Fecal-oral
pathogens are transmitted through complex, environmentally
mediated pathways. Sanitation interventions that isolate human feces
from the environment may reduce transmission but have shown limited
impact on environmental contamination. We conducted a study in rural
Bangladesh to (1) quantify domestic fecal contamination in settings
with high on-site sanitation coverage; (2) determine how domestic
animals affect fecal contamination; and (3) assess how each environmental
pathway affects others. We collected water, hand rinse, food, soil,
and fly samples from 608 households. We analyzed samples with IDEXX
Quantitray for the most probable number (MPN) of E. coli. We detected E. coli in source water (25%), stored
water (77%), child hands (43%), food (58%), flies (50%), ponds (97%),
and soil (95%). Soil had >120 000 mean MPN E. coli per gram. In compounds with vs without animals, E. coli was higher by 0.54 log10 in soil, 0.40 log10 in stored water and 0.61 log10 in food (p < 0.05). E. coli in stored water and food increased
with increasing E. coli in soil, ponds, source water
and hands. We provide empirical evidence of fecal transmission in
the domestic environment despite on-site sanitation. Animal feces
contribute to fecal contamination, and fecal indicator bacteria do
not strictly indicate human fecal contamination when animals are present.
We
evaluated whether provision and promotion of improved sanitation
hardware (toilets and child feces management tools) reduced rotavirus
and human fecal contamination of drinking water, child hands, and
soil among rural Bangladeshi compounds enrolled in a cluster-randomized
trial. We also measured host-associated genetic markers of ruminant
and avian feces. We found evidence of widespread ruminant and avian
fecal contamination in the compound environment; non-human fecal marker
occurrence scaled with animal ownership. Strategies for controlling
non-human fecal waste should be considered when designing interventions
to reduce exposure to fecal contamination in low-income settings.
Detection of a human-associated fecal marker and rotavirus was rare
and unchanged by provision and promotion of improved sanitation to
intervention compounds. The sanitation intervention reduced ruminant
fecal contamination in drinking water and general (non-host specific)
fecal contamination in soil but overall had limited effects on reducing
fecal contamination in the household environment.
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.
Enteric pathogens can be transmitted through multiple environmental pathways, yet little is known about the relative contribution of each pathway to diarrhea risk among children. We aimed to identify fecal transmission pathways in the household environment associated with prospectively measured child diarrhea in rural Bangladesh. We measured the presence and levels of Escherichia coli in tube wells, stored drinking water, pond water, child hand rinses, courtyard soil, flies, and food in 1843 households. Gastrointestinal symptoms among children ages 0-60 months were recorded concurrently at the time of environmental sample collection and again a median of 6 days later. Incident diarrhea (3 or more loose stools in a 24-h period) was positively associated with the concentration of E. coli on child hands measured on the first visit (incidence rate ratio [IRR] = 1.23, 95% CI 1.06, 1.43 for a log increase), while other pathways were not associated. In cross-sectional analysis, there were no associations between concurrently measured environmental contamination and diarrhea. Our findings suggest higher levels of E. coli on child hands are strongly associated with subsequent diarrheal illness rates among children in rural Bangladesh.
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