title: Comparison of blood polymerase chain reaction and enzyme-linked immunosorbent assay for detection of Mycobacterium avium subsp. paratuberculosis infection in cattle and sheep.
abstract: A study was carried out to compare the performance of enzyme-linked immunosorbent assay (ELISA) and blood polymerase chain reaction (PCR) for diagnosis of paratuberculosis in cattle and sheep. For cattle, a set of 278 samples from 1 paratuberculosis-affected Friesian farm was used; it included 80 ELISA-positive samples and 198 ELISA-negative samples from an age-matched group. Ninety-four samples were from heifers and 184 were from 2-5-year-old cows. The overall analysis showed a clear association (Fisher exact test [FET] P = 0.0049) but a weak negative agreement (45.3%, kappa = -0.1665 +/- 0.0994) between the 2 tests. It reflected a moderate agreement among heifers (87.7%, kappa = 0.4471 +/- 0.2435) and a moderate disagreement among cows (62.7%, kappa = -0.3670 +/- 0.1057). For sheep, 496 blood samples from 53 Latxa dairy flocks were used; 180 of the blood samples were from dam/offspring pairs. The overall association between the 2 tests on ovine samples was strong (FET, P = 0.0005), whereas the agreement was low (kappa = 0.1622 +/- 0.1188). There was slightly better agreement for ewes (kappa = 0.2135 +/- 0.1992) than for lambs (kappa = 0.1193 +/- 0.1301). There was also a highly unlikely proportion of dam/offspring positive results (FET, P < 0.0001, kappa = 0.6269 +/- 0.1854). Four of 6 lambs that were necropsied 1 year after testing had paratuberculosis microscopic lesions in the ileocecal valve (3 lambs) or a PCR-positive result (4 lambs). These results suggest that blood PCR testing might be a potentially useful new approach in paratuberculosis diagnosis, especially in young animals.
authors.affiliation: Instituto Vasco de Investigación y Desarrollo Agrario (NEIKER), Berreaga, 1, Derio 48160, Bizkaia, Spain. rjuste@neiker.net
authors.forename: Ramon A
authors.initials: RA
authors.lastname: Juste
authors.forename: Joseba M
authors.initials: JM
authors.lastname: Garrido
authors.forename: Marivi
authors.initials: M
authors.lastname: Geijo
authors.forename: Natalia
authors.initials: N
authors.lastname: Elguezabal
authors.forename: Gorka
authors.initials: G
authors.lastname: Aduriz
authors.forename: Raquel
authors.initials: R
authors.lastname: Atxaerandio
authors.forename: Iker
authors.initials: I
authors.lastname: Sevilla
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000662:veterinary*; D005260:Female; D009162:Mycobacterium avium / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D010283:Paratuberculosis / Q000175:diagnosis*; D016133:Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary*; D012680:Sensitivity and Specificity; D012756:Sheep; D012757:Sheep Diseases / Q000175:diagnosis*