Will there be any more classical scrapie cases in sheep in Great Britain? A modelling study to predict future cases

Arnold, Mark; Rajanayagam, Brenda

doi:10.1017/s0950268820001855

Cited by 3 publications

(3 citation statements)

References 9 publications

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“…Breeding programs can contribute to the reduction of prevalence of the typical form of scrapie in sheep. Arnold and Rajamyagam [ 22 ] estimated an annual reduction of 28% in scrapie prevalence cases between 2005 and 2019 in Great Britain. Hagenaars et al [ 20 ] reported a trend for reduction of scrapie prevalence in active scrapie surveillance in Netherland between the years 2002 and 2008.…”

Section: Discussionmentioning

confidence: 99%

Prediction of Genetic Resistance for Scrapie in Ungenotyped Sheep Using a Linear Animal Model

Boareki

Schenkel

Kennedy

et al. 2021

Genes

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Selection based on scrapie genotypes could improve the genetic resistance for scrapie in sheep. However, in practice, few animals are genotyped. The objectives were to define numerical values of scrapie resistance genotypes and adjust for their non-additive genetic effect; evaluate prediction accuracy of ungenotyped animals using linear animal model; and predict and assess selection response based on estimated breeding values (EBV) of ungenotyped animals. The scrapie resistance (SR) was defined by ranking scrapie genotypes from low (0) to high (4) resistance based on genotype risk groups and was also adjusted for non-additive genetic effect of the haplotypes. Genotypes were simulated for 1,671,890 animals from pedigree. The simulated alleles were assigned to scrapie haplotypes in two scenarios of high (SRh) and low (SRl) resistance populations. A sample of 20,000 genotyped animals were used to predict ungenotyped using animal model. Prediction accuracies for ungenotyped animals for SRh and SRl were 0.60 and 0.54, and for allele content were from 0.41 to 0.71, respectively. Response to selection on SRh and SRl increased SR by 0.52 and 0.28, and on allele content from 0.13 to 0.50, respectively. In addition, the selected animals had large proportion of homozygous for the favorable haplotypes. Thus, pre-selection prior to genotyping could reduce genotyping costs for breeding programs. Using a linear animal model to predict SR makes better use of available information for the breeding programs.

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Section: Discussionmentioning

confidence: 99%

Prediction of Genetic Resistance for Scrapie in Ungenotyped Sheep Using a Linear Animal Model

Boareki

Schenkel

Kennedy

et al. 2021

Genes

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show abstract

“…Therefore, the epidemiology techniques of spatiotemporal prediction or modeling have become effective alternatives. For example, Ancelet et al [16] applied Bayesian shared spatial component models to analyze spatial variations in the risk of scrapie infection affecting sheep in Wales (United Kingdom); Arnold and Rajanayagam [17] used a back-calculation model to predict the prevalence and trends of classical scrapie in Great Britain, which showed a possible further increase in classical scrapie cases in Great Britain. Several studies have focused on scrapie epidemic trends in European regions [17][18][19][20]; however, very little information is available on the global occurrence of prion infection and whether the ecological environment in China has an epidemic potential for scrapie.…”

Section: Introductionmentioning

confidence: 99%

Predicting Risk Areas of Classical Scrapie in China Based on Environmental Suitability

Hong

Pan

et al. 2023

Transboundary and Emerging Diseases

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Classical scrapie is a transmissible spongiform encephalopathy that attacks the central nervous system of sheep and goats. Since its discovery in the 18th century, the disease has caused enormous economic losses and public health impacts in continental Europe. In the late 20th century, classical scrapie began to spread to places, such as Asia and the Americas, becoming a disease of global concern. In this study, based on prion occurrence records and high-resolution environmental layers, a risk assessment of classical scrapie in China was performed using a maximum entropy model. The model achieved an area under the curve value of 0.906 (95% confidence interval, 0.0883–0.0929). Sheep distribution density, road density, goat distribution density, minimum temperature of the coldest month, port density, and precipitation of the driest quarter were identified as important factors affecting the occurrence of classical scrapie. The risk map showed that potential high-risk areas in China were mainly located in Northeast China, North China, and Northwest China. This study can provide a valuable reference for the prevention of classical scrapie in China. According to the environmental variables and risk areas of classical scrapie, implementing monitoring and early warning measures in these areas is recommended to reduce the possibility of classical scrapie occurrence and transmission.

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“…According to the World Organization for Animal Health (OIE), Scrapie is an infectious and notifiable disease that naturally affects both sheep and goats (Arnold & Rajanayagam, 2020;Greenwood, 2002;Konold et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Scrapie in Eastern Libya: Case Report in Sheep

Abdalla

Sharif

2022

MJSc

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Here we report neuropathological features of scrapie cases detected between 2018 and 2022. Fourteen cases of sheep older than 2 years from several areas in Libya with neurological clinical signs resembling those with Scrapie were submitted to the Veterinary Teaching Hospital at Omar Al-Mukhtar University / Al-Beida. Postmortem examinations were performed on all animals after euthanasia. Samples from different organs were submitted for histopathological examination. Routine Hematoxylin and Eosin stain (HE) was used. Nine cases showed neuronal vacuolation that is characteristic of Scrapie in sheep. Two cases were suspected for Scrapie and need more advanced methods such as Immunohistochemistry (IHC) to confirm the diagnosis. The other three cases were diagnosed with Rabies, Listeria, and Echinococcus granulosus.

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Will there be any more classical scrapie cases in sheep in Great Britain? A modelling study to predict future cases

Cited by 3 publications

References 9 publications

Prediction of Genetic Resistance for Scrapie in Ungenotyped Sheep Using a Linear Animal Model

Prediction of Genetic Resistance for Scrapie in Ungenotyped Sheep Using a Linear Animal Model

Predicting Risk Areas of Classical Scrapie in China Based on Environmental Suitability

Scrapie in Eastern Libya: Case Report in Sheep

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