Tests that have fallen out of favor because of reports of low sensitivity and/or specificity are microscopic examination of Ziehl-Neelsen–stained fecal samples and the IV Johnin test. The complement fixation (CF) test also reportedly is less accurate than other serologic tests. The CF test is still required by many countries for importation of animals, although many of the reagents used in the CF test are made to different specifications in different countries, resulting in a lack of standardization.