Aspects of the epidemiology and dynamics of the spread of Escherichia coli O157:H7 in different cattle production systems
Bibliographic record
Abstract
To address important aspects of the epidemiology and dynamics of the spread of 'Escherichia coli' O157:H7 ('E. coli ' O157) in different cattle production systems, three studies were conducted: a cross-sectional study of 119 cow-calf operations in Ontario, Canada, a longitudinal study of 168 feedlot steers, and a repeated cross-sectional study of 150 dairy farms in Ohio, USA. Risk factors associated with the prevalence of 'E. coli' O157 among cattle in cow-calf operations included the presence of pigs on farm, use of corn silage supplementation in winter, number of times cattle were taken to a show in the previous 12 months and the proportion of cows that make up the total herd. However, for dairy cattle, risk factors associated with 'E. coli' O157 shedding included contact between adult cattle and calves, the types or number of ventilation and manure management systems on the farm as well as the number of European starlings ('Sturnus vulgaris') per milking cow. Furthermore, in order to investigate the effect of dietary interventions on 'E. coli' O157 shedding in cattle, a group of feedlot steers was followed throughout a feeding period of 14 weeks. We found that the type of corn and feed supplement in the diet had an impact on the shedding of'E. coli ' O157 in this group of animals, but the effect may vary if there is a super-shedding pen-mate present on the same sampling date depending on the type of diagnostic protocol used to identify shedding animals. However, none of these factors affected the sensitivity of the diagnostic protocols and apparent differences in the effect of dietary factors on the shedding of 'E. coli' O157 based on RAMS-IMS or fecal-IMS is likely due to their impact on other bacterial species present in the gastrointestinal tract. Understanding the epidemiology of this pathogen in different cattle environments, the role of non-bovine species in maintaining 'E. coli ' O157 and in the manner in which diagnostic tests may be affecting our perception of the epidemiology of 'E. coli' O157 in cattle are discussed in this thesis as critical points for controlling this zoonotic pathogen along the farm-to-fork continuum.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".