INFECTIOUS DISEASE CQ\CTION

Molecular epidemiology of tuberculosis in the territory in Canada

1 1 2 3 Sara Christianson , Meenu K. Sharma • , Maureen Baikie , Elaine Randell3 and Joyce Wolfe1*

1 Public Health Agency of Canada, Winnipeg, MB, Canada; 2 Department of Medical Microbiology, University of , Winnipeg, MB, Canada; 3Department of Health and Social Services, Government of Nunavut, , NU, Canada

Introduction data were analysed in BioNumerics 5.0 (Applied Maths, Tuberculosis (rB), caused by the organism Mycobacteriwn Belgium). Dendrograms for MIRU-VNTR data were tuberculosis, is a global health problem, with more than 8.5 created using the categorical coefficient and UPGMA. million cases and more than 1.2 million deaths reported in 2010 (1). While worldwide rates of TB remain high, first­ Results world countries, including Canada, have typically experi­ The 24 locus-MIRU-VNTR data clusters into 2 major enced much lower rates than those seen in third world groups (clusters A and B) containing 10 8 of the isolates, 2 countries. Despite this fact, in 2010, the Canadian territory smaller groups (C and D) that account for 12 of the of Nunavut saw rates of TB more than 65 times the isolates and 4 unique patterns. Cluster A contains 39 Canadian national average and double their previous isolates and is predominated by isolates from Cape year's rate, with approximately 304 cases per 100,000 Dorset. Eighty-seven percent of the Cape Dorset isolates population (2). fall into this group. The MIRU-VNTR pattern for Molecular genotyping, such as Mycobacterial Inter­ Cluster B differs from that of Cluster A at locus 2163b. spersed Repetitive Unit Variable Number of Tandem This cluster of 69 isolates contains the majority of Repeat (MIRU-VNTR) genotyping, is an invaluable tool isolates. Fifty-nine of Cluster B isolates are from Iqaluit, in the public health approach to investigating and while all 3 isolates from are located in this curtailing TB outbreaks (3). In this study, we aimed to cluster. Cluster C is closely related to Cluster B, differing get a more accurate picture of the current state of TB in at locus 3171. This small set of 5 isolates is entirely Nunavut by comparing MIRU-VNTR genotyping pat­ associated with samples collected in Iqaluit. Eighty-nine terns with the regions where the patients sought medical percent of the Iqaluit isolates fall into clusters B and C. attention. Seven isolates were submitted from Arviat, all of which belonged to a 4th cluster (Cluster D), not closely related Methods to clusters A, B and C. Locus 2163b routinely did not One hundred and twenty four M. tuberculosis isolates amplify in this MIRU-VNTR pattern. Four samples had collected from the Nunavut territory between January unique MIRU-VNTR types. Three of the unique samples 2009 and January 2010 were analysed. These isolates were were from Iqaluit and 1 sample was the sole isolate from collected at 8 different locations in the territory. The . locations and the number of isolates submitted by each are Iqaluit (72), Cape Dorset (37), Arviat (7), Qikiqtar­ Discussion juaq (3), (2), Repulse Bay (1), Clyde River We have used MIRU-VNTR genotyping to investigate (1) and Igloolik (1). the current picture of TB in Nunavut. Genotyping has DNA was extracted from actively growing cultures by indicated that there are predominantly 4 distinct strains boiling a cell suspension in tris-EDTA buffer for 10 currently in circulation. Three of these 4 strains are minutes followed by sonication for 15 minutes. Samples closely related, with one being geographically distinct, were spun down and the supernatant containing the isolated primarily in the Cape Dorset region. The other 2 DNA was removed from the cell debris. closely related strains are primarily isolated in the Iqaluit Genotyping was performed using the 24 locus MIRU­ area. The appearance of a single locus variant in the VNTR set according to the MIRU-VNTR genotyping Iqaluit strains points to the possible evolution of this Technical Guide available at: h ttp://88.198. 5.195/MIRU/ outbreak, or the possibility of 2 originating strains, and, files/MIRUVNTRtypingn1anualv4-l.pdf. The resulting therefore, 2 simultaneous outbreaks. This information

Citation: Int J Circumpdar Health 2013, 72: 22447 - http://dx.doi. org/10.34021ijch.v72i0.22447 711 Infectious Disease

can be useful in conjunction with traditional epidemio­ References logical data in the location of contacts and sites of transmission. 1. World Health Organization. Global tuberculosis control: WHO report 2011. Geneva: World Health Organization; 2011. 2. MacDonald N, Hebert PC, Stanbrook MB. Tuberculosis in Conclusions Nunavut: a century of failure. CMAJ. 2011;183:741-3. Genotyping data is especially valuable in small commu­ 3. Oelemann MC, Diel R, Vatin V, Haas W, Rusch-Gerdes S, nities such as those in Nunavut, where there may be a Locht C, et al. Assessment of an optimized mycobacterial interspersed repetitive- unit-variable-number tandem-repeat great deal of crossover in contact investigations within typing system combined with spoligotyping for population­ 2 simultaneous outbreak events. The discrimination of based molecular epidemiology studies of tuberculosis. J Clin strains through MIRU-VNTR genotyping is valuable Microbiol. 2007;45:691-7. towards social network and traditional epidemiological investigations as well as helpful in infection control *Joyce Wolfe applications. Email: [email protected]

712 Citatim: Int J Circumpolar Health 201 3, 72: 22447 - http://dx.doi.org/10.34021ijch.v72i0.22447