Comparison of Three Enzyme-Linked Immunosorbent Assay (ELISA) Kits for Diagnosis of Dairy Cattle Shedding Mycobacterium Avium Subsp. Paratuberculosis in Feces

Abstract

Sera from dairy cattle in herds free of paratuberculosis (n = 411) or infected with Mycobacterium avium subsp. paratuberculosis (n = 411) were tested using a new ELISA kit (A-ELISA) for bovine paratuberculosis and two USDA-licensed commercial ELISA kits (B-ELISA and C-ELISA). Non-infected cattle were Holstein cattle in 8 Minnesota herds. Infected cattle were Jersey cattle from 28 herds across the U.S. Reference tests to classify cattle as M. paratuberculosisinfected were either fecal culture (n = 250) or real-time PCR on feces (n = 161). MAP (Mycobacterium avium subsp. Paratuberculosis) infected cattle were selected to represent the full range of infection severity using the prior original ELISA results (O-ELISA) as a surrogate marker. Among the 411 cases of bovine paratuberculosis 100 were O-ELISA-negative, 10 were O-ELISA-suspect, 97 had lowpositive O-ELISA results, 103 had moderate-positive O-ELISA results, and 101 had strong-positive O-ELISA results. Sensitivity estimates for the A, B and C-ELISAs were: 68.1% (CI: 63.4-72.6), 74.9% (CI: 70.979.1), and 69.8% (CI: 65.1-74.2) respectively. Specificity estimates for the A, B and C-ELISAs were: 99.3% (CI: 97.9-99.9), 100% (99.1100.0), and 100% (99.1-100.0), respectively. The accuracy of the new ELISA was statistically not different from the currently licensed ELISA kits for use on bovine serum to detect cattle infected with and shedding M. paratuberculosis in feces. The new ELISA, like the others, is quantitative and the magnitude of the result (S/P value) reflects the probability that the animal is shedding M. paratuberculosis in feces, providing a cost-effective tool for identification of infectious cattle as part of a comprehensive paratuberculosis control program.