Ans. is 'b' i.e., Percentage of new patients positive for tuberculin test Epidemiological indices of tuberculosis Indices or parameters are needed to measure the tuberculosis problem in a community as well as for planning and evaluation of control measures. The following epidemiological-indices are used in tuberculosis problem measurement and programme strategy :? 1. Prevalence of infection It is the percentage of individuals who show a positive reaction to the standard tuberculin test. 2. Incidence of infection (Annual infection rate) It is the percentage of population under study who will be newly infected by M.tuberculosis among the non-infected of the preceding survey during the course of one year. It reflects the annual risk of being infected (or reinfected) in a given community, i.e. it expresses the attacking force of tuberculosis in a community. It is also known as tuberculin conversion index. This parameter is considered one of the best indicators for evaluating the tuberculosis problem and its trend. 3. Prevalence of disease or case rate It is the percentage of individuals whose sputum is positive for tubercle bacilli on microscopic examination. It is the best available practical index to estimate the number of infectious cases or case load in a community. 4. Incidence of new cases It is the percentage of new TB cases (confirmed by bacteriological examination) per 1000 population occurring during one year. 5. Prevalence of suspected cases This is based on X-ray examination of chest. 6. Prevalence of drug resistant cases It is the prevalence of patient excreting tubercle bacilli resistant to anti-tubercular drugs. 7. Moality rate The number of deaths from tuberculosis every year per 1,000 population. In this question Option a - Prevalance of infection. Option b - Incidence of infection (annual infection rate). Option c - Prevalance of disease (case rate) Option d - Incidence of disease.