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TB Skin Testing

TB (tuberculosis) skin testing for public safety

After years of decline TB is back and on the increase. Pima County has had the highest rates in the state.


Skin test:

10 mm or more of induration (swelling) is positive for health care and public safety workers with normal immunity. Redness alone doesn’t count.  If positive the doctor/nurse practitioner will decide:


  1. Need for initial chest x-ray (may have just had one elsewhere so no need to repeat).
  2. Radiologist may request extra x-ray views if any concerns on initial x-ray.


If your Chest x-ray is negative you do not have active TB

  1. You can’t give it to anyone at home or work
  2. Because ten percent of people with a positive skin test and NEGATIVE chest x-rays will develop active TB later in life there’s a medication to prevent that.


TB prophylaxis (medication):

  1. Risks of medication to the liver increase with age, especially after age 35.
  2. Usual medication is INH (isoniazid) 300 mg a day for 9 months
  1. If you are placed on medication have your liver functions (blood test) tested periodically.


Where to go for help:

  1. See your personal physician.
  2. Pima County Health Department – Note, there is a charge.
  3. If positive skin test is from an exposure, then see (1) or (2) or your companies/organizations occupational medical clinic.


Who pays:

  1. Your agency covers cost of TB skin tests.
  2. If you need a chest x-ray or medication you would have to prove to your worker’s compensation carrier that you became ill at work for it to be considered an industrial case.
  3. Some agencies will pay cost of the above.
  4. Most do not and advise you to seek care at your personal physician


Symptoms of TB:

  1. Chronic cough with phlegm, often bloody.
  2. Night sweats, fever, weight loss.


Further information:, Pima County Health Department, Tuberculosis.