Coughs and Sneezes Spread Diseases. Replication and Modelling of Infectious Airborne Respiratory Droplets

Robert Alexander, Jianghan Tian, ALLEN E. HADDRELL, Henry Oswin, Edward Neal, Jamie Mann, Tristan Cogan, Andrew Davidson, Darryl Hill, Jonathan P. Reid, University of Bristol

     Abstract Number: 321
     Working Group: Aerosol Science of Infectious Diseases: Lessons and Open Questions on Models, Transmission and Mitigation

Abstract
Determining what contributes to the viability of a pathogen in the aerosol phase is beneficial to forecasting the likelihood of airborne disease transmission and mathematically modeling outbreaks. This research can contribute to public health response for future pandemics and also help tackle endemic diseases in our communities currently.

Pathogen viability measurements made using Controlled Electrodynamic Levitation and Extraction of Bioaerosol onto Substrate (CELEBS) in tandem with comparative kinetics electrodynamic balance (CK-EDB) measurements, allow for direct comparison between viral viability and evaporation kinetics of the bioaerosol droplet as a function of time (Fernandez et al. 2020).

Recent studies suggest that the loss of infectivity of SARS-CoV-2 in the aerosol phase is driven by two mechanisms. Firstly, the phase change associated with a complete drying of the respiratory droplet. Secondly, the non-physiological, high alkaline conditions of a partially evaporated respiratory aerosol. Over the course of the pandemic, as different variants of concern predominated, an aero-stable phenotype was selected for, with viral stability at high pH as the best indicator for aero-stability (Oswin et al 2022). Alternatively, E coli viability decay in the aerosol phase was seen to be driven by oxidative stress, rather than the physicochemical mechanisms described for viruses (Oswin et al 2023).

To be presented is the airborne survival of commensal Neisseria species as a surrogate model for meningococcal disease. The interplay between microphysical droplet dynamics (pH and phase change) and microbial phenotype such as mobility and structure (e.g. capsid) are explored. The project aims to develop a robust model for bacteria-laden respiratory droplets through single-particle electrodynamic levitation experiments.