ARCHIVE: BSE: Other TSEs - Scrapie

Scrapie is a fatal brain disease (a transmissible spongiform encephalopathy) of sheep and goats.

Classical scrapie has been reported in many countries and has been recognised in British sheep flocks since 1732. It is notably absent in Australia and New Zealand.

Atypical scrapie was first detected in Norway in 1998 has since been reported in the UK and many other countries, particularly as a result of active surveillance programmes. Cases of atypical scrapie in the UK have been detected retrospectively as early as 1987.

The importance of scrapie

Scrapie has been a notifiable disease since 1993 for international trade reasons (Council Directive 91/68/EEC). Any animal suspected of being affected with scrapie must be reported to Animal Health.

Further information on how to recognise scrapie is given in the leaflet: Scrapie: Advisory Notes for Farmers PDF (287 KB) produced by the Agriculture Departments of Great Britain.

In the wake of the BSE epidemic in cattle, there was concern about the possibility of bovine spongiform encephalopathy (BSE) in sheep and goats. The clinical signs of TSEs in sheep and goats are very similar and without differential tests it was possible that scrapie was masking BSE. In recent years tests have been available to differentiate BSE from scrapie. BSE has never been detected in sheep. In 2006, the Spongiform Encephalopathy Advisory Committee (SEAC) advised that the prevalence of BSE in sheep in the UK may be zero and in the worse case no more than 10 flocks would be affected. BSE has been detected in two goats. One case was a French goat which was born in 2000 and died in 2002. The second was a British goat which was born in 1987 and died in 1990.

Clinical signs of classical scrapie

Classical scrapie occurs most commonly between 2 and 5 years of age. The onset is insidious and frequently subtle.

Animals affected with classical scrapie usually show a combination of the following clinical signs. None of these clinical signs in combination or individually are a definite indication of scrapie.

Skin irritation
  • repeated scratching of the flanks and hindquarters against fixed objects
  • repeated scratching of the shoulder or ear with a hind foot
  • nibbling or grinding teeth when scratching themselves or when rubbed firmly on the back
  • nibbling of the feet, legs or other parts of the body
  • excessive wool loss or skin damage
Behavioural changes
  • excitability
  • increased nervousness or fear
  • lagging behind
  • aggression
  • depression or vacant stare
Changes in posture and gait
  • incoordination and weakness leading to recumbency
Later clinical signs
  • weight loss
  • death

Clinical signs of atypical scrapie

Most cases of atypical scrapie have been identified through the testing of fallen stock or sheep slaughtered for human consumption. The few clinical cases have shown signs similar to those for classical scrapie although skin irritation may be less evident. Most cases are in animals aged over 5 years old. Cases generally occur singly.

There is further information about the clinical signs of scrapie on the Veterinary Laboratories Agency (VLA) website.  A DVD on the clinical signs of scrapie is available from Animal Health.

Factors which influence the spread and incidence of classical scrapie

Classical scrapie is an infectious disease with a long incubation period. Flocks and herds are at risk of purchasing infected animals before they develop clinical signs. A significant route of transmission is thought to be the ingestion of birth fluids or placental material from infected animals at lambing or kidding. Transmission via faeces is also a possibility. The classical scrapie agent can persist for many years in the environment and it is resistant to most disinfectants. There is experimental evidence of transmission of classical scrapie via sheep milk and colostrum.

Polymorphisms of the prion protein (PrP) gene confer susceptibilty or resistance to the development of classical scrapie in sheep. (Goats appear to be more uniformly susceptible to classical scrapie). Selective breeding of sheep flocks to increase resistance to classical scrapie has been in progress under the National Scrapie Plan since 2001.

Farmers considering breeding for resistance to classical scrapie in their flocks should discuss this with their private veterinary surgeon. Further information on genotyping.

Farmers considering joining the Scrapie Monitoring Scheme should contact the Scottish Agricultural College which administers the scheme.

Factors which influence the spread and incidence of atypical scrapie

It is not yet known whether atypical scrapie spreads from animal to animal although the available evidence suggests that it may be spontaneous and that it is not particularly contagious, if at all. The genetic susceptibility of sheep to atypical scrapie differs from that for classical scrapie and atypical scrapie has been reported in sheep which are most genetically resistant to classical scrapie.

Statutory control of scrapie

Under Regulation (EC) 999/2001, there is an extensive EU wide programme of scrapie control.

The National Scrapie Plan’s Compulsory Flocks Scheme was launched on 20 July 2004 in England and Scotland (November 2004 in Wales.)

Scrapie Surveillance

The UK TSE Testing programme page on the Defra BSE website gives details of the annual  surveillance programme for TSEs in sheep and goats.

Research

In addition to work on the role of the PrP genotypes in scrapie susceptibility, a large research effort is being directed at the epidemiology, modes of transmission and diagnosis of TSEs in sheep and goats. Further information on the research into TSEs in sheep and goats is available.

Page last reviewed: 7 June, 2010
Page last modified: 7 June, 2010