Epidemiology and zoonotic potential of Cryptosporidium parvum in dairy calves in Ontario
Bibliographic record
Abstract
The work described in this thesis investigated the prevalence of 'Cryptosporidium parvum' in dairy calves in southern Ontario, and identified farm characteristics and management practices associated with within-herd prevalence of 'C. parvum' and the calf-level risk of shedding and diarrhea. In addition, the performance, cost and general user-friendliness of two simple and inexpensive tests for the detection of 'C. parvum ' in calf feces were assessed. Finally, the importance of ' C. parvum' in dairy calves as a source of human infections in Ontario was investigated by genotyping and sub-typing 'Cryptosporidium' isolates from humans and dairy calves. The point prevalence of the parasite in various studies ranged from 30 to 40%. Furthermore, in one study, 78% of 919 calves were found to be shedding ' C. parvum' oocysts, and 73% were diarrheic, within the first month of life. Several calf-level factors were significantly associated with the risk of 'C. parvum' shedding, including the feeding of milk replacer to young calves, use of calf diarrhea prophylaxis in pregnant cows, and the type of maternity facilities in which calves were born. Factors associated with an increased risk of diarrhea were leaving the calf with the dam for more than an hour after birth, and the birth of a calf in the summer as opposed to winter. Calves shedding 'C. parvum' oocysts had more than 4 times the odds of diarrhea than non-shedding calves. In the herd-level study, management practices associated with the within-herd prevalence of shedding included the use of calf scour prophylaxis, the feeding of milk replacer, and the presence of concrete flooring in calf pens. Assessment of the sucrose wet mount test used for this research, as well as a lateral immunochromatography test, showed that both tests performed well and were inexpensive and user friendly. All subtyped isolates from calves belonged to 'C. parvum' allele IIa. Three of the 11 'C. parvum' isolates from humans were of the same subtype as isolates from the calves, implying that ' C. parvum' oocysts shed by calves may be important sources of human cases of cryptosporidiosis in southern Ontario.
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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 | 0.002 |
| 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) | 0.001 | 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".