R. Pouillot et al., THE BRUCELLIN SKIN-TEST AS A TOOL TO DISCRIMINATE FALSE-POSITIVE SEROLOGICAL REACTIONS IN BOVINE BRUCELLOSIS, Veterinary research, 28(4), 1997, pp. 365-374
Three experiments were performed in order to assess the diagnostic val
ue of the Brucellin allergic skin test (AST) in a brucellosis false po
sitive serological reactions (FPSR) context. First, 1 259 cattle from
20 Brucella-free herds in a FPSR area were tested twice with AST to es
timate its specificity. Secondly, AST and serological tests (complemen
t fixation test [CFT], tube agglutination test, dithiothreitol-microag
glutination test and ELISA) sensitivities were evaluated on 111 cattle
positive to the Rose Bengal test (RBT) belonging to 15 Brucella-infec
ted herds. Thirdly, AST was used in a field trial to discriminate FPSR
from true brucellosis reactions. AST specificity in non-vaccinated ca
ttle 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 speci
ficity decreased significantly to 78% (CI95%: 68-87%). Individual sens
itivity of AST relative to Rose Bengal test was 64% (CI95%: 54-72%), w
hile all infected herds were AST positive (n = 15). When associated wi
th CFT, it detected 95% (CI95%: 90-98%) of the infected cattle. These
results were consistent with the field trial. In a FPSR context, AST w
as more specific than RBT or CFT. Therefore, this test could be used a
t herd level as a confirmation test, on cattle non vaccinated against
brucellosis.