<prompt> True statement regarding tuberculine test is ?Used for diagnosis of TBMeasures incidence of diseaseMore than 1 Omm induration in 72 hrs. indicates positive testMeasure immunity status  <response>: Ans. is c i.e., More than 10 mm induration in 72 hrs indicates positive test Repeat tuberculin test two step testing o Induration is measured, erythtna is not taken into account. Uses of tuberculin test o Diagnosing active infection in infants and young children. o Measure prevalence of infection. o Select susceptibles. o As an indication of sucessful vaccination. 