Serological studies of mucosal disease virus in England and Wales.

A survey of the cattle population in England and Wales showed that about 62 per cent of animals had neutralising (SN) antibody to BVD-MD virus in their serum. Fewer seropositive individuals were detected by immunodiffusion (53 per cent), and complement fixation (CF) tests (34 per cent). The prevalence of antibody was not affected by herd size, but some variation was found between various regions of the country, and the proportion of animals seropositive rose markedly with age. The immunodiffusion test was a specific but relatively insensitive method of detecting antibody compared with the SN test. The data suggest that the CF test may detect a different, short-lived antibody. For diagnostic serology, the SN test was superior to the other methods. No antibody to the virus was detected in human or equine sera but about 7.3 per cent of sheep sampled had serum antibody to the virus in the immunodiffusion test.