Scrapie is a deadly, degenerative and transmissible disease that affects the central nervous system of sheep and goats.
Scrapie has been known since the 18th century. This disease has been present in sheep and goats for centuries and has been observed worldwide, but especially in Western Europe and North America. In French the disease is called Tremblante and in German Traberkrankheit.
The name Scrapie is derived from one of the symptoms. Due to severe itching, sick animals scrape their skin against fences or other fixed objects. Other symptoms are a dry coat and skin, and severe weight loss. Movement disorders can also occur. However, these are not as pronounced as with BSE in cattle; usually only one animal of the herd is affected.
Long incubation time
Scrapie has an incubation period of more than two years. As a result, the disease symptoms are only seen in adult animals. In non-susceptible animals, the pathogen has virtually no chance of causing disease symptoms during their relatively short lives.
There are classical forms and atypical forms of scrapie. Scrapie, like BSE, is a transmissible spongiform encephalopathy (TSE) or prion disease. Prion diseases are very unusual; unlike bacterial, viral or parasitic infections, prion diseases are caused by a protein that is normally present in the host. This protein is known as a prion protein or simply PrP.
Spreading the infection
Scrapie is an infectious disease. The nature of the agent (the prion) that causes Scrapie is not fully understood, and the mode of transmission is not entirely clear. It has been established that the Scrapie agent can survive several years in the environment, that it is relatively resistant to disinfectants and that host genetic (hereditary) factors mainly determine the susceptibility to the disease. In sheep, the assumption is that an important route of horizontal and vertical transmission is via the placental material (afterbirth) of infected ewes during lambing.
Scrapie incidence and PRNP polymorphisms : Rare small ruminant breeds of Sicily with TSE protecting genetic reservoirsBMC Veterinary Research 12 (2016)1. - ISSN 1746-6148
Variation in the prion protein sequence in Dutch goat breedsJournal of Animal Breeding and Genetics 133 (2016)5. - ISSN 0931-2668 - p. 366 - 374.
Prion type-dependent deposition of PRNP allelic products in heterozygous sheepJournal of Virology 90 (2016)2. - ISSN 0022-538X - p. 805 - 812.
Prion protein genotype survey confirms low frequency of scrapie-resistant K222 allele in British goat herdsVeterinary Record 178 (2016)7. - ISSN 0042-4900 - p. 168 - 168.
Fokken en scrapie resistentie in Nederlandse geiten
Behoud TSE-ongevoelige geiten (TSE=overdraagbare sponsvormige hersenaandoening zoals scrapie, atypische scrapie, of BSE)Zeldzaam huisdier 2015 (2015). - ISSN 0929-905X
Effect of Q211 and K222 PRNP polymorphic variants in the susceptibility of goats to oral infections with Goat Bovine Spongiform EncephalopathyThe Journal of Infectious Diseases 212 (2015)4. - ISSN 0022-1899 - p. 664 - 672.
Goat scrapie resistance: Monitoring, genotyping and breeding
Investigation of a simple model for within-flock transmission of scrapiePLoS ONE 10 (2015)10. - ISSN 1932-6203 - 13 p.
Sheep prions with molecular properties intermediate between classical scrapie, BSE and CH1641-scrapiePrion 8 (2014)4. - ISSN 1933-6896 - p. 296 - 305.