Scientists Devise Cheap, Easy
Test For Sheep Disease Scrapie

PULLMAN, Wash. —(AP)— Washington State University scientists recently announced that they have developed an inexpensive test to easily diagnose a fatal brain disease that strikes sheep and goats.

The test will allow farmers and veterinarians to detect scrapie, a degenerative disease that affects the central nervous system of these animals, said Borje Gustafsson, dean of WSU's College of Veterinary Medicine.

Scrapie is an incurable type of spongiform enchephalopathy, similar to the disease known as mad cow disease.

The test, developed in conjunction with the U.S. Department of Agriculture, is an important step in controlling the disease, Gustafsson said.

"Being in the forefront of disease research ... is essential to protecting both human and animal health in the state, the region, and worldwide," he said.

Previously, scrapie could only be confirmed by examining the brains of dead animals. The new test uses an antibody to identify disease-causing proteins in the animal's eyelid.

After trials on flocks of sheep, the test could be used in programs to control sheep scrapie, said Donald P. Knowles, head of the USDA Agricultural Research Service lab here, where researchers discovered that a third eyelid in sheep collects the proteins believed to cause scrapie.

"You have an opportunity now to go in and sample whole flocks and see who is incubating the disease," he said.

Knowles said he did not know when the test would be available for commercial use.

There is no known cure or treatment for scrapie, and scientists are still trying to find out how it is transmitted. Sheep can harbor the disease for as many as five years before showing symptoms, which include trembling, loss of coordination and scraping against objects.

USDA regulations require producers with infected sheep to destroy their flocks.

Scientists at the federal lab here have been researching spongiform encephalopathies for nearly two decades.

Scrapie was first recognized as a sheep disease more than 250 years ago in Great Britain and other Western European countries. The first U.S. case occurred in 1947 in the flock of a Michigan farmer who had imported sheep from Britain through Canada.

The disease has subsequently been diagnosed in more than 900 flocks in this country.

The test developed by the scientists at WSU takes about 48 hours to diagnose the disease.

Lymphoid follicle tissue is snipped from the animal's third eyelid and sent to a lab, where microscope slides are stained to detect the newly discovered antibody, Knowles said.

Once the new eyelid test is commercially available, it will cost about $25, WSU spokesman Charlie Powell said.

Current tests for scrapie require biopsies of internal organs and can cost as much as $500 per animal.

Microbiologist Katherine O'Rourke led the research team, joined by Knowles, WSU veterinary college faculty Timothy Baszler and Steven M. Parish, and Janice M. Miller of the ARS National Animal Disease Center at Ames, Iowa.

As the test becomes more widely available, USDA is contemplating an update to rules controlling the movement of sheep and goats infected with scrapie. Current regulations do not restrict movement of animals within a state.

"There is a risk that scrapie infection that originated in an infected or source flock could spread interstate," the department said in a notice about the rules. "The risk is higher in states that do not quarantine scrapie-infected and source flocks."

Possible new regulations could include further restrictions on states that don't impose such quarantines and on flocks considered to be at high risk. In addition, officials are examining whether to impose a better identification system to keep track of sheep and goats and enable infections to be traced to the source.

"These changes would help protect all American livestock," said Joan Arnoldi, deputy administrator for veterinary services at the USDA's Animal Health and Plant Inspection Service.

Right now, the Agriculture Department is in the fact-gathering stage, with proposed rules the next step and a final resolution unlikely for at least a year.

The American Sheep Industry Association is welcoming the regulations, even if they might restrict movement of flocks. The promise of eliminating scrapie, producers say, is worth the trouble.

"We need to continue to take the lead in this," said Steve Raftopoulos, past president of the association. "We have to focus on the ultimate benefits, not the short-term hardships of taking an aggressive stance on disease control."