Evaluation of four serological tests to detect prevalence of bovine brucellosis in Khartoum State

To estimate the prevalence rate of bovine brucellosis in Khartoum State of Sudan and to compare the different serological tests, 636 stratified random samples of milk from farms and markets in the state were collected. Individual milk and blood samples were also collected from farms which showed positive reaction to the bulk milk ring test. All these samples were tested for Brucella antibodies using the milk ring test (MRT), Rose Bengal plate test (RBPT) and indirect ELISA test on milk and serum. The prevalence of Brucella antibodies was higher in milk compared with serum samples. In Enzyme-linked Immuno Sorbent Assay (ELISA) test using milk samples, it was 34.7%, followed by Milk Ring Test 32.5%, while the prevalence when using the serum was 27% with the Rose Bengal Plate Test and 24.4% when using serum-ELISA. The sensitivity and specificity of MRT were 85 and 95% and for RBPT were 92 and 94%, respectively. There were association between the MRT and milk-ELISA (p < 0.01) and between RBPT and serum-ELISA (p < 0.05). The percentage agreement among MRT and milk- ELISA was 83% Kappa (p < 0.01), while the percentage agreement between RBPT and serum-ELISA was 86% Kappa (p < 0.01). When comparing the sensitivity, specificity and percentage agreement between milk-ELISA and serum-ELISA for the same cows, sensitivity for milk-ELISA was 92.8% and the specificity was 98.8%. The percentage agreement between milk-ELISA and serum-ELISA was 79% Kappa (p < 0.01). Milk-ELISA will provide an easy and significant contribution to detect brucellosis compared to other serological tests.   Key words: Sudan, milk, ELISA, serology, serum-ELISA, brucellosis.