What You Need to Know About Tuberculosis

Tuberculosis (TB) is a disease caused by germs that are spread from 

person to person through the air. TB usually affects the lungs, but it

can also affect other parts of the body, such as the brain, the kidneys,

or the spine.

Not everyone infected with TB germs becomes sick. As a result, 

two TB-related conditions exist: latent TB infection (or inactive TB) 

and TB disease. If not treated properly, TB disease can be fatal.

The Difference Between Inactive TB and Active TB Disease

A Person With Inactive TB

• Has a small amount of TB germs in their

body that are alive but inactive.

• Has no symptoms and does not feel sick. 

• Cannot spread TB germs to others.

• Usually has a positive TB blood test or TB

skin test indicating TB infection.

• Has a normal chest x-ray and a negative

sputum smear.

• Needs treatment for inactive TB to prevent

active TB disease.

A Person With Active TB Disease

• Has a large amount of active TB germs

in their body.

• Has symptoms and feels sick.

• May spread TB germs to others.

• Usually has a positive TB blood test or

TB skin test indicating TB infection.

• May have an abnormal chest x-ray, or

positive sputum smear or culture.

• Needs treatment for active TB disease.

If your body cannot stop TB germs from growing, you develop 

active TB disease. Symptoms of active TB disease include:

A cough that 

lasts 3 weeks 

or longer

Coughing 

up blood or 

sputum

Weakness 

or fatigue

Chest pain Fever Chills

Night sweats Loss of appetite Weight loss

U.S. Department of

Health and Human Services

Centers for Disease 

Control and Prevention

301332 | October 2023
TB Can Be Treated

Testing for TB

Getting tested and treated for TB can protect yourself, your family and friends, 

and your community. There are two types of tests for TB infection: the TB blood test

and the TB skin test.

A Positive Test For TB Infection

You have TB germs in your body. Your 

doctor will do other tests to determine if you 

have inactive TB or active TB disease. These 

tests may include a chest x-ray, and a test of 

the sputum you cough up.

A Negative Test For TB Infection

A negative test means you likely do not have 

inactive TB or active TB disease.

Your doctor may do more tests if:

• You have symptoms of active TB disease,

like coughing, chest pain, fever, weight

loss, or tiredness.

• You have HIV infection.

• Your exposure to TB germs was recent.

Tell Your Doctor if You Received a TB Vaccine

TB blood tests are the preferred test for people who have received the bacille 

Calmette-Guérin (BCG) TB vaccine. Unlike the TB skin test, TB blood tests are not 

affected by BCG vaccination.

Many people born outside of the United States have received the BCG TB vaccine. 

BCG vaccination does not completely prevent people from getting TB. A positive reaction

to a TB skin test may be due to the BCG vaccine itself or due to infection with TB germs. 

TB germs can live in your body for years without 

causing symptoms. If you have inactive TB, 

treating it is the best way to protect you from 

getting sick with active TB disease.

If you have been diagnosed with active TB disease, 

you can be treated with medicine. You will need to 

take and finish all of your TB medicine as directed 

by your doctor or nurse. This is to help you feel 

better and prevent other people from getting sick.

The best way to remember to take your medicines for active TB disease is by receiving directly observed 

therapy (DOT). Through DOT, you will meet with a health care worker every day or several times a week 

either in-person or virtually. The health care worker will make sure that the TB medicines are working as 

they should. 

BCG

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