Tuberculosis Testing, Treatment and Prevention

Tuberculosis (TB) has been one of the deadliest diseases in the world for centuries. People of all ages, nationalities and income levels can get TB.

Most people do not know they have TB until they become sick. If you are at a high risk for TB, you should get tested. Since TB’s worst enemy is a strong immune system, people with HIV or another disease that weakens the immune system should get tested for TB regularly.

With proper care and treatment, TB can be cured and prevented from spreading.

Active and Latent TB

Most people who breathe in TB germs do not get sick. When a person's immune system is strong, it builds walls around the germs, called tubercles. The tubercles stop TB from spreading and hurting the body. This is called “TB infection”, or latent (sleeping) TB.

As long as their immune system stays strong, people with TB infection do not feel sick and will not spread TB to others. However, if their immune system becomes weak, people with TB infection can become sick, as the TB germs wake up and begin to spread. This is called “active TB”.

If you have TB infection, your health care provider will tell you if you should take medicine to avoid active TB.


Ask your doctor or other health care provider for a TB test. You can go to your own provider, or visit a Health Department TB Clinic Chest Center for free.

There are two tests for TB: a skin test and a blood test. Your health care provider will talk to you about the tests and choose the right one for you.

The Skin Test

When you get a TB skin test, your doctor or other health care provider will use a small needle to put a few drops of test solution under your skin. You will be asked to return after two to three days for the results.

The Blood Test

When you get a TB blood test, your health care provider will collect a small sample of your blood. The blood sample will be sent to a laboratory and tested for TB. Your provider will give you the test results in two to three days.


A negative test result usually means you do not have TB germs in your body. The test may not work if the TB germs are new in your body, or if your immune system is weak (for example, if you have HIV). In this case, you may need a chest X-ray.

A positive test result usually means you have TB germs in your body, but you may have active TB (ie, feel symptoms or be contagious). Your health care provider will use other tests, such as a chest X-ray or sputum cultures (a test on mucus coughed up from your lungs), to look for signs of active TB.


When a person cannot fight TB germs, they become sick. The TB germs multiply and do a lot of damage to the body. This is called “active TB”. People with active TB usually show the following symptoms:

  • Coughing for more than three weeks
  • Weight loss
  • Heavy sweating at night
  • Fever
  • Feeling tired all the time
  • Chills
  • Loss of appetite

People with active TB must take medicine to kill the germs and prevent damage to the lungs and other parts of the body, including the brain, spine and kidneys. Until someone with active TB in their lungs is treated, they can spread the disease to others when they speak, cough or sneeze.


If a person with active TB does not take medicine, they will remain sick and may die.

Not everyone with TB infection needs to take medicine. People with TB infection who are more likely to get sick usually take medicine to kill TB germs and prevent active TB. These people include those who have a high risk for developing active TB, as well as people who:

  • Had a TB test result changed from negative to positive within the past two years.
  • Have recently spent a long time around someone who has active TB.
  • Have recently immigrated to the US from countries with a high rate of TB.

TB medicine has to be taken for several months to work. People with active TB feel better quickly once they start taking medicine. The TB germs may come back if a person does not take their medicine long enough. If this happens, the TB germs may be stronger and much harder to kill.

If you have active TB, your health care provider will tell you what medicines you need to take, and how long to take them. You will have to take TB medicine until you are cured — usually four to nine months.

People who have trouble remembering to take their TB medicine daily can get help through directly observed therapy at a Health Department TB Clinic. This free program provides a health care worker to remind you to take your medicine every day.

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