General Questions About Tuberculosis (TB)

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What is tuberculosis?

Tuberculosis is a bacterial disease caused by Mycobacterium tuberculosis. TB usually affects the lungs but it can also affect other parts of the body such as the brain, lymph nodes, kidneys, bones, joints, larynx, intestines or eyes. As a result, two TB-related conditions exist:  TB infection and TB disease.  TB when found outside the lungs is referred to as extrapulomary TB.

What is the difference between tuberculosis infection and tuberculosis disease?

There are generally two stages of TB infection, one where the bacteria can be spread and can cause illness and one where the bacteria is in a person’s body, but is not causing disease and cannot be spread.

People with TB infection have TB bacteria in their bodies but they are not sick because the bacteria are not active. These people do not have symptoms of TB disease and they cannot spread the bacteria to others. However, they may develop TB disease in the future. They are often prescribed treatment to prevent them from developing TB disease.

People with TB disease are sick from TB bacteria that are active, meaning that they are multiplying and destroying tissue in their body. They usually have symptoms of TB disease. People with TB disease of the lungs or throat are capable of spreading their illness to others. They are prescribed drugs that can treat TB disease.

Who is at risk for tuberculosis?

Persons who are at high risk for TB infection include people who:  have been in close contact with a person with tuberculosis disease; immigrated from or spent a considerable amount of time in a country where there are high rates of TB; are homeless; injects drug; are living with HIV infection; live in congregate settings; and/or have a medical condition that weakens the immune system.  

Overall, about 5 to 10% of infected persons who do not receive treatment for TB infection will develop TB disease at some point in their lives.  For persons who have weakened immune systems, that risk is much higher than people with normal immune systems.  

What are the symptoms of tuberculosis?

People with TB infection do not feel sick and not not have any symptoms.  

People who develop TB disease have symptoms based on where in the body the TB bacteria are growing.  TB bacteria usually grow in the lungs and symptoms can include:  bad cough that last 3 weeks or longer, pain in the chest, coughing up blood or sputum, weakness/fatigue, weight loss, chills, fever and night sweats.  

How soon do symptoms appear after you are infected?

People can be tested to see if they have TB infection 8-10 weeks after they are initially infected.  People with only TB infection are unlikely to have any symptoms. 

If infected, people may develop to TB disease at anytime during their lifetime or not at all.  There is not a standard time period in which this happens, but is dependent on other conditions a person has that could weaken their immune systems and allow TB disease to develop.  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 is tuberculosis spread?

The bacterium causing tuberculosis is spread through the air. When a person with TB disease TB coughs, sneezes, speaks or sings the bacteria is put into the air. The bacteria can stay in the air for several hours depending on the environment. Prolonged exposure to the tuberculosis is normally necessary for infection to occur.  People with TB infection are not able to transmit to others.  

How long can someone spread tuberculosis?

A person with TB disease may remain contagious until he/she has been on appropriate treatment for several weeks. It is important to note that a person with TB infection, but not disease, cannot spread the infection to others, since there are no TB bacteria in the sputum.

How is someone diagnosed with tuberculosis?

There are two kinds of test that are used to detect TB in the body:  The TB skin test (TST) and TB blood tests.  A positive TB skin test or TB blood tests only tells that person has been infected with TB bacterial.  Other tests are needed to determine if someone is only infected or has progressed to TB disease.  A chest x-ray or CT scan and a sample of sputum are needed to determine if a person has TB disease.  

What is the treatment for tuberculosis?

TB infection ( is usually treated with isoniazid (INH), rifampin (RIF) or isoniazind and rifapentine (3HP). Regimens, dosage and duration will be determined by a medical provider.  

TB disease generally is treated with a combination of several medications 6 to 12 months. It is important that people who have TB disease finish the medicine and take the drugs exactly as prescribed by their doctor. If they stop taking the drugs too soon they can become sick again. If they do not take the drugs correctly, the bacteria that are still alive may become resistant to those drugs. TB that is resistant to drugs is harder and more expensive to treat.

What would happen to a person if they don't take treatment for tuberculosis?

If you have TB infection, you have a 10 percent chance of developing active disease over the course of your lifetime if you remain untreated. The chance of developing TB disease increases if you develop diabetes, are immunocompromised, have HIV, have a gastric by-pass or require prolonged use of corticosteroids or other immunosuppressive agents.

If you have TB disease, in addition to spreading the disease to others, an untreated person may become severely ill or die.

Does having tuberculosis in the past make a person immune?

People who have been treated for TB infection or TB disease are able to become infected again.  

Should children or others be excluded from child care, school, work or other activities if they have tuberculosis?

Yes. People diagnosed with TB disease should isolated from the public until they have been determined by a doctor to no longer be infectious.  This can occur within a few weeks of initiating therapy, however, infectious periods may vary.  

People with TB infection who have been cleared of a TB disease diagnosis can participate in all activities whether they are receiving treatment or not. As always, respiratory etiquette is recommended.

What can be done to prevent the spread of tuberculosis?

People with TB disease should be excluded from school, day care or the work place until the sputum is negative (about 2-4 weeks after the beginning of treatment). All household and close contacts of a person with active TB disease should be screened using the TB skin test or TB blood test for evidence of infection. All contacts with evidence of infection should be evaluated by a physician for disease.

Routine screening of people who are at high-risk populations may help to diagnose TB infection.  By treating TB infection, people can prevent the chance of developing TB disease and reduce the risk of infecting other people.