Tests on 125 sheep confiscated from a Vermont farm one year ago indicate two of the animals may have been suffering from a form of mad cow disease, but further tests will be required to confirm the results, the U.S. Agriculture Department said Thursday.
USDA officials seized 125 East Fresian sheep from Linda and Larry Faillace of Warren, Vt., and Houghton Freeman of Stowe, Vt., in March 2001 because it was believed they had been exposed to feed that had been contaminated with bone meal from animals afflicted with bovine spongiform encephalopathy, or mad cow disease, before they were imported from Belgium and the Netherlands in 1996.
The USDA said two of the sheep tested positive for atypical undifferentiated transmissible spongiform encephalopathy but it could not immediately be determined whether the disease was the more common scrapie or mad cow. Further tests were to be conducted and expected to take as long as another year.
Neither the Faillaces nor their attorney returned phone calls seeking comment.
"These results confirm our previous conclusions were correct and that we took the appropriate preventative actions in confiscating these animals," said Bobby Acord, administrator of USDA's Animal and Plant Health Inspection Service. "USDA's actions to confiscate, sample and destroy these sheep were on target. As a result of our vigilance, none of these confiscated animals entered the animal or human food supply."
The sheep had been under quarantine for two years before they were seized. Four had died in July 2000 and senior USDA veterinarian Linda Detwiler said two had tested positive for transmissible spongiform encephalopathy, prompting the USDA to seek an emergency order to seize the rest of the sheep.
Both scrapie and mad cow are neurological disorders that cause infected animals to waste away and die. Mad cow devastated the British cattle industry during the 1990s.
Scrapie has no known human variant while mad cow disease is suspected of causing a variant of Creutzfeldt-Jakob disease in humans, which has affected about 100 people in Europe.
Long prevalent in Europe, scrapie was first reported in the United States in 1947 in a Michigan flock. It creates lesions in a sheep's brain that are believed spread by an abnormal form of a prion protein. The incubation period can last five years or longer. Finally, the central nervous system of the infected animal degenerates into dementia and the animal dies.
Scientists are not sure how scrapie is transmitted. One theory holds the scrapie agent spreads from a ewe to its offspring through the placenta or placenta fluids. Unlike mad cow disease, scrapie is not considered a human health risk.
Another related malady is chronic wasting disease in deer and elk. It was first recognized in 1967 in northern Colorado and has since been detected in Wyoming and Nebraska. It is not believed that the wasting disease spreads to other animals.
In addition to Britain, mad cow has been detected in native cattle in Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Japan, Luxembourg, Liechtenstein, the Netherlands, Northern Ireland, Portugal, Slovakia, Slovenia, Spain and Switzerland. While there is a decline in the number of cases of BSE in the United Kingdom, confirmed cases of BSE have risen in other European countries. Oman, the Falkland Islands, Germany, Denmark, Ireland, Canada, Italy, and the Azores have also detected BSE in cattle imports from other countries.
There have been no cases of BSE in native cattle in North America. The one case of BSE in a single cow in Canada in 1993 imported from Great Britain was dealt with by destroying the affected cow and the rest of the herd, as well as other cattle determined to be at risk by animal health officials in Canada.
No treatment exists for either mad cow disease or scrapie and there is no way to test live animals for either disease. The only way to verify mad cow disease or scrapie is a postmortem examination of the animal's brain tissue.
The government began taking precautionary measures against mad cow in 1989, banning the import of live cattle from Britain. In 1997, the government outlawed meat and bone meal from countries affected by the disease and last year declared some 1 million Americans who lived in Britain during the mad cow crisis could not donate blood.
In addition, the government kept careful track of more than 300 cattle imported from Europe since 1996. As of March 8, only five -- two each in Minnesota and Texas and one in Illinois -- remained alive. None of the dead animals exhibited any signs of mad cow.