Description
Scrapie belongs to a group of related diseases called Transmissible Spongiform Encephalopathies (TSEs), which include:
- Chronic Wasting Disease in cervids Chronic Wasting Disease – Surveillance and response
- Bovine Spongiform Encephalopathy (BSE) in cattle
- Creutzfeldt-Jakob Disease (CJD) in humans
Scrapie occurs through the misfolding of the normal cellular prion protein (PrPc) into the abnormal form (PrPSc), which then accumulates in the tissues and causes disease. Currently, no treatments or vaccines are available.
While scrapie and BSE are both TSEs, it is important to note that they are not the same disease and have differences in mode of transmission and clinical signs. Also, scrapie is not known to affect humans.
Since 1998, there have been 2 types of scrapie recognized: classical and atypical.
Classical scrapie can affect sheep and goats of any age and can spread between animals or from mothers to their offspring. Some animals naturally have genes that make them more resistant to this form.
Atypical scrapie was first identified in Norway in 1998, though later testing found it had been present earlier in the United Kingdom. It appears to happen sporadically in single, older animals and does not spread easily between animals.
Clinical signs
Farmed small ruminants may not exhibit observable signs of disease for several years. Eventually, as more brain tissue is affected, animals may exhibit:
- poor body condition
- increase in nervous and aggressive behaviours
- tremors
- incoordination
- difficulty standing and walking
- loss of muscle control
- trouble swallowing
- sudden death
- excessive scratching which removes large patches of wool/hair
Unfortunately, these signs are not specific to scrapie and can occur with other diseases as well.
Currently, the only way to diagnose scrapie is by examining the brain or lymph nodes after the animal has died.
How to report
Scrapie is a federally reportable disease under the Health of Animals Act. It is also a provincially reportable disease under Alberta's Animal Health Act.
All suspected or confirmed cases must be reported by contacting the:
- district veterinarian at your nearest Canadian Food Inspection Agency CFIA office
- Office of the Chief Provincial Veterinarian (OCPV) within 24 hours:
Hours: 8:15 am to 4:30 pm (open Monday to Friday, closed statutory holidays)
Phone: 780-427-3448
Toll free: 310-0000 before the phone number (in Alberta)
Where it’s found
Classical scrapie has been documented for 300 years in western Europe. Classical scrapie is found worldwide, with the exception of Australia and New Zealand. Scrapie was detected in Canada for the first time in sheep in 1938. The last confirmed case of scrapie in Canada was detected in Alberta in 2019.
Learn more about flocks infected with scrapie in Canada.
How it spreads
Infected animals may shed scrapie prions in saliva, urine, feces, blood or birthing fluids. Transmission occurs through ingestion of infectious prions in these fluids either directly or indirectly from a contaminated environment like a barn or pasture.
Scrapie prions are found in very high amounts in the placenta, birthing fluids, colostrum and milk of infected animals. This makes the period around birth the highest risk time for spreading classical scrapie. Most animals become infected by their mothers at or soon after birth. Other animals can also get infected if they come into contact with contaminated birthing materials. There is evidence that infection can happen before birth. One study showed that even delivering lambs by caesarean section and removing them right away did not stop the disease from spreading.
Risk to other species
Classical scrapie has been found in wild sheep. In certain research settings, other species such as voles, raccoons, pigs and cattle have been experimentally infected (for example by direct inoculation into brain tissue). However, there is no evidence that cattle can be infected by natural exposure (that is by ingesting contaminated materials).
Researchers have also explored possible links between scrapie and chronic wasting disease in deer. In controlled experiments, white tailed deer exposed to the scrapie agent all developed a disease that looked like chronic wasting disease. However, there is no evidence that scrapie spreads across species in the wild.
Although a modified classical scrapie prion has been experimentally transmitted to macaques, there is no evidence to suggest that scrapie can affect humans.
Under Alberta’s Scrapie Program, sheep and goat producers are encouraged to submit the heads for scrapie testing from all animals over one year of age that die or are slaughtered. Meat from any scrapie positive animal must be removed from the food chain.
Prevention and control
Canada’s National Scrapie Eradication Program works to eliminate classical scrapie from Canadian sheep and goat farms. The program helps protect flock health, reduce production losses and maintain strong market access for producers.
Producers can register in the Scrapie Flock Certification Program (SFCP) which provides surveillance testing on all deceased animals over one year of age that originate from certified premises. The primary benefit to participating producers is that over time, their flock or herd will be recognized as being at a much lower risk for scrapie than the rest of the farms in the national herd, potentially increasing marketing opportunities.
Alberta small ruminant producers that are not part of the SFCP can still participate in scrapie surveillance through the Alberta Scrapie Program.
If scrapie is confirmed in an animal, the CFIA takes action to control the disease. Learn more about what to expect if scrapie has been detected on your farm.