The effect of calfhood vaccination with strain 19 on the serological diagnosis and eradication of bovine brucellosis.

Abstract

Data from 42,224 cattle from 694 herds collected during the brucellosis eradication campaign were used to examine the effects of calfhood strain 19 vaccination. The prevalence to infection in vaccinated herds was 1.8% compared with 9.1% in non-vaccinated herds (p less than 0.005). The mean titre in the former group was lower (p less than 0.001). Vaccinated herds required 3.3 herd tests to achieve a provisionally free status compared with 4.8 in non-vaccinated herds (0.001 less than p less than 0.005). Vaccination did not significantly reduce the number of herd test in herds with less than 100 breeding females. In tests after the initial herd test only 0.5% reactors were found in vaccinated herds compared with 6.9% in non-vaccinated herds (p less than 0.005). There were 0.9% false positive to the Rose Bengal plate test in non-vaccinated and 2.1% in vaccinated animals (p less than 0.005) in non-infected herds. In infected herds this percentage was 3.0% and 4.2% respectively by (p less than 0.05). In the non-infected herds there were 0.04% false positives to the complement fixation tests out of 10,506 non-vaccinated cattle tested and 0.2% out of 24,734 vaccinated cattle.