Basic TB Facts
Tuberculosis (TB) 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 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 TB diseas
Latent TB Infection
TB bacteria can live in the body without making you sick. This is called latent TB infection. 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. People with latent TB infection are notinfectious and cannot spread TB bacteria to others. However, if TB bacteria become active in the body and multiply, the person will go from having latent TB infection to being sick with 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. People with TB disease are sick. They may also be able to 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 people whose immune systems are weak, especially those with HIV infection, the risk of developing TB disease is much higher than for people with normal immune systems.
Symptoms of TB disease depend on where in the body the TB bacteria are growing. TB bacteria usually grow in the lungs (pulmonary TB). TB disease in the lungs may cause symptoms such as
- a bad cough that lasts 3 weeks or longer
- pain in the chest
- coughing up blood or sputum (phlegm from deep inside the lungs)
Other symptoms of TB disease are
- weakness or fatigue
- weight loss
- no appetite
- sweating at night
Symptoms of TB disease in other parts of the body depend on the area affected.
Babies and young children often have weak immune systems. Other people can have weak immune systems, too, especially people with any of these conditions:
- HIV infection (the virus that causes AIDS)
- Substance abuse
- Diabetes mellitus
- Severe kidney disease
- Low body weight
- Organ transplants
- Head and neck cancer
- Medical treatments such as corticosteroids or organ transplant
- Specialized treatment for rheumatoid arthritis or Crohn’s disease
Testing for TB Infection
Tuberculosis (TB) is a disease that is spread through the air from one person to another. There are two kinds of tests that are used to determine if a person has been infected with
TB bacteria: the tuberculin skin test and TB blood tests.A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria. It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease. Other tests, such as a chest x-ray and a sample of sputum, are needed to see whether the person has TB disease.
Tuberculin skin test: The TB skin test (also called the Mantoux tuberculin skin test) is performed by injecting a small amount of fluid (called tuberculin) into the skin in the lower part of the arm. A person given the tuberculin skin test must return within 48 to 72 hours to have a trained health care worker look for a reaction on the arm. The health care worker will look for a raised, hard area or swelling, and if present, measure its size using a ruler. Redness by itself is not considered part of the reaction.
The skin test result depends on the size of the raised, hard area or swelling. It also depends on the person’s risk of being infected with TB bacteria and the progression to TB disease if infected.
Positive skin test: This means the person’s body was infected with TB bacteria. Additional tests are needed to determine if the person has latent TB infection or TB disease. A health care worker will then provide treatment as needed.
Negative skin test: This means the person’s body did not react to the test, and that latent TB infection or TB disease is not likely.