The study of infections disease epidemiology is usually based on transmission. Applying concepts of regulation of parasite population size to tuberculosis, it is shown that the resistence to infection is the underlying mechanism that produces the trend in the tuberculosis situation. The resistence to infection is the result of genetic feed-back and also of the socioeconomic situation. The genetic feed-back disapears as the tuberculosis mortality rate falls. Control programmes based on the reduction of the transmission are not likely to reduce the tuberculosis problem, for it is not a transmission limited infection.