Human Illness and Isolation of Low‐Pathogenicity Avian Influenza Virus of the H7N3 Subtype in British Columbia, Canada
Bibliographic record
Abstract
To the Editor —In the 15 October 2005 issue of the Journal Puzelli et al. reported the first serological evidence for transmission of low-pathogenicity avian influenza (LPAI) viruses to humans and suggested that all previous human infections have involved only high-pathogenicity avian influenza (HPAI) strains [1]. We would like to respond to this assertion, on the basis of our experience with the H7N3 subtype of avian influenza virus in British Columbia, Canada, during 2004 Between 16 February and 18 May 2004, an outbreak of HPAI subtype H7 occurred among poultry in the Fraser Valley of British Columbia. The index farm had 2 flocks of chickens—an older flock of egg layers and a younger flock of broilers, housed in separate barns. On 4 February, the older flock experienced a transient reduction in egg production and a slight increase in mortality (0.5% over 72 h), which subsequently resolved. On 16 February, the younger flock, in the adjacent barn, experienced a sudden substantial increase in mortality (>25% over 48 h). Virus from the first flock was characterized as LPAI subtype H7N3 (intravenous pathogenicity index [IVPI], 0), and that from the second flock was characterized as HPAI subtype H7N3 (IVPI, 2.96). Conversion of this strain’s pathogenicity was attributed to a recombination event in which a 21-nt sequence from the matrix gene was inserted into the protease-cleavage site of the hemagglutinin gene. By 5 April, 20 commercial flocks in the region had become infected, and preemptive depopulation of all poultry (population, ∼19 million) in the Fraser Valley was initiated. Ultimately, 42 commercial farms and 11 backyard flocks, representing ∼1.3 million birds, were considered to have been infected with HPAI subtype H7N3 [2–4]
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.008 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.005 | 0.005 |
| 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".