This study was aimed at building a stochastic mathematical model of porcine reproductive and respiratory syndrome virus (PRRSv) intra-farm spread and control in sows and piglets in the United States. Model parameters were obtained through peer-reviewed literature searches, empirical evidence, and expert opinion. Based on those estimated parameters, a production-stage structured susceptible, infected, and recovered (SIR) model for sows and an age-stage structured maternally immune, susceptible, infected, and recovered (MSIR) model for piglets were built to reflect a typical farrow-to-wean farm in the United States. The model consisted of 5000 iterations and 9 simulations, which resulted from the combination of high, medium, and low virulences and small, medium, and large population size. The hypothetical herd was assumed to have a prevalence of ELISA positive sows, ranging from 0.282 to 0.505, compatible with that observed in pig farms in the United States. It was assumed that transmission between sows and piglets did not occur. Control strategies including herd closure, gilt acclimatization, and mass immunization, which were contrasted as 4 alternative control strategies. Simulation results suggest that a combination of gilt acclimatization and vaccination may be almost as effective as herd closure in controlling PRRSv. These results will help to develop and implement effective protocols for controlling PRRS in swine farms in the United States.
|Advisor:||Perez, Andres M.|
|Commitee:||Aly, Sharif S., Kass, Philip H.|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||MAI 51/03M(E), Masters Abstracts International|
|Keywords:||Infectious disease modeling, Mathematical, PRRS, Stochastic, Swine, Vaccination|
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