Ruminants contribute fecal contamination to the urban household environment in Dhaka, Bangladesh. Env Sci Tech, April 2016. Authors: Angela Harris, Amy Janel Pickering, et al.
In Dhaka, Bangladesh, the sensitivity and specificity of three human, three ruminant, and one avian source-associated QPCR microbial source tracking assays were evaluated using fecal samples collected on site. Ruminant-associated assays performed well, while the avian and human assays exhibited unacceptable cross-reactions with feces from other hosts.
Subsequently, child hand rinses (n=44) and floor sponge samples (n=44) from low income-households in Dhaka were assayed for fecal indicator bacteria (enterococci, Bacteroidales, and Escherichia coli) and a ruminant-associated bacterial target (BacR). Mean enterococci concentrations were of 100 most probable number (MPN)/2 hands and 1000 MPN/225 cm2 floor. Mean concentrations of Bacteroidales were 106 copies/2 hands and 105 copies/225 cm2 floor. E. coli were detected in a quarter of hand rinse and floor samples. BacR was detected in 18% of hand rinse and 27% of floor samples.
Results suggest that effective household fecal management should account not only for human sources of contamination but also for animal sources. The poor performance of the human-associated assays in the study area calls into the question the feasibility of developing a human-associated marker in urban slum environments, where domestic animals are exposed to human feces that have been disposed in pits and open drains.