The confirmatory tests have not yet been done and there have been other recent suspicious cases that turned out not to be positive. But I have to say that IMHO the US beef industry is asking to be destroyed. In Japan, ALL beef is tested and no "ruminate" products or byproducts are allowed in animal feed. Here, industry pressure has kept testing limited only to cows that appear sick and, while beef products are banned in cattle feed, they are still put in feed for other animals that is sometimes fed to cattle by stupid/greedy/desperate farmers.
The result, I believe, is that it’s inevitable that "mad cow" will eventually get into US beef herds and then US beef exports will evaporate as will a large part of domestic sales, wrecking the industry–and they deserve it.