Host factors in tuberculosis

Tuberculosis (TB) caused by Mycobacterium tuberculosis (MTB) continues to remain one of the most deadly infectious diseases worldwide especially in the developing countries. The lack of new drugs for TB, vaccine availability, with increasing global antimicrobial resistance, has prompted more research into defining host factors and developing immunomodulatory strategies. Some of the known risk factors that increase the susceptibility to TB include immunocompromised states such as human immunodeficiency virus (HIV) infection, smoking, socioeconomic deprivation, malnutrition, diabetes mellitus, air pollution, occupational exposures, and alcohol consumption. In this chapter we review the available information about host factors that help understand susceptibility to TB. Defining the host factors is critical to develop host-directed therapies that may enhance host defenses and perhaps reduce tissue damage from chronic TB infections.