Tuberculosis – Definition
Tuberculosis (TB) is a contagious infectious disease. It can have either active or inactive forms. Although it can affect many organ systems, it mostly affects the lungs.
Tuberculosis – Causes
TB is caused by the bacterium Mycobacterium tuberculosis. When a person with active TB of the lungs coughs or sneezes, people nearby may inhale the bacteria. TB is easily spread in crowded conditions, though it may take several hours of continuous exposure to transmit infection. Brief or casual contact with someone who has TB will usually not lead to infection. TB is most likely to become active when spread among people who are ill or have weakened immune systems.
Tuberculosis – Risk Factors
These factors increase your chance of developing active TB:
- Weakened immune system or chronic diseases (highest risk)
- HIV infection
- Intravenous drug use
- Leukemia, lymphoma, and other cancers
- Poorly controlled diabetes mellitus
- Severe kidney disease
- Some medicines used for treating rheumatoid arthritis and other diseases, including etanercept, infliximab, and adalimumab
- Suppressed immune system caused by medicines, such as drugs to prevent rejection of a transplanted organ
- Other risks factors include:
- Silicosis (an occupational lung disease)
- Living in crowded, indoor conditions (eg, homeless shelters, dormitories, military barracks)
- Age (infants, young children, and elderly people)
Tuberculosis – Symptoms
TB causes no symptoms in most patients. In others it is fatal. The bacteria lie dormant in the lungs. Bacteria may remain there permanently without causing illness. During this time, the infected person cannot spread TB to others. The infection spreads once the bacteria are active.
If you have any of these symptoms do not assume it is due to TB. These symptoms may be caused by other conditions. Tell your doctor if you have any of these:
- Severe cough that lasts more than two weeks
- Coughing up blood and sputum (mucus from deep in the lungs)
- Pain in the chest
- Weakness or fatigue
- Unexplained weight loss
- Night sweats
- Loss of appetite
Tuberculosis – Diagnosis
A skin test is used to screen for TB. A small amount of tuberculin test fluid is injected into the skin of the lower part of your arm. The test is positive if after 2-3 days a raised, firm welt appears at the injection site. The welt is 10 millimeters (mm) or greater in diameter (5 mm or 15 mm under some situations).
A positive test means you were exposed to TB, even if you never became ill. People at high risk for getting TB should have a skin test regularly. Also, new blood tests are available to screen for TB. Talk to your doctor to learn more.
If you have symptoms or signs of active TB, your doctor may order the following:
- Chest x-ray
- Samples of your sputum to be tested for the bacterium
Tuberculosis – Treatment
Medicine can prevent TB from becoming active. It can also help cure active TB. It is very important that you take all medicine exactly as prescribed. Take all the medicine, even if the symptoms go away. If you do not finish your medicine, you may develop drug-resistant TB. This form is very difficult to cure.
For Inactive TB
If you have a positive skin test but no signs of active TB, you may need to take medicine to prevent active TB. The drug isoniazid is usually given for nine months. Another option is taking a combination of isoniazid and rifapentine for three months.
For Active TB
Your doctor may give you a combination of the following drugs:
- Under special circumstances, other drugs may be used
If you have active TB, you will need to use special precautions to prevent transmission to others. This will help prevent the spread of TB. You may need to stay home or stay away from crowded public places. You will also need to cover your mouth whenever you cough. You can resume your normal activities after your doctor says that you are no longer infectious. You will need to keep taking medicine until your doctor tells you to stop. Treatment for active TB typically lasts six months or longer.
Tuberculosis – Prevention
If you have a positive skin test, you might prevent active TB from developing by taking medicine. There is a vaccine. It is not routinely used in the United States because of the unreliable protection it provides. Talk to your doctor to learn more.
If you have active TB, you can prevent its spread by:
- Covering your mouth and nose with tissue or a handkerchief whenever you cough.
- Avoiding contact with people until your doctor says you are no longer contagious
- Taking all medicine as prescribed for the full course of treatment