Kestler and Tyler highlight need for better TB diagnostic tools

Shannon Tyler, M.D., an infectious diseases physician and assistant professor of internal medicine, examines a patient. 

Tuberculosis has plagued mankind for millennia and is responsible for more deaths than any other infectious disease.

In a search for answers, Bri Kestler, a Ph.D. student in the Basic Medical Sciences Graduate Program at the USA College of Medicine, and Shannon Tyler, M.D., an infectious diseases physician at USA Health and an assistant professor of internal medicine at the USA College of Medicine, recently published a historical review on latent tuberculosis in the American Journal of Physiology.

Bri Kestler is the lead author of

an article on latent tuberculosis. 

Mycobacterium tuberculosis, the organism that causes TB, primarily infects humans through a respiratory route. Most of the time, the immune system of the infected person contains the pathogen, not allowing it to spread. This condition is known as latent TB infection (LTBI.)

The article, “Latent tuberculosis testing through the ages: the search for a sleeping killer,” explores the history of latent tuberculosis diagnosis infection and discusses the limitations of modern testing.

Tyler, who has seen countless patients with LTBI and treated many with active TB throughout the span of her 20-year career, said though significant advances have been made, the ability to diagnose LTBI – an asymptomatic condition – remains problematic.

Those with LTBI are currently diagnosed by an immune response to tuberculous antigens without any evidence of clinical disease. “Latent tuberculosis has always been a diagnostic challenge as it is the only infection that is diagnosed by the inability to isolate the organism,” Tyler said.

While patients with LTBI are asymptomatic and are considered not infectious, they pose roughly a 10% risk of developing active tuberculosis over their lifetime, at which time they may become contagious. Because of this increased risk, identification and treatment of LTBI is crucial to reducing the incidence of TB. Hence, the authors highlight the importance of identifying the “sleeping killer” before it awakens.

“Although it is clear that the development of active tuberculosis most commonly occurs within the first two years of infection and those certain conditions predispose individuals for reactivation, there is no test available that can determine who has cleared the infection and there is no test that can effectively rule out infection,” Tyler said. “Until better diagnostic tools are widely available, the sleeping killer remains elusive.” 

Read the article in the American Journal of Physiology.