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Tuberculosis

(TB)

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
Air pathway breathing
Mycobacterium tuberculosis is inhaled through the mouth and nose and travels down into the lungs causing TB.
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Risk Factors

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

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

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

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.

For Inactive TB

Inactive TB will have a positive skin test but you will have no symptoms. You may need to take medicine to prevent active TB. You may need to take this medicine over a 3-9 month period. Again, it is important to take all the medication as recommended to prevent drug-resistant TB.

For Active TB

Your doctor may give you a combination of drugs. Continue with medication until your doctor tells you to stop. Treatment for active TB typically lasts six months or longer.
You will need to take special steps to prevent spreading TB to others. You may be asked to stay home or stay away from crowded public places. Make sure to cover your mouth whenever you cough. You can resume your normal activities after your doctor says that you are no longer infectious..

Prevention

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.

RESOURCES

American Lung Association http://www.lungusa.org/

National Institute of Allergy and Infectious Disease http://www.niaid.nih.gov/

CANADIAN RESOURCES

The Canadian Lung Association http://www.lung.ca/

Health Canada http://www.hc-sc.gc.ca/

References

Division of Tuberculosis Elimination. Centers for Disease Control website. Available at: http://www.cdc.gov/tb/topic/basics/default.htm . Updated March 13, 2012. Accessed December 28, 2012.

Hawkridge T, Mahomed H. Prospects for a new, safer and more effective TB vaccine. Paediatr Respir Rev . 2011 Mar;12(1):46-51.

Active Tuberculosis. EBSCO DynaMed website. Available at: https://dynamed.ebscohost.com/about/about-us . Updated December 7, 2012. Accessed December 28, 2012.

Latent Tuberculosis. EBSCO DynaMed website. Available at: https://dynamed.ebscohost.com/about/about-us . Updated October 29, 2012. Accessed December 28, 2012.

Updated Guidelines for Using Interferon Gamma Release Assays to Detect Mycobacterium tuberculosis Infection—United States, 2010. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5905a1.htm . Published June 2010. Accessed December 28, 2012.

12/16/2011 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed/what.php : Sterling T, Villarino E, Borisov A, et al. Three months of rifapentine and isoniazid for latent tuberculosis infection. N Engl J Med. 2011;365(23):2155.

Revision Information

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

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