Epidemiology and Transmission of Porcine Circovirus Type 2
(PCV2) PCV2 has been highly prevalent in the pig population for
decades, prior to the emergence of associated clinical disease
manifestations that severely affected the pig production
worldwide in the late 90s. PCV2 can be further subdivided into
several genotypes. From descriptive epidemiologic data, there is
evidence of a global shift of the main PCV2 genotypes in
different countries from PCV2a to PCV2b, which is generally
associated with more severe disease. In addition, from analytic
epidemiologic studies, the modified within-herd PCV2 dynamics of
infection is strongly related to the increased incidence of
clinical disorders associated with PCV2 infection. Because PCV2
is shed for a long time by an extremely large variety of routes,
it easily spreads within the population both through horizontal
and vertical transmission. Even if airborne transmission cannot
be formally excluded, direct contact is certainly the most
efficient infectious route due