PRRSv Exposure Dynamic in Growing Pigs in European Farms Part I

21-04-2015


Article by:

J. Angulo, O. Duran, E. Lewandowski, P. H. Rathkjen, I. Hernandez, S. Figueras, V. Torres, L. Eppink,
A. Kirwan, N. Westenbroek, M. Steenaert, E. De.Jonghe, A. Warzecha, N. Tommasini, R. Langhoff, E. Schacht, A. Negatsch, C. Keller. ESPHM 2015.

INTRODUCTION
The objectives of this large study were to determine PRRSv exposure pattern and virus genetic diversity in growing pigs in European farms; to capture key information about common farm practices on biosecurity, diagnostic monitoring, and control tools and to capture mortality impact at the moment of sampling.

MATERIALS AND METHODS
Thirty four farms were identified across Europe in thirteen countries: Germany n:2; Ireland n:1; UK n:2; Italy n:3; France n:4; Spain n:3; Belgium n:3; Poland n:3; Hungary n:2; Romania n:2; Austria n:3; Denmark n:3; The Netherlands n:3. These farms were typical production systems for each country and with PRRSv clinical problem history. All farms represented 41,329 sows. At each farm, a cross sectional sampling was implemented taking three sampling points: at weaning; end of nursery and mid finisher. At each sampling point, 20 blood samples were taken running PRRS IDEXX ELISA 3x and PRRS rt-PCR in all samples, getting serum individual results for ELISA (60 samples per farm) and pooled (1:5) for PCR (12 pools per farm). In total, 1,980 individual ELISAs, 396 pooled PCRs and 55 ORF5 sequences from selected positive results were added in the analysis. In addition to diagnostic work; an on-farm questionnaire was implemented at each farm at the moment of sampling, capturing information about: Production System; Mortality; PRRS status; Semen source; previous information about PRRS sequencing; biosecurity and PRRS monitoring programs in place and PRRS control strategies at different levels of production system: gilts, breeding herd and growing pigs. This part I shows results on farms stats description and cross sectional serum profiles ELISA and PCR from farms. F-test for SP ratio variability and Mann-Whitney tests were used for diagnostic results analysis.

RESULTS
FIGURE 1: PRODUCTION SYSTEM AND PRRS STATUS FROM SAMPLED FARMS 

 
FIGURE 2: SP VALUE DISTRIBUTION AT EACH SAMPLING POINT. 

 
Cross sectional profile on ELISA (N: 1620 samples; 540 per sampling point) and PCR (N:99 pools; 33 per sampling point) showed end of nursery phase as the highest PRRSv circulation sampling point in growing pigs. Profile results for at weaning; end nursery and mid finisher were: S:P ratio mean: 0.622 / 0.796 / 1.664; stdev: 0.621a / 0.796b / 0.901c; PRRS Wild Type median: 0 % a / 100 % b / 25 % c respectively.

FIGURE 3: PRRS PCR SERUM RESULTS BY SAMPLING POINT. 

CONCLUSION
  1. Farms selected for this study were representative for European conditions (production type and herd size).
  2. Wild type PRRSv prevalence by pig flow was 85%.
  3. Highest circulation at the end of nursery phase.
  4. PRRS genotype I was identified in 96% of pig flows.
  5. Confirms the presence and circulation PRRSv in growing pigs as an important epidemiological event that should be addressed in control and eradication programs.
  6. Information on virus genetic variability, mortality impact and control practices are discussed in part II.

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