Evaluation of the tuberculin sensitivity test in a healthy Sudanese population

Three-hundred and seventeen healthy individuals were investigated on a volunteer basis for tuberculin sensitivity using the dual-intradermal tuberculin test technique. 251 of them were in contact with dairy animals and 64.9 per cent of such people were found specific reactors. Those who were not in contact with dairy animals (66 persons) gave 65.2 per cent rate of specific reactivity. To interpret the tuberculin sensitivity reaction, non-specific reactivity must be excluded, especially in tropical countries. Positive tuberculin reaction is defined when the diameter of induration is 10 mm or more for persons in contact with dairy animals and tuberculous patients or consuming raw milk and 5 mm or more for other persons.