Increased risk of Mycobacterium tuberculosis infection related to the occupational exposures of health care workers in Chiang Rai, Thailand.

Setting: Chiang Rai, the northernmost province of Thailand.
Objective: To evaluate the occupational risk for tuberculous infection of health care workers (HCWs) and the utility of tuberculin skin test (TST) in a developing country setting.
Design: A cross-sectional TST survey, including a risk assessment questionnaire, of Chiang Rai Hospital HCWs.
Results: Of 911 HCWs tested, 623 (68%) had indurations of > or = 10 mm and 322 (35%) indurations of > or = 15 mm. Factors most predictive for TST positivity, using either cut-off, were employment > 1 year, frequent direct patient contact, and male sex. Moreover, having a bacillus Calmette-Guérin (BCG) scar was predictive of a > or = 10 mm, but not a > or = 15 mm, reaction.
Conclusions: Chiang Rai Hospital HCWs had an increased risk for Mycobacterium tuberculosis infection, which was significantly associated with occupational exposure. Where BCG coverage is high, a TST cut-off of > or = 15 mm may correlate better with M. tuberculosis infection than does a cut-off of > or = 10 mm. Effective, affordable infection control measures are needed for health care facilities in developing countries such as Thailand, where HCWs may be at increased risk for M. tuberculosis infection from occupational exposures.