Tuberculosis elimination in the Canadian First Nations population: assessment by a state-transfer, compartmental epidemic model

Background: Tuberculosis (TB) remains an important public health problem in Canadian Aboriginal (First Nations and Inuit) communities. The objectives of this study were to predict future disease burden and set feasible targets for the elimination of TB in the First Nations population, using retrospective data and an epidemic model. Methods: Reported TB incidence data (1974-2002), previously published TB meningitis data from the pre-chemotherapy era, and previous estimates of disease risk following infection were used to estimate a trend in the annual risk of infection from 1929 to 2002, and the age-specific prevalence of infection in 2002. A state-transfer, compartmental model was then developed to predict future disease burden. Two scenarios were simulated, with different disease risk parameters. Results: The estimated prevalence of infection in 2002 was 20.9% in scenario 1 and 25.5% in scenario 2. Predicted incidence rates in 2015 were 16.8 per 100 000 and 11.7 per 100 000 for the two scenarios, respectively. The incidence of disease was not tower than 1 per 100 000 for either scenario in 2034, the arbitrarily chosen last year of the model. Conclusions: The goal of eliminating TB among Aboriginal peoples in Canada is a feasible one, but will only be achieved with continued investment in programs designed to control and prevent transmission. Reactivation disease cases may occur for a number of years to come, making rapid elimination a difficult goal. (C) 2008 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.