An epidemiologic investigation of occupational transmission of Mycobacterium tuberculosis infection to dental health care personnel : Infection prevention and control implications

ABSTRACTBackgroundThe authors describe an investigation of a dental hygienist who developed active pulmonary tuberculosis (TB), worked for several months while infectious and likely transmitted Mycobacterium tuberculosis in a dental setting in Washington state.MethodsClark County Public Health (CCPH) conducted an epidemiologic investigation of 20 potentially exposed close contacts and 734 direct-care dental patients in 2010.ResultsOf 20 close contacts, one family member and two coworkers, all of whom were from countries in which TB is endemic, had latent TB infection (LTBI). One U.S.-born coworker experienced a tuberculin skin test (TST) conversion from 0 to 8 millimeters. Of the 305 of 731 (41.7 percent) potentially exposed patients who received a single TST, 23 (7.5 percent) had a positive TST result of at least 5 mm. Among the subset of 157 patients tested by CCPH staff, 16 (10.2 percent) had a positive TST result. The dental office did not have infection prevention and control policies related to TB identification, prevention or education.ConclusionsThe coworker's TST conversion indicated a recent infection, likely owed to occupational transmission. The proportion of dental patients with positive TST results was greater than the 1999-2000 National Health and Nutrition Examination Survey prevalence estimate in the general population, and it may reflect transmission from the hygienist with active TB or a prevalence of LTBI in the community.Practical ImplicationsAll dental practices should implement administrative procedures for TB identification and control as described in this article, even if none of their patients are known to have TB.