Granulomas

Abstract

Tuberculosis remains a serious public health threat, with ten million new cases and nearly two million deaths annually. The disease is caused by Mycobacterium tuberculosis (Mtb). The bacterium is a respiratory pathogen usually transmitted by the cough of a person with active disease. The majority of infected humans effectively contain the disease as a latent, asymptomatic, and not contagious disease. People with active disease can be cured by treatment with several drugs over a period of at least 6 months, although there are obstacles to recovery such as access to health care, compliance, side effects, and, for some populations, efficacy of the drugs. But even recovered individuals have residual Mtb which is blocked by the same mechanism as in latent infections. It is estimated that 1∕3 of the human population are latently infected with Mtb, so an important question is what is the mechanism that blocks these latent infections from progressing to active disease.