RESUMO
1- Tuberculin (Mantoux) and lepromin (Dharmendra) tests have been carried out among leprosy patients and normal and tuberculous controls in Malaya and Singapore. 2- Leprosy patients were found to have a much lower positive Mantoux rate than the normal population, although this difference was more marked in children than in adults. In Singapore, the figure among adults with leprosy approached that of the normal population. 3- Children with leprosy were found to respond to BCG vaccination, giving a Mantoux conversion rate very little lower than that found in normal children. 4- It is suggested that leprosy infects a selected population, consisting of Mantoux negatives. That is, tuberculosis infection may give some protection against leprosy. On the other hand, evidence is produced which demonstrates that tuberculosis is readily superimposed on existing leprosy. 5- The conversion to a Mantoux positive state appears to be the essential feature, not the positive lepromin response, that may result from such vaccination. This latter response, it is suggested, is nonspecific.