QUEBEC CITY – After centuries of being considered a nuisance disease, scrapie today has the full attention of animal health specialists.
A degenerative condition affecting the central nervous system of sheep and goats, scrapie is a prion protein disease from the same family as BSE in cattle and chronic wasting disease in deer and elk.
“It was often looked at as a minor disease,” said animal health consultant Linda Detwiler. “When BSE hit the world, things were different.”
Detwiler, formerly with the U.S. Department of Agriculture’s scrapie certification program and national scrapie eradication program, explained the history of the disease at the World Sheep Congress in Quebec City July 17-24.
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She said the disease has been known since the mid-1700s, when shepherds in Germany and England reported sheep wobbling, nibbling at themselves, wasting away and rubbing until they scraped off their wool. Some had tremours, failed to thrive, had poor wool coats or were found dead.
Farmers were told as early as 1759 to isolate these animals from the rest of the herd. Until the 1800s the main control was to use rams from unaffected breeds.
As sheep exports increased, the disease spread from Europe to South Africa, Australia, New Zealand and North and South America.
It was first found in Canada in the late 1930s and in a Michigan flock in 1947. The owner had imported sheep from Britain through Canada.
Today, the scrapie agent is thought to be spread most commonly from the ewe to its offspring and other lambs through contact with the placenta and placental fluids. Symptoms usually appear in two to five years.
Sheep may live one to six months or longer after the onset of clinical signs, but death is inevitable.
More effort is now going into defining a genetic link because certain breeds seem less susceptible than others.
Scrapie is a reportable disease, so any suspected case must be reported to the Canadian Food Inspection Agency. Sheep known to be infected with or exposed to scrapie are euthanized and their carcasses burned or buried under CFIA supervision. Owners are compensated for disposal costs.
