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Tuberculosis

Latent TB Treatment

07/05/2006

Question:

I just found out that my mother, who is 70 years old, is positive for latent TB. She says that when she was a teenager she lived with a couple and one of them had TB. About 20 years ago she was given a TB test and it came back positive for exposure. As far as I know, there was no additional testing and she did not take the 9 month course of treatment that is often recommended for latent TB. After all this time since her exposure, which is at least 50 years ago, should she repeat the test and have treatment?

Answer:

Your 70 year old mother who has a history of exposure to TB as a teenager and a positive TB skin test 20 years ago is almost certainly latently infected with tuberculosis, so there would be little value to repeating a TB skin test at this point in her life. Without knowing more about your mother's other medical conditions (if any), the chances of this latent tuberculosis infection could reactivate and cause tuberculosis disease at some point during the rest of her life cannot be estimated.

If she has had solid organ transplantation (such as kidney or heart), or has silicosis of the lungs, or has kidney failure on dialysis, then her chances of reactivating TB are at least 10 times higher than if she is otherwise healthy. This is because those conditions weaken different aspects of the immune system that is controlling her TB infection. Even having diabetes mellitus, having had a gastrectomy, or being underweight increases the risk of reactivation TB by 2 1/2 times.

But, if she is otherwise healthy, her chances of reactivating TB are probably less than 1% per year. Your mother should see her doctor for a chest x-ray if she has any of the signs or symptoms of active tuberculosis: cough, fever, night sweats, fatigue, chest pain, or hemoptysis (coughing up blood). Even if she doesn't have these signs or symptoms, she can talk with her doctor about the chances of reactivating TB, and the risk-benefit ratio of taking medications to treat latent TB infection.

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Response by:

Lisa A Haglund, MD Lisa A Haglund, MD
Associate Professor of Clinical Medicine
College of Medicine
University of Cincinnati