Potential mad cow disease case requires further testing
June 15, 2005
BSE Effects
Mad cow disease, also known as Bovine Spongiform Encephalopathy, is a disease that causes neurological damage and death in cattle. It is caused when normal proteins, called prions, are altered and stimulate the production of abnormal prions.
The disease is transmitted by the ingestion of infected material. It only affects the nervous system, so material of significant risk would be the brain, spinal cord, eye balls or anything directly attached to the brain. Only the parts where the disease exists in the animal need to be ingested for the disease to be passed on.
– Provided by the Iowa Beef Center
Scientists in Ames are performing additional tests on bovine tissue that could show signs of mad cow disease.
Last November, a suspected case of mad cow disease was found in Texas. After two tests showed conflicting results, a sample was sent to the U.S. Department of Agriculture lab in Ames for more accurate testing, which came up negative for the disease.
Recently, three additional tests were requested because of the initial positive test.
“At the request of the Inspector General, all inconclusive results were re-tested using the Western Blot test,” said Jim Rogers, USDA public affairs officer.
The commonly used Western Blot test was performed on three separate samples from the same animal.
“The Western Blot test is internationally recognized and used by other countries,” said Shane Ellis, extension program specialist.
When the samples were tested with the Western Blot test, two came up negative and one a slight positive, giving a conflicting result, he said.
Ellis said the samples are now being sent to England because it is a trusted country with labs that are familiar with mad cow disease.
The tests could take at least two weeks.
“They’re doing the test one more time so no one can question it,” Ellis said.
Rogers said it is extremely unusual to have a negative Immunohistochemical test, which was the initial test performed in this case, and a positive Western Blot test result.
Since last June, about 380,000 animals have been tested for the disease using a rapid test, Rogers said.
Tissue samples that come back inconclusive are then subjected to additional testing.
The animal in question was born before the 1997 ban on using meat and bone in cattle feed. Ellis said he thought the calf was about 12 years old.
If the tests done in England provide a positive result, the animal should be traced looking for the source of the infection and possible additional infections, Ellis said. A negative result would confirm the tests and there would be less reason for concern.
“We’re basically saying, we’ve done our homework here,” Ellis said.
“Check it so no one thinks otherwise.”
