Multi-pathway assessment of fecal contamination in urban areas of Abidjan: The case of Abobo municipality

Abstract

The presence of septic tank effluents in open spaces and roads due to poor fecal sludge management (FSM) in low-income cities represents a source of fecal contamination and potential risk of fecal-oral disease transmission. This study aimed at assessing fecal contamination exposure through six exposure pathways in Abobo, District of Abidjan in Côte d’Ivoire. The public health risk was evaluated in two clusters to identify the dominant exposure pathways and to compare which populations were most exposed. The SaniPath approach used included behavioral surveys (transect walk, household survey, school survey and community survey) and laboratory analysis. Surveys were conducted among 200 households, 6 schools and 4 community groups. In addition, 120 environmental samples were collected (in 2 clusters of 6 pathways with 10 samples per pathway per cluster). The colony forming unit (CFU) of E. coli was determined in samples using the surface plating technique on agar medium. Bayesian analyses were performed to estimate the distributions of fecal concentration and contact frequency, and exposure to fecal contamination was estimated using the Monte Carlo method with 1000 iterations. The highest concentrations of E. coli were observed in open drains (6.1 log CFU/ml), gullies (6 log CFU/ml) and soil (5.8 log CFU/ml) samples. The dominant exposure pathways were determined by multiplying the dose and the percentage of the population exposed, which was then log-transformed and denoted by (E). The study found that street food and gullies are the two dominant exposure pathways among the population living in Abobo. 100% of the children and between 73% and 91% of the adults are exposed to these dominant pathways in low and poor areas. In middle and high-income areas this concerns 75% to 95% of children and between 26% and 70% of adults. As well, the risk of exposure to the dominant pathways hits 9.2 in children and 8.6 for adults living in poor areas. While it reaches 8.1 and 7.1 respectively in children and adults living in middle and high-income areas. The study outcomes could help the authorities to structure how to target municipal wide interventions toward improving the sanitation conditions in the different neighborhoods.