Definition

Tuberculosis (TB) is an infection caused by a bacteria, It is easily spread from one person to another. TB may be in an active or inactive forms. Inactive forms can stay in your body and not make you sick. At some point the bacteria may become active which makes you sick. You can only pass the infection to other people if you have the active version.

TB can affect many organ systems but most often affects the lungs.

Causes

TB is caused by a bacteria. When a person with active TB of the lungs coughs or sneezes it releases the bacteria into the air. Nearby people may then inhale the bacteria. Brief or casual contact with someone who has TB will usually not lead to infection.

Your immune system may also be able to stop the bacteria from growing. This will lead to an inactive (or latent) form of TB. This inactive form may become active if you are ill or have a weakened immune systems. If you are ill or have a weakened immune system when you are exposed to TB you may quickly develop an active TB.

Pathway to the Lungs Mycobacterium tuberculosis is inhaled through the mouth and nose and travels down into the lungs causing TB. Copyright © Nucleus Medical Media, Inc.

Risk Factors    TOP

You are more likely to develop active TB if you have:

• Weakened immune system or chronic diseases (highest risk)
• HIV infection
• Malnutrition
• Intravenous drug use
• Alcoholism
• Leukemia, lymphoma, and other cancers
• Poorly controlled diabetes
• Severe kidney disease
• Medications that lower the immune system response such as those use to treat rheumatoid arthritis
• Suppressed immune system caused by medicines, such as drugs to prevent rejection of a transplanted organ
• Smoking habit

Factors that could increase your risk of contracting TB include:

• Silicosis (an occupational lung disease)
• Living in crowded, indoor conditions (eg, homeless shelters, dormitories, military barracks)
• Age (infants, young children, and elderly people are more susceptible)

Symptoms    TOP

TB causes no symptoms in most patients. In others it is fatal. .

If you have any of these symptoms do not assume it is due to TB. These symptoms may be caused by other conditions.

• Severe cough that lasts more than two weeks
• Coughing up blood and mucus from deep in the lungs
• Pain in the chest
• Weakness or fatigue
• Unexplained weight loss
• Chills
• Fever
• Night sweats
• Loss of appetite

Talk to your doctor if you are having these symptoms.

Diagnosis    TOP

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.

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

Treatment    TOP

Medicine can keep TB from becoming active. It can also help cure active TB. It is very important that you take all the 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.

Prevention    TOP

If you have a positive skin test, you might prevent active TB from developing by taking medicine.

There is a TB vaccine. It is not often used in the United States because the amount of protection is unclear. Talk to your doctor to learn more.