2006 Auvigne Circovac Ipvs

Abstract No: P.07-06

EVALUATION OF THE FIRST FIELD RESULTS OF VACCINATION AGAINST PCV2 WITH CIRCOVAC®

V Auvigne1, JB Hérin2, B Fily2, F Joisel2 1

EKIPAJ, SAINT-GRÉGOIRE, France 2 MERIAL SAS, LYON, France

Introduction Post-weaning multisystemic wasting syndrome (PMWS) was first diagnosed in France in 1996. In 2000, Porcine Circovirus type 2 (PCV2) was identified as the key PMWS triggering factor (1). In October 2004, a provisional license was issued to MERIAL by the French Agency for Animal Health and Food Safety (AFSSA) for CIRCOVAC, an inactivated PCV2 vaccine intended for the vaccination of sows and gilts to reduce PMWS in piglets through passive immunity. Vaccination was recommended in farms with high mortality and presenting individual diagnosis of PMWS according to S. Sorden’s criteria (2). The goal of this study was to evaluate the effects of vaccination in the field in the first vaccinated herds. Materials and Methods Selection of farms: Twenty-six veterinary practitioners received temporary authorization for the use of the vaccine until the 31st of December 2004 and were contacted for inclusion in the study, with a total of 40 farms. To be included in the study, the farms had to have sent to slaughter at least three batches of pigs from vaccinated sows, and technical data for these batches had to be available. Using these criteria, 25 farms were excluded because of insufficient technical data from the batches (23 cases) or a recent vaccination (2 cases). Fifteen farms were included in the study representing a total of 4800 sows (average 340, median 150). Sows were vaccinated twice by IM route at 6 and 3 weeks before farrowing. The geographical locations of the farms were representative of the French pig farming distribution. Vaccination started between Dec. '04 and Feb. '05. Criteria of evaluation: The impact of the vaccination was evaluated by comparing the results of the first three batches of pigs born from vaccinated sows to the last three batches born from non-vaccinated sows. Data was processed using the EDIPORC® software evaluation. Criteria were mortality during post-weaning and fattening and the standard age at 115 kg. Statistical methods: For each farm, results were analysed using the rank sum test, with the batch considered as the statistical unit. Changes were considered as significant if p<0.05 and as showing a ‘tendency’ if p<0.30 (Table 1). Overall, the mean results of the three batches ‘before vaccination’ and ‘during vaccination’ were compared using Wilcoxon's matched-pairs signed-ranks test. Intercurrent factors: Some changes in farm management or in health situation sbetween the two periods were noticed for 6 farms: feed formula, turn to male genetic line Piétrain (2 cases), occurrence of E. coli diarrhoea, a episode of severe cannibalism and a change of the Porcine Reproductive and Respiratory Syndrome (PRRS) vaccination protocol of sows.

during fattening (1.8-12) and the standard age at 115 kg was 182 days (170-198). In the period ‘during vaccination’, the mortality rates decreased to 2.6% in postweaning (0.7-6.5) and 5.1% in fattening (2.5-10). Overall analysis (Table 2) showed a significant decrease (p=0.05) of total mortality in the nursery between the periods ‘before vaccination’ and ‘during vaccination’. Mortality during fattening was just below the limit of significance (p=0.08). Table 1 Classification of the changes (in no. of farms) Mortality Age at Post-Wean. Fattening 115 kg Significant improvement 5 2 1 Tendency to improvement 2 4 2 Stable 5 8 2 Tendency to deterioration 1 0 2 Significant deterioration 1 1 1 Missing data 1 0 7 Table 2 Differences between batches from vaccinated and non-vaccinated sows n mean Med. best worst p PW mortality (%) 14 -1.8 -1.2 -8.4 +2.9 0.04 Fatt. mortality(%) 15 -1.5 -0.5 -8.5 +1.8 0.08 Age at 115 kg (j) 8 -0.5 -1.0 -7.7 +5.6 0.84 Discussion The first preliminary results of the vaccination with CIRCOVAC in the field show a significant impact on nonqualified total mortality. It should be noted that the farms were only partially vaccinated and that sows only received two injections. However, it has been previously shown that the antibody titre in the sows, and therefore the colostral immunity, increases with the number of injections (3). Clinical information supplied by the veterinarians showed that the reduction in mortality was linked to a decrease in PMWS symptoms, even if it was not possible to substantiate this in the absence of systematic information on the causes of death. The study was carried out over a short period (six successive batches) in order to limit the impact of possible intercurrent events that would complicate the interpretation. It would, however, be interesting to carry out multicentric studies including growth data over a longer period of time. CIRCOVAC® is a registered trademark of Merial and EDIPORC is a registered trademark of EDIVIAL, France References 1. Kennedy S. et al., (2000), J Comp Path, 122, 9-24 2. Sorden S., (2000), Swine Health Prod 8, 133-136 3. Charreyre C. et al., (2006), 19th IPVS, Copenhagen, Denmark (submitted)

Results In the period ‘before vaccination’, the mean mortality rate was 4.4% during post-weaning (range 1.4-13.8), 6.6% Proceedings of the 19th IPVS Congress, Copenhagen, Denmark, 2006 · Volume 2

105