Last April, when a dairy cow in California was discovered to have bovine spongiform encephalopathy (BSE), federal officials were quick to point out that it never posed a threat to the food supply.

In addition, they said it appeared to involve a rare “atypical” form of BSE. Read more.

Now, following a three-month investigation, those findings have been confirmed.

On Friday, the U.S. Department of Agriculture reported that cow found in April was an isolated case ― no other cases of BSE were found.

"The results of this thorough investigation confirmed that at no time was the U.S. food supply or human health at risk, and that the United States' long-standing system of interlocking safeguards against BSE continues to be effective," said John Clifford, USDA's chief veterinary officer.

The 10-year-old dairy cow had been delivered to a rendering facility in Hanford, Calif., and was killed prior to the BSE being detected by random testing.

USDA investigators tracked the cow from the ranch where she was born to a heifer operation where she was raised and bred and then to a Tulare County dairy where she spent her life, according to this article from The Associated Press.

Clifford and other scientists have said the "atypical" strain of BSE, which occurred here, is rare and not well understood. It may be a random mutation.