With approximately 25 percent of the global population infected, tuberculosis is one of the leading causes of death by an infectious disease. A third of infected people are in an asymptomatic, non-infectious dormant phase called “latent tuberculosis,” which, in a subset of people, can develop into active (symptomatic) disease if not treated. A session on Monday, “Advances in Tuberculosis Screening and Testing,” featured two speakers at the forefront of tuberculosis diagnosis and treatment.
C. Robert Horsburgh, MD, discussed tuberculosis disease and treatment guidelines. He emphasized that non-drug-resistant tuberculosis infection can be treated if detected early. From Horsburgh, attendees learned that tuberculosis infection can develop into a latent form of the tuberculosis infection, where tuberculosis bacteria are sequestered in granulomas, and the host is not infectious. However, in a small subset of individuals with latent tuberculosis, the infection may progress to active disease. It is in this active form of the disease that people are infectious and can transmit to others.
People with HIV and immunosuppressive conditions are at higher risk of developing active tuberculosis. In the US, active tuberculosis developed from the latent form is a significant public health concern. Delivering treatment to people infected with tuberculosis can stop the progression to disease and prevent transmission, but this is wholly dependent on the early diagnosis of tuberculosis infection. Here, laboratory testing plays a vital role.
L.V. Rao, PhD, FAACC, presented the latest advances in the diagnosis of and screening for tuberculosis infection. Currently, the tuberculin skin test and the interferon gamma release assays are used to detect tuberculosis infection, but they have limited availability in most parts of the world, he said. Also, both tests have limitations and considerations for test interpretation. Rao highlighted the urgent need for better tools to detect tuberculosis with faster turnaround times that allow the patient to receive results while at the clinic for a visit with their healthcare provider.
Technological advances include molecular, genetic, and rapid assays in development. Several of the newer tests being developed for diagnosis of tuberculosis infection incorporate antigen detection. Rapid, sensitive, and easy-to-administer tests hold the promise to widen accessibility and increase screening for tuberculosis, especially in populations at high risk of infection.
The speakers also pointed out that during the COVID-19 pandemic, tuberculosis detection has dropped, likely due to a redirection of resources and testing toward COVID-19—and the two diseases’ overlapping symptoms. Attendees at yesterday’s session gained a deeper appreciation for the global threat of tuberculosis and the role we, as laboratorians, can play in implementing quality diagnostics. The burden of tuberculosis infection in the world is large and, in the US, most cases of tuberculosis disease are potentially preventable by diagnosing asymptomatic tuberculosis infection. Healthcare institutions should be prepared for increased demand for diagnosis of tuberculosis detection.