Effect of Circovirus on Pig Immune Systems

It is a pleasure to see some science on pig epidemics being done in Britain and published.

Circovirus and PMWS were always dangerous subjects in Britain because of the potential significance to the 2000 - 2001 epidemics of Classical Swine Fever (CSF) and, Foot and Mouth (FMD).

Britain, and the world, were not told that these disastrous epidemics occurred first in Britain in pig herds already sick with Porcine Circovirus and with damaged immune systems, before later spreading throughout the country. The health status of the pigs before CSF struck in 2000 seems to some kind of state secret, then and now.

Well, they did have to cancel a General Election in the ensuing chaos.

The habit of British civil service to cover up their mistakes is well noted elsewhere. This was a bad one and the government veterinarians blamed the innocent.

The key lies in the last sentence "The findings of this study highlight the potential role of the immune status of the sow on the occurrence of PMWS."

http://veterinaryrecord.bmj.com/content/early/2012/05/29/vr.100276.short?rss=1

Veterinary Record doi:10.1136/vr.100276

·         Papers

Porcine circovirus type 2 infection before and during an outbreak of postweaning multisystemic wasting syndrome on a pig farm in the UK

1.     B. Wieland, DrMedVet, PhD¹, 

2.     D. Werling, DrMedVet, PhD, MRCVS¹, 

3.     A. Nevel, BVetMed, PhD, MRCVS¹, 

4.     S. Grierson, BSc (Hons), PhD¹, 

5.     A. Rycroft, BSc (Hons), PhD, C.Biol., FSB, FRCPath¹,

6.     T. G. Demmers, PhD¹, 

7.     A. J. C. Cook, BVetMed, MSc, MRCVS², 

8.     S. H. Done, BA, DVetMed, PhD, Dipl ECPath, Dipl ECPHM, FRCPath, FRCVS, AHVLA, Thirsk, UK³, 

9.     D. Armstrong, BVetMed, MRCVS³ and 

10.   C. M. Wathes, BSc, PhD, FIAgrE¹

+Author Affiliations

1.        Epidemiology and Veterinary Public Health, Royal Veterinary College, London, UK

2.        Animal Health and Veterinary Laboratories Agency (AHVLA), Weybridge, UK

3.        BPEX Ltd, Stoneleigh Park, Kenilworth, UK

The presence of porcine circovirus type 2 (PCV-2) and other pathogens before and during an outbreak of postweaning multisystemic wasting syndrome (PWMS) in pigs is evaluated in this study. At the time of the outbreak on a large commercial pig farm in the UK, serum samples and data were collected in two independent on-going research projects, one in weaned pigs and the other in sows. Serum samples of growing pigs and sows were PCV-2-antibody and PCR positive before and during the PMWS outbreak. Upon sequencing, PCV-2 isolates collected before the outbreak were identified as PCV-2a, and isolates collected during the outbreak were identified as PCV-2b, suggesting a shift of PCV-2 genotypes present on the farm. Pigs in the weaner study were from sows originating from different breeders and an association of sow origin and PCV-2 serostatus in offspring was found. Further, pigs had higher odds to be PCV-2 antigen positive if the sow was PCV-2 antibody positive around farrowing, the sow was of higher parity, and were less likely to test antigen positive if the sow was sourced from a particular breeder. The findings of this study highlight the potential role of the immune status of the sow on the occurrence of PMWS.

·         Accepted March 29, 2012.

·         Published Online First 29 May 2012