Comparison of two enzyme-linked immunosorbent assays for serologic diagnosis of paratuberculosis (Johne's disease) in cattle using different subspecies strains of Mycobacterium avium

Serologic diagnosis of bovine paratuberculosis (Johne's disease) with curre ntly available tests may give false-positive results due to cross-reactions with avian and bovine tuberculosis viruses and other infectious agents. In direct enzyme-linked immunosorbent assays (ELISA) for detection of antibodi es against paratuberculosis based on antigens from Mycobacterium avium subs p. avium (A-ELISA) and M. avium subsp. paratuberculosis (P-ELISA) were comp ared. Despite an expected higher specificity for M. a. paratuberculosis in the P-ELISA, the 2 antigens were equally suitable for demonstration of anti body to M. a. paratuberculosis in cattle. Receiver operating characteristic (ROC) curves was used to demonstrate the possible antigenic relationship. The area under the curve (AUC) was calculated for each of the 2 ROC curves. The AUC for the P-ELISA ROC curve was 0.9197, and the AUC for the A-ELISA ROC curve was 0.9149, demonstrating a negligible difference in efficiency o f the 2 tests (z = 0.182).