Assessment of Fecal Exposure Pathways in Low-Income Urban Neighborhoods in Accra, Ghana: Rationale, Design, Methods, and Key Findings of the SaniPath Study

Abstract

Abstract.Rapid urbanization has contributed to an urban sanitation crisis in low-income countries. Residents in low-income, urban neighborhoods often have poor sanitation infrastructure and services and may experience frequent exposure to fecal contamination through a range of pathways. There are little data to prioritize strategies to decrease exposure to fecal contamination in these complex and highly contaminated environments, and public health priorities are rarely considered when planning urban sanitation investments. The SaniPath Study addresses this need by characterizing pathways of exposure to fecal contamination. Over a 16 month period, an in-depth, interdisciplinary exposure assessment was conducted in both public and private domains of four neighborhoods in Accra, Ghana. Microbiological analyses of environmental samples and behavioral data collection techniques were used to quantify fecal contamination in the environment and characterize the behaviors of adults and children associated with exposure to fecal contamination. Environmental samples (n = 1,855) were collected and analyzed for fecal indicators and enteric pathogens. A household survey with 800 respondents and over 500 hours of structured observation of young children were conducted. Approximately 25% of environmental samples were collected in conjunction with structured observations (n = 441 samples). The results of the study highlight widespread and often high levels of fecal contamination in both public and private domains and the food supply. The dominant fecal exposure pathway for young children in the household was through consumption of uncooked produce. The SaniPath Study provides critical information on exposure to fecal contamination in low-income, urban environments and ultimately can inform investments and policies to reduce these public health risks.

Multipathway Quantitative Assessment of Exposure to Fecal Contamination for Young Children in Low-Income Urban Environments in Accra, Ghana: The SaniPath Analytical Approach

“…Some neighborhood characteristics, like SES, population density, geographic factors, education, and access to sanitation, have been reported to be associated with exposure to fecal contamination. 26,27 In this study, children in Alajo, the highest SES neighborhood, had the lowest total exposure to fecal contamination, whereas Shiabu, a mixed (formal and unplanned) settlement with a highly contaminated river, had the highest total exposure (neighborhood characteristics described by Peprah et al 19 and Robb et al 8 ). Less latrine access and more open defecation, in neighborhoods such as Old Fadama, were likely to lead to higher fecal exposure via soil, floor, off-ground, and direct contact with child’s own feces.…”

“…Additional details of study design, sampling methods, and primary results are provided by Robb et al 8 …”

“…7 Therefore, the absence of an observed impact on illness does not imply that exposure must be unchanged—any intervention that blocks a specific exposure pathway is expected to reduce exposure, just not always to an extent that reduces the overall dose (i.e., the sum of contributions from all pathways) to levels that reduce the risk of acute enteric illness or other adverse health effects associated with fecal contamination (e.g., environmental enteropathy). 8–10 It is critical to know how much each pathway contributes to overall exposure, and which pathways may be expected to have the greatest contribution. Such information strengthens the basis for designing intervention strategies.…”

“…8 As exposure is a covert variable (it cannot be directly measured in an observational population study), a bottom-up approach must be used, as developed for microbial risk assessment. 11,12 Concentrations of fecal microbes in the environment, exposure behaviors (frequency, duration, and order), and the associated intakes (amount ingested) must be quantified for each exposure pathway.…”

Quantitative assessment of fecal contamination in multiple environmental sample types in urban communities in Dhaka, Bangladesh using SaniPath microbial approach

“…Direct ingestion of fecal contamination through contaminated drinking water has been studied extensively both at household and community levels in urban Bangladesh by measuring fecal indicator bacteria [16][17][18][19]. Other exposure pathways in urban Bangladesh, including contaminated soil [13], market produce [12], and street food [14] have been linked to adverse health outcomes such as diarrhea, environmental enteric dysfunction, and stunting [20,21]. Yet the contribution of these pathways to total fecal exposure remains understudied.…”