Evaluation of results from occupational tuberculin skin tests--Mississippi, 2006

In October 2006, the National Institute for Occupational Safety and Health (NIOSH) received a request for a health hazard evaluation from a fire department in Mississippi. In June 2006, the fire department had administered two-step tuberculin skin tests (TSTs) and determined that nine firefighters tested positive for tuberculosis (TB) infection. Local investigation had identified no source of TB infection. The NIOSH evaluation was conducted to 1) determine whether TB transmission was occurring among department firefighters, 2) assess the accuracy of positive TST results, and 3) make recommendations regarding administration of future fire department TB-testing programs. This report describes the results of that evaluation, which indicated that all nine firefighters had false-positive TST findings, likely caused by errors in interpretation of the test results. These results highlight the importance of conducting TB testing only when indicated by TB risk assessment and following CDC guidelines to avoid errors in TST administration and interpretation that might result in unnecessary medical evaluation and follow-up.