THE ORIGIN AND ERRATIC GLOBAL SPREAD OF TUBERCULOSIS - HOW THE PAST EXPLAINS THE PRESENT AND IS THE KEY TO THE FUTURE

Although tuberculosis is a disease known in antiquity, it was not dist ributed equally or simultaneously throughout the world. Recent genetic studies of the various species of mycobacteria give strong evidence o f evolution of M. tuberculosis from saprophytic soil bacteria to M, bo vis, which attacks a wide spectrum of lower animals, and then to M. tu berculosis, with the pathogenicity largely limited to humans. The grea t discrepancies in the time of arrival of this organism to diverse par ts of the world, and in its ability to kill the young, account for sig nificant differences in the emergence of innate resistance to tubercul osis in various populations. Innate resistance to particular infection s are highly specific, and are derived from whatever scourge one's anc estors had to survive.