A Comparative Analysis of Contamination in Point-of-Drinking and Source Water in a Low-Income Urban Community, Bangladesh.

Bangladesh is a cholera endemic country with a population at high risk of cholera. Toxigenic and non-toxigenic () can cause cholera and cholera-like diarrheal illness and outbreaks. Drinking water is one of the primary routes of cholera transmission in Bangladesh. The aim of this study was to conduct a comparative assessment of the presence of between point-of-drinking water and source water, and to investigate the variability of virulence profile using molecular methods of a densely populated low-income settlement of Dhaka, Bangladesh. Water samples were collected and tested for from "point-of-drinking" and "source" in 477 study households in routine visits at 6 week intervals over a period of 14 months. We studied the virulence profiles of positive water samples using 22 different virulence gene markers present in toxigenic O1/O139 and non-O1/O139 using polymerase chain reaction (PCR). A total of 1,463 water samples were collected, with 1,082 samples from point-of-drinking water in 388 households and 381 samples from 66 water sources. was detected in 10% of point-of-drinking water samples and in 9% of source water samples. Twenty-three percent of households and 38% of the sources were positive for in at least one visit. Samples collected from point-of-drinking and linked sources in a 7 day interval showed significantly higher odds ( < 0.05) of presence in point-of-drinking compared to source [OR = 17.24 (95% CI = 7.14-42.89)] water. Based on the 7 day interval data, 53% (17/32) of source water samples were negative for while linked point-of-drinking water samples were positive. There were significantly higher odds ( < 0.05) of the presence of O1 [OR = 9.13 (95% CI = 2.85-29.26)] and O139 [OR = 4.73 (95% CI = 1.19-18.79)] in source water samples than in point-of-drinking water samples. Contamination of water at the point-of-drinking is less likely to depend on the contamination at the water source. Hygiene education interventions and programs should focus and emphasize on water at the point-of-drinking, including repeated cleaning of drinking vessels, which is of paramount importance in preventing cholera.