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Understanding TB and the TB Test

The Relationship of HIV and TB


Updated June 27, 2014

You now know that active tuberculosis affects those with weakened immune systems, specifically people with HIV. Let's explore the relationship between HIV and tuberculosis.

Am I at Greater Risk for TB Because I Have HIV?

Latent TB is much more likely to become active TB in someone with HIV. This is because HIV weakens the immune system, which makes it harder for the body to fight off diseases like TB. A weakened immune system allows TB to reproduce unchecked within the body, causing illness. In HIV infected people, TB infection of the lungs or anywhere else in the body is considered an AIDS-defining condition. In other words, a person with both HIV and active TB has AIDS.

A List of the AIDS Defining Illnesses

I'm HIV+. Should I Be Tested for TB?

Yes, particularly if you think you've been exposed to someone with TB. You should only be tested with the PPD injection skin test. A TB scratch test has not been proven to be as reliable as the PPD. A PPD involves injecting a small amount of testing fluid (called tuberculin) just under the skin of your inner forearm. After two to three days, you return to your healthcare professional to have the injection site evaluated.

The test is considered "positive for TB infection" if injection site is red, raised, itching and is swollen at least five millimeters in diameter. A hard lump will also be felt beneath the skin.

Care After Your TB Test

Positive Test - If you have a positive test result it usually means you have latent TB. You will need other tests to make sure you do not have active TB. These tests may include
  • A chest x-ray
  • A culture of the sputum produced by your cough, if you have one
  • Direct visualization (a "bronchoscopy") of your airway, including your bronchial tubes and lungs to rule out any other infections such as candida ("thrush") or PCP pneumonia

Negative Test - If your TB test is negative, you should be tested again at least once a year, depending on your risk of TB exposure. Discuss your TB risks with your doctor.

HIV Positive Mother - If you are an HIV positive mother whose baby was born after you got HIV, have your baby tested for TB when the baby is between nine and 12 months old.

Can TB Be Treated in HIV+ People?

Active TB - The medications that treat TB work as well as in people with HIV as they do in people who do not have HIV. Several medications are used to treat active TB. You will need to take more than one drug for several weeks. Your symptoms may go away within a few weeks after you start taking the medicine. TB bacteria die very slowly, so you will need to keep taking your medicine exactly as your doctor prescribes for as long as he prescribes.

Latent TB - If you are diagnosed with latent TB, you will still need treatment despite not having any symptoms or illness. The medications used to treat latent TB are the same as those used to treat active TB but the number of recommended medicines and doses differ. The goal of treating latent TB is to prevent the TB from becoming active later in the infected person's life. Latent TB is usually treated for a period of six to 12 months.

TB Medications - The medications used to treat active and latent TB include:

  • Isoniazid (INH)
  • Rifampin (RM)
  • Pyrazinamide (PZA)
  • Ethambutol (EMB)
  • Pyridoxine (Vitamin B6) - used to replace Vitamin B6 lost as a result of taking TB medications

Can I Take HIV Medications and TB Medications at the Same Time?

HIV and TB medications can often be taken at the same time, but there are some potential side effects and interactions that have to be considered depending on what medications you are on. In addition, HIV and TB medications can put considerable stress on the liver, so liver function must be monitored closely. Your doctor will decide which combination of medicines will work best for you.

Measuring Liver Function

HIV Medication Side Effects

Tuberculosis Information Brochures provided by the Centers for Disease Control, 2007.

MMWR Morb Mortal Wkly Rep. 2007 Mar 23; 56 (11): 245-50.

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