Dynamics of influenza A virus transmission in swine herds and analysis of risk factors for recurrent infections
Bibliographic record
Abstract
An investigation of the circulation of influenza A virus (IAV) and dynamics of the disease in swine populations is described in this thesis. The advent of more complex swine production systems can lead to changes in the pattern of disease making it difficult to predict IAV outbreaks and develop control programs. Factors such as host immunity, genetic and antigenic characteristics of the viruses, and fluctuations of temperature and humidity (seasonality), can be associated with the maintenance of the infection in swine populations. A longitudinal study evaluated, in two different cohorts, the dynamics of IAV circulation in multi-source nursery herds and identified risk factors associated with infection in nursery pigs. In addition, the circulation of IAVs between weaning and market age was characterized on the basis of development of antibody response and molecular epidemiology of detected viruses. Finally, a cross-sectional study was used to evaluate the association between environmental measurements such as temperature and humidity, and the presence of antibodies for two specific IAV. Virological tests showed a high prevalence of swine influenza and that influenza virus can circulate during the nursery phase in a cyclical pattern, with pigs becoming infected more than once with the same virus within a short time. The recurrent infection with the same virus was associated with the presence of maternal antibodies for a heterologous virus. In addition, the existence of antibodies titers for IAV other than the isolated virus confirmed that more than one viral subtype can circulate in the same population. Temperature and relative humidity can also be associated with development of influenza infection in swine populations based on cumulative exposure to the viruses. In conclusion, the research findings described in this thesis demonstrate that IAV transmission in complex swine systems can involve multiple virus subtypes and be influenced by environment and management factors, making the control of IAV complicated.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 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) | 0.001 | 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".