I heard a quote from vet on the radio who represented (I think) the USDA, who said that the "virus" (its not really a virus) is found in the brain and spinal cord. These are the infectious tissues, not the meat.
However, there's a like a 6 year latency period before the symptoms appear (in cattle, at least), so the one cow that was found indicates that there were likely many more infected, but not showing symptoms...
I plan on keepin' my freezer stocked. LOL
-Randy