Lifelong no longer: New research on TB infection rarely leads to active disease

 A new analysis challenges the longstanding notion that tuberculous infection is a lifelong 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 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 in the journal BMJ.

x-ray of lungs in purple

The findings upend commonly held beliefs, as well as approaches to care and research around the world, for the two billion people who test positive for TB and are thought to be persistently infected and at risk for active disease.

“The National Institutes of Health and other nonprofit organizations spend millions of dollars on studies of the latent state because of the assumption that TB infection is lifelong, held in check by the immune system. However, based on our analysis, we believe that it is rarely life-long, and in 90 percent or more of infected people, there is no possibility of TB development even with severe immunosuppression,” says co-author Paul H. Edelstein, an emeritus professor of pathology and laboratory medicine at Penn.

Read more at Penn Medicine News.