Evaluation of a fluorescence polarization assay for the detection of serum antibodies to Brucella abortus in water buffalo (Bubalus bubalis)

The effectiveness of Rose Bengal test (RBT) and fluorescence polarization assay (FPA) in diagnosing cattle brucellosis in endemic areas was assessed and RBT and FPA test agreement was compared (n = 319). The sensitivity of RBT and FPA in detecting low Brucella titres were evaluated in paired sera (n = 34). A logistic regression model was constructed to predict cattle test result in FPA using RBT as the main predictor and incorporating bio-data and animal history. There was 79.3% agreement between the RBT and FPA (Kappa = 0.59; Std error = 0.05; p = 0.000) and a high correspondence between high RBT scores and positive FPA results suggesting that sera with high RBT score may not require confirmation with tests such as competitive-ELISA or CFT. High FPA cut-off points were more likely to miss animals with low antibody titres. The RBT had a reduced ability in detecting low antibody titres compared to the FPA. FPA test interpretation was improved if a priori information, such as sex and age was used. Under the challenging disease surveillance conditions prevailing in rural Africa, field-testing methods that are sensitive and specific; allow single animal contact, low technical skills in data interpretation are suitable.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effectiveness of Rose Bengal test and fluorescence polarization assay in the diagnosis of Brucella spp. infections in free range cattle reared in endemic areas in Zambia

Muma

Lund

Nielsen

et al. 2008

“…Moreover, it is an important zoonosis threatening the public health in many countries of the world (Al-Majali et al 2007; Montagnaro et al 2008;Saegerman et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Small ruminant brucellosis and community perception in Jijiga District, Somali Regional State, Eastern Ethiopia

Bekele

Mohammed

Tefera

et al. 2011

A cross-sectional study of brucellosis in small ruminants was carried out from October 2008 to March 2009 in Jijiga District, Somali Regional State of Ethiopia. Seven hundred thirty sera samples (421 of sheep and 309 of goats) were randomly collected from purposively selected villages of the study area. Structured questionnaire format was developed, pre-tested and administered to assess the perception of the community pertaining to brucellosis in sheep and goats. Sera samples were screened by Rose Bengal Plate Test (RBPT), and all samples tested positive by the RBPT were subjected to Complement Fixation Test (CFT) for confirmation. Of 12 serum samples that were positive by RBPT, 11 were positive by CFT. Statistically significant differences were not observed between the species as well as the sex groups (P > 0.05); however, the variation between the age groups was statistically significant (P < 0.05). Analysis of the questionnaire survey suggests that improper handling of aborted materials, consumption of raw milk, and lack of awareness about the disease, among others, might greatly contribute to further spread of brucellosis in their livestock and exposes the community to a public health hazard. In general, the sero-prevalence in the study area was not so high; nevertheless, appropriate brucellosis control and prevention methods should be implemented to circumvent future potential for economic losses and the public health hazard of the disease.

“…Besides, the CFT is not successful on anti-complementary and hemolysed sera. Despite many limitations, CFT is recommended by OIE as a test prescribed for international trade for bovines (OIE 2004) and has been used as a reference test in a recent study on fluorescence polarization assay in water buffaloes (Montagnaro et al 2008). However, the notion of reference test for CFT is questionable in buffaloes in the light of work of Nicoletti (1992) on buffaloes which indicates false positive results in many sera.…”

Section: Discussionmentioning

confidence: 99%

Improvement in the diagnosis of Brucella abortus infections in naturally infected water buffaloes (Bubalus bubalis) using an ELISA with a Protein-G-based indicator system

Kumar

Chand

2011

Brucellosis caused by Brucella abortus in domestic water buffaloes (Bubalus bubalis) raised under the traditional system of husbandry in northern India was diagnosed using an enzyme-linked immunosorbent assays (ELISA) with a Protein-G-based indicator system (Protein-G ELISA). A total of 1,551 animals that are positive (N = 61), negative (N = 243), and suspected (N = 1,247) for brucellosis were examined. Rose bengal test (RBT) was used to predict the disease, and accordingly, animals were dichotomized in positive and negative population for receiver operating characteristic (ROC) curve analysis to determine the sensitivity, the specificity, and the performance index of Protein-G ELISA. Taking all animals (N = 1551) into account, the ROC curve analysis revealed cut off value of 29.6% positivity (%P) with 98.40% and 94.94%, sensitivity and specificity, respectively. The results were compared with ELISA in which anti-bovine conjugate was used. The cut off in ELISA was 37.9%P and sensitivity and specificity were 96.26% and 97.07%, respectively. The performance indexes of both the assays were almost equal and were 193.34 for Protein-G ELISA and 193.33 for ELISA. The cut off values of both the tests changed, if only known positive (N = 61) and known negative (N = 243) animals were used for ROC curve analysis, and accordingly, changes in sensitivity and specificity were observed with significant decrease of performance indexes of both the tests. The high optical density (P < 0.0001) background signal with negative serum control and high %P (P < 0.0001) in sera from negative population were noticed in ELISA in comparison to Protein-G ELISA.