Prevalence and geographic distribution of bovine viral diarrhoea (BVD) infection in Finland 1993-1997

Bulk milk samples from every herd supplying milk to dairies in Finland were examined for the presence of antibodies to BVD virus (BVDV) annually durin g 1993-1997. The highest prevalence, 0.99% in 1994. declined to 0.37% in 19 96; however, this favourable trend appeared to discontinue in 1997, where t he prevalence remained at 0.41%. In 1993, sera of all individual animals fr om bulk milk antibody-positive herds were examined for the presence of thes e antibodies. Since 1994, only sera of animals from herds with a bulk milk absorbance reading greater than 0.250 in the EIA test were examined individ ually. Three geographic foci of BVDV antibody-positive dairy herds were res olved in 1994, one in the north-western, another in the eastern and a diffu se third in the southern part of Finland. A distinct limiting of the spread was apparent in 1997. Beef cattle were also studied during 1993-1997; in 1 993 breeding units, in 1994 mainly beef suckler herds and in 1995-1997 seru m samples of beef animals at slaughter were examined for the presence of an tibodies to BVDV. The prevalence of seropositive herds in 1993 and 1994 was 30.2% and 3.2%, respectively, while the prevalence among slaughter animals ranged 0.8-1.6%. Seronegative animals in herds with >50% of seropositive a nimals were examined for the presence of BVD-virus. A total of 40 dairy her ds and two beef herds with viraemic (persistently infected, PI) animals was encountered during 1993-1997. A comprehensive control programme and a more specific, cooperatively funded eradication programme for dairy cattle were launched in 1994. These programmes most probably contributed to the declin e in prevalence during 1994-1996. (C) 1999 Elsevier Science B.V. All rights reserved.