Abstract :
Porcine circovirus type 2 (PCV2) is a small, non-enveloped, circular, single-stranded DNA virus
of economic importance in the swine industry worldwide. Based on the sequence analyses of
PCV2 strains, isolates can be divided into five subtypes (PCV2a–e). PCV2 is an ubiquitous virus
based on serological and viremia data from countries worldwide. In addition, PCV2 DNA was
discovered in archived samples prior to the first recognition of clinical disease. Recently, a
worldwide shift in PCV2 subtype from PCV2a to PCV2b occurred. PCV2 DNA can be detected
in fecal, nasal, oral and tonsillar swabs as well as in urine and feces from both naturally and
experimentally infected pigs. PCV2 DNA can be detected early in the infectious process and
persists for extended periods of time. The effectiveness of disinfectants for reducing PCV2
in vitro is variable and PCV2 is very stable in the pig environment. Limited data exist on the
horizontal transmission of PCV2. Direct transmission of PCV2 between experimentally or
naturally infected animals and naı¨ve animals has been documented and the incorporation of
clinical or subclinically infected animals into a population represents a risk to the herd. Indirect
transmission through the oral, aerosol or vaccine routes is likely a lesser risk for the
transmission of PCV2 in most swine populations but may be worth evaluating in high heath
herds. The objective of this review was to discuss data on the epidemiology and horizontal
transmission of PCV2.
