Approach for designing appropriate Johne's disease control programs on the farm

Abstract

Testing is a critical tool in controlling Johne's disease. However, the limitations and options associated with commonly used tests can create confusion about herd testing as a part of a control program. Rational test choices can be made by veterinarians and producers with a basic understanding of the tests available, what they do, what results mean, and how results can be appropriately used. Understanding the tests underlies their usefulness. The issues that influence choice of commonly used tests and test strategies include basic performance characteristics (sensitivity, specificity, predictive value), cost, interpretation of results, herd test strategies (frequency, portion of herd tested, one or combination of tests), and action to be taken based on test results. These issues preclude a generic proscription for the most appropriate test scheme. Instead, each should be weighed in the context of the farm situation to determine the most appropriate strategy for their control program.