits Bangladesh control arm found that domestic animal presence was associated with increased fecal contamination in the environment. 38 Another substudy within the sanitation and control arms found more animal-associated fecal genetic markers in the household environment than human-associated markers. 39 In this study, we found 0.14 to 0.26-log10 reductions in stored water and hand E. coli counts in some subgroups of animal ownership but no consistent patterns.…”

Section: ■ Discussionmentioning

confidence: 99%

Longitudinal Effects of a Sanitation Intervention on Environmental Fecal Contamination in a Cluster-Randomized Controlled Trial in Rural Bangladesh

Contreras

Islam

Mertens

et al. 2021

Self Cite

Household latrine access generally is not associated with reduced fecal contamination in the environment, but its long-term effectiveness has not been measured. We conducted an environmental assessment nested within the WASH Benefits Bangladesh randomized controlled trial (NCT01590095). We quantified E. coli and fecal coliforms in samples of stored drinking water, child hands, mother hands, soil, and food among a random sample of households from the sanitation and control arms of the trial. Samples were collected during eight quarterly visits approximately 1–3.5 years after intervention initiation. Overall, there were no substantial differences in environmental fecal contamination between households enrolled in the sanitation and control arms. Statistically significant reductions were found in stored water and child hands after pooling across sampling rounds, but the effects were small and not consistent across rounds. In addition, we assessed potential effect modification of intervention effects by follow-up time, season, wealth, community-level latrine density and coverage, population density, and domestic animal ownership. While the intervention had statistically significant effects within some subgroups, there were no consistent patterns of effect modification. Our findings support a growing consensus that on-site latrines are insufficient to prevent fecal contamination in the rural household environment.