(Updated February 2007)
Tuberculosis (often called TB) is an infectious disease that usually attacks the lungs but can attack almost any part of the body. Tuberculosis is spread from person to person through the air.
When people with TB in their lungs or throat cough, laugh, sneeze, sing, or even talk, the germs that cause TB may be spread into the air. If another person breathes in these germs, there is a chance that he or she will become infected with tuberculosis. Repeated contact is usually required for infection.
It is important to understand that there is a difference between being infected with TB and having TB disease. Someone who is infected with TB has the TB germs, or bacteria, in his or her body. The body’s defenses are protecting that person from the germs, and he or she is not sick. This is referred to as latent TB.
Someone with TB disease is sick and can spread the disease to other people. A person with TB disease needs to see a doctor as soon as possible. This is referred to as active TB.
It is not easy to become infected with tuberculosis. Usually a person has to be close to someone with TB disease for a long period of time. TB is usually spread between family members, close friends, and people who work or live together. TB is spread most easily in closed spaces over a long period of time. However, transmission in an airplane, although rare, has been documented.
Even if someone becomes infected with tuberculosis, that does not mean he or she will get TB disease. Most people who become infected do not develop TB disease because their body’s defenses protect them. Most active cases of TB disease result from activating old infection in people with impaired immune systems.
Experts believe that about 10 million Americans are infected with TB germs. Only about 10 percent of these people will develop TB disease in their lifetime. The other 90 percent will never get sick from the TB germs or be able to spread them to other people.
TB is an increasing and major worldwide problem, especially in Africa, where the spread has been facilitated by AIDS. It is estimated that nearly 1 billion people will become newly infected, more than 150 million will become sick, and 36 million will die worldwide between now and 2020—if control is not further strengthened. Each year there are more than 9 million cases and close to 2 million deaths attributed to TB; 100,000 of those 2 million deaths occur among children.
Anyone can get TB. However, some groups are at higher risk to get active TB disease. The groups that are at high risk include the following:
A person with TB infection will have no symptoms. A person with TB disease may have any, all, or none of the following symptoms:
These symptoms can also occur with other diseases, so it is important to see a doctor and let the doctor determine if you have TB.
It is also important to remember that a person with TB disease may feel perfectly healthy or may have a cough only from time to time. If you think you have been exposed to TB, get a TB skin test.
There are two possible ways a person can become sick with TB disease:
The TB skin test is a way to find out if a person has TB infection. Although there is more than one TB skin test, the preferred method of testing is to use the Mantoux test.
For this test, a small amount of testing material is placed just below the top layers of skin, usually on the arm. Two to three days later, a health-care worker checks the arm to see if a bump has developed and measures the size of the bump. The significance of the size of the bump is determined in conjunction with risk factors for TB.
Once the doctor knows that a person has TB infection, he or she will want to determine if the person has TB disease. This is done by using several other tests including a chest X-ray and a test of a person’s mucus (the material that is sometimes coughed up from the lungs).
Only if you are at high risk for getting or transmitting TB or your jobs request it.
The advice for most people is to get a tuberculin test if you have symptoms or if you are living in close contact or have otherwise been in close contact with someone who recently came down with active TB disease. (Some people get skin tests because of their jobs, in a school or hospital, for example, to make sure they have not contracted TB and will not infect others if they have TB).
If you fall into one or more of the high-risk categories for TB noted earlier—for example, if you are HIV positive, you have never had a skin test before, or there is no record of the last result—you should be tested.
If you’re not sure, ask your doctor. TB can be prevented, even if you are at risk.
Treatment for TB depends on whether a person has active TB disease or only TB infection.
A person who has become infected with TB but does not have active TB disease may be given preventive therapy. Preventive therapy aims to kill germs that are not doing any damage right now, but could do so in the future.
If a doctor decides a person should receive preventive therapy, the usual prescription is a daily dose of isoniazid (also called INH), an inexpensive TB medicine. The person takes INH for nine months (up to a year for some patients), with periodic checkups to make sure the medicine is being taken as prescribed.
Then treatment is needed. Years ago a patient with TB disease was placed in a special hospital for months, maybe even years, and would often have surgery. Today, TB can be treated with very effective drugs.
Often the patient will have to stay only a short time in the hospital and can then continue taking medication at home. Sometimes the patient will not have to stay in the hospital at all. After a few weeks, a person can probably even return to normal activities and not have to worry about infecting others.
The patient usually gets a combination of several drugs (most frequently INH plus two to three others including rifampin, pyrazinamide, and ethambutol). The patient will probably begin to feel better only a few weeks after starting to take the drugs.
It is very important, however, that the patient continue to take the medicine correctly for the full length of treatment. If the medicine is taken incorrectly or stopped, the patient may become sick again and will be able to infect others with TB. As a result, public health authorities recommend Directly Observed Therapy (DOT), in which a health-care worker ensures that the patient takes his/her medicine.
If the medicine is taken incorrectly and the patient becomes sick with TB a second time, the TB may be harder to treat because it has become drug resistant. This means that the TB germs in the body are unaffected by some drugs used to treat TB.
Multidrug-resistant TB is very dangerous, so patients should be sure that they take all of their medicine correctly.
Regular checkups are needed to see how treatment is progressing. Sometimes the drugs used to treat TB can cause side effects. It is important both for people undergoing preventive therapy and people being treated for TB disease to immediately let a doctor know if they begin having any unusual symptoms.
Multidrug-resistant tuberculosis (called MDR-TB for short) is a very dangerous form of tuberculosis. Some TB germs become resistant to the effects of some TB drugs. This happens when TB disease is not properly treated.
These resistant germs can then cause TB disease. The TB disease they cause is much harder to treat because the drugs do not kill the germs. MDR-TB can be spread to others, just like regular TB.
It is important that patients with TB disease follow their doctor’s instructions for taking their TB medicine, so that they will not develop MDR-TB.
Yes, if the patient has TB disease and it is not being treated. Once treatment begins, a patient ordinarily quickly becomes noninfectious; that is, he or she cannot spread the disease to others.
There is little danger from the TB patient who is being treated, is taking his or her medication as scheduled, and is responding well. The drugs usually make the patient noninfectious within weeks.
TB is spread by germs in the air—germs put there by coughing or sneezing. Handling a patient’s bed sheets, books, furniture, or eating utensils does not spread infection.
Brief exposure to a source of TB rarely infects a person. It’s day-after-day, close contact that usually does it.
Certain people, such as those infected with HIV or health-care workers, should be tested regularly. You should be tested if there’s any chance you have been infected, recently or many years ago.
A negative reaction usually means that you are not infected and no treatment is needed. However, if you have TB symptoms, your doctor must continue to look for the cause. Sometimes, when a person has only recently been infected or when his or her immune system isn’t working properly, the test may be falsely negative.
A significant reaction usually means that you have been infected with the TB germ. It does not necessarily mean that you have TB disease. Cooperate with the doctor when he or she recommends a chest X-ray and possibly other tests.
If the doctor recommends treatment to prevent sickness, follow the recommendations. If medicine is prescribed, be sure to take it as directed.
If you don’t need treatment, do what the doctor tells you to do about follow-up. The doctor may simply say to return for another checkup if you get into a special risk situation for TB sickness or develop symptoms.
If you are sick with TB disease, follow the doctor’s recommendations for treatment.
—This information was taken from the American Lung Association website.
For more information about TB and TB infections, visit the American Lung Association website, the Centers for Disease Control and Prevention website, or the Department of Health and Human Services website.