mantoux test using 2 iu of tuberculin prepared in iran was performed on 6675 healthy persons randomly selected from an urban population (shiraz) of iran. in 3776 persons with no evidence of previous bcg vaccination the rate of positive reaction was less than 2% up to the age of 14, slightly more than 2% among those 15-19 years of age, but strikingly higher (45.5%) in older age groups (p<0.001)....