Effect of multiple sampling on diagnostic sensitivity

Overall diagnostic sensitivity is the probability that a diagnostic procedure will detect an agent if the tested animal is indeed infected. The overall or effective sensitivity is a function of both the probability that the assay will detect the agent if it is present in the sample tested and the probability that the agent will be present in the sample tested if the animal is infected with the agent. Thus, even with a highly sensitive assay, the probability of detecting an infected animal may be low or nil if the sampling procedure failed to capture the agent in samples tested by the assay. In this article, it is demonstrated how increased frequency of testing, such as testing multiple subsamples, can have a profound effect on increasing the overall sensitivity of a diagnostic procedure.