"TB" is short for tuberculosis. TB disease is caused by a bacterium called Mycobacterium tuberculosis. The bacteria usually attack the lungs, but TB bacteria can attack any part of the body such as the kidney, spine, and brain. If not treated properly, TB disease can be fatal.
How TB Spreads
TB is spread through the air from one person to another. The TB bacteria are put into the air when a person with active TB disease of the lungs or throat coughs, sneezes, speaks, or sings. People nearby may breathe in these bacteria and become infected.
TB is NOT spread by:
- Shaking someone’s hand
- Sharing food or drink
- Touching bed linens or toilet seats
- Sharing toothbrushes
Latent TB Infection and TB Disease
Not everyone infected with TB bacteria becomes sick. As a result, two TB-related conditions exist: latent TB infection and active TB disease.
- Latent TB Infection - TB bacteria can live in your body without making you sick. This is called latent TB infection (LTBI). In most people who breathe in TB bacteria and become infected, the body is able to fight the bacteria to stop them from growing. People with latent TB infection do not feel sick and do not have any symptoms. The only sign of TB infection is a positive reaction to the tuberculin skin test or special TB blood test. People with latent TB infection are not infectious and cannot spread TB bacteria to others. However, if TB bacteria become active in the body and multiply, the person will get sick with TB disease.
- TB Disease - TB bacteria become active if the immune system can't stop them from growing. When TB bacteria are active (multiplying in your body), this is called TB disease. TB disease will make you sick. People with TB disease may spread the bacteria to people they spend time with every day. Many people who have latent TB infection never develop TB disease. Some people develop TB disease soon after becoming infected (within weeks) before their immune system can fight the TB bacteria. Other people may get sick years later, when their immune system becomes weak for another reason.
For persons whose immune systems are weak, especially those with HIV infection, the risk of developing TB disease is much higher than for persons with normal immune systems.
The Difference between Latent TB Infection and TB Disease
|A Person with Latent TB Infection||A Person with TB Disease|
|Has no symptoms:||
Has symptoms that may include:
- a bad cough that lasts 3 weeks or longer
- pain in the chest
- coughing up blood or sputum
- weakness or fatigue
- weight loss
- no appetite
- sweating at night
|• Does not feel sick||• Usually feels sick|
|• Cannot spread TB bacteria to others||• May spread TB bacteria to others|
|• Usually has a skin test or blood test result indicating TB infection||• Usually has a skin test or blood test result indicating TB infection|
|• Has a normal chest x-ray and a negative sputum smear||• May have an abnormal chest x-ray, or positive sputum smear or culture|
|• Needs treatment for latent TB infection to prevent active TB disease||• Needs treatment to treat active TB disease|