Progress of control and prevention programs for bovine viral diarrhea virus in Europe.

In Europe, nationwide BVD control programs based on the TC principle have been running for up to 10 years in the Nordic countries. The results have shown that BVD eradication by removal of PI animals without use of vaccines is effective and that today's diagnostic tests, when used by experienced diagnosticians, are suitable for this task. Furthermore, to avoid control programs becoming Sisyphean tasks, adherence to strict biosecurity guide-lines to minimize infection of susceptible herds is a crucial additional measure. Efficient organization of testing, with sufficient capacity of diagnostic laboratories, is also important to minimize the period of overlap when remaining infected and recently emerged naive herds coexist close to each other. Control programs based on voluntary participation are possible, but when approaching final clearance of a national herd, significant delays can easily be suffered if any herd owners are allowed not to clear their herds. The control schemes used in the Nordic countries were tailored to fit the structure of the cattle production in each country. If BVD control programs based on the same principles are to be set up for other bovine populations,it is important to recognize and take into account for differences in the epidemiology of BVD and in the structure of the animal production,including cattle density and husbandry practices. To ensure optimal performance of the diagnostic tests, the diversity of BVDV in the region to be tested should also be considered.