Active Tuberculosis among Homeless Persons, Toronto, Ontario, Canada, 1998–2007
Bibliographic record
Abstract
While tuberculosis (TB) in Canadian cities is increasingly affecting foreign-born persons, homeless persons remain at high risk.To assess trends in TB, we studied all homeless persons in Toronto who had a diagnosis of active TB during 1998-2007.We compared Canada-born and foreign-born homeless persons and assessed changes over time.We identifi ed 91 homeless persons with active TB; they typically had highly contagious, advanced disease, and 19% died within 12 months of diagnosis.The proportion of homeless persons who were foreign-born increased from 24% in 1998-2002 to 39% in 2003-2007.Among foreign-born homeless persons with TB, 56% of infections were caused by strains not known to circulate among homeless persons in Toronto.Only 2% of infections were resistant to fi rst-line TB medications.The rise in foreign-born homeless persons with TB strains likely acquired overseas suggests that the risk for drug-resistant strains entering the homeless shelter system may be escalating. I n Canada's major cities, tuberculosis (TB) is increasinglybecoming a disease of persons born outside Canada (foreign-born).In 2009 in the city of Toronto in Ontario, 94% of all persons with active TB were foreign-born (1).Although homeless and marginally housed persons represent a smaller proportion of TB case-patients, they remain a persistent high-risk population.Recent TB outbreaks and disease clusters among homeless persons have been reported in many cities in the United States (2-5) and have been associated with transmission at shelters, single-room-occupancy hotels, and rooming houses (which provide inexpensive rooms with shared bathrooms), prisons, and bars (6-10).Toronto is the largest city in Canada; among its population of 2.5 million persons, ≈50% were born outside Canada (11).Each year in Toronto, ≈29,000 persons use emergency shelters, and on any given night ≈5,000 are without homes (12).During 2001-2002, a large shelterbased TB outbreak occurred among homeless persons in Toronto.A coroner's inquest into the death of a homeless man in whom pulmonary TB developed during the course of this outbreak revealed the many challenges of diagnosing and managing TB in homeless populations (13).In response to the inquest and resulting jury recommendations, major changes to the management of homeless TB cases occurred in the public health and shelter systems, and local TB clinic capacity expanded.This case resulted in the creation of a public health team dedicated to case management, contact follow-up, advocacy, education, health promotion, and active case fi nding among the city's homeless and underhoused population.A comprehensive review of the population and molecular epidemiology, clinical features, management and health outcomes of homeless persons with TB in Canada is needed but lacking.To better understand and address the extent of disease in this vulnerable population, we studied TB among Toronto's homeless persons over a 10-year period. MethodsThe study population included all persons in Toronto for whom active TB had been reported to Toronto Public Health from January 1, 1998, through December 31, Active Tuberculosis among Homeless Persons, Toronto, Ontario,
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".