Human Tuberculosis I. Epidemiology, Diagnosis and Pathogenetic Mechanisms

Mycobacterium tuberculosis (M. tuberculosis), an almost genetically monomorphic pathogen is a human parasite, transmitted mostly by humans and causes tuberculosis (TB). TB is firmly associated to poverty, although lack of proper nutrition and lowered immune status are contributing factors for disease development. TB remains second only to HIV/AIDS as the leading cause of mortality worldwide due to a single infectious agent and is responsible for nearly 1.5 million deaths annually. Some steps of the progress of our knowledge of M. tuberculosis physiology and its interactions with human beings, are reviewed here. This progress has provided fertile ground for improving diagnosis and cure of TB infection. For TB diagnostics laboratories in high-burden countries, primary isolation is the first step before performing drug susceptibility testing (DST) of M. tuberculosis. IGRA (interferon-γ release assay)-based tests for diagnosis of active TB are sufficiently fast, specific and sensitive to allow to contain infection and distinguish among latent TB infection and BCG vaccination individuals from those who have clinically resolved M. tuberculosis infection after anti-TB treatment.