here to read a
USDA fact sheet on scrapie.
PULLMAN, Wash., April 9--USDA scientists have discovered that sheep
eyelids hold the key to an easy, relatively inexpensive test for diagnosing
scrapie, a fatal brain disease in sheep, Agriculture Secretary Dan Glickman
"This test will allow producers and veterinarians, for the first
time, to easily detect scrapie in sheep before the animals show signs of the
disease," said Glickman. "Until now, scrapie could only be confirmed by
examining the brains of dead animals. Clearly, this is an important step toward
controlling this disease."
Scrapie is a fatal, degenerative disease affecting the central
nervous system of sheep and goats. There is no cure or treatment for scrapie
and scientists do not fully understand how it is transmitted. Sheep can harbor
the disease for up to five years before they show signs such as trembling,
incoordination or scraping against objects. Under USDA regulations, producers
with confirmed cases of scrapie in their flock often must destroy animals in an
effort to eliminate the disease.
USDA estimates that the new eyelid test will be performed for
about $25 per animal once it is commercially available. Current tests require
biopsies of internal organs, which is more risky and can cost up to $500 per
In developing the test, researchers at USDA's
Agricultural Research Service discovered
that the third eyelid in sheep collects prions, a type of protein believed to
cause scrapie. They also designed a new antibody to identify prions in a sample
of eyelid tissue. USDA has applied for patents on both discoveries.
"This is another good example of the tremendous impact that
long-term investments in research can have on some of the toughest problems
facing American agriculture," Glickman said.
ARS microbiologist Katherine I. O'Rourke led the Pullman,
Washington-based team responsible for this important work. Others on the team
include Donald P. Knowles, who leads the Pullman lab, Timothy V. Baszler and
Steven M. Parish with Washington State
University in Pullman, and Janice M. Miller at the ARS
National Animal Disease Center in
Scientific contact: Donald P. Knowles, Agricultural
Research Service, Animal Diseases Research Unit, 337 Bustad, WSU, Pullman, WA
99164-7030. Phone (509) 335-6022; fax (509) 335-8328,