Tuberculosis, or TB, is a disease caused by bacteria called Mycobacterium tuberculosis. These bacteria can attack any part of the body, but usually affect the lungs, causing pneumonia (pulmonary TB). Worldwide, TB infects millions of people.
TB is spread through the air from one person to another. The bacteria become airborne when a person with TB disease of the lungs or throat coughs or sneezes. People nearby may breathe in these bacteria and become infected.
A person with latent TB has been infected with TB but has no symptoms and does not feel sick. If a healthy person has latent TB, he or she has only a 10 percent lifetime risk of developing the disease. People with latent TB are not infectious or contagious. People with TB disease have symptoms and are sick. Symptoms may include fever, night sweats, weight loss, a cough that lasts longer than two weeks, chest pain or coughing up blood. People who are sick with TB in their lungs or larynx are contagious to other people. People who have TB disease elsewhere in the body, such as the spine, are not usually contagious. Those with a weakened immune system are all at increased risk of developing TB disease, including people with
In addition, people who are very young or very old are at risk for developing TB disease. Some medications that suppress the immune system (e.g., steroids or transplant medications) also increase the risk of TB disease. People require treatment for both latent TB and TB disease, though the treatment is different for each.
A TB skin test (called a PPD test) is one way to find out if someone has latent TB infection. There is also a blood test under development called QuantiFERON®. During a PPD test, a health care worker injects a small amount of fluid under the skin of the arm. Three days later, he or she will look to see whether or not there is a bump at the site of the injection. If there is a bump, he or she will measure it and decide whether or not the person demonstrates a positive test. A positive test usually means that the person has been infected with TB, but it does not necessarily mean he or she has TB disease. Skin tests may be performed at the health department or at your doctor's office.
You should get a TB test if you
If you have a positive PPD test, your doctor will perform other tests, such as a chest X-ray, to determine whether you have latent TB or TB disease.
If someone has a positive PPD test but no evidence of disease, their doctor will recommend medication to kill the TB bacteria in the body in order to prevent the future development of TB disease. Latent TB is usually treated with only one or two medications. The most common medicine is called isoniazid (INH). Side effects of INH are listed below. These side effects are rare, but if they do occur, a doctor should be notified immediately. In addition, drinking alcohol while taking INH is dangerous because alcohol increases the risk of side effects.
If someone has symptoms of TB, his or her doctor will recommend at least four medications to treat the disease. Someone with active pulmonary (lung) TB is considered contagious until he or she has taken medication for at least two weeks and symptoms have diminished. In addition, the doctor will take cultures of the bacteria to establish whether or not it is resistant to any medications. The culture results will help determine which medicines need to be continued, and for how long. The most common drugs used to fight TB are
People with active pulmonary TB are asked not to go to work-or anywhere else where there are other people-to prevent the spread of infection to others. Individuals' doctors and the appropriate health departments will determine when it is safe to return to work.
Medicine for TB is relatively safe and side effects are rare, but serious side effects may sometimes occur, including
If a serious side effect does occur, call your doctor or nurse immediately. TB medicines may also have minor side effects, such as an increased sensitivity to the sun, and they may interact with other medications a person is already taking. Before you start treatment, your doctor or nurse should review the specific medicines and their side effects.
TB bacteria grow very slowly. Most of the medicines only work on bacteria that are growing, so it takes a long time to kill all the bacteria in the body. For latent TB, the recommendation is for nine months of treatment. For active TB in the lungs, the recommendation is for a minimum of six months of treatment. TB in other parts of the body, such as the spine, may take more than a year to cure. It is very important to take all TB medicines as prescribed. Missing doses may allow the TB bacteria to become resistant to the medicines prescribed, meaning that the medicine no longer kills the TB. Resistant TB can grow and cause symptoms to relapse even if you are still on medication.
Multidrug-resistant TB (MDR TB) features bacteria that are resistant to at least two of the common medicines used to treat TB. MDR TB occurs when people are exposed to someone who is either already infected with resistant TB or who has not taken all prescribed TB medicines regularly. MDR TB is very difficult to treat.
DOT involves a health care worker watching a TB patient take his or her medicines and is a way of making sure that people with TB take their medicine as prescribed. People on DOT may be able to take medicines three or four times per week instead of daily.
The Division of Tuberculosis Elimination of the Centers for Disease Control and Prevention provides answers to commonly asked questions about TB; this information is also available as a downloadable PDF document. http://www.cdc.gov/tb/topic/basics/default.htm http://www.cdc.gov/tb/publications/faqs/default.htm