Tuberculosis (TB) is an infection. TB may be either active or latent. Latent forms can stay in your body and not make you sick. Latent TB may become active if you are ill, have a weakened immune system, or for no known reason.
Active TB infection most is most common in the lungs, but it can occur in other places in the body.


TB is a highly contagious disease caused by a specific bacteria called Mycobacterium tuberculosis. It is transmitted by air from one person to another. This can happen during coughing, sneezing, or talking. Once airborne, the bacteria can be breathed in by other people causing exposure or active infection. You can only pass the infection to other people if you have active TB.
Pathway to the Lungs
Air pathway breathing
Bacteria is inhaled through the mouth and nose and travels down into the lungs causing TB.
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Risk Factors

Infants, young children, and older adults are more susceptible to TB.
Factors that may increase your chance of TB exposure include:
Factors that increase your chance of getting active TB after exposure:


Latent TB does not cause symptoms. When symptoms appear, the disease becomes active. Active TB may cause:


Active or latent TB may be found during a routine check-up.You will be asked about your symptoms and medical history, including if you think you were exposed to TB. A physical exam will be done. Tests that can detect the disease include:
If you have symptoms that indicate active TB, your doctor may do the following tests:


Medication can keep TB from becoming active. It can also help cure active TB. It is important that you take all the medication exactly as prescribed. Take all the medication, even if the symptoms go away. If you do not finish your medication, you may relapse or develop drug-resistant TB. This form is very difficult to cure.

For Latent TB

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

For Active TB

You will be given a combination of drugs. Continue with medication until your doctor tells you to stop. Treatment for active TB typically lasts 6 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.


To help reduce your chance of TB exposure, take these steps:
If you have been exposed to TB, take these steps to prevent it from becoming active:
If you have active TB, take these steps to protect others from infection:


American Lung Association

National Institute of Allergy and Infectious Disease


The Canadian Lung Association

Health Canada


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Tuberculosis (TB). Centers for Disease Control and Prevention website. Available at: Updated March 13, 2012. Accessed November 16, 2015.

12/16/2011DynaMed's Systematic Literature Surveillance 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.

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