A test for the determination of competency in clearing bacilli in leprosy patients.

A skin test has been developed to determine the degree of competency in clearing bacilli from the tissues of patients suffering from various forms of leprosy. The test involves the intradermal injection of a suspension of killed Mycobacterium leprae. The response of leprosy patients to the injection of other mycobacterial antigens, one prepared from M. lepraemurium and another from an atypical mycobacterium from a hamster, was also investigated in order to study the isopathic phenomenon. Since lepromatous patients react negatively in tests with standard Mitsuda antigen, a concentration of 640 x 10(6)M. leprae per ml was used to produce macroscopic responses. The results of the test can be applied to determine the duration of consolidation treatment for lepromatous and indeterminate bacteriologically negative patients after regular treatment has ended. The test can also be used to indicate which Mitsuda-negative contacts should be given preventive treatment, and might be used to identify a given mycobacterium as M. leprae.