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Tuberculosis (TB)

What is tuberculosis?

Tuberculosis (TB) is a bacterial infection that often infects the lungs. Other organs such as the kidneys, spine, or brain may also be affected. TB is mainly spread from person to person through the air, such as when an infected person coughs or sneezes. It can also cause an active infection after not being active, in someone who was exposed at an earlier time.

There is a difference between being infected with the TB bacteria and having active tuberculosis disease.

The stages of TB are:

  1. Exposure. This happens when a person has been in contact with, or exposed to, another person who has TB. The exposed person will have a negative skin test, a normal chest X-ray, and no signs or symptoms of the disease.

  2. Latent TB infection. This happens when a person has TB bacteria in their body, but no symptoms of the disease. The infected person's immune system walls off the TB organisms. And the TB stays inactive throughout life in most people who are infected. This person would have a positive skin or blood test for TB, but a normal chest X-ray. They would have no signs of active infection in other parts of the body.

  3. TB disease. This person has signs and symptoms of an active TB infection. The person could have a positive or negative skin or blood test for TB. And a positive chest X-ray, biopsy, or other finding showing an active infection.

What causes TB?

The main TB bacteria is Mycobacterium tuberculosis (M. tuberculosis). Many people infected with this bacteria never have active TB. They remain in the inactive (latent) TB stage. But some will develop active TB anytime from months to years or even decades after being exposed. The chance of developing active TB increases in babies and children and in older adults. It also increases in people with a weak immune system, especially those with HIV. Or in those getting medicines that suppress the immune system.

The TB bacteria is spread through the air when an infected person coughs, sneezes, speaks, sings, or laughs. It’s very unlikely to be spread from personal items that a person with TB has touched. Good ventilation can limit the spread of TB to other people. But early diagnosis and treatment of the person with active TB is most important. It's also important to limit other people's exposure. This means using masks and respiratory isolation.

Who is at risk for TB?

TB affects all ages, races, income levels, and genders. Those at higher risk include:

  • People who live or work with others who have TB

  • Those who can’t access healthcare

  • Homeless people

  • People from countries where TB is more common

  • People in group settings, such as nursing homes

  • People who abuse alcohol

  • People who use injection drugs

  • People with a weak immune system, including those who have HIV

  • The very young and older adults

  • Healthcare workers who come in contact with high-risk populations

What are the symptoms of TB?

Each person's symptoms may vary. The most common symptoms of active TB include:

  • Prolonged cough lasting weeks

  • Chest pain

  • Feeling tired and weak (fatigue)

  • Loss of appetite

  • Unintended weight loss

  • Poor growth in children

  • Fever

  • Coughing blood or sputum

  • Night sweats

  • Shortness of breath

  • Back pain

The symptoms of TB may look like other lung conditions or health problems. Talk with a healthcare provider for a diagnosis.

How is TB diagnosed?

TB infection is often diagnosed with a skin or blood test. In the skin test (called a PPD), a small amount of testing material is injected into the top layer of the skin. If a certain size bump develops within 2 or 3 days, the test may be positive for TB infection. A blood test called quantiferon may also be used. Other tests that may be key for diagnosing TB include X-rays and sputum tests.

TB skin or blood tests are suggested for people:

  • In high-risk categories

  • Who live or work in close contact with people who are at high risk

  • Who have never had a TB skin or blood test

In children, the American Academy of Pediatrics recommends testing:

  • If the child may have been exposed in the last 5 years

  • If the child has an X-ray that looks like TB

  • If the child has any TB symptoms

  • If the child comes from a country where TB is common

  • For children living with HIV

  • For children receiving medicines that suppress the immune system

  • For children who are in detention facilities

  • For children who are exposed to high-risk people

  • If the child's parent has come from a high-risk country

  • If the child has traveled to high-risk areas

  • If the child lives in a densely populated area

How is TB treated?

Treatment may vary depending on if you have latent or active TB. Treatment may include:

  • Short-term hospital stay.

  • For latent TB. Often a 3- to 9-month course of 1 or 2 antibiotics will be given to kill off the TB organisms in the body. The most common antibiotics prescribed are isoniazid, rifapentine, and rifampin. Your healthcare provider can review the treatment options. They may recommend one as the best option for you, taking into account many factors.

  • For active TB. Your healthcare provider may prescribe 2 to 4 or more antibiotics in combination for 6 to 9 months or longer. Examples include: isoniazid, rifampin, pyrazinamide, and ethambutol. People often begin to improve within a few weeks of starting treatment. After several weeks of treatment with the correct medicines, the person is often no longer contagious. But medicine must be finished for the greatest chance of cure, as prescribed by a healthcare provider.

What are possible complications of TB?

If TB of the lung is not treated early or if treatment isn’t followed, long-lasting (permanent) lung damage can result. TB can also cause infection of the bones, spine, brain and spinal cord, lymph glands, and other parts of the body. It can damage those areas and cause short-term (temporary) or permanent symptoms from the damage. Uncontrolled TB can lead to death. And TB remains one of the leading infectious causes of death worldwide.

What can I do to prevent TB?

If you will be spending time with anyone with active TB, wear a strongly filtering face mask. And try not to stay in a small enclosed space with poor ventilation. People who work in situations where there is a high risk for contact with people infected with TB should be tested for TB on a routine basis. This includes healthcare and shelter workers. In countries outside the U.S. where TB is more common, a childhood vaccine is often given. But it's not clear how well it works.

When should I call my healthcare provider?

Let your healthcare provider know if your symptoms get worse or you get new symptoms.

Key points about tuberculosis

  • Tuberculosis is a bacterial infection that often infects the lungs.

  • It may also affect the bones, spine, brain, lymph glands and other parts of the body.

  • Being infected with the TB bacteria is not the same as having active tuberculosis disease.

  • There are 3 stages of TB: exposure, latent, and active disease.

  • A TB skin test or a TB blood test can often diagnose the infection. But other testing is also often needed.

  • Treatment exactly as recommended is needed to cure the disease and prevent its spread to other people.

Next steps



  • Before your visit, write down questions you want answered.




  • Ask if your condition can be treated in other ways.





Online Medical Reviewer: Barry Zingman MD
Online Medical Reviewer: Marianne Fraser MSN RN
Online Medical Reviewer: Raymond Kent Turley BSN MSN RN
Date Last Reviewed: 11/1/2018
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