Tuberculosis (TB)

What is TB?
An infection, usually of the lungs, by bacteria called Mycobacterium tuberculosis.

What are the symptoms of TB?
Most people infected with TB have no symptoms. About 1 in every 10 infected people get sick and their symptoms are a cough (often with blood), fever, fatigue, night sweats, and weight loss.

Where do TB bacteria usually live?
The body reacts to TB bacteria by forming capsules around the germs in the lungs and holding them in check. At this stage, a person is infected with TB, but is neither sick nor contagious. Nine out of ten people who are infected with TB will never be sick or contagious. They have a latent TB infection. In one out of ten people who get infected, however, the TB bacteria will break out of the capsules and cause people to be sick and contagious. This is called active TB disease. The following table compares and contrasts TB infection and active TB disease.

How is tuberculosis spread?
TB bacteria spread through the air when a person with active TB disease coughs, sneezes, shouts, or even sings. When other people breathe these bacteria into their lungs, they become infected.

How long before symptoms appear?
Most (90%) infected people NEVER get sick. In those who do get sick their symptoms are most likely to appear within the first year or two after infection, although people may become sick decades after being infected.

When can someone with TB spread it to others?
From the time symptoms begin, usually until the person with active TB has taken TB medications for two weeks to two months.

What can be done to prevent TB?
The risk of being infected is low. It usually takes close contact, indoors, for a prolonged time to become infected. Those who have had such close and prolonged contact should have a TB skin test. If that test is negative, exposed persons should have a TB skin test 3 months after the last time they were exposed to the case of active TB during the contagious period. The reason for this is that it can take a maximum of 3 months after someone gets infected with TB for the TB skin test to become positive. A positive TB skin test usually means that a person has a latent TB infection. It is very important that a doctor evaluate someone with a positive test. This can be done through a person's doctor or Central District Health Department.

Is there treatment for latent TB infection?
It is very important for people with TB infection to talk with a doctor about taking a 9 month course of one antibiotic to prevent them from becoming sick and accidentally spreading TB to their family, friends or coworkers.

Is there treatment for active TB disease?
People with active TB disease will take a 6-12 month course of up to four different antibiotics.

If you have any questions, please call your doctor or local health department.