Author refers some data about prevalence and incidence of infection and morbidity in tubercular disease. These data are very discordant according to different social conditions of countries in which they are been derived. Particularly, he analyses the importance of an extended tuberculin survey, as the essential method to study both epidemiological parameters. In this paper, Author emphasizes how the test needs to be used systematically and in subjects of the same age. At last, mortality is more an indicator of the efficiency of the case finding and treatment programme than an epidemiological index. Indeed there is a parallel increase in the proportions of deaths of patients older than 45 years of age also in under-developing countries.
