The U.S. Department of Agriculture has confirmed an "atypical" case of bovine spongiform encephalopothy (BSE), commonly known as mad cow disease, in an 11-year old beef cow in Alabama but emphasized that the animal never entered the slaughterhouse and "at no time presented a risk to food supply or to human health."

According to a news release from the Alabama Department of Agriculture and Industries, the sick animal was discovered during routine surveillance at an Alabama livestock market. The animal died at the market before entering the slaughter channels and samples were sent to a USDA lab in Iowa for confirmation.

The department referred to this case as "atypical," and "a rare and spontaneous incident."

The USDA implemented enhanced surveillance testing programs in 2009 to protect animal and human health, and the cow was discovered through these protocols.

According to the USDA, BSE exists in two types - classical and atypical. Classical BSE is the form that occurred primarily in the United Kingdom, beginning in the late 1980s, and it has been linked to variant Creutzfeldt-Jakob disease in humans.

The most common cause of classical BSE is when cows are fed products that contain brain or spinal tissue from other bovine animals. The USDA banned banned the use of such protein supplements in cattle in 1997.

According to USDA, the World Organization for Animal Health has recognized the United States as having "negligible risk for BSE."

The atypical or L-type BSE that was confirmed in Alabama Tuesday "generally occurs in older cattle, usually 8 years of age or greater," according to the USDA news release. "It seems to arise rarely and spontaneously in all cattle populations."

This is the fifth detection of BSE in the United States and the second in Alabama. Of the four previous U.S. cases, the first was a case of classical BSE that was imported from Canada. The rest have been atypical (H- or L-type) BSE.

"The Alabama beef industry is vital to our state's agriculture economy," Alabama Agriculture Commissioner John McMillan said in a news release. "The response to this case by USDA officials and our department's professionals led by State Veterinarian Dr. Tony Frazier has been exemplary. This instance proves to us that our on-going surveillance program is working effectively."