Latent tuberculosis (LTB) happens when you have a tuberculosis (TB) infection without symptoms. LTB isn’t contagious, but it can progress to TB disease, which is infectious.

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LTB affects billions of people worldwide. It’s different from TB disease because it’s the inactive form of the infection. LTB infections aren’t contagious and don’t cause symptoms.

LTB infections can develop into TB disease, which is the active form of the infection. People with TB disease have symptoms and can pass the infection to others when they cough or talk.

This article explores LTB, including its causes, risk factors, and how doctors diagnose and treat it. This article also discusses prevention strategies to reduce the risk of LTB developing into TB disease.

LTB happens when you have TB bacteria (Mycobacterium tuberculosis) in your body, but you don’t have symptoms of an infection.

According to the Centers for Disease Control and Prevention (CDC), about 13 million people in the United States have LTB.

Is latent tuberculosis contagious?

No, LTB isn’t contagious. If you have LTB, you can’t pass it on to other people.

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If you have LTB, the bacteria remain “asleep” in your body, causing no harm. Because the bacteria are inactive, you can’t pass LTB on to other people.

But without treatment, LTB can develop into active TB disease. TB disease is a serious illness that can be life threatening. You can pass TB disease on to others when you cough, sneeze, or talk.

The short answer is no. If you have LTB, you won’t experience symptoms. LTB won’t make you feel sick like the active form of the disease.

But if your condition develops into active TB disease, you’ll have symptoms, such as:

LTB results from bacteria called Mycobacterium tuberculosis. You can get LTB when you’re near someone with active TB disease.

The most common way to get LTB is by inhaling droplets from the air that contain the bacteria. This can happen when someone with active TB coughs, sneezes, or speaks near you.

When you inhale TB bacteria, the bacteria might:

  • clear out of your body, and you won’t develop the infection
  • settle in your lungs (or someplace else) but remain inactive
  • grow out of control, causing an active infection

The primary risk factors for LTB involve close physical contact with someone with active TB disease. You may be more at risk of TB if you:

  • live in areas with high rates of active TB disease
  • have HIV
  • inject illegal drugs
  • work in areas with high TB rates
  • reside in close quarters, like hospitals, prisons, and refugee camps

You may also have a higher risk if you have chronic renal failure requiring hemodialysis or silicosis.

Other risk factors include:

There are two ways to test for LTB.

The first is a skin test called the tuberculin skin test. During this test, a nurse will inject a small amount of fluid containing proteins from the TB bacteria into your arm. After 48–72 hours, a doctor will check the injection site for swelling or discoloration, which can indicate a positive result.

The second is an interferon gamma release assay (IGRA) test. IGRA is a blood test that may work better than a skin test if you have diabetes. But it may be less accurate if you have a weakened immune system.

Will I get tuberculosis disease if I have latent tuberculosis?

About 5–10% of people with LTB who don’t receive treatment will develop active TB disease.

Limiting your risk factors and getting treatment as soon as possible is the best way to reduce your chance of getting active TB.

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Because of this, your doctor may need to perform other tests to confirm your diagnosis. This may involve a chest X-ray and a negative sputum smear test.

If you have LTB, your smear test will be negative, and your chest X-ray will show typical results. If you have active TB, your X-ray will show atypical results, and your smear test will show positive results.

According to the CDC, there are several treatment options for LTB. These include the following:

  • isoniazid (INH)
  • rifapentine (RPT)
  • rifampin (RIF)

Your doctor may prescribe one or more of these medications. The CDC recommends one of three treatment protocols, including taking:

  • INH and RPT once a week for 3 months
  • RIF daily for 4 months
  • INH and RIF daily for 3 months

It’s essential to take all medications as your doctor prescribes and finish the entire course of treatment. This’ll help ensure the infection won’t return or progress into active TB.

Does latent tuberculosis go away?

LTB is treatable with medication. Treatment for LTB usually involves taking one or more drugs for several months. This can clear out the bacteria and prevent the infection from progressing to active TB disease.

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The best way to prevent TB is by avoiding exposure to someone with active TB disease. If you’ve been in close physical contact with someone with active TB, get tested as soon as possible. Treating the infection in its latent form is much easier than treating TB disease.

HIV is one of the primary risk factors for LTB because it can make it harder for your body to clear out the TB bacteria. You may want to take extra precautions to prevent HIV when you’re in an area with a high TB rate. This may include:

  • using condoms or other barrier methods
  • taking medication to prevent HIV (preexposure prophylaxis, or PrEP)
  • getting regular testing for sexually transmitted infections

Keeping your immune system healthy can also help reduce your risk of developing TB. Eating nutrient-rich foods, exercising regularly, and getting enough sleep are all important for maintaining a healthy immune system.

LTB is an inactive TB infection. At this stage, the infection has no symptoms, and you can’t pass it on to others. You can go on to develop TB disease, which is contagious and involves symptoms.

The best way to prevent LTB from becoming TB is to take the necessary medication to clear the bacteria. You may also want to reduce your risk of getting TB by using a barrier method during sex and maintaining a healthy immune system.