Successful PRRSV area control by optimized biosecurity and pig flow management in 40 farms/sites in a highly pig dense area of Denmark within 6 months

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Country: Denmark
Source: 2020 The 26th International Pig Veterinary Society (IPVS) Congress

Introduction

PRRSV can be transmitted through aerosols. It travel associated with particles and has been detected in air as far as 9.1 km from swine herds (1,2). Growing pigs represents the absolute majority of PRRSV infected pigs in an area. Growing pigs have a longer duration of viremia and shed PRRSV for a longer period than the adult breeding stock (3) the control of PRRSV circulation in growing pig populations is essential. This can be achieved through a combination of correct biosecurity, pigflow, management and immunization (4).

Materials and Methods

The study, which started January 1. 2019 included 40 farms owned by 15 different producers and involved 10.035 sows from 8 farms, 53.230 nursery pigs placed in 14 different sites and 40.870 finishers placed 25 different sites. All sites and all stages of production, breeding, nursery and finishers were initially sampled to determine the current status following methods described in reference 4. All positive sites were followed by regular testing. A COMBAT (Comprehensive Online management Biosecurity Assessment Tool) survey was conducted in all farms/sites to guide improvement of the biosecurity level, management and pigflow. Depending on PRRS status, pigflow and placement in different sites were adjusted. Some sites were partlially de-populated.

Results

First of January 2019 all sow sites except one sow-nursery site were stable positive by Ingelvac PRRS MLV vaccination or negative (following AASV definition (5)) Only strain present in the area was PRRSV2. 4 nursery and 12 finisher sites were exposed to PRRSV. 6 month later, all nursery and finisher sites were PRRSV negative. The one sow-nursery site remained unstable. The progress in serologically PRRS negative sites is illustrated in fig1 and fig. 2.

Key points:

  • An area regional PRRSV control program was conducted in 40 farms from Denmark. It involved 10,035 sows from 8 farms, 53,230 nursery pigs placed in 14 different sites and 40,870 finishers placed in 25 different sites.
     
  • Within 6 months after the issues revealed using COMBAT (Comprehensive Online management Biosecurity Assessment Tool) were identified and improved on the different sites, all nursery and finisher sites were PRRSV negative.
     
  • Combination of improved biosecurity and pig flow management in many herds in a very pig dense area from Denmark was able to eliminate PRRSV circulation in sow, nursery, and finisher sites at the same time as immunization of breeding stock was systematically maintained.

Acknowledgments

Lars E. Larsen and Lise Kvisgaard, Danish Technical University, DK-2800 Kgs. Lyngby, Denmark

References

  1. Alonso C, et al. 2015. PLOS ONE DOI:10.1371.
  2. Dee S, et al. 2009. Vet Res 2009; 40 (4):39
  3. Klinge et al. 2009. Virology J. 6:177
  4. Rathkjen et al. 2017. Acta Vet. Scan. 59:4
  5. Holtkamp DJ. et al. 2011. Swine Heal Prod. 19:44

Figure 1: Area map January 2019. Green dots; location of sites without PRRS exposure. Red dots; location of sites, which had been exposed to PRRSV. Yellow dots; vaccinated gilt quarantine and acclimatization.

Figure 1 Image

Figure 2: Area map July 2019.

Figure 2 Image