Validation of Different Versions of The Card or Rose-Bengal Test for The Diagnosis of Brucella melitensis Infection in Ruminants

Abstract

A total of 543 sera from unvaccinated ruminant species, viz. cows, buffalo cows, ewes, female goats and she-camels in seven Nile Delta governorates were tested. Most animals had a history of Brucella melitensis biovar 3 infection. This study was to investigate the fitness of Rose-Bengal plate test (RBPT) formats namely the US brucellosis card (BCT) 8% and 3%, the UK RBPT and its modification, the Scottish RBPT and the French RBPT 4.5% for pre-confirmation of B. melitensis infection in non-bovine ruminants. Taking the complement fixation test (CFT) as the gold standard, the performance of RBPT assays and the buffered acidified plate antigen test was estimated as relative sensitivity, accuracy, kappa agreement with CFT and association with CFT based on Pearson's chi-squared test and Phi coefficient. Almost all acidified agglutination test formats were generally associated with CFT. The best performance of RBPT in cows, buffalo cows, ewes, female goats and she-camels was reached by the Scottish, the French, the French, the UK and the Scottish RBPT respectively. From the animal inter-species perspective, the performance of the BCT 8% considerably fell in buffaloes and goats improving greatly with its 3% version, but causing having extra drop in goats. The performance of the UK RBPT dropped in sheep and drastically fell in camels with its modification achieving some progress in buffaloes, sheep and camels, and minor drop in cattle and goats. The Scottish RBPT slightly dropped in buffaloes but noticeably in goats with good performance in cattle and camels. The French RBPT drastically fell in goats and less severely in camels. It was concluded that enhancing the sensitivity of the RBPT resulted in overall performance promotion especially in sheep, but still insufficiently accurate requiring some intervention in goats, buffaloes and camels in descending order of urgency