DNA fingerprinting substantiates finding of three epidemiologically distinct clusters of tuberculosis Yukon Territory, Canada, 2004-2008

Background: Tuberculosis (TB) incidence had risen in Yukon Territory since 2004 to reach 24.1 per 100,000 in 2008, five times the Canadian rate (4.8 per 100,000). One objective of this investigation was to determine epidemiological links between patients diagnosed from October 2004 to October 2008 in order to clarify patterns of ongoing transmission. Methods: Data on symptom onset, residential location and links between patients and their contacts were obtained by review of paper charts and electronic contact lists and interviews with public health nurses. The data were used to elucidate epidemiologic links and potential chains of transmission among patients. DNA fingerprinting of TB isolates was conducted by the National Reference Centre for Mycobacteriology, National Microbiology Laboratory, Winnipeg, Manitoba using the Mycobacterial Interspersed Repetitive Unit (MIRU) test. Results: Between October 2004 and October 2008, 20 patients were diagnosed with TB in three rural communities. The majority of diagnoses (12, 60%) occurred over a 49 month period (2004-2008) in one community. The remaining diagnoses occurred over four and three month periods (2008) in two communities (five, 25% and three, 15%). No links were found between patients from different communities. Although 16% (137/843) of all contacts were named by two or more patients, only 4% (5/137) of these contacts were named by patients from different communities. DNA fingerprinting of 10 (50%) of the patients (three, four and two in each community respectively) showed three distinct MIRU patterns, one for patients from each of the three communities. Conclusions: Although patients were diagnosed concurrently, traditional epidemiologic findings were corroborated by DNA fingerprinting results which demonstrated three distinct community-based clusters. DNA fingerprinting is a useful tool to support epidemiologic methods in TB outbreak investigations. For more information, email the presenter at: doctor.elliott@gmail.com

Author (s): 

Catherine T. Elliott (1), B. Hanley (2), B. Roberts (2), C. Stannard (2). (1) Canadian Field Epidemiology Program, Public Health Agency of Canada, Ottawa, Canada, (2) Yukon Health and Social Services, Whitehorse, Canada

Presenter (s): 
Dr. Catherine Elliott
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