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Major Mycobacterium tuberculosis lineages associate with patient country of origin.

https://arctichealth.org/en/permalink/ahliterature152671
Source
J Clin Microbiol. 2009 Apr;47(4):1119-28
Publication Type
Article
Date
Apr-2009
Author
Michael B Reed
Victoria K Pichler
Fiona McIntosh
Alicia Mattia
Ashley Fallow
Speranza Masala
Pilar Domenech
Alice Zwerling
Louise Thibert
Dick Menzies
Kevin Schwartzman
Marcel A Behr
Author Affiliation
Department of Medicine, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada. michael.reed@mcgill.ca
Source
J Clin Microbiol. 2009 Apr;47(4):1119-28
Date
Apr-2009
Language
English
Publication Type
Article
Keywords
Adolescent
Adult
Aged
Aged, 80 and over
Bacterial Typing Techniques
Canada
Child
Child, Preschool
Cluster analysis
DNA Fingerprinting - methods
DNA Transposable Elements
DNA, Bacterial - chemistry - genetics
Ethnic Groups
Female
Genotype
Humans
Infant
Male
Middle Aged
Mycobacterium tuberculosis - classification - genetics - isolation & purification
Polymorphism, Restriction Fragment Length
Tuberculosis - microbiology
Young Adult
Abstract
Over recent years, there has been an increasing acknowledgment of the diversity that exists among Mycobacterium tuberculosis clinical isolates. To facilitate comparative studies aimed at deciphering the relevance of this diversity to human disease, an unambiguous and easily interpretable method of strain classification is required. Presently, the most effective means of assigning isolates into a series of unambiguous lineages is the method of Gagneux et al. (S. Gagneux et al., Proc. Natl. Acad. Sci. USA 103:2869-2873, 2006) that involves the PCR-based detection of large sequence polymorphisms (LSPs). In this manner, isolates are classified into six major lineages, the majority of which display a high degree of geographic restriction. Here we describe an independent replicate of the Gagneux study carried out on 798 isolates collected over a 6-year period from mostly foreign-born patients resident on the island of Montreal, Canada. The original trends in terms of bacterial genotype and patient ethnicity are remarkably conserved within this Montreal cohort, even though the patient distributions between the two populations are quite distinct. In parallel with the LSP analysis, we also demonstrate that "clustered" tuberculosis (TB) cases defined through restriction fragment length polymorphism (RFLP) analysis (for isolates with >or=6 IS6110 copies) or RFLP in combination with spoligotyping (for isolates with
Notes
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PubMed ID
19213699 View in PubMed
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Repeat IGRA testing in Canadian health workers: conversions or unexplained variability?

https://arctichealth.org/en/permalink/ahliterature116572
Source
PLoS One. 2013;8(1):e54748
Publication Type
Article
Date
2013
Author
Alice Zwerling
Andrea Benedetti
Mihaela Cojocariu
Fiona McIntosh
Filomena Pietrangelo
Marcel A Behr
Kevin Schwartzman
Dick Menzies
Madhukar Pai
Author Affiliation
Department of Epidemiology, Biostatistics & Occupational Health, McGill University, Montreal, Canada.
Source
PLoS One. 2013;8(1):e54748
Date
2013
Language
English
Publication Type
Article
Keywords
Adult
Canada
Cohort Studies
Female
Health Personnel
Humans
Interferon-gamma Release Tests
Male
Mass Screening
Middle Aged
Mycobacterium tuberculosis
Occupational Exposure
Sensitivity and specificity
Tuberculin Test
Tuberculosis - diagnosis
Young Adult
Abstract
Although North American hospitals are switching from tuberculin testing (TST) to interferon-gamma release assays (IGRAs), data are limited on the association between occupational exposure and serial QuantiFERON-TB Gold In-Tube (QFT) results in healthcare workers (HCWs).
In a cohort of Canadian HCWs, TST and QFT were performed at study enrolment (TST1 and QFT1) and 1 year later (TST2 and QFT2). Conversion and reversion rates were estimated, and correlation with TB exposure was assessed.
Among 258 HCWs, median age was 36.8 years, 188/258 (73%) were female and 183/258 (71%) were Canadian-born. In 245 subjects with a negative QFT1 we found a QFT conversion rate of 5.3% (13/245, 95% CI 2.9-8.9%). Using more stringent definitions, QFT conversion rates ranged from 2.0 to 5.3%. No TST conversions were found among the 241 HCWs with negative TST1, and no measure of recent TB exposure was associated with QFT conversions. In the 13 HCWs with a positive QFT1, 62% reverted.
Using the conventional QFT conversion definition, we found a higher than expected rate of conversion. Recent occupational exposures were not associated with QFT conversions, and no TST conversions occurred in this cohort, suggesting the 'conversions' may not reflect new TB infection.
Notes
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PubMed ID
23382955 View in PubMed
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Social determinants of health among residential areas with a high tuberculosis incidence in a remote Inuit community.

https://arctichealth.org/en/permalink/ahliterature297978
Source
J Epidemiol Community Health. 2019 Feb 06; :
Publication Type
Journal Article
Date
Feb-06-2019
Author
Elaine Kilabuk
Franco Momoli
Ranjeeta Mallick
Deborah Van Dyk
Christopher Pease
Alice Zwerling
Sharon Edmunds Potvin
Gonzalo G Alvarez
Author Affiliation
Department of Internal Medicine, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada.
Source
J Epidemiol Community Health. 2019 Feb 06; :
Date
Feb-06-2019
Language
English
Publication Type
Journal Article
Abstract
Tuberculosis (TB) remains a significant health burden among Inuit in Canada. Social determinants of health (SDH) play a key role in TB infection, disease and ongoing transmission in this population. The objective of this research was to estimate the prevalence of social determinants of Inuit health as they relate to latent TB infection (LTBI) among people living in residential areas at high risk for TB in Iqaluit, Nunavut.
Inperson home surveys were conducted among those who lived in predetermined residential areas at high risk for TB identified in a door-to-door TB prevention campaign in Iqaluit, Nunavut in 2011. Risk ratios for SDH and LTBI were estimated, and multiple imputation was used to address missing data.
261 participants completed the questionnaire. Most participants identified as Inuit (82%). Unadjusted risk ratios demonstrated that age, education, smoking tobacco, crowded housing conditions and Inuit ethnicity were associated with LTBI. After adjusting for other SDH, multivariable analysis showed an association between LTBI with increasing age (relative risk, RR 1.07, 95% CI 1.04 to 1.11), crowded housing (RR 1.48, 95% CI 1.10 to 2.00) and ethnicity (RR 2.76, 95% CI 1.33 to 5.73) after imputing missing data.
Among high-risk residential areas for TB in a remote Arctic region of Canada, crowded housing and Inuit ethnicity were associated with LTBI after adjusting for other SDH. In addition to strong screening and treatment programmes, alleviating the chronic housing shortage will be a key element in the elimination of TB in the Canadian Inuit Nunangat.
PubMed ID
30728201 View in PubMed
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TB screening in Canadian health care workers using interferon-gamma release assays.

https://arctichealth.org/en/permalink/ahliterature121339
Source
PLoS One. 2012;7(8):e43014
Publication Type
Article
Date
2012
Author
Alice Zwerling
Mihaela Cojocariu
Fiona McIntosh
Filomena Pietrangelo
Marcel A Behr
Kevin Schwartzman
Andrea Benedetti
Nandini Dendukuri
Dick Menzies
Madhukar Pai
Author Affiliation
Department of Epidemiology, Biostatistics & Occupational Health, McGill University, Montreal, Canada.
Source
PLoS One. 2012;7(8):e43014
Date
2012
Language
English
Publication Type
Article
Keywords
Adult
Canada
Cross-Sectional Studies
Female
Health Personnel
Humans
Interferon-gamma - metabolism
Male
Mass Screening - methods
Middle Aged
Tuberculin Test
Tuberculosis - diagnosis - metabolism
Abstract
While many North American healthcare institutions are switching from Tuberculin Skin Test (TST) to Interferon-gamma release assays (IGRAs), there is relatively limited data on association between occupational tuberculosis (TB) risk factors and test positivity and/or patterns of test discordance.
We recruited a cohort of Canadian health care workers (HCWs) in Montreal, and performed both TST and QuantiFERON-TB Gold In Tube (QFT) tests, and assessed risk factors and occupational exposure.
In a cross-sectional analysis of baseline results, the prevalence of TST positivity using the 10 mm cut-off was 5.7% (22/388, 95%CI: 3.6-8.5%), while QFT positivity was 6.2% (24/388, 95%CI: 4-9.1%). Overall agreement between the tests was poor (kappa=0.26), and 8.3% of HCWs had discordant test results, most frequently TST-/QFT+ (17/388, 4.4%). TST positivity was associated with total years worked in health care, non-occupational exposure to TB and BCG vaccination received after infancy or on multiple occasions. QFT positivity was associated with having worked as a HCW in a foreign country.
Our results suggest that LTBI prevalence as measured by either the TST or the QFT is low in this HCW population. Of concern is the high frequency of unexplainable test discordance, namely: TST-/QFT+ subjects, and the lack of any association between QFT positivity and clear-cut recent TB exposure. If these discordant results are indeed false positives, the use of QFT in lieu of TST in low TB incidence settings could result in overtreatment of uninfected individuals.
Notes
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PubMed ID
22916197 View in PubMed
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Tuberculosis and homelessness in Montreal: a retrospective cohort study.

https://arctichealth.org/en/permalink/ahliterature130100
Source
BMC Public Health. 2011;11:833
Publication Type
Article
Date
2011
Author
Jason Tan de Bibiana
Carmine Rossi
Paul Rivest
Alice Zwerling
Louise Thibert
Fiona McIntosh
Marcel A Behr
Dick Menzies
Kevin Schwartzman
Author Affiliation
Respiratory Epidemiology and Clinical Research Unit, Montreal Chest Institute, McGill University, Montreal, Quebec, Canada.
Source
BMC Public Health. 2011;11:833
Date
2011
Language
English
Publication Type
Article
Keywords
Adult
Female
Genotype
Homeless Persons
Humans
Male
Middle Aged
Mycobacterium tuberculosis - genetics - isolation & purification
Odds Ratio
Quebec - epidemiology
Retrospective Studies
Tuberculosis - drug therapy - epidemiology - transmission
Urban Population
Abstract
Montreal is Canada's second-largest city, where mean annual tuberculosis (TB) incidence from 1996 to 2007 was 8.9/100,000. The objectives of this study were to describe the epidemiology of TB among homeless persons in Montreal and assess patterns of transmission and sharing of key locations.
We reviewed demographic, clinical, and microbiologic data for all active TB cases reported in Montreal from 1996 to 2007 and identified persons who were homeless in the year prior to TB diagnosis. We genotyped all available Mycobacterium tuberculosis isolates by IS6110 restriction fragment length polymorphism (IS6110-RFLP) and spoligotyping, and used a geographic information system to identify potential locations for transmission between persons with matching isolates.
There were 20 cases of TB in homeless persons, out of 1823 total reported from 1996-2007. 17/20 were Canadian-born, including 5 Aboriginals. Homeless persons were more likely than non-homeless persons to have pulmonary TB (20/20), smear-positive disease (17/20, odds ratio (OR) = 5.7, 95% confidence interval (CI): 1.7-20), HIV co-infection (12/20, OR = 14, 95%CI: 4.8-40), and a history of substance use. The median duration from symptom onset to diagnosis was 61 days for homeless persons vs. 28 days for non-homeless persons (P = 0.022). Eleven homeless persons with TB belonged to genotype-defined clusters (OR = 5.4, 95%CI: 2.2-13), and ten potential locations for transmission were identified, including health care facilities, homeless shelters/drop-in centres, and an Aboriginal community centre.
TB cases among homeless persons in Montreal raise concerns about delayed diagnosis and ongoing local transmission.
Notes
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PubMed ID
22034944 View in PubMed
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Source
Health Place. 2009 Sep;15(3):777-83
Publication Type
Article
Date
Sep-2009
Author
Andrew Carter
Alice Zwerling
Sherry Olson
Terry-Nan Tannenbaum
Kevin Schwartzman
Author Affiliation
Montreal Chest Institute, Montreal, Quebec, Canada H2X 2P4.
Source
Health Place. 2009 Sep;15(3):777-83
Date
Sep-2009
Language
English
Publication Type
Article
Keywords
Adolescent
Adult
Child
Child, Preschool
Cities - epidemiology
Databases as Topic
Female
Humans
Infant
Infant, Newborn
Male
Middle Aged
Quebec - epidemiology
Tuberculosis - epidemiology
Young Adult
Abstract
Unrecognized tuberculosis transmission outside the household has led to "micro-epidemics". We sought to evaluate how frequently locations outside the household were addressed in tuberculosis contact investigations, and to identify associated patient factors. We reviewed all tuberculosis patients reported in Montreal, Canada, during 1996-2004. Among this largely foreign-born patient population, investigation of locations outside the household was limited: there was documented attendance at 1 non-household location for 40% of the most contagious patients. Given complex, dispersed patterns of work, educational attendance, social activity, and transportation, contact investigation strategies may warrant reevaluation in large cities such as Montreal.
PubMed ID
19233710 View in PubMed
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