title: Bayesian estimation of diagnostic accuracy of a new bead-based antibody detection test to reveal Toxoplasma gondii infections in pig populations.
abstract: The success of a Toxoplasma gondii surveillance program in European pig production systems depends partly on the quality of the test to detect infection in the population. The test accuracy of a recently developed serological bead-based assay (BBA) was investigated earlier using sera from experimentally infected animals. In this study, the accuracy of the BBA was determined by the use of sera from animals from two field subpopulations. As no T. gondii infection information of these animals was available, test accuracy was determined through a Bayesian approach allowing for conditional dependency between BBA and an ELISA test. The priors for prevalence were based on available information from literature, whereas for specificity vague non-informative priors were used. Priors for sensitivity were based either on available information or specified as non-informative. Posterior estimates for BBA sensitivity and specificity were (mode) 0.855 (Bayesian 95% credibility interval (bCI) 0.702-0.960) and 0.913 (bCI 0.893-0.931), respectively. Comparing the results of BBA and ELISA, sensitivity was higher for the BBA while specificity was higher for ELISA. Alternative priors for the sensitivity affected posterior estimates for sensitivity of both BBA and ELISA, but not for specificity. Because the difference in prevalence between the two subpopulations is small, and the number of infected animals is small as well, the precision of the posterior estimates for sensitivity may be less accurate in comparison to the estimates for specificity. The estimated value for specificity of BBA is at least optimally defined for testing pigs from conventional and organic Dutch farms.
authors.affiliation: Institute for Risk Assessment Sciences (IRAS), Division of Veterinary Public Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 2, 3584 CM Utrecht, The Netherlands. Electronic address: G.C.A.M.Bokken@uu.nl.
authors.forename: Gertie C A M
authors.initials: GC
authors.lastname: Bokken
authors.affiliation: Institute for Risk Assessment Sciences (IRAS), Division of Environmental Epidemiology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 2, 3584 CM Utrecht, The Netherlands.
authors.forename: Lützen
authors.initials: L
authors.lastname: Portengen
authors.affiliation: Department of Infection Biology, Central Veterinary Institute of Wageningen UR, P.O. Box 65, 8200 AB Lelystad, The Netherlands.
authors.forename: Jan B W J
authors.initials: JB
authors.lastname: Cornelissen
authors.affiliation: Institute for Risk Assessment Sciences (IRAS), Division of Veterinary Public Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 2, 3584 CM Utrecht, The Netherlands; Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: Aldert A
authors.initials: AA
authors.lastname: Bergwerff
authors.affiliation: Institute for Risk Assessment Sciences (IRAS), Division of Veterinary Public Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 2, 3584 CM Utrecht, The Netherlands.
authors.forename: Frans
authors.initials: F
authors.lastname: van Knapen
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D001499:Bayes Theorem; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000662:veterinary; D018189:Immunomagnetic Separation / Q000379:methods / Q000662:veterinary*; D009426:Netherlands; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine; D013553:Swine Diseases / Q000175:diagnosis* / Q000469:parasitology; D014122:Toxoplasma / Q000276:immunology*; D014124:Toxoplasmosis, Animal / Q000175:diagnosis* / Q000469:parasitology
chemical_list: D000913:Antibodies, Protozoan
keywords: Bayesian inference; Bead-based assay; Pig; Sensitivity; Specificity; Toxoplasma gondii