title: Reemergence and amplification of tuberculosis in the Canadian arctic.
abstract: BACKGROUND
  Between November 2011 and November 2012, a Canadian village of 933 persons had 50 culture-positive cases of tuberculosis, with 49 sharing the same genotype.
  
  
  METHODS
  We performed Illumina-based whole-genome sequencing on Mycobacterium tuberculosis isolates from this village, during and before the outbreak. Phylogenetic trees were generated using the maximum likelihood method.
  
  
  RESULTS
  Three distinct genotypes were identified. Strain I (n = 7) was isolated in 1991-1996. Strain II (n = 8) was isolated in 1996-2004. Strain III (n = 62) first appeared in 2007 and did not arise from strain I or II. Within strain III, there were 3 related but distinct clusters: IIIA, IIIB, and IIIC. Between 2007 and 2010, cluster IIIA predominated (11 of 22 vs 2 of 40; P < .001), whereas in 2011-2012 clusters IIIB (n = 18) and IIIC (n = 20) predominated over cluster IIIA (n = 11). Combined evolutionary and epidemiologic analysis of strain III cases revealed that the outbreak in 2011-2012 was the result of ≥6 temporally staggered events, spanning from 1 reactivation case to a point-source outbreak of 20 cases.
  
  
  CONCLUSIONS
  After the disappearance of 2 strains of M. tuberculosis in this village, its reemergence in 2007 was followed by an epidemiologic amplification, affecting >5% of the population.
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health Department of McGill International TB Centre The Research Institute of the McGill University Health Centre.
authors.forename: Robyn S
authors.initials: RS
authors.lastname: Lee
authors.affiliation: The Research Institute of the McGill University Health Centre.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Radomski
authors.affiliation: Nunavik Regional Board of Health and Social Services, Kuujjuaq.
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Proulx
authors.affiliation: Department of Medicine Department of Human Genetics, McGill University Department of McGill International TB Centre The Research Institute of the McGill University Health Centre.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Manry
authors.affiliation: The Research Institute of the McGill University Health Centre.
authors.forename: Fiona
authors.initials: F
authors.lastname: McIntosh
authors.affiliation: Mycobacteriology Laboratory, Royal Victoria Hospital.
authors.forename: Francine
authors.initials: F
authors.lastname: Desjardins
authors.affiliation: Laboratoire de Santé Publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada.
authors.forename: Hafid
authors.initials: H
authors.lastname: Soualhine
authors.affiliation: The Research Institute of the McGill University Health Centre.
authors.forename: Pilar
authors.initials: P
authors.lastname: Domenech
authors.affiliation: Department of McGill International TB Centre The Research Institute of the McGill University Health Centre.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Reed
authors.affiliation: The Research Institute of the McGill University Health Centre Respiratory Epidemiology and Clinical Research Unit, Montreal Chest Institute, McGill University Health Centre.
authors.forename: Dick
authors.initials: D
authors.lastname: Menzies
authors.affiliation: Department of McGill International TB Centre The Research Institute of the McGill University Health Centre.
authors.forename: Marcel A
authors.initials: MA
authors.lastname: Behr
mesh_terms: D000293:Adolescent; D000328:Adult; D001110:Arctic Regions; D002170:Canada / Q000453:epidemiology; D021821:Communicable Diseases, Emerging / Q000453:epidemiology* / Q000382:microbiology; D004196:Disease Outbreaks; D005260:Female; D016680:Genome, Bacterial; D005838:Genotype; D006801:Humans; D008297:Male; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D014376:Tuberculosis / Q000453:epidemiology* / Q000382:microbiology; D055815:Young Adult
keywords: Mycobacterium tuberculosis; infectious disease outbreaks; molecular epidemiology; transmission; whole genome sequencing