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B Dufour

Publications and source records attributed to B Dufour.

148 records · Page 9Linked to original sources
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The Brucellin skin test as a tool to discriminate false positive serological reactions in bovine brucellosis.

Three experiments were performed in order to assess the diagnostic value of the Brucellin allergic skin test (AST) in a brucellosis false positive serological reactions (FPSR) context. First, 1259 cattle from 20 Brucella-free herds in a FPSR area were tested twice with AST to estimate its specificity. Secondly, AST and serological tests (complement fixation test [CFT], tube agglutination test, dithiothreitol-microagglutination test and ELISA) sensitivities were evaluated on 111 cattle positive to the Rose Bengal test (RBT) belonging to 15 Brucella-infected herds. Thirdly, AST was used in a field trial to discriminate FPSR from true brucellosis reactions. AST specificity in non-vaccinated cattle was very high (99.83%; confidence interval 95% [CI95%]: 99.67-99.96%). Skin thickening 72 h post-injection was significantly higher on vaccinated cattle (1.42 vs 0.15 mm). In this sub-population, AST specificity decreased significantly to 78% (CI95%: 68-87%). Individual sensitivity of AST relative to Rose Bengal test was 64% (CI95%: 54-72%), while all infected herds were AST positive (n = 15). When associated with CFT, it detected 95% (CI95%: 90-98%) of the infected cattle. These results were consistent with the field trial. In a FPSR context, AST was more specific than RBT or CFT. Therefore, this test could be used at herd level as a confirmation test, on cattle non vaccinated against brucellosis.

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PubMedDate not supplied

False positive serological reactions in bovine brucellosis: evidence of the role of Yersinia enterocolitica serotype O:9 in a field trial.

To investigate the epidemiology of false positive serological reactions (FPSR) in bovine brucellosis, 1259 bovines from 20 herds were sampled on three successive occasions during the winter of 1993-1994 in an area where the herd prevalence rate of FPSR was high. Serum samples were examined by classical brucellosis serological tests (Rose Bengal and complement fixation) and faeces were cultured for the presence of Yersinia enterocolitica O:9. Thirty-nine bovines expressed at least one positive serological reaction during the study. In the herds with FPSR during the 1993-1994 annual brucellosis surveillance campaign, the specificity of the brucellosis serological tests varied significantly from December to March (97.0% to 99.1%). Y enterocolitica O:9 was isolated from 42 bovines but only three of them showed a positive serological response during the study. Y enterocolitica O:9 isolation rates also decreased with time. Young animals and animals having demonstrated FPSR in the past had a greater risk of having a FPSR. Older animals, which rarely showed FPSR, could form a reservoir for Y enterocolitica O:9. While isolation of Y enterocolitica O:9 was not linked to presence of FPSR and conversely, the FPSR phenomenon should be considered, either at the herd level or at the individual level. This work reinforces the link, at least partial, between FPSR and infection by Y enterocolitica O:9.

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