Test Administration: Give 0.1 ml of 5 Tuberculin Units PPD intradermally. (Administration examples below.)
All tests should be read between 48 and 72 hours. If more than 72 hours has elapsed and there is not an easily palpable positive reaction, repeat the test on the other arm and read at 48 to 72 hours after the second administration.
Measure the induration - not erythema. Measure and report results in millimeters of induration.
All persons with positive reactions should be evaluated for preventive therapy, once TB disease has been ruled out.
For each of the categories, reactions below the cutting point are considered negative.
15 or more millimeters induration is always considered positive. Specifically, it is positive for persons with no risk factors for tuberculosis.
10 or more millimeters induration is considered positive for high risk groups, such as:
- Foreign-born persons from high prevalence areas (such as Asia, Africa, and Latin America)
- Intravenous drug users known to be HIV seronegative
- Medically-underserved low income populations, including high-risk racial or ethnic minority populations (especially blacks, Hispanics, and Native Americans)
- Residents of long-term care facilities (such as correctional institutions, nursing homes, mental institutions)
- Persons with medical conditions which have been reported to increase the risk of tuberculosis such as silicosis, being 10% or more below ideal body weight, chronic renal failure, diabetes mellitus, high dose corticosteroid and other immunospressive therapy, some hematologic sdisorders (such as leukemias and lymphomas), and other malignancies
- Locally identified high risk populations
- Children who are in one of the high risk groups listed above
- Health care workers who provide services to any of the high risk groups
5 or more millimeters induration is considered positive for the highest risk groups, such as:
- Persons with HIV infection
- Persons who have had close contact with an infectious tuberculosis case
- Persons who have chest radiographs consistent with old, healed tuberculosis
- Intravenous drug users whose HIV status is unknown
Needle Too Deep
Needle Too Shallow
Measure the Diameter
Positive Reaction: 18mm
Last updated: Aug 14, 1998
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