Beyond airborne spread: a dual-route Wells-Riley extension for estimating norovirus infection risk in Ghanaian pediatric wards

Background: The classic Wells–Riley model (CWRM) is a well-established framework for estimating airborne infection risk in shared indoor environments. This study extends the framework to simultaneously incorporate fecal–oral transmission, addressing an important gap in norovirus infection risk estimation for high-contact pediatric wards. Objective: To formulate a dual-route Wells–Riley extension (MWRM-D) integrating airborne and fecal–oral transmission pathways for pediatric healthcare settings. Methods: The CWRM was extended with a fecal–oral dose component capturing viral shedding, environmental transfer, and hand-mediated exposure. The model was parameterized for a simulated Ghanaian pediatric ward. Patient-specific reference infection probabilities were generated under a fixed reference parameterization, and predictive performance was evaluated using mean absolute error (MAE) and root-mean-square error (RMSE). Results: Under an intermediate quanta scenario (q = 500 quanta/h), the MWRM-D reduced the MAE from 0.0571 to 0.0374 (34.5%) and the RMSE from 0.1276 to 0.0977 (23.4%) relative to the CWRM. Similar improvements were observed across the full range of quanta generation rates and fecal–oral dose–response coefficients evaluated in the sensitivity analysis. Conclusion: The MWRM-D provides a more biologically realistic framework for estimating norovirus infection risk and supports integrated ventilation, environmental hygiene, and hand hygiene strategies in resource-limited pediatric wards.