Tuberculosis is a major public health problem in many regions of the world,
accounting for up to 2 million deaths per year. The main causative agent of tuberculosis
is Mycobacterium tuberculosis, which usually infects the lungs, causing symptoms
such as fever, cough and chest pain. After infection, the bacilli can be cleared by a
healthy immune system or, on the other hand, the infection may lead to latent
tuberculosis or progress to active pulmonary tuberculosis. Moreover, in certain
situations, such as cases of immunocompromised patients, these bacilli can spread
through the lymphatic or hematogenous route to more distant organs, leading to
extrapulmonary tuberculosis. Approximately 30% of the population worldwide has
latent tuberculosis and 5 to 10% of individuals infected with M. tuberculosis progress
to active tuberculosis disease. Although tuberculosis is a curable disease, some factors
have been associated with the morbidity and mortality of global tuberculosis, including
inadequate detection, increased abandonment rate of anti-TB treatment, co-infection
with human immunodeficiency virus, increased drug resistance and inefficiency of the
BCG vaccine in preventing the disease in adolescents and adults. New tools are
therefore urgently needed to control tuberculosis. Knowledge of the molecular
characteristics, immune response and pathogenesis of M. tuberculosis are essential for
the development of new approaches to diagnosis, drugs and vaccines to assist in the
clinical management and control of the disease. This first chapter on tuberculosis
describes the epidemiological, immunological and clinical aspects of the disease, as
well as the microbiologic and molecular characteristics of M. tuberculosis.
Keywords: Active pulmonary tuberculosis, Clinics aspects, Extrapulmonary
tuberculosis, Latent tuberculosis, Mycobacterium tuberculosis, Tuberculosis.
