Comparative-Cervical Retest of Tuberculosis Suspects

Abstract

The tuberculin test has proven its value as the principal tool for the detection of bovine tuberculosis in cattle throughout the world (1). Since the early 1920's the intradermal tuberculin test, applied in the skin of the caudal fold of cattle, has detected over four million tuberculin reactors in the United States and provided a means of eliminating this disease from all but a few hundred tuberculous cattle herds. In spite of this remarkable record achieved through the use of the caudal test, it is well-known that no skin test procedure is perfect, as evidenced by the high number of no gross lesion (NGL) reactors in re-cent years. As the prevalence of Mycobacterium bovis infected herds decreases (30 in fiscal year 1974), the relative importance of false-positive tuberculin responses increases. It is generally agreed that most false-positive responses in cattle are a result of the animal having been infected by microorganisms that contain some antigenic characteristics similar to M. bovis which causes the host to show some degree of heterospecific response (2,5).