Seventy-six organizations representing tens of millions of Americans today sent a letter to the U.S. Department of Agriculture asking that the agency immediately strengthen U.S. border protections to keep out cows from Canada with mad cow disease.

The letter is in response to the disclosure this month of Canada’s 18th case of bovine spongiform encephalopathy, BSE, also known as mad cow disease, in a Canadian-born animal.

The fatal disease in cattle causes a spongy degeneration of the brain and spinal cord. Humans can be infected by eating brain or spinal cord tissue of infected animals. The infectious agent is not a bacteria or virus but misfolded proteins known as prions.

On February 25, 2010, the Canadian Food Inspection Agency confirmed the 18th case of BSE in a 72 month-old cow found dead on an Alberta farm.

The case was detected through Canada’s national BSE surveillance program but was not made public on the CFIA website for two weeks. It was finally posted on March 10, hours after a press release was distributed by the advocacy group, Ranchers-Cattlemen Action Legal Fund, United Stockgrowers of America, known more simply as RCALF USA.

USDA regulations permit live Canadian cattle born after March 1, 1999, to be imported into the United States without mandatory BSE testing. This means that the infected cow would have been eligible for import into the U.S. cattle market had it been alive. The dead cow was the 11th case of BSE in a Canadian cow that met USDA’s age requirements to enter the United States.

The letter says regulations in Europe and Japan are stricter, so U.S. beef consumers are at greater risk than consumers in those countries.