Sensitivity refers to a tests ability to detect infected (positive) animals on a percentage
basis. Sincemany diseased animals are in the early stages of Johne's, current tests are unable
to detect these animals and thus, test sensitivity is approximately 50 percent.
Specificity refers to the tests ability to detect non-infected (negative) animals on a
percentage basis. Specificity is high for Johne's disease tests (> 95 percent) and
a single positive result in herds confirmed with Johne's disease is likely correct.