Multiple skin testing in leprosy.

Groups of patients with lepromatous and tuberculoid leprosy and hospital staff from six leprosaria in East Africa and 'non-contact' groups of villagers or staff from general hospitals have been skin tested with 10 reagents. These were prepared by ultrasonic disintegration from M. tuberculosis, M. duvalii, M. chelonei and 7 other species identified in the Ugandan environment. Comparisons were made of the percentages of positive reactors in each study group for each reagent. The 'specific' defect of lepromatous patients was found to apply to a variable extent to six of the species tested, but not to M. tuberculosis, M. avium or M. 'A'. The defect applied most noticeably to M. nonchromogenicum and M. vaccae, suggesting that they are more closely related to M. leprae than are the other species tested. The reagent Chelonin produced unexpected and anomalous results in the lepromatous group. It is suggested that this was due to an unusually slow clearing of Arthus' reaction.