Epidemiological insights from 11 years of active tuberculosis surveillance (2010-2020) and 6 years of voluntary latent tuberculosis infection surveillance (2015-2020) in Nunavut. A retrospective descriptive study.

BACKGROUND: Tuberculosis disease (TB) remains the leading infectious killer globally. Although Canada has a low overall TB incidence rate, it remains a significant public health concern in Nunavut territory, where the 2024 incidence rate was 87.5 per 100,000-14 times the national average. This disparity is exacerbated by limited healthcare access, the remoteness of Nunavut communities, and overcrowded living conditions. This study examines the epidemiology of TB and tuberculosis infection (TBI) in Nunavut and its communities using local data. METHOD: We analysed Nunavut surveillance data of TB cases from 2010 to 2020 to understand incidence rates at the territorial level and stratified by region, community, sex, and age. Treatment outcomes were also described. TBI program data from 2015 to 2020 were supplemented with community-wide screening (CWS) records. Descriptive statistics summarized key characteristics and proportions, while the modelling approach tested whether territorial TB incidence followed a dynamic temporal pattern rather than remaining constant, using generalized additive mixed models (GAMMs). RESULT: A total of 731 TB cases were reported from 2010 to 2020, along with 1538 TBI notifications between 2015 and 2020. Six communities accounted for 84% of all TB cases, mostly located in the Qikiqtani region. The majority of TB cases (61%) occurred in males and predominantly affected individuals aged 15 to 45 years (56%). Overall, 93% of TB cases were successfully treated. TBI treatment completion rates improved over time, rising from 69% in 2015 to 81% in 2020. Since 2018, over 60% of patients opted for shortened 12-week, once-weekly isoniazid-rifapentine regimen (3HP), likely contributing to improved completion. The models identified fluctuations in TB incidence during the study period, showing a non-linear relationship in both quarterly and monthly trends, with evidence of a significant seasonal (intra-annual cyclical) pattern throughout the year. CONCLUSION: Nunavut had the highest TB incidence rate in Canada between 2010 and 2020, with most cases in Qikiqtani region and among young males. TB treatment success was high, and TBI treatment completion improved, especially after introducing the shorter 3HP regimen. These insights highlight the need for region- and community-specific interventions to control TB effectively.