Session: Government Agency Student Posters

Paper Number: 173365

Decoding the Mechanophysiology of Inhaled Smallpox Onset: Modeling Implications for Mpox Transmission 

Airborne transmission remains a critical route for the spread of numerous infectious diseases, particularly those involving respiratory viruses capable of remaining viable in inhalable particulates. Among such pathogens, Orthopoxviruses—including the variola virus, the etiologic agent of smallpox, and the currently circulating mpox virus (MPXV)—pose unique challenges due to their environmental stability, virulence, and ability to invade the respiratory tract. While smallpox is no longer endemic, concerns persist about its potential reemergence via accidental or deliberate release. Meanwhile, recent mpox outbreaks have renewed interest in understanding its transmission dynamics. Traditional epidemiological and agent-based models often operate at coarse spatial scales and typically overlook the detailed fluid dynamic behavior of pathogen-laden aerosols within human airways. To address this gap, we present an experimentally validated, physics-informed computational framework designed to quantify intra-airway transport and deposition of inhaled viral particulates and to estimate the critical exposure duration required to initiate infection.

This study employs high-fidelity, anatomically accurate reconstructions of human upper airway geometries, derived from medical-grade computed tomography scans, to simulate airflow and particle transport under physiologically relevant breathing conditions. Large Eddy Simulations (LES) were used to resolve turbulent inhalation airflow, while a Lagrangian particle tracking method modeled droplet and aerosol dynamics across a wide size range (0.1–50 µm). Two distinct anatomical geometries and two inhalation flow rates (15 and 30 L/min) were tested. Computational results were benchmarked against physical experiments using 3D-printed airway models, with glottic-region deposition validated via UV-absorbance spectroscopy.

By integrating the simulated deposition data with virological parameters, including infectious dose (ID), viral load (VL), and virion potency (p), we computed the critical exposure duration (τₚ) necessary to achieve infection through inhalation. For variola viruses, estimated τₚ values ranged from approximately 1.1 to 18.6 hours, aligning well with literature-based estimates derived from the Wells-Riley model. When extended to MPXV, the model predicts a longer baseline exposure window of 24–40 hours, which can range from as short as 8 hours to over 120 hours depending on fluctuations in viral concentration associated with host variability or viral evolution.

This study introduces a novel, interdisciplinary methodology combining respiratory fluid dynamics, virological parameters, and host anatomical realism to mechanistically assess airborne transmission risk for Orthopoxviruses. The framework corroborates established transmission data for smallpox and provides new evidence supporting the plausibility of airborne mpox transmission under prolonged exposure. The approach is broadly applicable to other respiratory pathogens and offers a robust foundation for refining public health policies and aerosol risk assessments.

Presenting Author: Mohammad Yeasin South Dakota State University

Presenting Author Biography: This is Mohammad Yeasin, a graduate research assistant in the Department of Mechanical Engineering at South Dakota State University (SDSU). I am currently working in the BASU Lab under the supervision of Dr. Saikat Basu, Associate Professor at SDSU.

I completed my Bachelor’s degree in Mechanical Engineering from Bangladesh University of Engineering and Technology (BUET), Bangladesh. I earned my Master’s degree from South Dakota State University in Spring 2025, and I am now enrolled as a PhD student at SDSU.

Since Fall 2023, I have been working in the BASU Lab on infectious disease transmission, which is part of Dr. Saikat Basu’s CAREER grant project. My goal is to develop expertise in this area so that I can contribute to reducing the spread of such dangerous diseases in the near future.

Authors:

Mohammad Yeasin South Dakota State University
Saikat Basu South Dakota State University