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

Poul H Rathkjen,Johannes Dall

doi:10.1186/s13028-016-0270-z

Abstract

BackgroundPorcine 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.ResultsAt 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.ConclusionsThis 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 Additionally this study confirms the value of a previously unpublished, simplified alternative to the McREBEL system for controlling PRRSV.

Highlights

Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant animal and economic losses worldwide
Time taken to eliminate PRRSV from all farms on the Horne Peninsula The study extended from July 2013 to July 2015
All herds on the Horne Peninsula were initially PRRSV positiveunstable except F2B1 and F2B2, which were positivestable (Fig. 1; Additional file 1)

Summary

Introduction

Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant animal and economic losses worldwide. 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’ Golden Rules’ (10GR) for biosecurity management. Porcine reproductive and respiratory syndrome (PRRS) is one of the most prevalent viral swine diseases in the world, responsible for substantial economic losses worldwide [1]. Porcine reproductive and respiratory syndrome is caused by the PRRS virus (PRRSV) and was first reported in the late 1980s [4]. Porcine reproductive and respiratory syndrome causes high morbidity and mortality, poor reproductive performance and slow piglet growth rates [1]. In growing and finishing pigs, the severity of PRRS varies from no detectable signs to fatal pneumonia, depending on the viral strain and the presence of opportunistic bacterial or viral coinfections [13]

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Conclusion