It has been reported that a substantial proportion of the new cases arise from the previously infected population. Hence, it appears that exogenous reinfection and/or endogenous reactivation play a major role in the development of post-primary disease. Though the risk of disease due to recent infection is known, the risk of disease associated with exogenous reinfection and endogenous reactivation has not been computed in Indian conditions. The data collected during a longitudinal study by NTI, Bangalore was analysed to estimate the above mentioned risk rates. The risk of disease associated with exogenous reinfection was per year compared with yearly due to endogenous reactivation. To test the validity of the computed risk.
