Figure 1. Serologic and virologic profiles of herds with postweaning multisystemic wasting syndrome (PMWS) (A to E) or without PMWS (N and P). Blood was collected from 10 pigs per age group from 3 to 23 wk of age. The number of pigs positive for antibody to porcine circovirus type 2 (PCV2) (squares) was determined by indirect immunofluorescence. The level of antibodies to porcine reproductive and respiratory syndrome virus (PRRSV) was determined by enzyme-linked immunosorbent assay and expressed as mean S/P ratios (circles). The numbers of serum samples positive for PCV2 (black), PRRSV (grey), or porcine parvovirus (PPV; white) were determined by the polymerase chain reaction (PCR).