What is tuberculosis?
How is TB spread?
What is TB infection?
What is TB disease?
How can I get tested for TB?
If I have TB infection, how can I keep from developing TB disease?
How can I keep from spreading TB?

What is Tuberculosis?

TB, or tuberculosis, is a disease caused by bacteria called Mycobacterium tuberculosis.  The bacteria can attack any part of your body, but they usually attack the lungs.  TB disease was once the leading cause of death in the United States. In the 1940s, scientists discovered the first of several drugs now used to treat TB.  As a result, TB slowly began to disappear in the United States.  But TB has come back worldwide.  

TB is spread through the air from one person to another.  The bacteria are put into the air when a person with TB disease of the lungs or throat coughs or sneezes.  People nearby may breathe in these bacteria and become infected. 

People who are infected with latent TB do not feel sick, do not have any symptoms, and cannot spread TB.  But they may develop TB disease at some time in the future.  People with TB disease can be treated and cured if they seek medical help, although treatment may be long.  Even better, today people who have TB infection but are not yet sick can take medicine so that they will never develop TB disease.

How is TB spread?

TB is spread through the air from one person to another.  The bacteria are put into the air when a person with TB disease of the lungs or throat coughs or sneezes.  People nearby may breathe in these bacteria and become infected. 

When a person breathes in TB bacteria, the bacteria can settle in the lungs and begin to grow.  From there, they move through the blood to other parts of the body, such as the kidney, spine, and brain.

TB in the lungs or throat can be infectious.  This means that the bacteria can be spread to other people through the air.  TB in other parts of the body, such as the kidney or spine, is usually not infectious.  

People with TB disease are most likely to spread it to people with whom they regularly spend time, stay within a closed space, or who have a weakened immune system. 

What is TB Infection?

In most people who breathe in TB bacteria and become infected, the body is able to fight the bacteria to stop them from growing.  The bacteria are walled off and become inactive, but they remain alive in the body and can become active later.  This is called TB infection.  Many people who have TB infection never develop TB disease. People with TB infection:  

  • Have no symptoms
  • Don’t feel sick
  • Can't spread TB to others
  • Usually have a positive skin test reaction

Can develop TB disease later in life if they do not receive preventive therapy

What is TB Disease?

TB bacteria become active if the immune system can’t stop them from growing.  The active bacteria begin to multiply in the body and cause TB disease.  Some people develop TB disease soon after becoming infected before their immune system can fight the TB bacteria.  Other people may become sick later, especially people with any of these conditions:

  • AIDS
  • History of substance abuse
  • Diabetes Mellitus
  • Silicosis
  • Cancer of the head or neck
  • Leukemia or Hodgkin's disease
  • Severe kidney disease
  • Low body weight
  • Certain medical treatments (such as corticosteroid, treatment, or organ transplant)

Symptoms of TB depend on where in the body the TB bacteria are growing.  TB bacteria usually grow in the lungs.  TB in the lungs may cause:

  • A bad cough that persists longer than two weeks
  • Chest pain
  • Coughing up blood or sputum (phlegm from deep inside the lungs)

Other symptoms of TB disease are:

  • Weakness or fatigue
  • Weight loss
  • No appetite
  • Chills
  • Fever
  • Night sweats

How can I get tested for TB?

A TB skin test is the only way to find out if you have TB infection.  Obtain a skin test at the local health department or your doctor’s office.  You need to be tested for TB if: 

  • You have spent time with a person with infectious TB
  • You have HIV infection or another high-risk condition
  • You are from a country where TB disease is very common (most countries in Latin America, the Caribbean, Africa, and Asia (except for Japan)
  • You inject drugs
  • You live somewhere in the United States where TB disease is common, (homeless shelters, migrant farm camps, jails/prisons, some nursing homes, etc.)

A TB skin test requires the injection of a small amount of testing fluid (called tuberculin) just under the skin on the lower part of your arm.  After 2 or 3 days, you will need to return for the site to be tested.  You may have a small bump where the tuberculin was injected.  The healthcare worker will tell you if your reaction to the test is positive or negative.  A positive reaction may mean that you have TB infection. 

If you have a positive reaction to the skin test, your doctor or nurse may do other tests to see if you have TB disease.  These tests usually include a chest x-ray and a test of the phlegm you cough up.  Because the TB bacteria may be found somewhere besides your lungs, your doctor or nurse may check your blood or urine or do other tests.  If you have TB disease, you will need to take medicine to cure the disease. 

If you have recently spent time with someone with infectious TB, your skin test reaction may not be positive yet.  You may need a second skin test 10 to 12 weeks after the last time you spent time with the infectious person.  This is because it can take several weeks after infection for your immune system to be able to react to the TB skin test.  If your reaction to the second test is negative, you probably do not have TB infection.

If I have TB infection, how can I keep from developing TB disease?

Many people who have TB infection never develop TB disease.  But some people who have TB infection are more likely to develop TB disease than others.  These people are at high risk for TB disease.  They include: 

  • People with HIV infection
  • People in close contact with a person who has infectious TB
  • People who became infected with TB bacteria in the last two years
  • Babies and young children
  • People who inject drugs
  • People sick with other diseases that weaken the immune system
  • The elderly

If you have TB infection (a positive skin test reaction) and you are in one of these high-risk groups, you may need to take medicine to keep from developing TB disease.  This kind of treatment is called Preventive Therapy.  Also, if you are younger than 35 and you have TB infection, you may benefit from preventive therapy even if you are not in a high-risk group. 

People who have TB infection but do not receive preventive therapy need to know the symptoms of TB.  If symptoms of TB disease develop later on, see a doctor right away. 

The medicine usually used for preventive therapy is a drug called isoniazid or INH.  INH kills the inactive TB bacteria in the body.  If you take your medicine as prescribed, preventative therapy will keep you from ever developing TB disease from this infection. 

Most people must take INH for at least 6 months.  Children and people with HIV infection may need to take INH for a longer time. 

Sometimes people are given preventive therapy even if their skin test reaction is not positive.  This is often done with infants, children, and HIV-infected people who have recently spent time with someone with infectious TB disease.  This is because they are at a very high risk of developing serious TB disease soon after they become infected with TB bacteria. 

It is important that you take all the pills prescribed for you so that your preventive therapy is effective.  If you start taking INH, you will need to see your doctor or nurse on a regular schedule.  Very few people have serious side effects from INH.  However, if you have any of the following side effects, call your doctor or your nurse promptly: 

  • No appetite
  • Nausea
  • Vomiting
  • Yellowish skin or eyes
  • Fever for more than three days
  • Abdominal pain
  • Tingling in the fingers and toes.

All drugs to treat TB are available without charge to the patient through the DSHS TB Elimination Division.

How can I keep from spreading TB?

The most important way to keep from spreading TB is to take all your medicine, exactly as told by your doctor or nurse, and keep all of your clinic appointments!  Your doctor or nurse needs to see how you are doing.  You may need another chest x-ray or a test of the phlegm you may cough up.  These tests will show whether the medicine is working.  They will also show whether you can still give TB bacteria to others.  Be sure to tell the doctor about anything you think is wrong. 

If you are sick enough with TB to go to a hospital, you may be put in a special room.  These rooms use air vents that keep TB bacteria from spreading.  People who work in these rooms must wear a special face mask to protect themselves from TB bacteria.  You must stay in the room so that you will not spread TB bacteria to other people.  Ask a nurse if you need anything that is not in your room.  If you are infectious while you are at home, there are certain things you can do to protect yourself and others near you.  Your doctor or local health department professional may tell you to follow these guidelines to protect yourself and others: 

  • The most important thing is to take your medicine.
  • Always cover your mouth with a tissue when you cough, sneeze or laugh.  Put the tissue in a closed paper sack and throw it away.
  • Do not go to work or school.  Separate yourself from others and avoid close contact with anyone.  Sleep in a bedroom away from other family members.
  • Air out your room often (if it is not too cold outside).  TB spreads in small, closed spaces where air doesn't circulate.  Put a fan in your window to blow out (exhaust) air that may be filled with TB bacteria.  If you open other windows in the room, the fan also will pull in fresh air.  This will reduce the chances that TB bacteria stay in the room and infect someone who breathes the air.

Remember that TB is spread through the air.  People cannot get infected with TB bacteria through handshakes, sitting on toilet seats, or sharing dishes and utensils with someone who has TB. 

After you take medicine for about 2 or 3 weeks, you may no longer be able to spread TB bacteria to others.  If your doctor or nurse agrees, you will be able to go back to your daily routine.  Remember that you will get well only if you take your medicine exactly as your doctor or nurse tells you.






Mailing Address

Texas Center for Infectious Disease
2303 SE Military Drive
San Antonio, TX 78223
United States