title: Stochastic model of porcine reproductive and respiratory syndrome virus control strategies on a swine farm in the United States.
abstract: OBJECTIVE
  To use mathematical modeling to assess the effectiveness of control strategies for porcine reproductive and respiratory syndrome (PRRS) virus on a swine farm.
  
  
  METHODS
  A hypothetical small, medium, or large farrow-to-weaning swine farm in the Midwestern United States.
  
  
  METHODS
  Stochastic models were formulated to simulate an outbreak of PRRS on a farm. Control strategies assessed in those models included none (baseline) and various combinations of mass immunization, herd closure, and gilt acclimatization. Nine different models resulting from the combination of low, moderate, or high PRRS virus virulence and small, medium, or large herd size were simulated. A stabilized status, the outcome of interest, was defined as the absence of positive PCR assay results for PRRS virus in 3-week-old piglets. For each scenario, the percentage of simulations with a stabilized status was used as a proxy for the probability of disease control.
  
  
  RESULTS
  Increasing PRRS virus virulence and herd size were negatively associated with the probability of achieving a stabilized status. Repeated mass immunization with herd closure or gilt acclimitization was a better alternative than was single mass immunization for disease control within a farm.
  
  
  CONCLUSIONS
  Repeated mass immunization with a PRRS modified-live virus vaccine with herd closure or gilt acclimitization was the scenario most likely to achieve a stabilized status. Estimation of the cost of various PRRS control strategies is necessary.
authors.affiliation: Graduate Group in Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.
authors.forename: Jaewoon
authors.initials: J
authors.lastname: Jeong
authors.forename: Sharif S
authors.initials: SS
authors.lastname: Aly
authors.forename: Jean Paul
authors.initials: JP
authors.lastname: Cano
authors.forename: Dale
authors.initials: D
authors.lastname: Polson
authors.forename: Philip H
authors.initials: PH
authors.lastname: Kass
authors.forename: Andres M
authors.initials: AM
authors.lastname: Perez
mesh_terms: D000818:Animals; D000833:Animals, Suckling; D003198:Computer Simulation; D004196:Disease Outbreaks / Q000662:veterinary; D005260:Female; D015146:Midwestern United States; D008954:Models, Biological; D016133:Polymerase Chain Reaction; D019318:Porcine Reproductive and Respiratory Syndrome / Q000517:prevention & control*; D019316:Porcine respiratory and reproductive syndrome virus / Q000472:pathogenicity; D013269:Stochastic Processes; D013552:Swine; D014611:Vaccination / Q000662:veterinary*; D014613:Vaccines, Attenuated; D014765:Viral Vaccines / Q000276:immunology*; D014886:Weaning
chemical_list: D014613:Vaccines, Attenuated; D014765:Viral Vaccines