Modelling of infectious animal viral disease transmission by aerosols

An integrated model was developed to simulate airborne transmission of infectious animal viral diseases. Computational fluid dynamics (CFD), viral infectivity decay, and dose-response models were integrated to simulate physical and biological processes in the aerosol transmission pathway of animal disease. In the first part of this study, a CFD model was developed and validated for simulating movement of bioaerosols of porcine reproductive and respiratory syndrome virus (PRRSV) in laboratory conditions where air flowed from a source to a recipient chamber. The model performed well (normalized mean square error NMSE <0.25) at simulating steady-state PRRSV bioaerosol concentrations, but differences were greater (NMSE >0.25) during the transient stage of airflow. In the second part of this study, a series of dose-response models were performed for five infectious animal viruses on various transmission routes. The transmissibility of animal viruses varied with the transmission route, and aerosol transmission required lower doses to cause infection than intranasal and oral transmission for PRRSV. The CFD model was coupled with aerosol transmission dose-response models for PRRSV. The coupled models predicted probability of infection (82% to 100%), which was in good agreement with observed rates in two experimental studies (84% and 90%). In the third part of this study, an integrated model consisting of CFD, infectivity decay, and dose-response was developed to simulate the aerosol transmission of PRRSV between a source and a recipient building in field conditions, based on an experimental study reported in the literature. CFD was used to model the PRRSV aerosol movement towards and within the recipient building, and the infectivity decay and dose-response models were used to predict the probability of infection upon exposure to the calculated aerosol dose of PRRSV. The integrated model predicted that the aerosol transmission event occurred in the recipient building on a d