[Retrospective evaluation of data over five years of the BVDV prevention program using ear notch samples from the autonomous province of Bolzano (Italy)].

In 2005 the Autonomous Province of Bolzano implemented a BVD-Virus control programme by testing all newborn calves for Bovine Viral Diarrhoea Virus (BVDV) antigen by analysing ear notch samples. In eradication programs between November 2005 and October 2010 a total of 344,108 newborn calves were ear notch sampled and analysed for BVDV by an antigen ELISA detecting the E(rns) (HerdCheck BVDV Antigen/Serum Plus, Idexx Laboratories, Switzerland). The tissue samples were collected during calf ear tagging (within the first 20 days of life) using two sampling devices (TypiFix-System, Agrobiogen GmbH [Germany] and Allflex [France]). 0.4% (1400) of the collected samples showed a positive result, and of these, 583 calves were subjected to a follow-up examination, analysing the samples again by ELISA as well blood samples by Reverse transcriptase-PCR. Blood samples were also collected from the dam, if still present on the farm by the time of sampling. These results suggest that a BVDV control programme testing all newborn calves sampled for BVDV antigen by analysing an ear notch sample in principle is practicable. However, due to the low positive predictive value (75%) of the E(rns)-ELISA used, not all persistently infected calves can be detected.