A village has population of 150000 on 1st July. Total TB cases on January 1st was 200. There were 50 new cases of TB during that years. Total 25 patients of TB was cured during that period. What is the Incidence of TB-

Ans. is 'd' i.e., 33 per lac * In the question new cases are 50, total patients on Jan 1 are 200 and on Dec 31 are 225 (As 25 case out of total cases are cured).* Incidence =New cases----------------Population at riskx 1000 =50----------150000x 1000 = 0.33 per thousand* Point prevalence on Jan 1 = 200 per 1.5 lac =133 per lac.* Point prevalence on Dec 31 = 225 per 1.5 lac = 150 per lac.* Period prevalence during the year = 250 per 1.5 lac = 166 per lac.