US statement on 'mad cow' case

The US Agriculture Department (USDA) issued the following statement about the discovery of a suspected case of "mad cow disease" in Washington state:

Agriculture Secretary Ann M Veneman today [Tuesday] announced that the US 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.