Faecal Coliforms and Escherichia coli Contamination in Drinking Water Sources in Cholera Hotspot Areas of Lusaka District, Zambia: A Cross-Sectional Study

Abstract

The October 2023 to 2024 cholera outbreak demonstrates significant challenges related to water quality and sanitation, especially in peri-urban areas with limited access to clean water. This study assesses the presence of faecal coliforms and <i>Escherichia coli</i> (<i>E. coli</i>) in drinking water sources across five townships, identified as cholera transmission hotspots, two months post the cholera outbreak in the Lusaka District. A total of 169 water samples were collected from protected sources, treated piped water, and unprotected sources, including dams and shallow wells. Faecal coliforms and <i>E. coli</i> were detected across all source types. Among unprotected sources, 92.3% (12/13) of samples contained ≥100 CFU/100 mL of both faecal coliforms and <i>E. coli</i>. Protected sources showed variable contamination, with 18.3% exceeding ≥100 CFU/100 mL for faecal coliforms and 15.4% for <i>E. coli</i>. Treated water sources showed the lowest contamination, with 88.5% of samples having no detectable faecal coliforms and 90.4% having no detectable <i>E. coli.</i> Zero-inflated negative binomial regression showed that treated water sources were associated with substantially lower faecal coliform counts compared with protected sources (PR = 0.11, 95% CI: 0.03-0.35), while unprotected sources exhibited higher contamination intensity (PR = 1.77, 95% CI: 0.94-3.31). Treated sources were significantly more likely to be structurally free of contamination, whereas unprotected sources had an extremely low probability of yielding zero counts. These findings indicate that current water safety conditions in Lusaka's cholera hotspot areas remain inadequate for preventing faecal-oral transmission.