International Union for Circumpolar Health Ministry of Public Health and Social Development of RF Russian Academy of Medical Sciences Siberian Branch of Russian Academy of Medical Sciences Siberian Branch of Russian Academy of Sciences Medical Polar Fund “Science” The Northern Forum

Abstracts

Seminar Infection Diseases in Arctic

Objectives: To detect clusters of Mycobacterium tuberculosis infections through analysis of mapping indistinguishable fingerprinting patterns generated by IS6110- RFLP (Restricted Fragment Length Polymorphism) with the cases’ Northwest Territories (NWT) residences lived during their lifetime and relationships indicated through standard contact tracing.

Study design: In the Northwest Territories (NWT), all isolates of Mycobacterium tuberculosis are referred to the Provincial Laboratory in Edmonton Alberta. All initial cultures from confirmed cases were included in this study from January 1, 2000 to July 21, 2005, totaling 41 isolates. The clustered DNA fingerprints were mapped to show geographical links. Epidemiology data including age, gender, ethnicity and contact linking through standard contact tracing to demonstrate clustering.

Methods: DNA was extracted, quantified, restricted and hybridized with the insertion element IS6110 using the standardized protocol. All the fingerprinting patterns generated were entered into the BioNumerics database and comparison was made using dice coefficient with 1% tolerance. Epidemiology data review included communities in the Northwest Territories that the case resided from birth to date of diagnosis, contact tracing linking between cases through data review using a database application called iPHIS and chart review. Latent TB infection was defined as having tuberculin skin test greater than 10mm two years prior to diagnosis with active tuberculosis. Mapping each genotype was done using NWT Centre for Geomatics.

Results: A total of 41 isolates of M. tuberculosis were typed by IS6110- RFLP and analysed by the BioNumerics software. The analysis of the fingerprints showed that 23/41 isolates were grouped into 5 clusters. The major cluster consisted of 12 isolates where the cases resided in 6 of the 33 communities in the NWT. Further analysisof the case linking through contact tracing showed 7% of the major cluster were epidemiologically linked. Comparing all 41 isolates, 3 had epidemiological links (household contact) but different fingerprinting patterns. Seventy six percent of the cases had records of being infected using tuberculin skin test as an indicator of previous infection, i.e., infected at least 2 years prior to active disease.

Conclusions: Using molecular typing with IS6110-RFLP in surveillance, we have identified five clusters of TB in the NWT. The largest cluster of the same RFLP fingerprint had 12 isolates, through conventional contact tracing, only 3 were epi-linked. DNA fingerprinting is an important tool for detecting clusters otherwise unknown.

Note. Abstracts are published in author's edition

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Last update: 06-Jul-2012 (11:52:05)