BVD CONSULT

Estimation of sensitivity and specificity of two diagnostics tests for bovine immunodeficiency virus using Bayesian techniques

aDepartment of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA bDepartment of Dairy Science, Louisiana Agriculture Experiment Station, Louisiana State University, Agricultural Center, Baton Rouge, LA 70803, USA

Abstract

The validation of assays for  bovine  immunodeficiency virus (BIV) in cattle is hampered by the absence of a gold standard. Two tests that often are used to detect BIV are the indirect fluorescent-antibody assay (IFA) and the nested-set polymerase chain-reaction assay (PCR). IFA detects an antibody response whereas PCR detects the provirus in white blood cells.

Using Bayesian techniques performed simultaneously on animals from two different dairy herds, we estimated the performance of the IFA and PCR assays and infection prevalence. Bayesian techniques also were used to derive posterior distributions of sensitivities, specificities, and prevalences. The Bayesian estimates were IFA sensitivity=60%, IFA specificity=88%, PCR sensitivity=80%, PCR specificity=86%, Herd A prevalence=20%, and Herd B prevalence=71%. Although PCR was the more sensitive assay, substantial misclassification of infection would be expected in epidemiological studies of BIV regardless of which assay was used.

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This article was published in Preventive Veterinary Medicine, 61, K. A. Orra, K. L. O’Reillya and D. T. Scholla,b, Estimation of sensitivity and specificity of two diagnostics tests for bovine  immunodeficiency virus using Bayesian techniques, 79-89, Copyright Elsevier 2003.