Invasive group A streptococcal infection outbreaks of type emm118 in a long-term care facility, and of type emm74 in the homeless population, Montréal, Quebec
Bibliographic record
Abstract
Background: Two invasive group A streptococcus (iGAS) infection outbreaks occurred in Montréal in 2016 and 2017; one in a long-term care facility (type emm118) and one in the community, primarily involving homeless people (type emm74).Objective: To describe two recent iGAS outbreaks in Montréal and highlight the challenges in dealing with these outbreaks and the need to tailor the public health response to control them.Methodology: All cases of iGAS were investigated and the isolates were sent to the laboratory for emm typing.In both outbreaks, cases of superficial group A streptococcus (GAS) infection were identified, through 1) systematic case detection accompanied by screening for asymptomatic carriers among residents and employees of the long-term care facility and 2) sentinel surveillance among homeless people.Visits were made to community organizations providing homeless services (including shelters) and social networks were analyzed to establish whether there were any links among cases of GAS infection (both invasive and noninvasive) and locations frequented.In both outbreaks, recommendations were made to service providers regarding enhancement of infection prevention and control measures.Results: In the long-term care facility, five cases of type emm118 iGAS were identified over a 22-month period, one of which resulted in death.All residents were screened and no carriers were identified.Among the employees, 81 (65%) were screened and four carriers were identified.Of those, one was a carrier of type emm118 GAS.All carriers were treated, and subsequent follow-up sampling on three carriers (including the one with emm118) was negative.In the community, 23 cases of type emm74 iGAS were detected over a 16-month period, four of which resulted in death.Half of the cases (n=12) were described as homeless, and six others were users of services for the homeless.Sentinel surveillance of superficial infections yielded 64 cultures with GAS, chiefly on the skin, including 51 (80%) of type emm74.An analysis of the social networks revealed the large number and variety of resources for the homeless used by the cases.Visits to the community organizations providing homeless services revealed the heterogeneity and precariousness of some of these services, the difficulties encountered in applying adequate health and hygiene measures, and the high degree of mobility amongst those who use these services.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".