'20/20': Should Americans Fear Mad Cow?

Across Europe, hundreds of thousands of cows and bulls suspected of having mad cow disease have been ground up and stored in huge mounds in airplane hangars — still infected and dangerous to humans. Others are being incinerated but the ashes themselves are contaminated.

Michael Hansen, of the consumer advocacy group the Consumers Union, says the infectious strain is "virtually indestructible … it defies all of our thinking about what living things are and how they should act."

No cases of mad cow disease have been found yet in the United States, but some say America is not in the clear.

Possible Threat in United States

Professor Richard Lacey is one of the leading experts on mad cow disease and was one of the first to sound the alarm in Britain. He says America needs to be very much on the alert. "It is just possible that there is no mad cow disease in the U.S.A., but I believe it's more likely there is, but not detected yet," he says.

Lacey, a microbiologist at Leeds University in England, was perhaps the most outspoken scientist to warn British authorities that humans could contract bovine spongiform encephalopathy by eating infected beef. The warning was largely ignored and dismissed as scientifically impossible until five years ago when people began to die.

Victims of the degenerative brain disease lose their motor skills and slowly waste away. There is no vaccine and no treatment, which is why Lacey is concerned that the United States isn't doing all it could to protect itself.

The U.S. banned British beef and cattle products in 1989 and the American beef industry has taken additional precautions. The head of the National Cattleman's Beef Association, Chuck Shroeder, says that along with federal regulators, his group has actually gone through mock drills to prepare for the discovery of mad cow disease. Containment procedures have been planned and a full-scale public relations campaign is ready to go. "We're not just whistling on our way past the graveyard on this," he says.

Shroeder is confident that necessary measures have been taken and protections in place. "If the disease were ever discovered here, we could number one, identify it, number two contain it, and number three, eliminate it as quickly as possible." The government reports that its inspectors have yet to find a single cow with mad cow disease in the U.S.

Feeding Cattle to Cattle

How was mad cow disease able to spread from cow to cow in England and elsewhere in Europe?

A key reason, Lacey says, was the practice of including ground-up remnants of cattle in cattle feed. This practice was widespread in Europe and, to a lesser extent, the United States.

Lacey refers to this as a kind of forced animal cannibalism.

When mad cow disease broke out, the practice of feeding cattle back to cattle was stopped in England, but it continued in the United States until four years ago. And Hansen says other potentially dangerous feeding practices now banned in the U.K. continue in the United States today.

It remains legal in the United States, for example, to "grind up cattle, feed them to pigs, and then grind up the pigs and feed them to the cows," says Hansen. Lacey calls this a "real danger," that "must be stopped immediately."

But government and industry officials say there's no reason to follow Europe in banning the practice, because there's no evidence to date that the disease can spread between pigs and cattle.

Lacey says nevertheless the United States should adopt the same ban as a precaution: "My advice to the U.S. authorities is to simply ban the incorporation of animal remains in animal feed."

But Shroeder defends U.S. practices. "We have been driven here by the best science that we can access, we have protected the U.S. beef supply very, very carefully," he says.

Chronic Wasting Disease: a Different Strain?

There's another concern not so easily answered. There is growing concern about a possible American version of mad cow disease showing up in deer and elk in the West. It is called chronic wasting disease and some suspect it has already claimed human lives.

Hansen says this is chronic wasting disease is dangerously similar to mad cow disease. "It's a different strain of the disease and it appears to be spreading in the wild," he says.

Tracie McEwen believes her 30-year-old husband Doug, who ate elk all his life, may have been a victim. He died of a rare brain disorder normally only seen in people older than 55, with symptoms remarkably similar to those who died the slow, agonizing death of mad cow disease in England.

The death of Tracie McEwen's husband and that of two others under the age of 30 have raised questions for health officials concerned about the similarity to mad cow disease.

Lacey thinks the "link between eating deer and getting a type of mad cow disease is very plausible," and it's one more reason that American authorities shouldn't think they have all the answers about the disease. He says, "you have to act on the assumption that the disease may well be there, because if you wait until you know it's there, then it's too late."

Meanwhile, some members of Congress have asked for an investigation into whether the government should be taking additional steps to protect against the spread of mad cow disease should it arrive in this country.