BCG vaccination and the PPD test: what the clinician needs to know.

The resurgence in tuberculosis necessitates careful surveillance and sensitive detection of cases. The purified protein derivative (PPD) test is the foundation of tuberculosis control. Primary care clinicans are encountering increasing numbers of persons immigrating from countries in which BCG (bacille Calmette-Guérin) vaccination is common. Many health care providers believe that previous BCG vaccination usually results in a positive PPD test, and therefore consider BCG vaccination status when interpreting a positive result on the PPD test. All articles listed in MEDLINE that included BCG and PPD as key words, a total of 62, were reviewed. Articles published before computerization of the medical literature, a total of 35, were reviewed in Index Medicus. This literature review indicates that there is little relationship between BCG vaccination and PPD positivity, and that BCG vaccination status should not be considered in the interpretation of a positive PPD test.