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    TB and Hansen's Disease Branch

    MC 1939
    P.O. Box 149347
    Austin, TX 78756-9347

    Phone: 512-533-3000
    Fax: 512-533-3167

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Frequently Asked Questions About TB



For the general public:



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Courtesy of the CDC

For health care professionals:



TB Elimination

What is TB?

Tuberculosis (TB) is a disease caused by germs that are 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.  A person with TB can die if they do not get treatment.

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.

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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 is the difference between latent TB infection and TB disease?

People with latent TB infection (LTBI) have TB germs in their bodies, but they are not sick because the germs are not active.  These people do not have symptoms of TB disease and they cannot spread the germs 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 germs 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 germs to others.  They are prescribed drugs that can treat TB disease.

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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 should I do if I have been exposed to someone with TB disease?

People with TB disease are most likely to spread the germs to people they spend time with every day, such as family members or coworkers. If you have been around someone who has TB disease, you should go to your doctor or your local health department for tests.

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How do you get tested for TB?

There are two tests that can be used to help detect TB infection: a skin test or a special TB blood test. The Mantoux tuberculin skin test is performed by injecting a small amount of fluid (called tuberculin) into the skin in the lower part of the arm. A person given the tuberculin skin test must return within 48 to 72 hours to have a trained health care worker look for a reaction on the arm. The special TB blood test measures how the patient’s immune system reacts to the germs that cause TB.

Who can administer a tuberculin skin test (TST)?

A tuberculin skin test (TST) is considered a medical act and should only be performed by an individual working under the order of a licensed physician.  There is no requirement for the individual to be a licensed health care worker. DSHS recommends those that administer a TST meet knowledge and clinical skills requirements, have received training, and demonstrated competency before administering a TST.

TX DSHS TB Program recommends that anyone who administers a TST has reviewed, is familiar with, and able to readily access the recommendations within the following documents:

In person training on how to administer a tuberculin skin test (TST) is available through the Heartland National TB Center.  Please visit their website for a listing of training opportunities:

What does a positive test for TB infection mean?

A positive test for TB infection only tells that a person has been infected with TB germs. It does not tell whether or not the person 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.

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What is BCG?

Bacille Calmette-Guérin, or BCG, is a vaccine for TB disease. BCG is used in many countries, but it is not generally recommended in the United States. BCG vaccination does not completely prevent people from getting TB. It may also cause a false positive tuberculin skin test. However, persons who have been vaccinated with BCG can be given a tuberculin skin test or special TB blood test.

Why is latent TB infection treated?

If you have latent TB infection but not TB disease, your doctor may want you to take a drug to kill the TB germs and prevent you from developing TB disease. The decision about taking treatment for latent infection will be based on your chances of developing TB disease. Some people are more likely than others to develop TB disease once they have TB infection. This includes people with HIV infection, people who were recently exposed to someone with TB disease, and people with certain medical conditions.

How is TB disease treated?

TB disease can be treated by taking several drugs for 6 to 12 months. It is very important that people who have TB disease finish the medicine, and take the drugs exactly as prescribed. If they stop taking the drugs too soon, they can become sick again; if they do not take the drugs correctly, the germs that are still alive may become resistant to those drugs. TB that is resistant to drugs is harder and more expensive to treat. In some situations, local health department staff meets regularly with patients who have TB to watch them take their medications. This is called directly observed therapy (DOT). DOT helps the patient complete treatment in the least amount of time.

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Do all new students in Texas schools still need a tuberculin skin test?

No. A tuberculosis questionnaire to identify children at high risk for latent TB infection has been developed by pediatric and public health experts working with the Texas Department of State Health Services. This questionnaire should be used to determine if a child should be evaluated for TB infection with a TB skin test. Any new "yes" answers to a part of the questionnaire should trigger referral for or placement of a TB skin test and appropriate follow-up. The Texas Department of State Health Services has prepared a list of counties with a high incidence of TB where use of the questionnaire is recommended at entry to school. As resources allow, school districts in other counties may use the TB questionnaire to identify children who should receive a TB skin test prior to school entry. Children who have a positive reaction to the TB skin test but no symptoms of TB disease should not be kept out of school while they are being evaluated for treatment of latent TB infection.

The American Academy of Pediatrics (AAP) recommends that physicians routinely assess a child's risk of TB exposure with a questionnaire and offer tuberculin skin testing only to at-risk children. The AAP does not recommend routine tuberculin skin testing of children with no TB risk factors for school entry, day care attendance, WIC eligibility, or camp attendance.

A tuberculin skin test may be applied on the same day as routine immunizations. The skin test will need to be read 48-72 hours later. If a skin test is not placed on or before the day of a live virus immunization such as measles-mumps-rubella (MMR), then the skin test should be postponed at least six weeks.

For more information about TB screening for children in school settings click on the following links:

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Do all employees in Texas schools still need a tuberculin skin test?

No. There is no statewide requirement for teachers or other school employees to have a tuberculin skin test. The Centers for Disease Control and Prevention discourages the use of the tuberculin skin test for persons who have no risk factors for TB exposure.

What does a positive tuberculin skin test mean?

The tuberculin skin test is the most widely used test for identifying infection with Mycobacterium tuberculosis (the bacteria that cause tuberculosis) in people who do not have tuberculosis disease. A small amount of purified protein derivative (PPD) is injected between the layers of the skin, usually in the forearm. A trained health care worker measures any swelling 48-72 hours after the test was placed.

A measurement of 5 mm or greater is considered a positive result for people at the highest risk of exposure to someone with active TB disease or who have conditions that would be most likely to increase their risk of developing TB disease, if they are infected. A measurement of 10 mm or greater is considered a positive result for people with some risk factors for exposure to someone with active TB disease or who have conditions that would increase their chance of developing TB disease if infected. People with no known risk factors for TB are said to have a positive result if the swelling measures 15 mm or greater.

A positive tuberculin skin test result plus a chest x-ray that is not suggestive of TB disease leads to a diagnosis of latent TB infection for a person without any symptoms of TB disease. A positive tuberculin skin test result plus a chest x-ray that is suggestive of TB disease would trigger a request for laboratory tests of sputum coughed up from deep in the lungs. These further tests would look for the presence of the bacteria that cause TB and can confirm a diagnosis of active TB disease.

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Are routine chest x-rays recommended for health care workers, patients or institutional residents with a history of a positive tuberculin skin test result?

No, people who have a positive tuberculin skin test result should not have repeat chest radiographs performed routinely. Health care workers, patients or institutional residents with a baseline positive or newly positive tuberculin skin test result should receive one chest radiograph to exclude a diagnosis of TB disease. Afterwards, repeat radiographs are not needed unless signs or symptoms of TB develop, or a clinician recommends a repeat chest radiograph, or after a new exposure to M. tuberculosis. On a regular basis, the person in charge of infection control for their work area should ask about any signs or symptoms of TB disease instead of giving additional tuberculin skin tests. The frequency of their symptom screen should be determined by the risk assessment for the facility.

Health care workers who have a previously positive tuberculin skin test result and who change jobs should carry documentation of the results of their tuberculin skin test, chest radiograph and documentation of treatment history for latent TB infection, if applicable, to their new employers.

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How often do health care workers need a tuberculin skin test?

Both paid and unpaid health care workers should receive a two-step tuberculin skin test when they start work in a health care setting unless they have documentation of a negative tuberculin skin test result within the last twelve months or documentation of a positive tuberculin skin test result at any time in the past. The frequency with which they receive additional tuberculin skin tests should be determined by the risk of exposure to persons with active TB disease in their work setting.

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Does a history of BCG vaccination change the interpretation of a tuberculin skin test?

No. Bacille Calmette-Guerin (BCG) vaccine is given in many countries because it can protect children against some severe forms of TB disease. However, its efficacy in preventing TB in adults is variable and controversial. People from areas of the world where there is high incidence of TB are likely to be TB infected if they have a positive result to a tuberculin skin test. They are at risk of developing TB disease, even if they have been vaccinated with BCG. For more information about BCG, please use the following links to the CDC web page to obtain a copy of the publication “The Role of BCG Vaccine in the Prevention and Control of Tuberculosis in the United States” (Web Page/HTML) or (PDF, 266KB)

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Are correctional facilities in Texas required to screen inmates and employees for TB?

The law (Chapter 89 of the Texas Health & Safety Code) in Texas requires county correctional facilities that meet any one of three criteria to screen all inmates for TB by the seventh day of incarceration and annually thereafter, and to screen all employees and volunteers both pre-employment and annually thereafter.

The three criteria are as follows:

  1. a capacity of 100 or more beds,
  2. housing inmates transferred from a county that has a jail with a capacity of 100 or more beds, or
  3. housing inmates from another state.

The law also requires all correctional facilities in the state, including youth detention facilities, regardless of whether they meet the criteria stated above, to report to the Texas Department of State Health Services, Infectious Disease Intervention and Control Branch, the release of inmates being treated for TB so that the Department can arrange for continuity of care.

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How Often Can TSTs Be Repeated?

In general, there is no risk associated with repeated tuberculin skin test placements. If a person does not return within 48-72 hours for a tuberculin skin test reading, a second test can be placed as soon as possible. There is no contraindication to repeating the TST, unless a previous TST was associated with a severe reaction.


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Last updated October 23, 2015