An unusual case of haemorrhagic bursa in a pullet flock associated with a genogroup 2 infectious bursal disease virus
Bibliographic record
Abstract
An unusual case of infectious bursal disease (IBD) was observed in eight-week-old commercial caged pullets. This flock (House 1) exhibited a one-day spike in mortality. On gross necropsy examination, enlarged, diffusely haemorrhagic bursas were observed. This lesion has been frequently described in cases of very virulent infectious bursal disease virus (vvIBDV). A five-week-old caged pullet flock (House 2) in an adjacent building did not display haemorrhagic bursa lesions. Microscopic examination of bursas from the eight-week-old pullets in House 1 showed marked diffuse haemorrhages and extensive lymphoid necrosis. Histopathology of bursas from the five-week-old pullets in House 2 showed severe, diffuse lymphoid depletion without haemorrhages. IBD ELISA results from birds in House 1 at 9 weeks had a GMT of 6395 and birds in House 2 had a GMT of 82 in the same timeframe. Diagnostic testing for avian influenza virus, Mycoplasma gallisepticum, Mycoplasma synoviae, virulent Newcastle disease virus, infectious bronchitis virus, infectious laryngotracheitis virus, chicken anaemia virus and fowl pox virus were negative. The predicted amino acid sequence of the hypervariable region of VP2 indicated the IBDV observed in both flocks (1/chicken/USA/1300OH/19 from House 1 and 1/chicken/USA/1301OH/19 from House 2) was identical and was not a vvIBDV. Their sequences were similar to a genogroup 2 IBDV from Ontario, Canada (EF138967). No mortality was observed when the 1/chicken/USA/1300OH/19 virus was inoculated into specific-pathogen-free (SPF), four-week-old pullets. Gross and microscopic lesions were observed in bursa tissue, but the bursal haemorrhages observed in the original field case were not reproduced in challenged SPF pullets.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.004 | 0.002 |
| 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".