The role of Brucella infection in abortions among traditional cattle reared in proximity to wildlife on the Kafue flats of Zambia.

The role of Brucella infections in cattle abortions was investigated in 914 females from 124 herds. Animals were tested for exposure to Brucella species and history of abortion over the past three years. Sera were tested using the Rose Bengal test (RBT) and competitive enzyme-linked immunosorbent assay (c-ELISA). Of 886 females tested, 189 were positive on RBT, and 154 (81.5%) were confirmed by c-ELISA. At the individual animal level, 16.2% (95% confidence interval [CI]: 12.6% to 19.8%) of the cows had aborted their foetuses in the last three years, while Brucella seroprevalence was estimated at 23.9% (95% CI: 19.8% to 28.0%), after adjusting for area clustering and weighting according to sampling fraction. At the herd level, abortions were recorded in 50% of the herds (95% CI: 41.2% to 58.8%) and the seroprevalence was 58.1% (95% CI: 49.5% to 66.6%). A multiple logistic regression model identified the presence of anti-Brucella antibodies (odds ratio = 3.4; 95% CI: 1.6 to 7.4) and age as having significant effects on the risk of cattle abortion but no distinct factors could be identified at herd level. These results establish that Brucella infections contribute significantly to cattle abortions in the traditional livestock sector of Zambia.