Scientists have detected an atypical case of mad cow disease in a cow in Alabama. It has been stressed that this animal posed no danger to humans. Atypical cases can arise spontaneously in herds, and this one was revealed after the eleven-year-old animal began exhibiting signs at a livestock market. Learn more from the video.
There are two types of mad cow or Bovine spongiform encephalopathy (BSE), classical and atypical. The classical variety was what caused outbreaks in the United Kingdom in the 1980s, and it's caused by an infectious prion ingested with cattle feed; that can result from a feed that is derived from an infected animal. Mad cow has been associated with variant Creutzfeldt-Jakob disease (vCJD) in humans, a neurodegenerative disorder that is fatal.
When BSE was revealed as a danger potentially lurking in our food supply, our government took steps to ensure that people in the United States wouldn’t be impacted by this disease. Starting in 1997, mammalian protein was prohibited as an ingredient in cattle feed, and since 2009, no “high-risk tissue materials” can be included in any animal feed.
Atypical cases usually come about spontaneously in animals that are older than eight years, according to the U.S. Department of Agriculture (USDA). Of the five cases of mad cow found in the U.S., four were atypical.
"This animal never entered slaughter channels and at no time presented a risk to the food supply, or to human health in the United States. Following delivery to the livestock market the cow later died at that location,” commented the USDA.
"This finding of an atypical case will not change the negligible risk status of the United States, and should not lead to any trade issues," the USDA concluded.
The classical case, found in 2003, caused China to ban US beef imports. Last month, those imports were resumed.
Finding this errant case has shown that it is important to have a testing and detection system in place. The USDA currently tests 40,000 samples, focusing on areas with the highest risk. With a prevalence estimate of four to seven cases per 42 million adult cattle, that is a statistically meaningful number of assessments that should allow the USDA not to find the cases that occur, but to ensure that the levels of the disease are indeed as low as they should be. It is thought that the more stringent specifications on animal feed will provide adequate protection from an outbreak of this disorder.