Epidemiological evaluation of spatiotemporal and genotypic clustering of Mycobacterium tuberculosis in Ontario, Canada

• Published in: The international journal of tuberculosis and lung disease Vol. 17; no. 10; pp. 1322 - 1327
• Main Authors: Tuite, A. R., Guthrie, J. L., Alexander, D. C., Whelan, M. S., Lee, B., Lam, K., Ma, J., Fisman, D. N., Jamieson, F. B.
• Format: Journal Article
• Language: English
• Published: Paris, France International Union Against Tuberculosis and Lung Disease 01.10.2013; International Union against Tuberculosis and Lung Disease
• Subjects: Adult; Age Factors; Aged; Bacterial diseases; Bacterial Typing Techniques; Biological and medical sciences; Cluster Analysis; Epidemiology; Female; Genotype; Genotypes; Homeless Persons - statistics & numerical data; Human bacterial diseases; Humans; Indians, North American - statistics & numerical data; Infectious diseases; Logistic Models; Male; Medical sciences; Middle Aged; Mycobacterium tuberculosis; Mycobacterium tuberculosis - genetics; Mycobacterium tuberculosis - isolation & purification; Ontario - epidemiology; Pneumology; Poisson Distribution; Risk Factors; Sex Factors; Spatio-Temporal Analysis; Tuberculosis; Tuberculosis - epidemiology; Tuberculosis - ethnology; Tuberculosis - microbiology; Tuberculosis and atypical mycobacterial infections; Canada; North America; Ontario; America; Canada, Ontario; China, People's Rep., Beijing; Evaluation; Typing; Respiratory disease; genotypes; Genotype; Mycobacterial infection; Epidemiology; Infection; Tuberculosis; Mycobacterium tuberculosis; Mycobacteriales; Bacteriosis; Mycobacteriaceae; Bacteria; Actinomycetes; Public health
• ISSN: 1027-3719; 1815-7920
• DOI: 10.5588/ijtld.13.0145

BACKGROUND: In Canada, tuberculosis (TB) rates are at a historic low, with the remaining risk concentrated in a few vulnerable population subgroups.OBJECTIVES: To describe the epidemiology of TB in the Canadian province of Ontario and to characterise risk factors associated with transmission events, identified using genetic typing techniques.DESIGN: Retrospective analysis of 2186 culture-positive TB cases between August 2007 and December 2011. Temporal trends and risk of spatiotemporal and genotypic clustering were evaluated using Poisson and logistic regression models.RESULTS: Being in a spatiotemporal cluster was associated with Aboriginal status (odds ratio [OR] 3.63, 95% confidence interval [CI] 1.23-10.71). Cases in genotypic clusters were more likely to report homelessness as a risk factor (adjusted OR [aOR] 2.92, 95%CI 1.74-4.90) or be male (aOR 1.35, 95%CI 1.09-1.68), and were less likely to be aged ≥65 years (aOR 0.63, 95%CI 0.49-0.82), foreign-born (aOR 0.32, 95%CI 0.24-0.43) or Aboriginal (aOR 0.40, 95%CI 0.16-0.99). The Beijing lineage had an annual rate of increase of almost 10% (P = 0.047), and was associated with genotypic clustering (aOR 2.84, 95%CI 2.19-3.67).CONCLUSION: Genotypic data suggest that disease clusters are smaller, but far more common, than would be estimated using spatiotemporal clustering.