Much has been in the news in the past 30 days about Mad Cow Disease, a/k/a BSE (Bovine Spongiform Encephalopathy), with the confirmation of the first positive finding in an indigenous cow in the United States. As you may remember, in December 2003, a cow, which was of Canadian birth, was found to be positive in the State of Washington.
That cow we believe was linked with 3 other cows that the Canadians have found to be positive for BSE. What does this all mean? Are we at risk? Should every cow be tested? Bottom line: Should I still eat beef? I shall attempt to answer each of these questions with facts, as well as opinion.
What does this all mean?
Before I can answer this question, we have to go back in history, since, to most people, our surveillance and concerns about BSE started in December of 2003. This is the farthest from the truth. The United States, observing the significant outbreak of BSE in the United Kingdom (U.K.), started a committee in 1988—involving governmental agencies, academia, the research committee, and industry representatives—to review published literature and to discuss the science as it was emerging from the United Kingdom.
Scientists included those from the National Institutes of Health (NIH) and the Centers for Disease Control and Prevention (CDC). In 1989, the United States banned all ruminants, bovine semen, embryos, and meat and bone meal from the U.K. based on evolving science.
Additionally, the U.S. started policies and procedures for submission of brain tissue from any animal that could be suspect for having BSE—based on the experience of the U.K.—which included all neurological signs and symptoms seen publicly or privately by veterinarians.
The next year, 1990, the United States Department of Agriculture (USDA) initiated an active BSE surveillance program—looking at the brains of high-risk, suspect animals by a histo-pathological laboratory procedure. This has continued and been expanded upon—yet, many people believe that it was only in 2004 that we started looking for BSE in cattle in the United States.
Actually, that is not correct. Further measures to protect the public’s health and to understand if we had BSE in the United States continued from 1990 on—with the initiation of a traceback program to look back at cattle imported to the U.S. from the United Kingdom prior to the 1989 ban.
1991: The USDA banned and prohibited importation of ruminant products from any country in the world known to have BSE.
1992: The Food and Drug Administration (FDA) initiated an import alert banning products that they regulate; such as, gelatin found in drugs—from entering the U.S. from any country that had BSE. For the next several years, risk assessments and modeling were conducted.
1996: The first 10 cases of a new variant Creutzfeldt-Jakob disease (vCJD)—that is, CJD epidemiologically linked to BSE—were reported in the United Kingdom.
1997: The FDA published the final rule prohibiting the feeding to ruminants of any feed or food containing any animal proteins from ruminants (meat and bone meal).
1998: The USDA contracted with Harvard to analyze the prevention of BSE, which led to several risk assessments done, utilizing different modeling by Harvard.
2000: USDA commenced an enhanced surveillance program of non-ambulatory cattle (called “downers”), exceeding the international surveillance program by five times. No positives were ever detected.
2001: The first Harvard risk assessment was reported, using over 1,000 mathematical variables, to see if and how a positive cow were introduced into the food supply or would come into the U.S., what the public health hazard would be.
In January 2004, after the finding of the imported cow from Canada, the USDA initiated a ban on Specified Risk Materials (SRMs)—the bovine parts where research had shown infectious prions that cause BSE in cattle could be—that could pose a threat to human health.
The U.K. has done extraordinary research with cattle by feeding cattle infected brains and analyzing their tissue sequentially. From this data, we know that, in order to get an infection in the brain, it takes approximately 32 months.
As a matter of public policy to protect the public’s health, the USDA backed down its rule to make the age from which these SRMs must be removed 30 months of age, rather than the original 32 months. The British researchers showed that early infection occurs in the distal ileum of the small intestine and moves through the lymphatic system to the tonsils.
Therefore, the USDA banned, as a matter of food safety, the small intestine (which is approximately 130 feet in a cow) and the tonsils from all animals and, from animals over 30 months of age, the skull, eyes, brain, trigeminal ganglia, spinal cord, vertebral column and dorsal root ganglia. The removal of these specified risk materials and the strict enforcement of the removal of these tissues is a food-safety public health paradigm to protect human health.
Are we at risk?
With our history of commerce with the U.K. and European countries that were experiencing BSE in their bovine population, one would expect to find a very low level of prevalence in older animals that were born before the feed ban.
Nevertheless, the USDA commenced on June 1, 2004, a robust and aggressive surveillance, looking at high risk animals, to understand the prevalence in the U.S. bovine population. This data is reported publicly—weekly, if not daily—on the USDA’s BSE testing link on their website.
Through September 27, 2005, 478,050 animals have been tested, with 1 indigenous American cow found to be positive. This cow was destined for dog food, but never made it into the dog food plant because of our ban on dead and downed animals, which are automatically subjected to testing. This animal was incinerated. Therefore, not only did it not get into the human food supply, but it also did not get into the pet food supply.
By way of background, I hope that I have covered over 15 years of history—both factually and quickly. However, I’d like to address the question of “Should every cow be tested?” The answer, simply, is “No.” The U.S. embarked on a surveillance testing protocol that was over 10 times greater than recommended by the international body “IOE” (World Health Organization for Animals). Our testing protocol utilized the ELISA test kit, which was approved by the European Union (EU) and the U.S. government. Confirming testing was by immunohistochemistry (or IHC), which internationally has been regarded as the “Gold Standard.”
The protocol used by the United States with testing conducted throughout the U.S. at state veterinary diagnostic laboratories with confirmation at the USDA testing laboratory in Ames, Iowa, under a standardized protocol, is scientifically appropriate and scientifically sound from an epidemiological and laboratory science perspective.
We strongly believe that our surveillance of high-risk animals and the removal of SRMs to protect the public’s health from a food-safety perspective is not only adequate and satisfactory, but for our country—given the experience in the U.K. and in Europe—is best from a public health and public policy perspective.
Then, why not test every animal? First, testing every animal leads to a false sense of security on the part of the consumer. The countries that are testing every animal are basically ignoring the biology of the disease. Testing animals under 30 months of age is useless, since the British study showed that it took 32 months for the abnormal prions that cause the BSE to reach the cow’s brain.
Clearly, one would rather have untested beef with the SRMs removed where we know early disease can occur, then to rely strictly on testing. The only test kits that are used worldwide sample the cow’s brain, and that is why—in those countries that perform every animal testing, either at the surveillance site or at the slaughterhouse—testing can only be accomplished with the brain.
It must be underscored that our surveillance program targeted the older and sick, high-risk population and, therefore, is skewed to find the disease if it is present, rather than testing healthier animals at a younger age where there is virtually no probability of finding BSE.
For the United States and, even for a country like the United Kingdom with over 100,000 positive cows and tens of millions servings of infectious beef, they are not testing every animal. We have followed their lead and their research in devising our initial protocol—which I believe has proven to be not only effective, but right on target.
It is true that the Japanese have found 2 suspect animals under 30 months of age that did not confirm on the confirmatory test, and the world is waiting to see the results of their mouse bio-assay test. Until then, in my mind, the studies conducted by the British, upon which both we and they have relied, are valid, from a scientific perspective, to base good public policy.
From our surveillance of 412,359 through July 17th mostly all high-risk animals—although we have had one positive animal—one can conclude that the U.S. has not demonstrated an outbreak or a problem with BSE in our cattle population.
Therefore, we can be assured that our public policy decisions are not only scientifically based, but we are validating them via this enhanced surveillance program. Are we at risk? As stated, tens of millions of infectious meals were served in the United Kingdom.
Without minimizing or trivializing the suffering or loss of human life, as of July 1st, the U.K. has had 150 deaths from definite or probable vCJD. In the U.S., we have reported one case of vCJD in an individual who was born and lived over a decade in the U.K. during the time of their outbreak. We strongly believe that we will not have any cases of vCJD in any Americans, unless they spent a considerable amount of time in an area where BSE was occurring.
Therefore, from a risk perspective, the risk is virtually zero. That statement can be misinterpreted, because, if you are honest, one can never state that there is zero risk of anything. However, let’s put this in perspective.
In the United States annually, 50 Americans die due to wasp and bee stings, 2 Americans died due to shark bites in 2004. The bottom line: Should we still eat beef? My answer—scientifically, epidemiologically and individually—is unquestionably “Yes!” I eat beef and serve it to my family—including my children.
On a recent trip to Asia, where American beef was available, the first meal I had after landing was a filet mignon, medium rare, from grain-fed U.S. beef. It was delicious! And the media covering my lecture actually reported it.