A cluster of tuberculosis cases linked to smoking: An under-recognized challenge for tuberculosis elimination
Bibliographic record
Abstract
BACKGROUND: Smoking is known to increase the risk of tuberculosis (TB) infection, active TB disease, relapse following treatment and death from TB, but its significance is often underappreciated as a potentially reversible risk factor in public health and clinical TB practice in Canada. OBJECTIVE: To review the current evidence on smoking and the risk of TB, describe a cluster investigation of local TB transmission related to smoking in Toronto, Ontario, and discuss the practical implications of smoking for TB elimination in Canada. INVESTIGATION AND PUBLIC HEALTH RESPONSE: Three TB cases were identified at the same workplace over a two year period. All three strains matched on genotyping. Extensive interviews with the cases and workplace / building managers confirmed that the three cases did not work or socialize together. The only epidemiologic link identified was that all three were regular smokers and used the same location outside the building for smoke breaks. A building ventilation assessment confirmed that unfiltered air was not recirculated between floors. Based on the epidemiological and laboratory evidence, we determined that transmission likely occurred at the partly-sheltered smoking area outside of the worksite. We established and advertised an active case-finding clinic on-site to all workers who frequented smoking areas near the building. Of 60 individuals screened with tuberculin skin testing (TST), no additional active TB cases were identified. One Canadianborn person was found to be TST positive. We also offered TB education sessions to all staff in the building, and used the opportunity to promote smoking cessation for interested individuals. CONCLUSION: This cluster shows compelling evidence for smoking-related transmission of TB in Toronto. The World Health Organization has called for integration of anti-smoking efforts as a key strategy toward TB elimination. Opportunities to integrate smoking and TB work in Canada include assessment for smoking-related transmission during contact investigations, routine use of smoking cessation supports for contacts and others with latent tuberculosis infection as well as those with active TB, and public health outreach.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.007 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".