"TB" is short for tuberculosis. TB disease is caused by a germ, or bacteria, 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.
TB is spread through the air from one person to another. When a person with active TB disease of the lungs or throat coughs, sneezes or speaks, the TB bacteria can be spread into the air. People who are near to that person 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
Not everyone infected with TB bacteria becomes sick. There are two kinds of TB: 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). The immune system of people with LTBI is able to fight the TB bacteria to stop them from growing.
People with LTBI do not feel sick and do not have any symptoms. The only sign of TB infection is a positive reaction to a skin test or special TB blood test.
People with LTBI are not infectious and cannot spread TB to others. However, if TB bacteria becomes active and starts to multiply, the person will get sick with TB disease. Many people who have LTBI never develop TB disease.
Active 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 active TB disease. TB disease will make you sick.
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. People with TB disease can spread the bacteria to other people.
|A Person with Latent TB Infection:||A Person with TB Disease:|
|Has no symptoms||Has symptoms like:
|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|
TB bacteria can become resistant to the medicines used to treat TB disease.
This means that the medicine can no longer kill the bacteria. Resistance to TB drugs can occur when these drugs are not used or taken properly.
- when patients do not complete their full course of treatment
- when health care providers prescribe the wrong treatment, the wrong dose, or wrong length of time for taking the drugs
- when the supply of drugs is not always available
- when the drugs are of poor quality
Multidrug-Resistant TB (MDR TB)
MDR TB is TB that is resistant to at least two of the best anti-TB drugs, isoniazid and rifampicin. These drugs are used to treat persons with TB disease. Find out more: MDR TB fact sheet.
Extensively Drug-resistant TB (XDR TB)
Extensively drug-resistant TB (XDR TB) is a rare kind of MDR TB. XDR TB is TB that is resistant to isoniazid and rifampin, plus resistant to any fluoroquinolone and at least one of three injectable second-line drugs (i.e., amikacin, kanamycin, or capreomycin).
Because XDR TB is resistant to many of first and second choice drugs, patients are left with treatment options that are much less effective. Find out more: XDR TB fact sheet.
For people whose immune systems are weak, especially those with HIV infection, the risk of getting active TB disease is much higher than for people with normal immune systems.
While there are fewer people in this country suffering with TB, it remains a serious threat, especially for HIV-infected persons. In fact, TB is one of the leading causes of death among people infected with HIV.
Without treatment, people with HIV and TB may have a shorter life than expected. People with untreated LTBI and HIV are much more likely to develop active TB disease than people without HIV infection.
The good news is that HIV-infected persons with either LTBI or active TB disease can be effectively treated. The first step is to ensure that HIV-infected persons get a test for TB infection and any other needed tests. The second step is to help the people found to have either latent TB infection or active TB disease get the treatment they need.