USDA on July 18 announced it found an "atypical" case of mad cow disease -- bovine spongiform encephalopathy (BSE) -- in an 11-year old cow in Alabama. Because the form of the disease was atypical and the animal never entered slaughter channels, the agency is raising no red flags about food safety or dangers to human health.
USDA's Animal and Plant Health Inspection Service’s (APHIS) National Veterinary Services Laboratories determined the cow was positive for atypical (L-type) BSE. The animal was showing clinical signs and was found through routine surveillance at an Alabama livestock market. APHIS and Alabama veterinary officials are gathering more information on the case.
The agency notes BSE is not contagious and exists in two types. Classical BSE is the form that occurred primarily in the United Kingdom beginning in the late 1980s and has been linked to variant Creutzfeldt-Jakob disease (vCJD) in people. Atypical BSE is different, and it generally occurs in older cattle, usually 8 years of age or greater. It seems to arise rarely and spontaneously in all cattle populations.
The primary source of infection for classical BSE is feed contaminated with the infectious prion agent, such as meat and bone meal containing protein derived from rendered infected cattle. FDA regulations have prohibited mammalian protein in feed for cattle and other ruminants since 1997 and also have prohibited high risk tissue materials in all animal feed since 2009.
USDA says this is the nation’s fifth detection of BSE. Of the four previous U.S. cases, the first was a case of classical BSE in a cow that was imported from Canada (in late 2003); the rest have been atypical (H- or L-type) BSE.