Prevalence of porcine circovirus types 2a and b in pigs with and without post-weaning multi-systemic wasting syndrome.

The objective of this study was to determine the prevalence of porcine circovirus (PCV) type 2 genotypes in pigs with post-weaning multi-systemic wasting syndrome (PMWS) and in pigs that that did not have the disease. Nested PCR was used to analyse tissue from 540 formalin-fixed, paraffin-embedded lymph nodes. The number of PCV2a-positive pigs that had (χ(trend)(2)=54.584, P<0.001) and did not have (χ(trend)(2)=70.066, P<0.001) PMWS decreased significantly between the years 2000 and 2008. However, over this time-period, there was a significant increase in the number of animals infected with PCV2b that had (χ(trend)(2)=31.356, P<0.001) and did not have (χ(trend)(2)=9.494, P<0.001) PMWS. The findings demonstrate a significant overall increase in PCV2b infection in pigs that both have and do not have PMWS. Further studies will be required to determine the potential relationship between PCV2b infection and the increasing incidence of PMWS in Korea.