Comparison of rose bengal plate test, serum agglutination test, and indirect enzyme-linked immunosorbent assay in brucellosis detection for human and goat samples

Abstract

Background: In Uganda, detection of brucellosis in goats and humans is more frequently done using rose bengal plate test (RBPT) in comparison to other serological tests such as serum agglutination test (SAT) and indirect enzyme-linked immunosorbent assay (i-ELISA). Aim:This study aimed at estimating the degree of agreement, specificity and sensitivity of RBPT, SAT, and ELISA in brucellosis detection in human and goat samples.Materials and Methods: An analytical study was conducted involving parallel testing of 425 goat samples and 177 human samples to compare RBPT, SAT, and i-ELISA tests of brucellosis detection. Results:A seroprevalence of 14.82% in animals and 11.86% in humans was detected using RBPT, 7.06% in goats and 5.09% in humans using SAT, and 6.35% in humans and 4.52% in animals using i-ELISA. The degree of agreement between the three tests in humans and animals was compared using Fleiss' kappa statistics where a moderate agreement (MA) was obtained for both with kappa value 0.57 in animals and 0.51 in humans and p<0.001. Kappa values in animals were 0.52 (MA) for RBPT and i-ELISA, 0.61 (MA) for RBPT and SAT, and 0.82 substantial agreement (SA) for SAT and i-ELISA. The kappa values in humans were 0.52 (MA) for RBPT and i-ELISA, 0.57 (MA) for RBPT and SAT, and 0.82 (SA) for SAT and i-ELISA, respectively. The study revealed a significant agreement in the tests for all the three tests, but there was SA between SAT and i-ELISA in both animal and human samples. Sensitivity and specificity of RBT and SAT were estimated using i-ELISA as a gold standard as follows, in goats RBPT: 100 and 91% and SAT: 100 and 99%, respectively, and in humans RBPT: 100 and 92% and SAT: 88 and 99%, respectively. Conclusion:It appears that RBPT is good as a screening test, whereas SAT and i-ELISA are good for diagnosis purposes or confirmatory test.

Seromonitoring of brucellosis in goats and sheep slaughtered at an abattoir in Kampala, Uganda

“…3 Also, the basic RBT is extremely sensitive but heterospecific 16 ; infection caused by bacteria such as Vibrio cholerae , Yersinia enterocolitica 0:9, Pasteurella spp., Salmonella spp., or some other members of the Brucellaceae family could give more false-positive results in RBT than in the iELISA, a test that may eliminate heterospecific agglutination. The difference in our study results and those reported elsewhere 6,13 could be the result of the difference in the method of the RBT used; we based our results on a mRBT, which is more accurate than the basic RBT when testing small ruminants.…”

“…16 Noteworthy, slightly more positive cases were detected by the iELISA than the mRBT, a finding that differed from several studies. 6,13 In most of the latter studies, as well as our study, the iELISA kit used is a qualitative test that detects only IgG, whereas the RBT kit detects IgM, IgG, and IgA qualitatively. 3 Also, the basic RBT is extremely sensitive but heterospecific 16 ; infection caused by bacteria such as Vibrio cholerae, Yersinia enterocolitica 0:9, Pasteurella spp., Salmonella spp., or some other members of the Brucellaceae family could give more false-positive results in RBT than in the iELISA, a test that may eliminate heterospecific agglutination.…”

“…Based on the manufacturer’s instructions, S:P values were considered to evaluate a sample as positive if ≥120%. 6…”

“…Fifty-two (18.1%) were ≤1-y-old, 160 (55.7%) 2-3-yold, and 75 (26.1%) were ≥4-y-old. The sampled goat breeds included local (Mubende [72], local [42], small East African [21]) and exotic (Boer [38], Black Bengal [16], Saanen [12], Jamunapari [10], Toggenburg [6], Red Sokoto [3], Red Head [1]) breeds. The sampled sheep breeds included local (Red Maasai [32], white sheep [11], local [7], small East African [4], Mubende [2], Sebei [1]) and exotic (California Red [5], Blackhead Persian [4]) breeds.…”

“…Based on the manufacturer's instructions, S:P values were considered to evaluate a sample as positive if ≥120%. 6 Data were captured in Excel v.2016 (Microsoft) and analyzed with Stata 14 (StataCorp). Descriptive data were presented as calculated frequencies and percentages.…”