Breeder demographic survey and molecular period prevalence of equid alphaherpesvirus 1 in Ontario
Bibliographic record
Abstract
Equid alphaherpesvirus 1 (EHV-1) causes disease in all ages of horses, from abortion and neonatal death to encephalomyelopathy in adults. The main objective of this thesis was to investigate the current opinions of breeders in Ontario, provide prevalence estimates, and describe current vaccine use for EHV-1, which have not been studied. A survey of 88 breeders in Ontario indicated 72.7 % currently vaccinate their herds, and most consult veterinarians for assistance only when encountering abortions, not respiratory disease. Most herds were vaccinated either twice annually or using a "pre-foaling protocol". In a follow up study, a period prevalence estimate was generated by sampling 381 broodmares from 42 farms across Ontario every two months from December 2016 through October 2017. Samples were collected from the nose, blood and vaginal mucosa and analysed using droplet digital PCR (ddPCR). A total of 85.0 % of broodmares were positive for EHV-1 at some point during the sampling period, and vagina was identified as a source of EHV-1, with viral DNA collected more often from the vagina than the nose. Using mixed logistic regression models, we found no association between virus presence and age or breed. Nasal shedding occurred more often in pregnant mares, and vaccination was only associated with reduced virus in blood samples. When describing the virus neutralization titer response in this population, 32.3 % of mares did not respond to vaccination, and 48.5 % of all mares had no biologically significant changes in titers over the sampling period. Using IgG subisotyping, differing immune responses were observed depending on vaccine product most recently administered. There was no association between IgG subisotype and neutralizing virus titers, nor was there an association with serological titers and ddPCR positivity. Titers did generally increase with age and were typically highest in Standardbred and Thoroughbreds. In conclusion, although most respondents were concerned about EHV-1 enough to vaccinate, many did not, leaving the population at risk for outbreaks. Although vaccines were widely used, they were not consistent in their immune stimulation, potentially creating a false sense of security among breeders. Furthermore, most broodmares harbour the virus and shed intermittently.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".