ABSTRACT 

By integrating virological data with dynamics of inhaled particles in respiratory cavities, we can model infection onset for pathogens transmitted aerially or anisotropically with predominantly aerial routes. Here, this approach is explored to detect the droplet/aerosol sizes responsible for triggering smallpox infection at the vulnerable oropharynx. We use Large Eddy Simulation and Lagrangian techniques to track inhaled airflow and particle transport in three medical scan-based anatomic airways. For virological inputs, we source from literature the virion concentration in pathogenic respiratory emissions and particle size distributions inhaled by an exposed individual. The tracked 0.1-55 micron particles, with physical properties similar to virus-embedded ejecta, enter the in silico airspaces through nostrils and mouth at steady-to-moderate inhalation (15-85 L/min). Sample findings indicate that viral transmission to the oropharynx is most pronounced for particle diameters 29-41 microns, considering both oral and nasal pathways with 15 and 30 l/min breathing rate. Furthermore, viral transmission peaks when particle diameters of 6 and 7 microns are specifically inhaled through nose, also 30 L/min breathing rate. Using literature data on confirmed exposure durations for transmission, this study approximates the smallpox infectious dose at 17–177, which agrees with known estimates.  

Preprint: A mechanistic model for smallpox transmission via inhaled aerosols inside respiratory pathways