Evaluation of North American antibody detection tests for diagnosis of brucellosis in goats

The sensitivities and specificities of 17 antibody detection tests for brucellosis in goats were estimated. Tests evaluated included the USDA card test with 8% cell concentration (8%Card), USDA rapid automated presumptive test (RAP), Mexican Rose Bengal plate tests with 8 and 3% cell concentrations (8%RB and 3%RB), French Rose Bengal plate test with 4.5% cell concentration (4.5%RB), USDA standard plate test (SPT), USDA buffered acidified plate agglutination test (BAPA), USDA and Mexican rivanol tests (URIV and MRIV), USDA standard tube tests with Brucella abortus and Brucella melitensis antigens (SATA and SATM), serum ELISA, USDA cold-fixation complement fixation tests with B. abortus and B. melitensis antigens (CFA and CFM), USDA and Mexican milk ring tests (UBRT and MBRT), and a milk ELISA. Test sensitivity was evaluated by using 2 groups of 10 goats experimentally infected with B. melitensis or B. abortus and monitored for 24 weeks. Specificity was evaluated by using 200 brucellosis-free non-vaccinated goats from 10 California herds. The 3%RB was considered a good screening test because of high sensitivity at week 24 postinfection (90%), ease of performance, and low cost. The cold-fixation CFA and CFM had 100% specificity in the field study and were considered appropriate confirmatory tests. The milk ELISA was significantly more sensitive than the UBRT and significantly more specific than the MBRT. The milk ELISA also had the advantage of objectivity and ease of interpretation.