Latent tuberculosis infection

A latent (inactive) tuberculosis (TB) infection is the presence of TB bacteria in a person's lungs even though he or she does not have symptoms of TB (such as coughing, weight loss, fatigue, or fever).

A person with latent tuberculosis infection has no signs of active TB on a chest X-ray, and no TB-causing bacteria can be found in the mucus from the person's lungs (sputum). The only proof that the person has a TB infection is a positive tuberculosis skin test.

People who have a latent TB infection do not spread the disease to other people. They may need to take medicine to prevent the bacteria from becoming active in the future.

Last Updated: April 23, 2009

Author: Maria G. Essig, MS, ELS

Medical Review: Caroline S. Rhoads, MD - Internal Medicine & R. Steven Tharratt, MD, MPVM, FACP, FCCP - Pulmonology, Critical Care, Medical Toxicology

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