Bluetongue virus serotype 8 in healthy young calves

Following the detection in Northern Ireland of bluetongue serotype-8 (BTV-8) PCR-positive calves born from PCR-negative but seropositive heifers imported from the Netherlands, an investigation was started to determine whether PCR-positive calves were born in the first quarter of 2008 in the Netherlands. Blood samples were collected on 43 dairy farms from 388 cow-calf combinations. All calves were at least 10 days old and had been born after 1 January 2008. In total, 229 cows had had a BTV-8 infection, and from these cows 37 PCR-positive calves were born (16.2 %). If these calves are viraemic, they can contribute to BTV-8 overwintering in North-West Europe