Mad Cow Disease Found In Washington State Cow; Feds Tracing Where Meat Was Sent; Farm Quarantined; Disease Is 100% Fatal But USDA Says Risk To Humans "Is Extremely Low"

Agriculture Secretary Ann M. Veneman today announced that the U.S. Department of Agriculture has diagnosed a presumptive positive case of bovine spongiform encephalopathy (BSE) in an adult Holstein cow in the state of Washington.

"Despite this finding, we remain confident in the safety of our beef supply," Veneman said. "The risk to human health from BSE is extremely low."

Because the animal was non-ambulatory (downer) at slaughter, samples were taken Dec. 9 as part of USDA’s targeted BSE surveillance system. The samples were sent to USDA’s National Veterinary Services Laboratory in Ames, Iowa. Positive results were obtained by both histology (a visual examination of brain tissue via microscope) and immunohistochemistry (the gold standard for BSE testing that detects prions through a staining technique). Test results were returned on Dec. 22 and retested on Dec 23.

USDA has initiated a comprehensive epidemiological investigation working with state, public health, and industry counterparts to determine the source of the disease. USDA will also work with the Food and Drug Administration as they conduct animal feed investigations, the primary pathway for the spread of BSE.

This investigation has begun while the sample is being sent to the world reference laboratory in England for final confirmation. USDA will take the actions in accordance with its BSE response plan, which was developed with considerable input from federal, state and industry stakeholders.

BSE is a progressive neurological disease among cattle that is always fatal. It belongs to a family of diseases known as transmissible spongiform encephalopathies. Also included in that family of illnesses is the human disease, variant Creutzfeldt-Jakob Disease (vCJD), which is believed to be caused by eating neural tissue, such as brain and spinal cord, from BSE-affected cattle. USDA has determined that the cow comes from a farm in Washington State and as part of the USDA response plan, the farm has been quarantined. After the animal was slaughtered, the meat was sent for processing and USDA’s Food Safety and Inspection Service is working to determine the final disposition of products from the animal.

To date, no case of BSE has ever been found in the U.S., despite years of intensive testing for the disease.

After the original outbreak of BSE in the United Kingdom in 1986, the U.S. government established a comprehensive set of measures designed to protect Americans and U.S. cattle from BSE. These included a list of "BSE countries" from which cattle, meat, beef-derived products, and animal feeds could no longer be exported to the U.S...

Since 1997, America has been protected from BSE by the prohibition against using most mammalian protein to manufacture animal feeds given to "ruminant" animals such as cows, sheep, and goats. The BSE epidemic in the U.K. is thought to have spread through the addition of such mammalian protein to the feed consumed by cows. The regulation is designed to prevent the spread of BSE in the U.S. if a case ever occurred here.

In 2001, the Harvard Center for Risk Analysis concluded that the FDA’s "feed rule" provided the nation’s major defense against BSE.

BSE is one of several diseases known as transmissible spongiform encephalopathies. These diseases are characterized by a long incubation period, a relatively short clinical course of neurological signs, and 100 percent mortality...