The U.S. Department of Agriculture announced Aug. 29 an atypical case of bovine spongiform encephalopathy (BSE), a neurologic disease of cattle, in a six-year-old mixed-breed beef cow from Florida.
USDA said this animal never entered slaughter channels and at no time presented a risk to the food supply or to human health in the U.S.
The National Veterinary Services Laboratories (NVSL) of USDA's Animal & Plant Health Inspection Service (APHIS) confirmed that this cow was positive for atypical H-type BSE. The animal was initially tested at the Colorado State University Veterinary Diagnostic Laboratory (a National Animal Health Laboratory Network laboratory) as part of routine surveillance of cattle that are deemed unsuitable for slaughter. APHIS and Florida veterinary officials are gathering more information on the case.
USDA noted that BSE is not contagious and exists in two types: classical and atypical.
Classical BSE is the form that occurred primarily in the U.K., beginning in the late 1980s, and it has been linked to variant Creutzfeldt-Jakob disease (vCJD) in people. 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. Food & Drug Administration regulations have prohibited the inclusion of mammalian protein in feed for cattle and other ruminants since 1997 and have also prohibited high-risk tissue materials in all animal feed since 2009.
Atypical BSE is different and generally occurs in older cattle, usually eight years of age or older. It seems to arise rarely and spontaneously in all cattle populations, USDA said.
This is the sixth detection of BSE in the U.S. Of the five previous U.S. cases, the first — in 2003 — was a case of classical BSE in a cow imported from Canada; the rest have been atypical (H- or L-type) BSE, USDA noted.
The World Organization for Animal Health (OIE) recognizes the U.S. as negligible risk for BSE. As noted in the OIE guidelines for determining this status, atypical BSE cases do not affect the official BSE risk status recognition since this form of the disease is believed to occur spontaneously in all cattle populations at a very low rate. Therefore, this finding of an atypical case will not change the negligible risk status of the U.S., USDA emphasized, and should not lead to any trade issues.
The U.S. has a long-standing system of interlocking safeguards against BSE that protect public and animal health in the U.S., the most important of which is the removal of specified risk materials — the parts of an animal that would contain BSE if the animal had the disease — from all animals presented for slaughter.
USDA said another important safeguard — which led to this detection — is the ongoing BSE surveillance program that allows USDA to detect the disease if it exists at very low levels in the U.S. cattle population.
More information about this disease is available in the BSE factsheet.