SETTING: In Canada, tuberculosis (TB) is increasingly an urban health problem. Montreal is Canada's second-largest city and the second most frequent destination for new immigrants and refugees. OBJECTIVES: To detect spatial aggregation of cases, areas of excess incidence and local 'hot spots' of transmission in Montreal. DESIGN: We used residential addresses to geocode active TB cases reported on the Island of Montreal in 1996-2000. After a hot spot analysis suggested two areas of overconcentration, we conducted a spatial scan, with census tracts (population 2500-8000) as the primary unit of analysis and stratification by birthplace. We linked these analyses with genotyping of all available Mycobacterium tuberculosis isolates, using IS6110-RFLP and spoligotyping. RESULTS: We identified four areas of excess incidence among the foreign-born (incidence rate ratios 1.3-4.1, relative to the entire Island) and one such area among the Canadian-born (incidence rate ratio 2.3). There was partial overlap with the two hot spots. Genotyping indicated ongoing transmission among the foreign-born within the largest high-incidence zone. While this zone overlapped the area of high incidence among Canadian-born, genotyping largely excluded transmission between the two groups. CONCLUSIONS: In a city with low overall incidence, spatial and molecular analyses highlighted ongoing local transmission.
SETTING: In Canada, tuberculosis (TB) is increasingly an urban health problem. Montreal is Canada's second-largest city and the second most frequent destination for new immigrants and refugees. OBJECTIVES: To detect spatial aggregation of cases, areas of excess incidence and local 'hot spots' of transmission in Montreal. DESIGN: We used residential addresses to geocode active TB cases reported on the Island of Montreal in 1996-2000. After a hot spot analysis suggested two areas of overconcentration, we conducted a spatial scan, with census tracts (population 2500-8000) as the primary unit of analysis and stratification by birthplace. We linked these analyses with genotyping of all available Mycobacterium tuberculosis isolates, using IS6110-RFLP and spoligotyping. RESULTS: We identified four areas of excess incidence among the foreign-born (incidence rate ratios 1.3-4.1, relative to the entire Island) and one such area among the Canadian-born (incidence rate ratio 2.3). There was partial overlap with the two hot spots. Genotyping indicated ongoing transmission among the foreign-born within the largest high-incidence zone. While this zone overlapped the area of high incidence among Canadian-born, genotyping largely excluded transmission between the two groups. CONCLUSIONS: In a city with low overall incidence, spatial and molecular analyses highlighted ongoing local transmission.
Authors: Shelly Bolotin; David C Alexander; Jennifer L Guthrie; Steven J Drews; Frances Jamieson Journal: Can Respir J Date: 2010 May-Jun Impact factor: 2.409
Authors: H Lin; S Shin; J A Blaya; Z Zhang; P Cegielski; C Contreras; L Asencios; C Bonilla; J Bayona; C J Paciorek; T Cohen Journal: Epidemiol Infect Date: 2010-12-23 Impact factor: 2.451
Authors: Paul Brassard; Travis Salway Hottes; Richard G Lalonde; Marina B Klein Journal: Can J Infect Dis Med Microbiol Date: 2009 Impact factor: 2.471
Authors: 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 Journal: J Clin Microbiol Date: 2009-02-11 Impact factor: 5.948