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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 TB skin test or TB blood test (interferon-gamma release assay or IGRA).

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.

By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer R. Steven Tharratt, MD, MPVM, FACP, FCCP - Pulmonology, Critical Care Medicine, Medical Toxicology
Current as of April 4, 2013

WebMD Medical Reference from Healthwise

Last Updated: April 04, 2013
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.