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Novel Perspectives on Foreign-born Tuberculosis: Trends, Targets, and Transmission Open Access
- Other title
Tuberculosis, Epidemiology, Transmission, Immigrants, Genotyping
- Type of item
- Degree grantor
University of Alberta
- Author or creator
Langlois-Klassen, Deanne L
- Supervisor and department
Long, Richard (Medicine)
Saunders, L Duncan (Public Health Sciences)
- Examining committee member and department
Carroll, Linda (Public Health Sciences)
Kunimoto, Dennis (Medicine)
Senthilselvan, Ambikaipakan (Public Health Sciences)
Khan, Kamran (Medicine)
School Public Health Sciences
- Date accepted
- Graduation date
Doctor of Philosophy
- Degree level
Immigrant-receiving countries like Canada must meet the challenge of tuberculosis (TB) in their foreign-born populations. One puzzling question is why, despite fluctuating levels of immigration from high incidence source countries, only modest variations in foreign-born TB incidence have been reported for decades. An additional concern is the disproportionate reactivation of latent TB infection (LTBI) in certain groups within this population. Despite these factors, routine screening for LTBI has not been widely implemented, primarily due to concern regarding cost-effectiveness. Another issue related to foreign-born TB is the potential importation of hypervirulent strains and/or strains with increased transmissibility. It is frequently speculated that the Beijing family of strains is included in this category. If true, TB resulting from Beijing strains could impact national TB control efforts.
This thesis aimed to (i) explain the relative constancy of TB incidence in the foreign-born in Canada by examining the trends in TB incidence among immigrant groups; (ii) identify high-yield target groups for routine screening for LTBI; and (iii) determine whether Beijing strains constitute an increased public health threat relative to other genotypes in Alberta, Canada in terms of infectiousness, drug-resistance and transmission.
These investigations found that relative constancy in foreign-born TB incidence is explained by a complex convergence of factors, including annual immigration levels, age at arrival, country of birth, and time since arrival. Consequently, immigrants ≤2 years post-arrival who were aged 15-35 years at arrival and born within countries with TB incidence rates >50/100,000 population were recommended as high-yield targets for the screening for LTBI. In Alberta, Beijing strains had similar disease presentations as non-Beijing strains apart from the former having significant associations with polyresistant-TB and multidrug-resistant TB as well as an association of borderline significance with respiratory TB. Beijing strains also had no greater of an association with recent transmission than non-Beijing strains in Alberta.
The high global prevalence of TB, the emergence of extensively and totally drug-resistant TB, and unprecedented levels of human migration indicate that immigrant-receiving countries will be challenged by TB in their foreign-born populations for the foreseeable future. Serious consideration must be given to the implementation of effective screening strategies.
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
- Citation for previous publication
Langlois-Klassen D, Wooldrage KM, Manfreda J, Sutherland K, Ellis E, Phypers M, Gushulak B, Long R. Piecing the puzzle together: foreign-born tuberculosis in an immigrant-receiving country. Eur Respir J 2011;38(4):895-902.
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