Evaluation of Diagnostic Tests for Brucellosis in Cattle in Nigeria: Sensitivity, Specificity, and Agreement Analysis

This study empirically evaluates and compares the diagnostic performance of four serological tests for bovine brucellosis in Nigeria, addressing a critical research gap in the absence of Nigerian gold-standard validation data for brucellosis diagnostics. The choice of diagnostic test profoundly influences the accuracy of prevalence estimates and the efficiency of test-and-slaughter control programmes, and test performance data generated in other geographic contexts may not apply under Nigerian field conditions. Using a controlled evaluation design, 360 serum samples from cattle with known brucellosis status (confirmed positive by bacterial culture or negative by combined serological and clinical criteria) were tested blindly by the Rose Bengal Plate Test (RBPT), Serum Agglutination Test (SAT), competitive ELISA (cELISA), and indirect ELISA (iELISA). Sensitivity, specificity, positive predictive value, and negative predictive value were calculated for each test. Inter-test agreement was assessed using Cohen's kappa. Samples were sourced from farms in Plateau, Kaduna, and Kano States to represent diverse management contexts. The study provides the first Nigerian-context diagnostic test evaluation for bovine brucellosis. Findings revealed that cELISA achieved the highest diagnostic accuracy (sensitivity 94%, specificity 97%) compared to RBPT (sensitivity 87%, specificity 88%) when using bacterial culture as the reference. Test agreement was highest between cELISA and iELISA. The study recommends cELISA as the reference method for Nigerian brucellosis surveillance programmes and RBPT as a practical pen-side screening tool. Keywords: brucellosis diagnostics, sensitivity, specificity, cattle, Nigeria.