The prevalence of PCV2 viremia in newborn piglets on four endemically infected Dutch sow farms is very low.

Porcine circovirus type 2 (PCV2) systemic disease is currently considered one of the most relevant infectious diseases in swine industry worldwide from an economical point of view. Although piglets generally become diseased between 8 and 16 weeks of age, they can be infected much earlier, even already in utero. However, data on the prevalence of PCV2 infection in newborn piglets are very variable (lower than 40 up to 82%) and most of the studies have been performed in US. In European pig farms, using group-housing systems for gestating sows, a different herd PCV2 infection and immunological status may be expected and was recently reported in Germany. If that is the current scenario in most European farms, strategies to prevent horizontal transmission become essential for the control of the infection. The aim of our study was to determine the PCV2 prevalence in newborn piglets on 4 endemically infected farms in the Netherlands under European conditions. Eleven sows and 8 piglets per litter from 4 farms selected by their assumed PCV2 endemic infection status were sampled. Plasma from piglets was analysed with a PCV2 qPCR and serum from the sows was analysed with a commercial circovirus IgG ELSIA, circovirus IgM ELISA and PCV2 qPCR. In none of the samples from the piglets PCV2 was detected by the qPCR. None of the samples from the sows tested positive in the qPCR and circovirus IgM ELISA. The true- and apparent prevalence of IgG at herd and sow level were 0.75 and 0.81 and, 0.30 and 0.32, respectively, and no statistically significant association with sow parity was observed. These results reveal a very low prevalence of PCV2 in newborn piglets on endemically infected farms in The Netherlands, opening the opportunity of re-evaluation of the control measures applied in these farms.