Modeling the impact of optimized airflow and sick pen management on the spread of infectious diseases in swine barns

Abstract

The airborne spread of infectious livestock diseases plays a crucial role in the propagation of epidemics, particularly in populations confined to densely populated facilities, such as commercial swine barns. Therefore, quantitative assessments for the performance of barn ventilation systems may serve as an alternative biocontainment control strategy to reduce the spread of infectious pathogens. In this study, we present a framework to simulate airborne disease dissemination within swine barns and facilitate the strategic design of control actions, including optimization of ventilation and placement of sick animals (sick pen). This framework is based on a susceptible-infected-recovered (SIR) model that accounts for the between-pen disease spread within swine barns. A pen-to-pen contact network is used to construct a transmission matrix according to the transport of airborne respiratory pathogens across pens in the barns, via our Reynolds-averaged Navier-Stokes computational fluid dynamics (CFD) solver. By employing this CFD-augmented SIR model, we demonstrated that the location of the sick pen and the barn ventilation configuration played crucial roles in modifying disease dissemination dynamics at the barn level. In addition, we examined the effect of natural ventilation through different curtain adjustments. We observed that curtain adjustments either suppress the disease spread by an average of 56.5% or exacerbate the outbreak potential by an average of 5.7%, compared to the scenario where side curtains are not raised. Furthermore, we optimize the ventilation configuration via the selection and placement of ventilation fans through the integration of the CFD-augmented framework with the genetic algorithm to minimize the dissemination of swine disease within barns. Compared to regular barn ventilation settings, our optimized ventilation system significantly reduced disease spread by an average of 43.2%. Our study emphasizes the role of airborne transmission and a strategy for sick pen management in controlling the spread of within-barn disease.