PCV2 is highly prevalent in swine herds worldwide. The document summarizes research showing that: 1) Pigs are born already infected with PCV2, as the virus is present in pre-farrowing sows and transmitted to piglets in utero or during birth. 2) Piglets remain viremic for life even in the presence of antibodies, as PCV2 infection causes lifelong persistent infection. 3) The farrowing environment is thoroughly contaminated with PCV2, exposing growing piglets to constant viral challenge from the sow and environment.