PHILADELPHIA – A new analysis challenges the longstanding notion that tuberculous infection is a life-long infection that could strike at any time and cause tuberculosis (TB). Based on a review of clinical studies, researchers from the Perelman School of Medicine at the University of Pennsylvania and colleagues show that people who test positive with immunologic TB skin or blood tests rarely develop TB. They suggest it’s because the infecting organism, Mycobacterium tuberculosis, is likely dead, wiped out naturally by people’s immune systems. Despite that, these people retain an immunological memory to the disease, which the authors say likely explains why standard TB tests show a positive result, since those tests look for an immune response and not live bacteria. The study was published this week in the journal BMJ.

PHILADELPHIA — Doctors treating patients battling both HIV and tuberculosis (TB)—many of whom live in Africa—are faced with the decision when to start those patients on antiretroviral therapy (ART) while they are being treated with antibiotics for active TB disease.  Some patients fare well on both interventions, with the immune system in check and the TB controlled.  Others undergo complications from TB, such as paradoxical immune reconstitution inflammatory syndrome (IRIS), a worsening of TB symptoms despite response to therapy, while still others experience immune failure and early death.  The best way to determine which patients go on to develop IRIS or die after treatment begins is not fully understood.