Absence of evidence of porcine circovirus infection in piglets with congenital tremors.

Porcine circovirus types 1 (PCV1) and 2 (PCV2) have been associated with congenital tremors (CTs) in piglets in the United States. In this study, central nervous system and nonneural tissues of 40 CT piglets from Spain, the United Kingdom, Ireland, and Sweden were investigated for the presence of PCV1 and PCV2 using in situ hybridization and immunohistochemical labeling on paraffin sections. The polymerase chain reaction for PCV2 was also carried out on sera from the Spanish CT cases. No evidence of circovirus nucleic acid or antigen was found in any CT piglet. Although these results do not support the hypothesis that PCV1 or PCV2 are linked to porcine CT, they cannot disprove it.