QMRA of Waterborne Adenovirus and Rotavirus: A Source Tracking and RT-qPCR Approach

Abstract

Surface water used for domestic purposes in under developed countries presents a critical pathway for the transmission of enteric viruses. This research combines molecular detection, faecal source tracking, and quantitative microbial risk assessment (QMRA) to develop a predictive framework for assessing viral infection risks associated with domestic water use in Essien Udim Local Government Area in Akwa Ibom State, Nigeria. Surface water samples were analyzed for adenovirus and rotavirus using RT-qPCR to determine viral concentrations and spatial–temporal variability. Somatic coliphages were quantified as indicators of faecal contamination sources. Exposure scenarios encompassing drinking, bathing, and food preparation were modeled to estimate daily viral dose, while infection probabilities were calculated using exponential and Beta-Poisson dose–response models. Annual infection risks were derived and compared with WHO acceptable risk level of 10^-4 infections/person/year. Sensitivity and uncertainty analyses were performed to identify dominant risk drivers. Results showed widespread detection of enteric viruses with significant variability across sites and seasons. Estimated annual infection risks exceeded acceptable thresholds (10⁻⁴ infections person⁻¹ year⁻¹) in multiple exposure scenarios, particularly for direct ingestion pathways. Source tracking indicated that human-derived faecal contamination was the dominant contributor to viral loads. Sensitivity analysis identified viral concentration and ingestion rate as the most influential parameters. This research highlights the value of combining environmental virology with predictive risk modeling to inform water safety management. The findings provide actionable insights for mitigating viral transmission risks and contribute to the development of sustainable water quality management strategies aligned with global health targets.