Tuberculosis
- What is TB?
- How TB spreads
- How do I know if I have TB?
- If I was exposed to someone with active TB disease, can I give TB to others?
- Latent TB Infection & TB Disease
- Differences between Latent TB Infection & TB Disease
- What are multidrug-resistant TB (MDR TB) and extensively drug-resistant TB (XDR TB)?
- Related Links
What is TB?
"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 kidneys, 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
How do I know if I have TB?
If you have been around someone who has active TB disease, you should go to your health care provider or your local health department for tests. TB testing is done at Student Health Service through our walk-in Nurses Clinic (hours are 8-11 and 1-3:30, except Tu and Th, opens at 9). If you were involved in a known exposure, and received notification of this exposure, follow the instructions regarding special clinic arrangements for testing.There are two tests that can be used to help detect latent TB infection: a skin test or a special TB blood test. The skin test is used most often. A small needle is used to put some testing material, called tuberculin, under the skin. In 2-3 days, you return to the health care worker who will check to see if there is a reaction to the test. In some cases, a special blood test (Quantiferon Test) is done for TB infection. This blood test measures how a person's immune system reacts to the germs that cause TB. This test is especially useful if you have had a positive skin test in the past, or have received BCG vaccine, which can cause positive skin tests without TB infection.
Other tests are needed to show if you have active TB disease. TB disease may be deep inside your lungs. An x-ray of your chest can tell if there is damage to your lungs from TB. If you have an abnormal x-ray, or if you have suspicious symptoms, sputum you cough up may be tested in a laboratory to see if the TB germs are in your lungs.
If I was exposed to someone with active TB disease, can I give TB to others?
If you were exposed to someone with active TB disease, you may become infected with TB bacteria, but you would not be able to spread the bacteria to others right away. Only persons with active TB disease can spread TB to others. Before you would be able to spread TB bacteria to others, you would have to breathe in TB bacteria and become infected. Theactive bacteria would then have to multiply in your body and cause active TB disease. At this point, you could possibly spread TB bacteria to others.Some people develop active TB disease soon (within weeks) after becoming infected, 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. Many people with TB infection never develop TB disease.
In most people who breathe in TB bacteria and become infected, the body is able to fight the bacteria to stop them from growing. The bacteria become inactive, but they remain alive in the body and can become active later. This is called latent TB infection. People with latent TB infection cannot spread TB bacteria to others. People who have latent TB infection can be treated to prevent developing active TB disease. There is a 10% chance that people with latent TB will develop active TB disease at some point later in their lives.
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. Up to 10% of people with latent TB will develop active TB disease later in their lives.
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.
Differences between Latent TB Infection and TB Disease
| A Person with Latent TB Infection | A Person with TB Disease |
| Has no symptoms | May have symptoms that include: |
| 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 for active TB disease |
What are multidrug-resistant TB (MDR TB) and extensively drug-resistant TB (XDR TB)?
Sometimes the TB bacteria are resistant to the medicines used to treat TB disease. This means that the medicine can no longer kill the bacteria. Multidrug-resistant TB, or MDR TB, is caused by bacteria that are resistant to two of the most important TB medicines: Isoniazid (INH) and Rifampin (RIF).A more serious form of MDR TB is called extensively drug-resistant TB (XDR TB). XDR TB is a rare type of TB that is resistant to nearly all medicines used to treat TB disease.
If you do not take your medicines as directed by your health care provider, the TB bacteria may become resistant to a certain medicine. Also, people who have spent time with someone sick with MDR TB or XDR TB can become infected with these drug-resistant bacteria.
Drug resistance is more common in people who:
- have spent time with someone with drug-resistant TB disease
- do not take their medicines as directed by their doctor or nurse
- develop active TB disease again, after having taken TB medicines in the past
- come from areas where drug-resistant TB is common
People with MDR TB or XDR TB must be treated with special medicines. These medicines may cause more side effects, and may not be as effective as other medicines. Also, people with MDR TB and XDR TB must see a TB expert who can closely observe their treatment to make sure it is working. Treatment takes much longer than regular TB. And, people with MDR TB and XDR TB are at greater risk of dying from the disease.
