University of Wisconsin–Madison


A diagnostic test result that is negative even though the tested subject IS infected/diseased. Test sensitivity is the measure of test accuracy that describes the rate of false-negative test results. For example, a test with 60% sensitivity has a 40% false-negative rate (100%-sensitivity). False-negative results are common with Johne’s disease. This is not because of a failure of the testing technology. Rather, it is because the MAP infection progresses so slowly and during the incubation phase is very hard to detect because few if any MAP are being shed in feces and the animal has not yet mounted an antibody response.