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.
Copyright © Nucleus Medical Media, Inc.

Risk Factors

Infants, young children, and older adults are more susceptible to TB.

Factors that may increase your chances of TB exposure include:

  • Close contact with a person infected with active TB
  • Living in or traveling to an area where there are high rates of TB
  • Working in certain occupations, such as farming, funeral homes, and healthcare
  • Living or working in crowded, indoor conditions, such as prisons, hospitals, homeless shelters, or nursing homes

Factors that increase your chance of getting active TB after exposure:

  • Having been infected with TB bacteria in the last 2 years
  • Chronic diseases that weaken the immune system:
    • HIV infection
    • Poorly controlled diabetes
    • Severe kidney disease
    • Rheumatoid arthritis
    • Silicosis or other occupational lung diseases
    • Malnutrition
    • Active or passive smoking
    • Alcohol or substance abuse
    • Low socioeconomic status
  • Certain medications that weaken or suppress the immune system, such as chemotherapy drugs that treat cancer or medication to prevent organ rejection.



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

  • Severe cough that lasts more than 2-3 weeks
  • Coughing up blood and mucus
  • Pain in the chest
  • Weakness or fatigue
  • Unexplained weight loss
  • Chills
  • Fever
  • Night sweats
  • Loss of appetite


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:

  • Blood tests
  • Skin test

If you have symptoms that indicate active TB, your doctor may do the following tests:

  • Chest x-ray
  • Samples of your sputum
  • Fluid or tissue tests, especially if the disease is not in the lungs



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 chances of TB exposure:

  • Follow occupational guidelines at your work place.
  • Try to avoid contact with people who have active TB.
  • Limit travel to areas with high rates of TB.

If you have been exposed to TB, take these steps to prevent it from becoming active:

  • Get regular skin testing.
  • Take all antibiotic medication.
  • Manage any chronic diseases as directed by your doctor.
  • If you smoke, find out the best ways you can quit.
  • Drink alcohol in moderation. That is a maximum of 2 drinks per day for men, and a maximum of 1 per day for women.
  • Eat a healthy diet.
  • Talk with your doctor about the TB vaccine . It is not often used in the US because the amount of protection is unclear.

If you have active TB, take these steps to protect others from infection:

  • Stay at home.
  • Circulate air in your rooms.
  • Cover your mouth when you cough or sneeze.
  • Wash your hands frequently, especially after coughing or sneezing.
  • Consider wearing a surgical mask.

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.

Edits to original content made by Denver Health.

a (TB)


American Lung Association 

National Institute of Allergy and Infectious Disease 


Health Canada 

The Lung Association 


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Latent tuberculosis infection (LTBI). EBSCO DynaMed Plus website. Available at:  . Updated October 30, 2017. Accessed December 11, 2017.

Tuberculosis (TB). Centers for Disease Control and Prevention website. Available at: Updated March 20, 2016. Accessed December 11, 2017.

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