Patient Information: Childhood Illnesses

What You Should Know About

Tuberculosis

Tuberculosis (TB) is an infection caused by a bacterium known as Mycobacterium tuberculosis. TB affects mainly the lungs, although other parts of the body may be affected as well. The infection is contagious, and bacteria can spread from person to person in the air. Usually, someone with the active disease coughs the bacteria into the air, where someone else inhales it.

Most people who inhale the TB bacteria don't develop active TB and can't transmit the bacteria to other people. They simply become carriers of the infection. Of the 10% or so who do develop active disease, most have low resistance or substantial exposure that overcomes the body's normal defenses.

Diagnosing TB

To diagnose TB, your doctor will consider your symptoms, the proximity of possible exposure to the start of your symptoms, and the results of a tuberculin skin test, a chest X-ray, and a sputum test.

Symptoms

Active TB causes a number of symptoms, including prolonged coughing, blood in the sputum, repeated night sweats, unexplained weight loss, loss of appetite, fever, chills, and malaise. Because these problems also can be caused by other diseases, your doctor will recommend that you undergo one or more tests to confirm TB.

TB test

In a TB test, a small drop of liquid is injected into the skin of your forearm. The liquid contains killed TB bacteria. If you have TB, your body will react to the liquid and form a red welt at the site of the test. A trained health care provider, usually a doctor or nurse, will look at the test site after 48 to 72 and determine whether the reaction indicates a positive test result. If so, then you probably have a TB infection. This doesn't necessarily mean you have active TB, however. To determine that, you'll need to have a chest X-ray.

Chest X-ray

If you've been infected with the TB bacteria but you haven't developed the active form of the disease (as is the case for most people), your chest X-ray most likely will be normal. You'll probably continue to be healthy with no symptoms of TB, although your doctor may want you to take medication to help make sure you don't get the active form of the disease.

If the TB infection has caused inflammation in your lungs, an abnormal shadow probably will appear on your chest X-ray. If that happens, then your doctor will want you to have a sputum test and most likely will start you on treatment.

Sputum Test

In a sputum test, laboratory staff examine mucus from your lungs to see if it contains TB organisms. If so, they'll culture those organisms to see which TB medications will make the most effective treatment for you.

Keep in mind that sputum is different from spit. To get a sputum sample, you'll need to cough up some mucus (or phlegm) from your lungs. This may be easiest when you first wake up. If you have trouble coughing up mucus, your doctor may have you breathe some very humid air to help loosen mucus deposits. It may also help to take two or three deep breaths before trying to cough up your sample.

Treatment and Tips

Even if you have a positive TB test, you may need no treatment for TB. If you've recently been in close contact with someone who has active disease, however, your doctor may want to treat you to help reduce your risk of developing active disease. You may need to take a medication called isoniazid (INH) for 6 to 9 months as a preventive measure (12 months if you're HIV positive).

If you have active TB, you may need some initial treatment in a hospital to get the disease under control. Then you'll probably be able to receive the rest of your treatment at home. If you have a typical TB infection, your doctor will prescribe two to four medications that you'll need to take for 6 to 9 months, possibly longer. The medications may include isoniazid, rifampin, pyrazinamide, ethambutol, streptomycin, and rifapentine. One potential advantage of rifapentine is that it can be taken less often in the final 4 months of treatment?once weekly compared with twice weekly for the standard regimen.

Since active TB is slow to respond completely to therapy, it's crucially important that you take your prescribed medications faithfully and for as long as your doctor prescribes. If you don't, the bacteria could become resistant to the drugs you're taking, you could have toxic reactions to the medications, or the infectious, active form of TB may recur.

Given the many effective medications available today, the chances are excellent that your TB can be cured. It is important, however, that you understand the disease and cooperate fully in your treatment program.

Where to Get More Information

• American Lung Association
• The Centers for Disease Control and Prevention
• An interactive site for professionals and the public
• The National Institute of Allergy and Infectious Disease,
  a branch of the National Institutes of Health
• Medical Societies