About LTBI

 Let's face it: latent tuberculosis sounds scary, and most of my friends got the jitters when I first told them about it.  Then I decided to modify my description to say this: It's kind of like cold sores...cold sores aren't contagious unless they are present.  Latent Tuberculosis Infection (LTBI) is very similar.  If your body is healthy, it will most likely isolate the bacteria so that you don't become sick.  At this point, you are not contagious.  However, if your body has a depressed immune system, or you become ill, there is a chance that the tuberculosis bacteria will become active and begin to grow in your body.  At this point, you would have Active TB. And that's a whole different story.


Here are some FAQ's on LTBI: 

1. What is tuberculosis?
  • The tuberculosis bacteria (Mycobacterium tuberculosis) was first discovered in 1822 by a Nobel prize winning German physician, Robert Koch. (Source) There are more than 70 species of mycobacteria, rod-shaped bacteria with waxy outer coats that can be found throughout the world. Tuberculosis and leprosy (Hansen’s disease) are the best known mycobacterial diseases. People may also be infected by any of a group of mycobacterial species collectively called non-tuberculous mycobacteria. While tuberculosis and leprosy are most common in resource-limited countries, non-tuberculous mycobacterial infections occur worldwide. (Source)
2. How did I get it?
  • At some point, you were exposed to a person with active TB who shared it with the air and you.  In some places, TB micro-particles are thick in the air and I've heard (possible exaggeration) that just by walking through it with no-one around, you are exposed. You must actually inhale the droplets of sputum (I think you must be a healthcare professional to say that word without stumbling).  Once exposed, tuberculosis may find that you would be a nice, warm host to hang around in, which would show up on a TST (tuberculin skin test) done on the arm.
  • An undetected infectious TB victim will, on average, infect another 10 cases in a year, each of whom could transmit the disease in turn. (Source)
  • A third of the world's population are thought to be infected with M. tuberculosis,[3] and new infections occur at a rate of about one per second. (Source - Wikipedia) 
3.  What is the difference between Active TB and Latent TB? 




Tuberculosis: Infection vs Disease
TB Infection (LTBI) TB disease in lungs (Active TB)
MTB present MTB present
Tuberculin skin test positive Tuberculin skin test positive
Chest X-ray normal Chest X-ray usually reveals lesion
Sputum smears and cultures negative Sputum smears and cultures positive
No symptoms Symptoms such as cough, fever, weight loss
Not infectious  Often infectious before treatment
Not defined as a case of TB Defined as a case of TB

 Source


4.  What are my chances of developing Active TB if I have LTBI now?
  • Over 8 million new cases of TB occur each year worldwide. In the United States, it is estimated that 10-15 million people are infected with the TB bacteria and 22,000 new cases of TB occur each year.
  • 5-10% of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life. People with HIV and TB infection are much more likely to develop TB.  (Source) 
  • The risk of developing active tuberculosis is highest within the first 2 years of infection. (Source)
 5. What drugs are used to treat LTBI?
  • INH (isoniazid)
  • If resistant to INH, or allergic reactions appear, providers may switch to Rifampin.
Some resources:


DISCLAIMER:  I am not a medical professional.  All information on this page is credited to its source; please feel free to review sources and come to your own conclusions! 
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