As Bovine Spongiform Encephalopathy (BSE), or Mad Cow disease, has raged through Europe, many American officials have looked on with concernbut confidence at the same time that U.S. meats are safe. They may want to think again. Yesterday the U.S. Department of Agriculture (USDA) seized several sheep suspected of carrying BSE or a related condition on a farm in Vermont.

In fact, the U.S. government prohibited importation of ruminants from countries where BSE existed in 1989only three years after BSE was first diagnosed in Great Britain. But according to a statement by the USDA, there was significant interest in importing live sheep from overseas in the early 1990s for a variety of reasons. So in 1996, they opened a tiny window allowing some animals through, among them two shipments of sheep from Belgium. These 65 animals were consigned to two farms in Vermont.

It is flock mates of these same animals that are now causing alarm. In early July of last year, the USDA bought 376 of the animals after four of them were diagnosed with scrapie, the sheep-version of BSE. Later that same month, the USDA bought another 21 sheep as a precaution. Yesterday's seizure the first of its kindclaimed another 233 of the already quarantined animals against the protest of their owner. The USDA has promised to compensate the farmer at fair market value.

It is unclear whether the animals have BSE or scrapie, both classified as transmissible spongiform encephalophathy or TSE. (Human versions include kuru, Creutzfeldt-Jakob disease and Gerstmann-Straussler syndrome.) While no cases have been recorded in the past, it also remains unclear whether BSE-infected lamb, is dangerous to humans in the same way as BSE-infected beef. Regardless, the USDA hopes that such seizures will contain the threat of TSEs stateside.