There are different approaches on how you can test Johne’s disease or paratuberculosis in sheep and goats. It can be through direct detection of causal bacterium through microscopy, isolation of bacteria and use of DNA based techniques or it can be through indirect detection of causal bacterium through AGID, CF or ELISA. AGID stands for agar-gel immunodiffusion, CF stands for complement fixation and ELISA stands for enzyme-linked immunoassay. Although these three can be used, the most common tests are that of AGID and CF.
ELISA is also helpful but it can cause false positives in the detection or diagnosis of Johne’s disease. AGID, on the other hand, is helpful in the diagnosis of Johne’s disease because it shows a relationship with the heavy shedding of Mycobacterium paratuberculosis in the feces of goats and sheeps.