Control of BVDV-infection on common grassland--the key for successful BVDV-eradication in Lower Austria.

A bovine viral diarrhea/mucosal disease (BVD/MD) control and eradication program was introduced in Lower Austria in 1996, according to the Swedish model. At present 9800 out of 17,000 herds are part of this program. An important risk factor for BVDV-transmission under local conditions is communal grazing. Approximately 3-4% of livestock share common pastures, in which susceptible pregnant cattle may be mixed with unrecognised persistently infected (PI) animals. Rules and regulations were defined to allow only herds free from BVDV-infection on to common grassland. At the moment, 5067 herds are certified free from BVDV. The percentage of BVDV-free herds in regions with intensive pasture utilisation is higher (57.3%) than in the other regions (43.0%) of Lower Austria. With a reliable system for identification of PI-animals and a high certainty of prevention of PI-animals on common grassland, the main transmission of BVDV infection can be stopped, even if the animals are derived from infected herds and transiently infected animals cannot be excluded.