Reactions of delayed hypersensitivity in patients with tuberculosis in its dormancy and pandemic

Comparison of the results of tuberculin diagnosis in patients with tuberculosis during two studies made by the same procedure in 1973 and 1998 showed a marked increase in delayed hypersensitivity, which is indicative of higher sensitization in persons inoculated with Mycobacterium tuberculosis. This appears to be associated with the higher frequency and spread of exogenous reinfections and with the increased virulence of the causative agent.