Latent Tuberculosis: New Testing Recommendations

Philip LoBue, MD


December 19, 2016

Editorial Collaboration

Medscape &

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Hello, I'm Dr Philip LoBue, director of the Division of Tuberculosis Elimination at the Centers for Disease Control and Prevention (CDC). I'm pleased to speak with you as part of CDC's Expert Video Commentary Series on Medscape. Today, I would like to share important information about the latest recommendations for testing for and treating latent tuberculosis (TB) infection.[1]

TB cannot be eliminated in the United States without increased efforts to test and treat latent TB infection. CDC estimates that up to 13 million people in the United States have latent TB infection.[2] Without treatment, 1 in 10 people with latent TB infection will develop TB disease. For some, that risk is higher.[3]

CDC supports a new recommendation from the US Preventive Services Task Force (USPSTF) that encourages providers to test for TB infection in populations that are at increased risk—specifically, people born in or who frequently travel to countries where TB disease is common, including Mexico, the Philippines, Vietnam, India, China, Haiti, and Guatemala, or other countries with high rates of TB. Providers should consult with their local or state health departments for populations at risk in their communities based on local demographic patterns.

The USPSTF also recommends testing anyone who currently, or used to, live in large group settings, such as homeless shelters, prisons, or jails. In addition, CDC recommends TB testing for healthcare workers, contacts of people with confirmed or suspected TB disease, and as part of disease management for people with certain conditions, such as HIV and diabetes, or as indicated before the use of certain medications.

Both blood and skin tests are available to identify TB infection: the interferon-gamma release assays (IGRAs) and the TB skin test, commonly called "TST." There are several advantages of IGRAs over the TST. IGRAs require only a single visit and results can be available within 24 hours. IGRAs also offer an advantage over TST when testing people who have received bacille Calmette-Guérin (BCG) vaccination, because they do not cause the false-positive reactions that sometimes occur when using the TST.

However, TSTs are still useful for certain groups. CDC guidelines can help providers decide which test to use. A diagnosis of latent TB infection is made if a person has a positive IGRA or TST result and a medical evaluation does not indicate TB disease. The presence of TB disease must be excluded before treatment for latent TB infection is initiated.

Several regimens are available for the treatment of latent TB infection. Newer short-course treatment regimens using isoniazid and rifapentine (often referred to as "3HP") given once weekly for 12 weeks, or rifampin alone given daily for 4 months, have been shown to have higher completion rates with less liver toxicity compared with the older regimen of 9 months of daily isoniazid.[4] 3HP is a "directly observed therapy" that requires each dose to be supervised, usually by a healthcare worker, to ensure adherence to and tolerability of the regimen.

TB control and prevention have traditionally been functions of state and local public health departments. However, many of those at high risk for TB infection and TB disease who need to be tested and treated receive care from private healthcare providers and community health centers. The new USPSTF recommendation provides expanded opportunities for private healthcare providers to play a critical role in TB control and prevention, because targeted testing and treatment of persons at greatest risk for TB is the most effective way to further reduce the number of new TB cases in the United States.

For more information on latent TB infection, please visit the CDC website.

Web Resources

CDC: Tuberculosis

CDC: Latent Tuberculosis Infection: A Guide for Primary Health Care Providers

CDC: Latent Tuberculosis Infection (LTBI) Mobile Application for Health Care Providers

US Preventive Services Task Force: Latent Tuberculosis Infection: Screening