Innate and Adaptive Immune Responses to Bacterial and Parasite Infections

A vast spectrum of illness can result from infection owing to M. tuberculosis, Mycobacterium avium, and Mycobacterium leprae, but the representative organism of this genus is M. tuberculosis. M. tuberculosis infection is estimated to infect 1.6 billion people worldwide or approximately one-third of the world’s population, killing about 3 million people each year (1,2). More than 90% of tuberculosis (TB)-related deaths occur in developing countries, and the disease has huge social and economic costs. Nations with a high prevalence of HIV have witnessed the greatest increase in the number of TB cases (3). Diffusion of the infection depends on inhalation of aerosols from individuals with pulmonary infection. The development of the disease occurs in less than 10% of infected persons and is significantly increased by impaired cell-mediated immunity. Liver involvement varies with the stage of pulmonary or systemic infection, being common in the case of miliary disease. However, it had been demonstrated that up to two-third of patients with primary pulmonary TB have some kind of liver involvement (4).