Outbreaks of West Nile virus in captive waterfowl in Ontario, Canada
Bibliographic record
Abstract
The detrimental effects of West Nile virus (WNV) have been well characterized in several taxonomic groups of North American birds, such as corvids and raptors. Relatively less is known about the virus' effects in waterfowl species, many of which are abundant in North America and occupy habitats, for example wetlands and marshes, likely to harbour dense mosquito populations. In two successive years, outbreaks of WNV-associated disease were observed in waterfowl at a rehabilitation centre. In the present report, clinical and pathological findings are provided for seven mallards (Anas platyrhynchos) and one Canada goose (Branta canadensis) that developed acute disease and either died or were killed humanely. The most severe and consistent microscopic lesion in mallards was myocardial degeneration and coagulative necrosis consistent with acute heart failure. The Canada goose had necrotizing myocarditis. Other lesions included pulmonary perivascular oedema, lymphoplasmacytic hepatitis, and splenic and bursal lymphoid depletion. WNV infection was confirmed using reverse transcriptase-polymerase chain reaction and immunohistochemical staining. Myofibres within all cardiac muscle layers had positive immunohistochemical staining, as did blood vessel walls in the heart and spleen. These results suggest that juvenile mallards are highly susceptible to fatal WNV-associated cardiac failure, and confirm that adult Canada geese are susceptible to fatal WNV-associated disease. The synchronous timing of clinical disease and death in these waterfowl are consistent with WNV mosquito-borne infections within a WNV transmission focus during the summer (July and August) of 2012 and 2013.
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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 | 0.001 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".