Black-faced sheep, including Suffolks, have had the majority of the cases detected nationwide. The disease's effect on the global marketplace, though, is far greater. American sheep are big, meaty, and fast-growing, so other countries are hungry for our genetics. But from a health protocol standpoint, we're not able to export animals to those countries. Other livestock exports are also affected.
Related diseases affect cattle, elk, deer, mink, cats, and humans.
BSE has never been detected in American cattle, and a strict surveillance and prevention program is in place to prohibit its entry. The fact that we have scrapie affects our BSE statusthat is, other countries have not declared us totally free of BSE for trading purposes, even though we don't have that diseasebecause any TSE is considered a risk factor. The problem is that until now, the only way to confirm any TSE has been to examine the brain of a dead animal. Now that could change. A research team headed by ARS microbiologist Katherine I. O'Rourke discovered that prions collect in pockets of lymphoid tissue in a sheep's nictitating membrane, or third eyelid.