Transmission of Diarrheal Pathogens through Drinking Water in Rural Gambia

Preliminary data analysis from the Global Enteric Multi-Center Study (GEMS) has incriminated several water, sanitation, and hygiene (WSH) variables as risk factors in The Gambia for transmission of several diarrheal pathogens. Specifically, data obtained from questionnaires conducted during a case-control study in children less than five years of age has identified several risk factors for moderate and severe diarrhea (MSD). The practices of filtering water through a cloth and of storing drinking water in the household are significantly associated with a pediatric diarrhea episode. Etiology determined from the stool of the child has permitted specific identification of pathogens in association with those risk factors. A nested microbiological study was designed to investigate those epidemiologic incriminations. Household water treatment practices are being studied using a field investigation to better describe the risk factors that contribute to the risk of fecal contamination in household drinking water. We have also recorded the proximity and type of available source-water for each household. Concentrations of total and E. coli contamination in source, stored, and cloth-filtered water samples collected from the households were evaluated using microbial indicator tests. Contamination was compared between samples to determine whether water quality in a Gambian household changes due to the practice of cloth filtration or storage. Conventional bacteriology has been used to isolate Salmonella and E. coli from water samples. The data generated to this point have revealed a surprisingly high level of overall and fecal contamination in both unimproved and improved water sources. We have also found that passing water through a cloth filter is an ineffective treatment method for removing fecal contamination from drinking water, and can contribute to increased levels of total coliform contamination. Incriminating the specific local practices that lead to an increased risk for having contaminated water in the household will be useful for designing future WSH interventions that can improve the quality of household drinking water. Improvements in drinking water should reduce the likelihood that diarrheal pathogens will be transmitted to a child and cause pediatric diarrhea.