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Tuberculosis Information

What is tuberculosis?

Tuberculosis (TB) is caused by a bacterium called Mycobacterium tuberculosis. TB bacteria usually attack the lungs, but can attack any part of the body such as the kidney, spine and brain. Not everyone infected with TB bacteria develops active disease and becomes sick. As a result, two TB-related conditions exist: latent TB infection (LTBI) and TB disease. If not treated properly, TB disease can be fatal.

How is tuberculosis spread?

People with active TB disease can pass infection to other people through the air. TB is not easily spread; it’s much harder to spread than a cold or the flu. It typically takes repeated and prolonged exposure in a confined indoor space to become infected with TB. People with latent TB infection can’t spread it to others and are not ill with the disease. Approximately 100,000 people in King County have latent TB infection. While they aren’t contagious now, they could potentially develop active TB in the future if the infection is not treated. Without treatment, approximately one in 10 people with latent TB infection will develop active TB in their lifetime. Most cases of active TB are readily treatable with antibiotics that are commonly available; treatment typically takes six to nine months.

Can tuberculosis be spread within a household?

People with TB disease are most likely to spread it to people they spend time with every day. This includes family members, friends, and coworkers or schoolmates. It is important to know that a person who is exposed to TB bacteria is not able to spread the bacteria to other people right away. Only people with active TB disease can spread TB bacteria to others.

What are the symptoms of tuberculosis?

Symptoms of TB disease depend on where in the body the TB bacteria are growing. TB bacteria usually grow in the lungs (pulmonary TB). TB disease in the lungs may cause symptoms such as:

  • A bad cough that lasts three weeks or longer
  • Pain in the chest
  • Coughing up blood or sputum (phlegm from deep inside the lungs)

Other symptoms of TB disease are:

  • Weakness or fatigue
  • Weight loss
  • No appetite
  • Chills
  • Fever
  • Sweating at night

Symptoms of TB disease in other parts of the body depend on the area affected. People who have latent TB infection do not feel sick, do not have any symptoms and cannot spread TB to others.

How soon after exposure to tuberculosis do symptoms appear?

Some people develop TB disease soon (within weeks) after becoming infected, before their immune system can fight the TB bacteria. Other people may get sick years later, when their immune system becomes weak for another reason. Many people with TB infection never develop TB disease.

How do you get tested for tuberculosis?

There are two kinds of tests that are used to detect TB bacteria in the body: the TB skin test (TST) and TB blood tests. A positive TB skin test or TB blood test only indicates that a person has been infected with TB bacteria. It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease. Other tests, such as a chest X-ray and a sample of sputum, are needed to see whether the person has TB disease.

Can tuberculosis be treated?

Not everyone infected with TB bacteria becomes sick. As a result, two TB-related conditions exist: latent TB infection and TB disease. Both latent TB infection and TB disease can almost always be treated and cured with medicine.

What is the treatment for tuberculosis?

Treatment of latent TB infection and TB disease differ. If you are diagnosed with TB, you should discuss the right treatment for you with a medical professional based on your test results and medical history. Most cases of active TB are readily treatable with antibiotics that are commonly available; treatment typically takes six to nine months.


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