Efforts to Prevent U.S. Mad Cow Disease Are Too Little, Too Late

Last April, British authorities announced a connection between mad cow disease (a brain disease, formally known as bovine spongiform encephalopathy, or BSE) and a rare human brain disease, Creutzfeldt-Jakob Disease (CJD). British authorities have confirmed fourteen cases of a variant form of CJD and French doctors have reported one case. The U.S. held its collective breath, then exhaled, thinking, "It's horrible what's happening in the U.K., but we're safe in the United States, right?" Alarmingly enough, cattle in the U.S. may not be safe from the disease at all.

One-third of British sheep flocks are currently affected by scrapie. More than 165,000 cattle in Great Britain have been infected with BSE since it was first detected in 1986. Scrapie has been present in U.S. sheep flocks since 1947. Moreover, ten billion pounds of processed animal remains were "recycled" into animal feed in the U.S. in 1995, and, as late as 1993, 71 percent of renderers who process animal remains for feed were still processing adult sheep.

In addition, there is evidence that cattle feed has spread brain diseases to other animal species in the U.S. Mink fed remains from cattle have developed a disease called transmissible mink encephalopathy, which is remarkably similar to BSE. Since 1947, five outbreaks of transmissible mink encephalopathy have occurred. Department of Agriculture researchers estimate that the brain and spinal cord of a single BSE-infected cow could easily contain enough infective material to cause disease in 1,000 mink.

Moreover, University of Wisconsin researchers, noting that the mink disease was linked to the use of cattle remains in mink feed, concluded, "If this is true, there must exist an unrecognized bovine spongiform encephalopathy (BSE)-like infection in American cattle."

This finding indicates that BSE may have been present in U.S. cattle for decades.

Furthermore, there are presently 499 head of cattle from the U.K. in the U.S., imported primarily for breeding purposes. If scientists discover a definite genetic predisposition to acquiring BSE, the U.K. cattle may have passed the predisposing gene to U.S. cattle.

First, the FDA should expand the proposal to prohibit the use of all animal tissue in animal feed. At this time, there is no evidence that non-ruminant animals are not carriers of dangerous prions. While cattle have been considered the most likely species to have passed transmissible encephalopathies to humans, they are not the only species under suspicion.

As The Lancet reported on April 6, 1996, other animals have routinely been fed feed containing rendered cow and sheep remains: "[S]heep, pigs, and chickens have also been exposed to BSE and scrapie-contaminated feed. While there is no evidence of natural transmission of BSE to these species, it would be prudent to remain open-minded about dietary exposure." It is common practice on farms for chickens to be fed cattle remains, and then the chicken manure is fed directly back to cattle, thus increasing the potential for contamination and spread of disease. Until the prion diseases are more fully understood, all animal tissues (not just the tissues of ruminant animals) should be banned from livestock feed.

Secondly, the FDA should ban the practice of adding manure to livestock feed. In this technological age of livestock rearing, a cow is fattened for slaughter in just over a year. Volume is profit, and fattening enormous populations of animals as quickly and cheaply as possible is the name of the game. Believe it or not, that cheap feed often includes manure. Manure can carry a variety of pathogens, diseases, and parasites. In one case, prion-infectivity was found in manure. Feed products containing manure are only tested for salmonella and E.coli contamination, and if a livestock producer chooses to use manure produced on-farm, he or she is not required to process- - or even test -- it for disease-causing organisms. This means raw manure containing disease-causing organisms can be fed without regulation. The FDA should ban the practice.

Increased surveillance for BSE must be made a greater priority. Presently, no one is even looking for BSE in cattle in a systematic way. The USDA's Animal and Plant Health Inspection Service has tested only three-one-thousandths of one percent of all cattle in the U.S.

The line must be drawn, and it must be drawn soon. Based upon the prevailing evidence, the FDA must ban livestock feeding practices that present a public health risk. It is far better to err on the side of caution rather than to expose the American public to a health risk as serious as BSE and related prion diseases.

The urgency for action is underlined given that BSE and CJD are 100 percent fatal and 100 percent untreatable. Of course, we already know that meat-eating leads to the big three killers -- heart disease, stroke, and cancer. Americans shouldn't wait for a mad cow epidemic to erupt in this country to kick the meat habit; but while they are making the transition to healthier diets, Americans should not have to risk a fatal brain disease.