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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 prevalence 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:
- Recommendations of Blue Ribbon Committee on Childhood TB (MS word, 35 KB)
- Tuberculosis Questionnaire in English (MS word, 43 KB)
- Tuberculosis Questionnaire in Spanish (MS word, 37 KB)
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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.
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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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What is the difference between TB infection and TB disease?
People with latent TB infection do not feel sick, do not have any symptoms, and cannot spread the bacteria that cause TB disease. But they may develop TB disease at some time in the future. People with active TB disease can be treated and cured if they seek medical help. Even better, people who have latent TB infection but are not yet sick can take medicine so that they will not develop TB disease later.
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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:
- a capacity of 100 or more beds,
- housing inmates transferred from a county that has a jail with a capacity of 100 or more beds, or
- 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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