The brucellin skin test as a tool to discriminate false positive serological reactions in bovine brucellosis.

摘要

Three experiments were carried out to assess the diagnostic value of the brucellin allergic skin test (AT) [in France?] between January and March 1994. First, 1259 Charolais cattle from 20 Brucella-free herds in which brucellosis false positive serological reactions (FPSR) had been recorded using Rose Bengal (RBT) and/or complement fixation (CFT) tests were tested twice with AT to evaluate its specificity. Secondly, AT and serological tests (CFT, tube agglutination test, dithiothreitol-microagglutination test and ELISA) sensitivities were evaluated in 111 cattle from 15 herds which tested positive for Brucella by the RBT. Thirdly, AT was used in a field trial to discriminate FPSR from true brucellosis reactions. AT specificity in non-vaccinated cattle was 99.83%. Skin thickening 72 h after injection was significantly higher in vaccinated cattle (1.42 compared with 0.15 mm). AT specificity decreased significantly to 78% in vaccinated cattle. 70 of 111 animals from all 15 herds were positive by AT.The sensitivity of AT relative to RBT was 64%. In the field trial, AT was more specific than RBT or CFT. It is concluded that AT may be used at herd level as a confirmation test in cattle unvaccinated against brucellosis.