Porcine circovirus type 2 (PCV2) has emerged as a major contributor to disease and mortality in swine, with reports from around the globe. In the last decade, there has been an epidemic of a new manifestation and magnitude of disease associated with PCV2 in Europe and North America. While porcine circovirus (PCV) has been present in swine populations for decades, emergence of a cluster of the virulent phenotypic variants are now referred to as PCV2.