Task Force Recommends Latent TB Infection Screening
May 22, 2023, News Staff — The U.S. Preventive Services Task Force recently issued an updated final recommendation to screen asymptomatic adults who are at increased risk for latent tuberculosis infection. The update clarifies information about diagnosis and testing, and links to resources.
The update is consistent with the task force’s 2016 recommendation statement on the topic, including the “B” grade. It stresses that patients who screen positive for infection should receive appropriate followup care and treatment.
“Screening for latent tuberculosis infection in people at increased risk is an effective way to identify the infection so that it can be treated before it progresses to active TB,” said Gbenga Ogedegbe, M.D., M.P.H., a member of the USPSTF, in an agency bulletin. “The task force continues to underscore the importance of latent TB infection screening in reducing rates of active TB, protecting the health of people nationwide.”
The CDC estimates that up to 13 million people in the United States have latent TB infection. In 2021, the last year for which data are available, more than 71% of all cases of active TB occurred in individuals born outside the United States. Unlike people with active TB show clear signs of illness and may be infectious, people with latent TB do not have symptoms or feel sick, and cannot spread the bacteria to others. While many people with latent TB infection never develop TB, others can become ill weeks or even years after becoming infected.
“People at increased risk for tuberculosis who would benefit from screening include people born or who have lived in countries with increased rates of TB and those who have lived in certain group settings, like prisons or homeless shelters,” added Michael Barry, M.D., the task force’s chair. “Importantly, anyone who screens positive needs further clinical tests to rule out active TB and confirm an LTBI diagnosis.”
Story Highlights
Screening and Treatment
Although there is no direct test to diagnose latent infection with Mycobacterium tuberculosis, two types of screening tests for latent TB infection are available in the United States: the tuberculin skin test and the interferon-gamma release assay. Both are moderately sensitive and highly specific, and each has certain advantages and disadvantages.
For example, while the TST test is less invasive than the IGRA, it requires that patients return to the clinic or physician’s office 48 to 72 hours after the test is administered to interpret the results, meaning planning for an additional visit. The IGRA test, meanwhile, can be performed in a single office visit, but it requires a venous blood sample that must be delivered to a laboratory for analysis within a specific timeframe (between 8 and 30 hours, depending on the version of the test).
Latent TB infection can be treated effectively with antibiotics. Preferred treatment regimens, according to the CDC and the National Tuberculosis Controllers Association, include rifampin (daily for 4 months), isoniazid plus rifapentine (once weekly for three months) and isoniazid plus rifampin (daily for three months) based on safety, effectiveness and high completion rates.
Responses, Resources and Research
In response to public comments on a draft of the recommendation statement, the task force added clarifying information indicating that clinical assessment, physical examination and diagnostic workup are necessary for diagnosis. The task force also clarified scenarios where IGRA testing could be preferable to the TST and added more guidance about screening and treatment to the Practice Considerations section.
In addition, the USPSTF provided links to 11 new resources, including
- the CDC’s Think. Test. Treat TB campaign;
- latent TB infection resources for clinicians and patients;
- education and training on tuberculosis, latent TB infection, and TB screening and testing;
- updated information on the CDC’s TB Centers of Excellence;
- guidance on preventing and treating opportunistic infections in adults and adolescents with HIV;
- a World Health Organization Global Tuberculosis Report and a customizable WHO Tuberculosis Profile; and
- a JAMA patient page and podcast on screening for latent TB.
Due to several evidence gaps, the task force also called for studies to determine the accuracy of risk assessment tools in identifying which individuals are at increased risk for latent TB infection and who should receive screening; determine which populations should receive repeat screening and how frequently; and which screening strategies are more effective for specific patient populations.