How disease develops in hosts infected with Mycobacterium tuberculosis, the bacterial pathogen that causes the disease tuberculosis (TB), is unclear. It is well known that only a small fraction of individuals infected with M. tuberculosis become sick, yet we do not yet fully understand the host or bacterial mechanisms that underlie disease, nor can we effectively predict TB disease outcome. The main research goals are to identify immunologic or inflammatory markers that may be associated with TB disease, or may cause controlled M. tuberculosis infection to progress to TB disease.