Indeterminate leprosy in a population survey and in the subsequent follow-ups of children in Burma.

The paper discusses various aspects of indeterminate (I) leprosy in the initial survey undertaken in the Burma BCG trial (69,242 inhabitants), and in the annual examinations of 28,220 children in the trial followed up over periods of five to eight years. Age-specific rates in the initial mass survey are presented. In total 1914 cases were detected (6.2% I, 76% T, 16% L and 1.8% B). Among the children in the BCG trial 768 cases were detected: 255 of them had the I form and their proportion (33%) was much higher than in the population survey. Of these 255 I cases only 4.3% had a negative or doubtful lepromin reaction. Two-thirds of these 255 cases evolved to the tuberculoid pole in less than one year. No L cases appeared in the trial population until ten and eleven years after the start of the trial. It is concluded that whereas a high proportion of indeterminate cases regress spontaneously or evolve towards the T pole, the indeterminate lepromin negative cases are important in the dynamics of the disease, because a proportion of them, if untreated, tend to envolve towards the L form. This stresses the importance of detection and treatment of I cases at an early stage in an effective strategy for controlling leprosy.