Impact of Genotype on Scrapie Prevalence in Sheep
Author Information
Author(s): Angel Ortiz-Pelaez, Juana Bianchini
Primary Institution: Centre for Epidemiology and Risk Analysis, Veterinary Laboratories Agency, Weybridge, UK
Hypothesis
Does the genotype of sheep affect the prevalence of classical scrapie at the population level?
Conclusion
The study found that an increased proportion of the ARR allele in sheep reduces the overall risk of scrapie at the population level.
Supporting Evidence
- Increased prevalence of the ARR allele reduces the overall risk of scrapie.
- Genotypes associated with higher scrapie risk include ARR/AHQ, AHQ/VRQ, ARH/VRQ, and ARQ/VRQ.
- 67.2% of holdings had no positive cases of scrapie.
- Significant differences in genotype distribution were found across countries.
Takeaway
This study shows that if more sheep have a certain gene (the ARR allele), fewer of them get sick with scrapie.
Methodology
The study analyzed genotype data from sheep in the Compulsory Scrapie Flock Scheme and used statistical models to assess the relationship between genotype and scrapie prevalence.
Potential Biases
Potential bias from farmers altering breeding practices based on genotype information.
Limitations
The study may have biases due to the management practices of flocks and the inclusion of animals not present at the time of culling.
Participant Demographics
The study included sheep from 168 holdings across England, Wales, and Scotland.
Statistical Information
P-Value
p<0.01
Confidence Interval
95% CI: 0.58-0.82
Statistical Significance
p<0.05
Digital Object Identifier (DOI)
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