How can tuberculosis spread from the lungs to other parts of the body?

Tuberculosis spreads from the lungs to other parts of the body primarily through the bloodstream.12

In cases of latent tuberculosis, the body initially sequesters the bacteria within hard, nodular tubercles. However, if these tubercles break down—sometimes decades after the initial infection—viable bacilli are released into the bloodstream. Once the bacteria enter the circulatory system, they can travel to and infect almost any tissue or organ in the body.1

Common sites for this secondary spread include:
* Lymph nodes, bones, and joints1
* Kidneys and bladder1
* Skin and intestines1
* Genital organs1
* The meninges, which cover the brain, leading to tuberculous meningitis1

In certain individuals, such as infants, the elderly, or those who are immunocompromised, the primary infection can disseminate rapidly throughout the body, resulting in a highly fatal form of the disease known as miliary tuberculosis. Prompt medical intervention is essential to prevent this systemic spread.12