Tuberculin test is a cheap and easily available test. In which of the following situations there is high failure in the interpretation of the test?

Ans: A. High percentage of immunized people(Ref Park 24/e p195-196, 23/e p186)High failure of tuberculin test:High percentage of immunized people - Due to higher BCG coverage producing tuberculin hypersensitivity.Exaggerated responses:In presence of atypical mycobacteria infection & 'boosting effect' of second tuberculin dose producing larger reaction than 1st.Tuberculin test lost its sensitivity as an indicator of true prevalence of infection.