The dynamics of tuberculosis epidemiology

Abstract

A conceptual framework to study the epidemiologic basis of tuberculosis control is provided. The basic model to discuss the epidemiology of tuberculosis is based on a classification of tuberculosis based on its pathogenesis with exposure, latent infection, tuberculosis, and death from tuberculosis, showing the conditional probabilities leading from one to the next step in the chain of events. Historical data are utilized to demonstrate how the dynamics of tuberculosis over multiple decades have contributed to shape the present. It is shown that the key concept to understand the dynamics is related to current and past incidence and prevalence of latent infection with M. tuberculosis. The dynamics of the epidemic are shaped both by the behaviour of the causative organism of tuberculosis as well as the population structure and changes that take place in parallel in which M. tuberculosis thrives. Both the present and the future shape of the epidemic, as well as the principles applied to its control lie very much in the past of a society. While new risk factors such as HIV or diabetes have been or are emerging more strongly, it is noted that the majority of all new cases emerging cannot be pinned to one or the other such factor. It is the historical experience of a population that offers the most valuable key to understanding the present and the future.