Voluntary and compulsory eradication of bovine viral diarrhoea virus in Lower Austria

A voluntary BVDV eradication program without vaccination was introduced in Austria in 1997, according to the Swedish model employing herd-level antibody tests. Since this time, identified persistently infected (PI) animals have to be slaughtered. In order to protect non-infected herds, the major routes of introduction of BVDV infection into a herd, such as communal grazing and livestock trade, have to be controlled. In 1998 PI animals were identified in 7.5% of affiliated herds of herd book breeders. During the voluntary program, the majority of the 2455 herd book breeders who actively participated in the BVDV program had cleared up their herds. Hence, in 2005 only nine infected herds (0.36%) remained under clearance. These data show that BVDV control can be achieved at the farm level without a nation-wide BVDV eradication program. A federal law was passed in 2004, obligating all herd owners to follow the BVDV eradication program. Between 2005 and 2007, the number of herds with a certified BVDV-free status increased from 7931 to 9952 (2006) and 11,166 (2007), respectively. Currently (2008), 11,017 of 12,031 existing herds have been certified as BVDV-free herds (91.57%). Nearly all certified BVDV-free dairy herds can now be monitored by testing milk samples because the cows have no antibodies to BVDV. This signifies a marked improvement since 1998, when 46% of the 5024 tested dairy herds had a high level of BVDV antibodies in bulk tank milk. Total eradication of BVDV-infected herds will need a further 1 or 2 years.