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Comparative evaluation of the diagnostic performance of four serological assays for bovine brucellosis in African buffalo (Syncerus caffer)

Mini-dissertation (MSc)--University of Pretoria, 2015.

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Other Authors: Michel, Anita Luise
Format: Thesis
Language:English
Published: University of Pretoria 2016
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access_status_str Open Access
author2 Michel, Anita Luise
author_browse Michel, Anita Luise
author_facet Michel, Anita Luise
collection Thesis
dc_rights_str_mv ©2016 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria.
description Mini-dissertation (MSc)--University of Pretoria, 2015.
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institution University of Pretoria (South Africa)
language English
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license_str Other — see source repository
provenance_str_mv Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository
publishDate 2016
publishDateRange 2016
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publisher University of Pretoria
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spelling oai:repository.up.ac.za:2263/52378 Comparative evaluation of the diagnostic performance of four serological assays for bovine brucellosis in African buffalo (Syncerus caffer) Michel, Anita Luise jcwessels@mpg.gov.za Dongo, Jacoba Cecilia UCTD Bovine brucellosis Cattle -- Diseases African buffalo Mini-dissertation (MSc)--University of Pretoria, 2015. The diagnostic performance of four serological assays for bovine brucellosis in African buffaloes, namely Rose-Bengal test (RBT), complement fixation test (CFT), indirect enzyme-linked immunosorbant assay (iELISA) and fluorescence polarisation assay (FPA) were evaluated and compared in a case-control study. The study followed the OIE assay validation pathway for validation of diagnostic tests applicable to wildlife species where there is a validated test available in a taxonomically closely related species. Two uninfected and four infected herds were recruited and an uninfected composite reference panel of 107 sera and infected composite reference panel of 93 were selected using composite reference standards. Diagnostic sensitivity (DSe) and diagnostic specificity (DSp) were calculated for individual tests and for different combinations of two tests in series and in parallel. Cut-off points were adjusted using receiver operating characteristics (ROC) analysis. Using these cut-off values, the index tests performed as follows: RBT DSe of 98.9% (95% CI 96.83% - 100%) and DSp of 98.1% (95% CI 95.6% - 100%), iELISA (cut-off >40.5%) DSe 98.9% (95% CI 94.2% - 100%) and DSp 100% (95% CI 96.6% - 100%), CFT (cut-off >0 iU/ml) DSe 74.2% (95% CI 64.1% - 82.7%) and DSp 100% (95% CI 96.6% - 100%) and FPA (cut-off >16 mP) DSe 97.9% (95% CI 94.2% - 99.7%) and DSp 100% (95% CI 96.6% - 100%). Based on performance index and area under the ROC curve, the iELISA performed best (198.9% and 1.0), followed closely by the FPA (197.9% and 0.989) and the RBT (197.0%). The CFT s lower performance (174.2%, and 0.871) was due to low DSe. Kappa values for test agreement between the index tests was above 0 for all combinations, and varied from unweighted Kappa of 0.685 (95% CI 0.608 0.762) between FPA and iELISA to 0.26 (0.136-0.383b) between CFT and RBT. Consideration of the indices for positive and negative test agreement between the index tests supported the differential specificity of tests for different immunoglobulin classes and higher in line with the findings in cattle. Positive predictive value in herd C and E were 100% for the iELISA, CFT and FPA, 97.3% in herd C and 98.4% in herd E for the RBT. Negative predictive values in herd C ranged from 89% for the CFT to 99.2% for the RBT and in herd E 73.1% for the CFT to 98.7% for the RBT. Overall repeatability was satisfactory, except for the FPA, which was considered the result of sample quality related to prolonged storage in a freezer. The index tests were all found fit for use to detect or confirm brucellosis in populations and individual animals. The values for DSe and DSp that were estimated will be of use in the interpretation of serological results and determination of diagnostic strategies in different circumstances. Different combinations of tests in series and parallel increased the DSp and DSe. Using the RBT in combination with the CFT/FPA/iELISA interpreted in series or in parallel in relation to the epidemiological setting and objective of testing is recommended. tm2016 Veterinary Tropical Diseases MSc Unrestricted 2016-05-04T13:46:05Z 2016-05-04T13:46:05Z 2015-09-04 2015 Mini Dissertation Dongo, JC 2015, Comparative evaluation of the diagnostic performance of four serological assays for bovine brucellosis in African buffalo (Syncerus caffer), MSc Mini-dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/52378> S2015 http://hdl.handle.net/2263/52378 en ©2016 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. application/pdf University of Pretoria
spellingShingle UCTD
Bovine brucellosis
Cattle -- Diseases
African buffalo
Comparative evaluation of the diagnostic performance of four serological assays for bovine brucellosis in African buffalo (Syncerus caffer)
title Comparative evaluation of the diagnostic performance of four serological assays for bovine brucellosis in African buffalo (Syncerus caffer)
title_full Comparative evaluation of the diagnostic performance of four serological assays for bovine brucellosis in African buffalo (Syncerus caffer)
title_fullStr Comparative evaluation of the diagnostic performance of four serological assays for bovine brucellosis in African buffalo (Syncerus caffer)
title_full_unstemmed Comparative evaluation of the diagnostic performance of four serological assays for bovine brucellosis in African buffalo (Syncerus caffer)
title_short Comparative evaluation of the diagnostic performance of four serological assays for bovine brucellosis in African buffalo (Syncerus caffer)
title_sort comparative evaluation of the diagnostic performance of four serological assays for bovine brucellosis in african buffalo syncerus caffer
topic UCTD
Bovine brucellosis
Cattle -- Diseases
African buffalo
url http://hdl.handle.net/2263/52378