Reproductive losses associated with porcine circovirus type 2 in a Japanese herd of seronegative sows.

From April to July 2009, there was a high rate of reproductive losses in a 30-sow, farrow-to-finish swine herd in Yamagata Prefecture, Japan. Histopathological examinations of heart tissue from stillborn and preweaning piglets showed nonsuppurative, necrotizing lesions. Immunohistochemical staining and polymerase chain reaction analysis of myocardial lesions revealed the presence of porcine circovirus type 2 (PCV2) antigens and DNA in these tissues. Indirect immunofluorescence also showed that the PCV2 antibody positive rate in the sows was higher in May 2009 than in December 2008. The results of this study suggest that PCV2 spread to this farm and caused a high rate of reproductive losses.