What Rare Mad Cow Case Means for U.S. Consumers

BY Allie Morris  April 26, 2012 at 5:27 PM EST


Photo by Peter Cade via Getty Images

For the first time in six years, a case of mad cow disease surfaced in the U.S. this week. But there’s no need to fear the beef aisle.

Why not? The California dairy cow infected with the disease never threatened the food supply, according to a USDA official.

“The carcass of the animal is being held under State authority at a rendering facility in California and will be destroyed,” John Clifford, the chief veterinary officer at the USDA, said in a statement. “It was never presented for slaughter for human consumption, so at no time presented a risk to the food supply or human health.”

The Center for Science in the Public Interest, a consumer group, agreed that the case shouldn’t raise alarm. “A case of a single cow with Bovine Spongiform Encephalopathy is not a reason for significant concern on the part of consumers, and there is no reason to believe the beef or milk supply is unsafe,” Sarah Klein, the organization’s food safety attorney, said in a statement.

But at the same time, Klein said the United States is lagging behind many developing-world countries when it comes to tracking animals. Botswana, for example, uses microchips to track its animals up and down the supply chain.

“If American cattlemen suffer economic losses at the news of this discovery of BSE, they should blame only themselves and other opponents of a mandatory animal identification system,” she said.

The animal in question this time around was found to be infected through a Department of Agriculture surveillance program, which annually tests some 40,000 cows for the disease, according to the Associated Press.

Formally known as Bovine Spongiform Encephalopathy (BSE), the disease is fatal in cattle, and humans who eat contaminated beef can be affected.

In the United States, there have only been four confirmed cases of mad cow disease, including this one.

Linda Detwiler, a Clinical Professor at the College of Veterinary Medicine at Mississippi State University, answers our questions about the causes, prevention and future of the mad cow disease below.

How is mad cow disease contracted and spread?

Detwiler: Bovine Spongiform Encephalopathy (BSE), also called mad cow disease, has been found to have several different types, known as Classical and Atypical BSE. The classical form, which is responsible for the majority of cases worldwide, usually spreads by an infected cow being slaughtered, rendered, processed into meat and bone meal and fed back to cattle. It does not spread from cow to cow by contact or from the environment. Thus, around the world, there have been many feed bans put in place, in the United States, Canada, Europe, etc. These measure are responsible for the large decline in cases.

In regard to the atypical cases, these were just reported in 2004. There is still research to get a better understanding of these diseases. The most recent case reported by the USDA is an atypical case. We do not know the origin of this disease or how it spreads (if it does) in nature. The origin may be sporadic (meaning it just occurs), genetic, or it may be a modification of classical BSE. It will take time for science and epidemiology to figure this out.

Should the public be concerned about this new mad cow finding?

Detwiler: I think all of us as consumers should maintain an awareness about BSE so that we can make informed choices. Currently, there are many safeguards in place to protect consumers as well as our national herd. I continue to stress that we must be vigilant in looking for ways to improve the system.

When mad cow first popped up, what types of precautions were taken?

Detwiler: BSE was actually first recorded in 1986 in the United Kingdom and rose to the epidemic proportions that peaked in ’92 and ’93. The UK put a ruminant-to-ruminant feed ban in place in 1988 (“ruminant” refers to the type of mammal that includes cows, sheep and goats). Even though they put the regulation in place in 1988, there was exposure to their cattle prior to the ban. That is, when a cow was to eat contaminated feed, you wouldn’t see the disease for usually 3 to 8 years or so, due to the long incubation.

The UK then took precautions to protect the human food supply by removing tissues (from the animals) most likely to be high risk, such as brain and spinal cord.

What types of restrictions does the U.S. have?


Detwiler: In the late 1980s, the USDA restricted imports from the United Kingdom and other countries in Europe that had BSE and this proved to be very important. In 1997, the FDA prohibited the feeding of most mammalian protein to ruminants through a feed ban. In 2004, high-risk tissues (like brain and spinal cord) were removed from the food supply for humans to protect public health.

This is the first case since 2006 and the fourth ever found in the U.S. How significant is that?

Detwiler: I don’t know if I can say that there is a significance to the individual case other than that it’s good to know that our the surveillance system picked it up. It established that our diagnostic laboratories can diagnose the various types of BSE. The fact that it’s an atypical case will hopefully provide us with some more information to study because we know so little about this disease.

Does it make a difference that it was a dairy cow as opposed to a cow sent to slaughter?

Detwiler: By having the animal sent to a rendering plant (and the carcass held) versus being sent to slaughter prevents any exposure to the food or feed chains. Our safeguards, as previously mentioned, are in place to reduce the risk that animals incubating the disease are presented for slaughter or are rendered.

Could milk pass along mad cow disease?

Detwiler: There has been a considerable amount of research done with classical BSE and there’s been no evidence of infectivity in the milk. Currently, research is in the early stages of understanding which tissues are infectious in cases of atypical BSE.

Do you have any recommendations going forward?

Detwiler: We do know that in both classical BSE and atypical BSE there is infectivity in certain tissues, hence it is important to not become complacent and to abide by our current regulations. It is also extremely important for the U.S. to monitor ongoing research and epidemiological evidence and modify policies if needed.