What Is Latent Tuberculosis?

Dr. Timothy Sterling, Professor of Medicine and Director of the Tuberculosis Center in the Division of Infectious Diseases and Institute of Global Health at Vanderbilt discusses latent tuberculosis (TB) infection and the importance of and recommendations for treatment.

Begin Transcript

Welcome to this edition of the Vanderbilt Health and Wellness wellcast.  I'm Shaina Farfel with Occupational Health.

Shaina Farfel:  Hello, everyone.  Today, we are speaking with Dr. Timothy Sterling, Professor of Medicine and Director of the Tuberculosis Center in the Division of Infectious Diseases in the Institute of Global Health at Vanderbilt.  Hi, Dr. Sterling.  Thank you so much for being with us.  So, we are coming up on World Tuberculosis (or "TB") Day, which is on March 24th.  I know here at Occupational Health, we perform a lot of screenings for TB and we do diagnose many employees with potential latent TB infection, which we may be referring to as LTBI during this conversation.  So, today, I wanted to discuss the importance of and recommendations for treatment for LTBI.  Let's just jump right in.  What is latent tuberculosis and how would someone know if they had it?

Dr. Timothy Sterling:  People can get infected with tuberculosis after they have been exposed to someone who has what we call "active tuberculosis," which is usually in the lungs.  Someone with active TB has symptoms.  They usually have cough, night sweats, fever, chills, weight loss.  They can even cough up blood.  And if someone is exposed to someone who has active TB, they can become infected with tuberculosis, and initially, that infection is quiet or asymptomatic or what we call "latent."  That's identified by one or two diagnostic tests.  The traditional test is the tuberculin skin test and that has been performed by Occupational Health, at least in the past, to where it's done under the skin and people come back two or three days later after the test is placed to see if it's positive or not.  More recently, there have been blood-based tests, the Interferon Gamma Release Assays, and Occupational Health also does this, and it's just another way to identify tuberculosis.  These tests do not distinguish between latent infection and active disease, but in someone who has a positive test, if they do not have symptoms, and they have a normal chest x-ray, then they are felt to have latent tuberculosis infection.

Shaina Farfel:  And so, if latent TB is asymptomatic, if it's not causing the individual any issues at the time, is it important still to receive treatment for it, and I guess, would it be more important in populations of a medical center?

Dr. Timothy Sterling:  It's important to treat people with latent tuberculosis infection who are at increased risk of progressing to active TB, and that includes people who have been recently infected but may also include people who have underlying medical conditions that.  It increases their risk.  That includes HIV, kidney failure, diabetes mellitus, those sorts of things.  There are also certain medications that people may be taking that weaken their immune system and that would also increase the risk of progressing to TB.  So, in those groups in particular, it's important to prevent active TB with what we call treatment of latent infection.

Shaina Farfel:  What is the likelihood of latent infection turning into an active infection in at risk populations?

Dr. Timothy Sterling:  Well, approximately 5-10% of people with latent infection will progress to active TB, but in groups that are at increased risk, that is higher.  So, within two years of infection, the risk is increased.  People with HIV, particularly if the HIV is not being treated, they are at increased risk, and people with poorly-controlled diabetes or on other medications.  So, in those groups, the risk is higher.

Shaina Farfel:  And what are the current available treatments for latent TB at this time?

Dr. Timothy Sterling:  There are several options.  Traditionally, it has been isoniazid given for six to nine months, but more recently, there has been a push toward shorter regimens, primarily because they are as safe and effective as isoniazid, actually potentially a little safer, but because they are shorter, the treatment completion rates are higher, and that's a good thing.  So, those regimens include a three-month regimen of isoniazid and rifapentine, given once a week, so for 12 doses, isoniazid and Rifampin, given every day, also for 12 weeks, and then Rifampin given every day for 16 weeks.

Shaina Farfel:  If I have been diagnosed with latent TB and was potentially interested in receiving treatment, where could I seek care?

Dr. Timothy Sterling:  Well, you can get it at Occupational Health, at that clinic, but you can also receive it through your primary provider and also the Health Department in Nashville.  If you are a resident of Davidson County, you can seek care through the Metro Health Department.

Shaina Farfel:  Well, Dr. Sterling, thank you so much for sharing your expertise with us today.  I am sure many of our employees will find this information very helpful in making decisions about their health.  So, thank you so much.

Dr. Timothy Sterling:  You're welcome.

Thanks for listening.  If you have a story suggestion, please email it to us at health.wellness@vanderbilt.edu or you can use the "Contact Us" page on our website at www.vumc.org/health-wellness.