Tuberculosis in the Inuit Community of Quebec, Canada

Abstract

In low-incidence countries targeting tuberculosis (TB) elimination, TB remains a problem of a few high-risk groups. In Canada, Aboriginals, and particularly the Arctic Inuit communities, have witnessed dramatic decreases in TB during the 1960s to 1970s, but rates remain at least 10 to 20 times higher than the national average. We are describing the results of an integrated traditional and molecular epidemiology study of all culture-positive Mycobacterium tuberculosis cases in the Arctic Inuit communities of Quebec from 1990 until 2000. The demographic characteristics of the 46 TB cases included in the study were most notable for a bimodal age distribution (48% under 25 years). Genotyping analysis using multiple modalities (IS6110 restriction fragment length polymorphism, spoligotype, mycobacterial interspersed repetitive units-variable number tandem repeats) showed that 76% (35/46) of TB cases were clustered (six clusters, median size four cases) and estimated that at least 62.5% of TB cases were due to ongoing transmission. By integrating the epidemiologic and genotyping data, we observed that the genotyping clustering results were concordant with recognized epidemiologic links but most notably identified previously unrecognized intervillage transmission. This study demonstrates significant ongoing transmission in a geographically isolated, low-density population. In a resource-rich country such as Canada, these communities illustrate some of the persistent challenges of TB control and elimination.

Dispersal of Mycobacterium tuberculosis via the Canadian fur trade

“…3); we did not have detailed geographic data that would allow us to classify M. tuberculosis strains from Manitoba according to the scheme we used in Saskatchewan (i.e., NRS vs. RS). We note that molecular epidemiological studies of other historically remote/traditional regions are consistent with low genetic diversity of the M. tuberculosis population (30,31).…”

Population genomics ofMycobacterium tuberculosisin the Inuit

“…In contrast to the global diversity of M. tuberculosis strains (1-3), we have previously observed limited genetic diversity in the Nunavik region of Québec (4). One possible explanation is a founder strain, wherein genetic similarity is due to a single recent introduction of a bacterium and may not necessarily represent ongoing spread between communities.…”

International Circumpolar Surveillance, An Arctic Network for the Surveillance of Infectious Diseases

“…The introduction of antimicrobial drugs and vaccines and the establishment of robust public health systems have greatly reduced illness and deaths caused by infectious diseases in many Arctic countries. Despite these interventions, high rates of invasive diseases caused by bacterial pathogens such as Streptococcus pneumoniae (3)(4)(5), Haemophilus infl uenzae (6), Helicobacter pylori (7,8), and Mycobacterium tuberculosis (9)(10)(11)(12) continue to persist. In addition, the emergence of antimicrobial drug resistance among bacterial pathogens once easily treated with commonly used antibiotics (10,(13)(14)(15), the entrance of HIV into Arctic communities (10,16), and the specter of pandemic infl uenza or the sudden emergence and introduction of new viral pathogens such as severe acute respiratory syndrome (SARS) are of increasing concern to residents, governments, and public health authorities of all Arctic countries.…”