What is TB?

Tuberculosis (TB) is a disease caused by a germ called Mycobacterium tuberculosis that is spread from person to person through the air. TB usually affects the lungs, but it can also affect other parts of the body, such as the brain, the kidneys, or the spine. When a person with infectious TB coughs or sneezes, droplet nuclei containing M. tuberculosis are expelled into the air. If another person inhales air containing these droplet nuclei, he or she may become infected. However, not everyone infected with TB bacteria becomes sick. As a result, two TB-related conditions exist: latent TB infection and active TB disease.

What is Latent TB Infection?

Persons with latent TB infection do not feel sick and do not have any symptoms, but usually have a positive reaction to the tuberculin skin test. They are infected with M. tuberculosis, but do not have active TB disease. Persons with latent TB infection are not infectious and cannot spread TB infection to others.

What Are the Symptoms of TB?

The general symptoms of TB disease include feelings of sickness or weakness, weight loss, fever, and night sweats. The symptoms of TB disease of the lungs also include coughing, chest pain, and the coughing up of blood. Symptoms of TB disease in other parts of the body depend on the area affected.

How is TB Spread?

TB germs are put into the air when a person with TB disease of the lungs or throat coughs, sneezes, speaks, or sings. These germs can stay in the air for several hours, depending on the environment. Persons who breathe in the air containing these TB germs can become infected; this is called latent TB infection.

What Should I Do If I Have Spent Time with Someone with Latent TB Infection?

A person with latent TB infection cannot spread germs to other people. You do not need to be tested if you have spent time with someone with latent TB infection. However, if you have spent time with someone with TB disease or someone with symptoms of TB, you should be tested.

What Is the Difference Between Latent TB Infection and Active TB Disease?

Latent TB Infection	Active TB Disease
TB germs are dormant (asleep) in your body. This phase can last for a very long time - even decades.	TB germs are reproducing and spreading in your body, causing tissue damage.
You don't look or feel sick. Your chest x-ray usually is normal.	You usually feel sick. Typical symptoms include: cough lasting >3 weeks, weight loss, night sweats, and fever. A chest x-ray and other tests are needed to diagnose TB disease.
You can't spread TB to other people.	If the TB germs are in your lungs or voicebox, you may spread TB to other people by coughing, sneezing, talking, or singing.
Usually treated by taking one medicine for 9 months.	Treated by taking three or four medicines for at least 6 months.

 

For more information: 

Contact Health Services 651-523-2204 or

CDC Division of Tuberculosis Elimination

Minnesota Department of Health