MU specialist says mad cow risk to humans is low

By Justin Baldwin

For people associated with the cattle business each day that the U.S. stays under international beef quarantine is nerve wracking. On Wednesday afternoon local producers as well as many from around the state gathered, via teleconferencing, to hear BSE expert Dr. Jeff Tyler, a MU professor of veterinary medicine.

Bovine Spongiform Enceph-alopathy, also known as mad cow disease, is a neurological disease, similar to the human Czeutzfeld-Jakob Disease and Curu, and is caused by eating neural tissue, like brain or spinal cord. The USDA outlawed the use of animal proteins for cattle feed in 1997 but continues to test for the disease. In 2002, the USDA tested 19,990 head of cattle for BSE in their program of surveillance for herd and health threatening diseases. December was the first time that BSE has ever been found in the United States.

Tyler offered a unique point of view on the American BSE case. "When I heard the announcement that a cow had been recognized as having bovine spongiform encephalopathy in Washington state my immediate reaction was probably different than some of you might have anticipated. My reaction was: 'I'm not terribly surprised we have diagnosed this disease," said Tyler. He went on to report that the spongiform encephalopathy family is fairly large and encompasses several species from scrapie in sheep to chronic wasting disease in deer and elk. It is caused by the mutation of a neural protein into a prion. Since this mutation occurs naturally in about one in a million cases and the U.S. domestic cow herd is numbered at 30 million it was only a matter of time before a case was reported.

University of Missouri Extension Office Livestock Specialist Al Decker wondered about the implication of this statistic. He felt that given the numbers and the fact that only one BSE cow had ever been found then either there is a problem with the testing mechanism or the statistics are wrong.

However, Tyler feels that the risk to the human population is very low. "When you talk about a spongiform encephalopathy it is possible, but not easy, to take a spongiform encephalopathy and transmit it to a new host," he said. Tyler went on to say that even in the height of the British BSE outbreak, in which more than 200,000 head of cattle were destroyed the risk of a human coming down with the variant CJD was only one in 400,000. When compared to the fact that the U.S has only found one cow that tested positive the risk is not zero, but pretty small. "I worry about traffic accidents and I worry about falling down the stairs. I don't worry about being struck by lightning but my risk of being struck by lightning is far higher than my risk of acquiring variant Czeutzfeld-Jakob Disease."