title: Control and eradication of porcine reproductive and respiratory syndrome virus type 2 using a modified-live type 2 vaccine in combination with a load, close, homogenise model: an area elimination study.
abstract: BACKGROUND
  Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant animal and economic losses worldwide. The infection is difficult to control and PRRSV elimination at local level requires coordinated intervention among multiple farms. This case study describes a successful elimination of PRRSV from all 12 herds on the Horne Peninsula, Denmark, using a combination of load, close, homogenise (LCH) using PRRSV type 2 modified-live vaccine, optimised pig flow, and'10 Golden Rules' (10GR) for biosecurity management. To the authors' knowledge, this is the first successful European PRRSV area elimination project documented in detail. The PRRSV type 2 modified-live vaccine was used as part of the LCH method in breeding herds. Complete or partial depopulation was performed in some infected herds. A simplified biosecurity protocol (10GR) based on the McREBEL™ system of pig flow management, was employed in all herds and at all times throughout the study.
  
  
  RESULTS
  At study commencement, all herds were infected with PRRSV, and most were actively shedding virus. In just over 18 months, all 12 herds on the Horne Peninsula were confirmed to be PRRSV negative by polymerase chain reaction testing and negative for antibodies against PRRSV by enzyme-linked immunosorbent assay testing. All herds were subsequently obtained 'Specific Pathogen Free' status for PRRSV.
  
  
  CONCLUSIONS
  This study provides compelling evidence suggesting that an area elimination plan combining LCH with PRRSV type 2 vaccination, optimised pig flow, and 10GR for biosecurity management can effectively eliminate PRRSV from a geographic area. Additionally this study confirms the value of a previously unpublished, simplified alternative to the McREBEL system for controlling PRRSV.
authors.affiliation: Boehringer Ingelheim Vetmedica GmbH, Binger Straße 173, 55216, Ingelheim, Germany. poul.rathkjen@boehringer-ingelheim.com.
authors.forename: Poul H
authors.identifier: http://orcid.org/0000-0001-9942-4070
authors.initials: PH
authors.lastname: Rathkjen
authors.affiliation: PORCUS svinefagdyrlaeger og agronomer, Oerbaekvej 276, 5220, Odense, Denmark.
authors.forename: Johannes
authors.initials: J
authors.lastname: Dall
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D003718:Denmark; D060740:Disease Eradication / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay; D008962:Models, Theoretical; D016133:Polymerase Chain Reaction; D019318:Porcine Reproductive and Respiratory Syndrome / Q000517:prevention & control* / Q000821:virology; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics / Q000276:immunology; D013047:Specific Pathogen-Free Organisms; D013552:Swine; D014765:Viral Vaccines / Q000235:genetics / Q000276:immunology / Q000592:standards*
chemical_list: D000914:Antibodies, Viral; D014765:Viral Vaccines
keywords: Area regional control; Elimination; Load close homogenise; Modified-live vaccine; PRRS