Tuberculosis (TB) is an infectious disease caused by a type of bacteria called Mycobacterium tuberculosis. TB usually affects the lungs, but it can affect the brain, bones, lymph nodes, joints, kidneys, and other parts of the body. It's one of the most common diseases in the world, but it's relatively rare in the U.S. There are only about 2-4 cases in Whatcom County each year.
The first phase of TB infection happens when a person breaths in TB bacteria during exposure to a person who has TB disease. In healthy people, the TB bacteria are contained by the immune system and become dormant (asleep) in their body. This phase - called latent TB Infection - can last a long time, often decades.
A person with TB infection has no symptoms. An X-ray of their chest is normal.
TB infection is not contagious during the latent phase. Because TB bacteria are dormant (asleep) and not active, a person with latent infection cannot spread TB or infect others.
Two types of TB tests are most often used to check for TB infection:
Only a positive TB test detects latent TB Infection.
People with latent TB infection should complete treatment for latent TB Infection to prevent getting active TB disease. It also prevents them from exposing other people to TB.
Latent TB Infection is treated by taking 1-2 medications for 3 to 4 months.
In the active TB phase, the immune system isn't able to contain the TB bacteria. TB bacteria start growing and spreading in the lungs or other parts of the body. Signs and symptoms of TB disease develop due to inflammation and damage caused by the spreading bacteria.
A person with active TB disease has symptoms and feels sick. The chest X-ray is abnormal.
Common symptoms of TB disease:
TB bacteria are spread into the air and can be breathed in by others when a person with active TB disease coughs, sneezes, talks, or sings.
Being infected with TB requires close contact with a person who has TB disease in closed airspace for a long time, usually days or weeks. TB isn't spread easily outdoors because of airflow and sunlight, which kills the TB bacteria.
Diagnosing active TB disease requires several tests from the area of the body that is affected. Sometimes this might include:
TB screening tests for Latent TB infection are not the same as the tests used to diagnose TB disease.
Active TB disease is treated by taking 3 or 4 medicines for at least 6 months. Our public health nurses give the medications using "Directly Observed Therapy." This means the nurse visits you in person or by video to make sure the treatment is completed correctly.
Treatment of active TB prevents TB from spreading to others and prevents drug-resistant strains of TB (strains that aren't killed by standard antibiotics) from developing.