by EBSCO Medical Review Board
(Latent TB; Latent Tuberculosis Infection; Latent TB Infection)


Latent tuberculosis (TB) is a type of inactive infection. People with latent TB have the bacteria but are not ill. Latent TB can become an active infection later in life.


TB is caused by a bacteria. It is spread by people who have an active form called TB disease or active TB. The bacteria are passed through the air in droplets from a person with TB disease. In this case, it enters the body but does not cause illness. The bacteria do stay in the body.

Latent TB does not spread to other people. Only active TB can be passed from person to person.

Risk Factors

Babies, young children, and older adults are more likely to get any form of TB when exposed.

Other things that may raise the risk of TB exposure are:

  • Close contact with a person who has active TB
  • Living or traveling to an area where TB rates are high
  • Working in certain jobs, such as farming, funeral homes, and healthcare
  • Living or working in crowded, indoor conditions, such as prisons, hospitals, homeless shelters, or nursing homes


Latent TB does not cause symptoms.


Latent TB may be found during a routine check-up. You will be asked about your symptoms and past health. You will also be asked about your TB exposure. A physical exam will be done.

Signs of TB bacteria can be found in:

  • Skin test
  • Blood tests

A chest x-ray may be taken to rule out active TB.


Latent TB can become active. This is more likely in people who develop weaker immune systems. It can happen with medicine, illness, or increased age.

The goal of treatment is to clear TB before it becomes active and causes illness. Antibiotic medicine can clear TB bacteria. The medicine will need to be taken over 3 to 9 months. All the medicine must be finished to prevent drug-resistant TB.


To lower the risk of TB:

  • Avoid contact with people who have active TB.
  • Limit travel to areas with high rates of TB.


American Lung Association 

National Institute of Allergy and Infectious Diseases 


Health Canada 

The Lung Association 


Chee CBE, Reves R, et al. Latent tuberculosis infection: Opportunities and challenges. Respirology. 2018 Oct;23(10):893-900.

Latent tuberculosis infection (LTBI). EBSCO DynaMed website. Available at: Accessed September 24, 2020.

Pulmonary tuberculosis. EBSCO DynaMed website. Available at: Accessed October 13, 2020.

Tuberculosis (TB). Centers for Disease Control and Prevention website. Available at: Accessed October 13, 2020.

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