Epidemiology of tuberculosis in a large-scale manufacturing enterprise in Quebec

Objectives: To determine the prevalence of tuberculosis infection related to a case of pulmonary and laryngeal tuberculosis in a work-place and to stud PPD predictors. Methods: The Mantoux skin test (PPD) was offered to all potentially infected contacts. Participants were asked to answer a questionnaire. Results: Among 112 exposed employees, 92 (82.1%) were tested. At the 5 mm level, 65.2% of employees had positive tuberculin skin test (PPD). By controlling prior BCG and the degree of exposure, it showed a positive association between age and PPD (RC: 3.5; 95% CI: 1.25-10.03). When age and BCG were controlled, high exposure was statistically associated with PPD results (RC: 5.6; 95% CI: 1.25-24.68). Conclusion: The observed prevalence rate is probably related to the fact that the index case was very infectious and had contact in an enclosed area over a long period of time before withdrawal from work.