Improved quantitative microbial risk assessment (QMRA) for drinking water sources in developing countries

This study seeks to improve the QMRA of drinking water sources in the context of developing countries. Existing QMRA dose–response models were modified to use data generated from the developing country environment and scenarios. The modified model assessed drinking water borehole supplies in Afikpo North Local Government Area, Nigeria. Water samples were taken every three days from July 2019 to December 2019. They were assessed for concentrations of E. coli, Salmonella spp, Shigella spp, Campylobacter , Giardia lamblia and Cryptosporidium parvum. Other input parameters to the modified model were obtained in the study environment through survey instruments; they include per capita water consumption per day, % exposed population, % vulnerable population and pathogen strike rate. The daily mean risk of infection was determined to be 0.236, standard deviation, 0.056, while the daily mean risk of diarrhea was 0.039, standard deviation , 0.016. The predicted mean diarrhea risk values showed a positive correlations ( C = 0.74) with the observed diarrhea disease prevalence rate among the study communities. Mean values of diarrhea risk obtained using the modified model were compared with those obtained using formulations adopted by some recent studies that used existing QMRA models in the developing countries. The mean risk values were further compared with values obtained by using other existing QMRA dose–response models/parameters. The study found no statistical significant difference in the predicted risk of diarrhea of the two types of models. The modification is intended to facilitate a better interest on and the acceptability of QMRA in the developing countries.