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


METHODS
Clark County Public Health (CCPH) conducted an epidemiologic investigation of 20 potentially exposed close contacts and 734 direct-care dental patients in 2010.


RESULTS
Of 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.


CONCLUSIONS
The 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 Implications All 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.
Ms. Merte was a Centers for Disease Control and Prevention/Council of State and Territorial Epidemiologists Applied Epidemiology Fellow, Clark County Public Health, Vancouver, Wash., when this article was written. She now is a public health analyst, U.S. Public Health Service, Washington, D.C.
Jennifer L
JL
Merte
Catherine M
CM
Kroll
Amy S
AS
Collins
Alan L
AL
Melnick
D003756:Dental Hygienists; D005260:Female; D006801:Humans; D017758:Infectious Disease Transmission, Patient-to-Professional / Q000517:prevention & control*; D008875:Middle Aged; D009784:Occupational Diseases / Q000517:prevention & control; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission*; D014861:Washington / Q000453:epidemiology
Mycobacterium tuberculosis; contact investigation; delayed diagnosis; dental office; infection prevention and control; occupational infection