Sign In
Boston Public Health Commission Home

Tuberculosis

What is TB?

“TB” is a short name for a disease called tuberculosis and it is spread by tiny germs that can float in the air.  When a person with TB disease coughs, sneezes or shouts they can spray these germs into the air.  If another person breathes in these germs, they can get tuberculosis (TB).  TB can make you feel tired, have a cough, fever and night sweats.  Most people think that TB can only affect your lungs.  Even though 70% of those infected with TB have the germs in their lungs, TB can also infect other places in the body such as the bone, brain or heart.  

Some people may have the TB germ in their body, but do not feel sick.  This is called latent “sleeping” TB infection.  Others feel sick, and they have active TB disease. 

Symptoms that can occur in the body when TB becomes active include:

Body LocationSymptoms​
lungs​cough, increased sputum (phlegm), coughing blood​
glands of the neck​lumps in the neck​
bones​pain in the bones or back​
brainheadache, pain when moving head, stiff neck, fever​
 

Click here to learn more about active vs. latent TB.

How do I know if I am infected with TB?

A simple test on your arm (TB skin test) can tell if you have the TB germ in your body.  A blood test is also sometimes used to see if a person has the TB germ in their body. You may need additional tests such as a chest x-ray or sputum (phlegm) test.  

What is the difference between “sleeping” TB and “Active (awake)” TB?

Latent Tuberculosis Infection (LTBI) is also called “sleeping” TB because the germs will stay asleep as long as your body can fight them off. You may have a positive test for TB but no signs that the germ is awake. You cannot spread "sleeping" TB to others. If you take TB medications, there is less chance the germs will wake up. 

Active (awake) TB germs cause disease in the lungs or other parts of the body and you feel very sick.  You could give TB to others by coughing, sneezing or shouting and transferring the germs in the air that others breathe in.

What if I have TB?

You can take medication to stay healthy.  TB can be cured!  But if you do not take the medication, TB can make you feel very sick.  Even if you feel better after you begin taking the medication, do not stop taking the pills until your doctor or nurse tells you to stop.  If you stop taking the medication too soon, the TB germ can come back and be very hard to fight off. People with active TB work very closely with health care providers to make sure they get the right treatment and feel better.

What is the  TB skin test?

The TB skin test is when a small amount of fluid is injected just under the skin on your forearm.  It makes a small bubble disappears in about 5-10 minutes.  It is very important to go back to your doctor or nurse in 2-3 days (48-72 hours) after the injection so they can look at your arm and determine if it is a positive or negative skin test. If it is not read in this time frame, the test will need to be repeated.

How do I take care of my arm after the test?

  • Do not cover the spot with a band-aid or tape.
  • Do not rub or scratch the area.

What if I have a negative TB skin test?

In most cases, if there is no bump where the testing fluid was placed, you probably are not infected with TB. A doctor or nurse must look at the area to be sure. 

What if I have a positive TB test?

A positive test will look like a raised bump on your arm where the test was placed.  This means that you probably have the TB germ in your body. A doctor or nurse must look at the area to measure the size. The doctor may want to do other tests to see where the TB germ is in the body. 

What if I had the BCG vaccine?

Even if you had the BCG vaccine, you can have a TB skin test.
  •  People who have had the BCG vaccine can still become infected with the TB germ.

If you know you have the TB germ, you can take medication to fight off the germ and stay healthy. 

It is important for a doctor or nurse to see your skin test 48-72 hours after it is placed.

What is Bacillus Calmette-Guerin (BCG)?

BCG is a vaccine given to protect people against tuberculosis (TB).  BCG is NOT used in the United States.  It is usually given in parts of the world where TB is common.  The BCG vaccine cannot “give you tuberculosis (TB).”

Why was I given BCG?

In countries where TB is very common BCG is usually given to infants and very young children to try to keep them from getting very sick with TB.  It does not protect adults.

Does BCG work?

There are many different BCG vaccines used around the world. Some offer a small amount of protection against tuberculosis (TB) in the brain in young children.  It is unlikely to offer protection many years after it is given. But some BCG vaccines do not give any protection at all.   

How long does BCG vaccine last?

If the BCG vaccine works at all, it will usually only protect a person for a few years.  

If I had BCG can I still get a TB skin test?

Yes.  The TB skin test can detect the tuberculosis (TB) germ inside your body.  If you have the TB germ inside your body, the test will be positive.

Will the BCG vaccine cause me to have a positive TB skin test?

If you were given BCG many years ago, a positive TB skin test now most likely means that you have the TB germ in your body. 

Does a positive TB skin test mean that the BCG is working? 

No. A positive TB skin test means that you most likely have the TB germ inside your body.

If you have the tuberculosis (TB) germ in your body, you can take medication now to stay healthy.   
OnlineNewsRoomStyles
Boston Public Health Commission
1010 Massachusetts Ave, 6th Floor, Boston, MA 02118.
Phone:(617) 534-5395 Email: info@bphc.org