Enzootic bovine leukosis: an epidemiological survey among cattle in the west of France by precipitating antibody detection.

In order to inform the sanitary veterinaty authorities, an epidemiological survey was carried out in the West of France to appreciate the level of infection by BLV in cattle. More than 10,000 sera from 763 herds were tested by agar gel immuno-diffusion. The animals were more than one-year-old dairy cattle. 23 sera (0.22%) from 11 herds (1.44%) were found positive. In the 11 herds the levels of serologically positive animals ranged from 1.6 to 40% with a 9% average. These levels are comparatively low and are almost in correspondence with the number of leukotic tumours recorded in the slaughter houses and knackeries.