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Am Fam Physician. 2009;79(10):1-2

See related article on tuberculosis.

What is tuberculosis?

Tuberculosis, or TB, is a disease caused by bacteria (germs). It usually attacks the lungs, but it can also attack other parts of your body, such as the brain, bones, and kidneys. If not treated, TB can cause serious illness or death.

How is it spread?

When people with active TB disease cough, the germs may spread through the air. Other people can become infected if they breathe in these germs. It's not easy for a healthy person to become infected with TB. You usually have to be around someone with active TB disease many times before you get the infection.

How do I know if I have it?

The most common test to find out if you have TB is the TB skin test. If the skin test is positive, it means that you are infected with the TB germs. Your doctor will then find out if you have the active disease or a latent infection. Your doctor may ask if you have any symptoms of active TB disease, such as fever or cough. Your doctor may also order tests, such as a chest x-ray. If your skin test is positive and the other tests are negative, you have latent TB infection.

What is latent TB infection?

There is a difference between having latent TB infection and having active TB disease. People with active disease are sick and can spread the germs to other people. People with latent infection have the TB germs in their body, but they are not sick. A person with latent TB infection can't spread the germs to other people.

Why is it important to treat latent TB infection?

If you have latent TB infection, there is a one in 10 chance that it will turn into active TB disease, even if you are healthy. Getting treatment can lower this chance. The risk of getting active TB disease is highest in the first two years after getting latent TB infection, so it is important to start treatment right away.

How is latent TB infection treated?

Latent TB infection is treated with medicines that kill the TB germs. Usually, a medicine called isoniazid is used once a day for nine months. There are other medicines available, so ask your doctor about your options. It is important to take the medicine exactly the way your doctor tells you. You will need to visit your doctor every month while taking the medicine to check for side effects.

Can I still get active TB disease after treatment?

Even after nine months of taking medicine for latent TB infection, there's still a small chance that you could get active TB disease. Symptoms of active disease include tiredness, weight loss, a cough that won't go away, fevers, and night sweats. If you have any of these symptoms, you should see your doctor right away. The treatment for active TB disease is different from the treatment for latent TB infection.

Where can I learn more about TB?

Your doctor

American Academy of Family Physicians

American Lung Association

Centers for Disease Control and Prevention

World Health Organization

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