Occupational transmission of Mycobacterium tuberculosis to health care workers in a university hospital in Lima, Peru

From November 1996 through March 1997, presumptive active pulmonary tuberculosis (TB) was detected in 44 health care workers (HCWs) at a university hospital in Lima, Peru. To further assess the magnitude of the outbreak and determine risk factors for occupational Mycobacterium tuberculosis transmission, we identified HCWs in whom active pulmonary TB was diagnosed from January 1994 through January 1998, calculated rates by year and hospital work area, and conducted a tuberculin skin test (TST) survey. Thirty-six HCWs had confirmed active pulmonary TB. The rate of TB was significantly higher among the 171 HCWs employed in the laboratory than among HCWs employed in all other areas. In multivariate analysis, the only independent risk factor for HCW M. tuberculosis infection in HWCs employed in the laboratory was the use of common staff areas. Very high rates of active pulmonary TB were detected among HCWs at this hospital, and occupational acquisition in the laboratory was associated with HCW-to-HCW transmission.