Abstract
Household environments in informal settlements may serve as potential environmental reservoirs or contamination points and transmission interfaces for enteric pathogens, particularly where water, sanitation, and hygiene (WASH) services are inadequate. Conventional WASH monitoring often focuses on infrastructure and source-water quality, providing limited information regarding potential household-level exposure pathways. A pilot cross-sectional study was conducted in Zandspruit, an informal settlement in Johannesburg, South Africa, using a multi-matrix environmental sampling approach. A total of 143 samples, including drinking water (n = 29), dishcloths (n = 28), Bio-Wipes of hand (n = 29), surfaces (n = 28), and toilet seats (n = 29), were collected from participating households (n = 30). Physicochemical water-quality parameters, according to the South African National Standard (SANS) 241: 2015 by the South African Bureau of Standards (SABS), and microbial indicators were assessed. Deoxyribonucleic acid (DNA) was extracted using a silica-based method, and multiplex polymerase chain reaction (m-PCR) assays were used to detect Escherichia coli (E. coli) and Vibrio species (spp.) from environmental samples. The measured physicochemical parameters were generally within the applicable national standards guideline ranges; however, enteric pathogen-associated genetic markers were detected in selected water samples. Molecular analysis demonstrated marked differences in the occurrence of E. coli pathotype-associated markers across household environmental matrices. ETEC was detected in drinking water (5/29, 17.2%) and was most frequent in dishcloths (12/28, 42.9%), followed by surfaces (10/28, 35.7%) and hands (9/29, 31.0%). STEC was detected in hands (10/29, 34.5%), surfaces (9/28, 32.1%), dishcloths (6/28, 21.4%), and toilets (6/29, 20.7%), but not in water. Matrix-specific associations were observed for STEC, typical EPEC, ETEC, and astA-positive E. coli after Benjamini–Hochberg correction. Vibrio-associated markers were detected occasionally: wbeO in one dishcloth (1/28, 3.6%) and sodB in one hand (1/29, 3.4%) and one surface sample (1/28, 3.6%); ctxA was not detected. These findings indicate that household contact matrices may represent important points of molecular contamination and potential cross-contamination. Molecular approaches such as Polyemerase Chain Reaction (PCR) does not establish viability, infectivity, toxin expression, or transmission, therefore the findings should not be interpreted as evidence of viable pathogens or disease. Longitudinal studies incorporating culture-based confirmation and quantitative molecular approaches are needed. Nevertheless, the results support the importance of household hygiene interventions targeting hands, dishcloths, and frequently touched surfaces.