Evaluation of a commercial ELISA for diagnosis of paratuberculosis in cattle.

OBJECTIVE To evaluate sensitivity and specificity of a new ELISA for antibodies against Mycobacterium avium subsp paratuberculosis. DESIGN Cross-sectional observational survey. SAMPLE POPULATION Serum samples from 590 cattle that were infected with M avium subsp paratuberculosis and 723 cattle that were not infected. PROCEDURE Serum samples were tested by use of an ELISA for antibodies against M avium subsp paratuberculosis. RESULTS Sensitivity of the test varied from 15.4 to 88.1%, depending on the clinical stage and bacterial shedding status of the cattle. CONCLUSIONS AND CLINICAL RELEVANCE Results obtained with use of the new ELISA agreed favorably with those of a previous ELISA. Practitioners must be aware of variability in the sensitivity of the test, which depends on the clinical and shedding status of the cattle, because this may affect interpretation of test results.