Mad Cow Disease: The Myths, the Facts, and a Prescription for Food Safety
Monograph: 29 December 2003 Updated: 28 September 2004
by Frederick W. Scalise, Ph.D., RPIH, CHMM
The following monograph was prepared in a response to the confirmation of Bovine Spongiform Encephalopathy (BSE: "Mad
Cow" Disease) in a dairy cow that was slaughtered in Washington state in mid-December 2003. First offered is a review of
the scientific facts, and a discussion of how little is actually known about this disease. A list of precautionary steps that we
believe must be immediately taken to protect public safety is then presented at the end of this monograph.
"Mad Cow" disease, more correctly known as bovine spongiform encephalopathy (BSE), became epidemic in Europe (first
in Great Britain in 1985) in the mid- and late 1980s. The disease is characterized by the formation of vacuoles (holes) in
the animal's brain, giving the brain a "spongy" appearance. As the disease progresses, the animal tremors, displays
abnormal and sometimes aggressive behaviors, and then begins to lose muscle control eventually leading to death.
The appearance of BSE in European cattle is thought maybe to have resulted from the previously-common practice of
including slaughtering by-products from sheep (including brain, spinal cords, lymphatic tissues, and bone meal) in cattle
feed as a protein supplement. Sheep and goats have been known for hundreds of years to suffer from a similar spongiform
encephalopathy, called "scrapie". However, even though the cause of this disease was unknown, it was long regarded
that scrapie was unique to sheep and could not be transmitted to other species of animals.
The European BSE epidemic was regarded as solely an agricultural disaster, with millions of animals being destroyed to
prevent the spread of the disease.
Creutzfeldt-Jakob Disease (CJD) has been recognized as a specific and relatively rare human disease since the 1920s.
It too is a spongiform encephalopathy, and there has long been discussion as to whether there was some connection
between CJD and scrapie.
"Classical" CJD typically strikes people between the ages of 50 years and 75 years, and generally is seen at an
occurrence rate of only 1 - 5 cases per million people per year.
In 1995, eight years after the "Mad Cow" epidemic was first recognized in Great Britain, a sudden "explosion" of cases of
a CJD-like disease was seen in the British population. However, the new British CJD was different than "classical" CJD
in that it was striking much younger people (teenagers and young adults). In 1996, British authorities acknowledged that
there might be a correlation between this new variant CJD (nv-CJD or v-CJD), and BSE.
In 1999, it was demonstrated that a small protein particle called a prion, isolated from nervous tissues of cattle with
BSE, was in fact the infectious agent that caused the "mad cow" disease. This prion was also shown to be able to
infect other animal species besides cattle.
Since 1999, it has been shown that there are various strains of prions, and that the prions associated with nv-CJD and
BSE are of very similar, if not identical, strain types (i.e., the prion that causes BSE probably also causes nv-CJD).
From 1995 through the end of 2003, there have been 153 deaths world-wide confirmed to be nv-CJD, and presumed to be
the result of eating prion-contaminated beef products.
Prions, short-hand for "proteinaceous infectious particles", were first described and named in the early 1970s in
association with scrapie-infected brain tissues. Similar protein particles were subsequently observed in brain tissues
from CJD patients. However, at that time, scrapie, CJD, and other known spongiform encephalopathies were thought to
be slow-onset viral diseases. The concept that a protein could, by itself, be infectious was considered ludicrous and
soundly dismissed by the scientific community (I remember the idea being derided as "science fiction" in a graduate-
level virology course in 1975).
But an infecting virus was never found, and following the surge in nv-CJD cases in 1995, interest in the prion concept was
renewed. And the molecular biology techniques available today have unlocked many of the secrets of this tiny protein
It turns out that all mammals, likely all vertebrates, and very possibly all animal species make a "normal" prion-like
protein. In higher animals, this normal protein appears to be concentrated in (and possibly exclusive to) central nervous
system tissues. In its normal form, the prion-like protein is benign and undoubtably performs some necessary function.
However, if a misshapen prion-like protein (as in its three-dimensional folding structure is altered) gets into the central
nervous system, it has the nasty habit of "warping" all of the other prion-like proteins it encounters, causing them to form
clumps. It is the original and subsequently-created misshapen protein particles that are called prions, and that are
(disease; affected animals)
- Scrapie: sheep and goats
- Transmissible Mink Encephalopathy (TME): mink
- Chronic Wasting Disease (CWD): muledeer; elk (first identified in 1967)
- Bovine Spongiform Encephalopathy (BSE): cattle; cows; various other mammals
- "classical" Creutzfeldt-Jakob Disease (CJD)
- "new variant" CJD (nv-CJD or v-CJD: Believed to be a BSE strain)
- Gerstmann-Strausler-Schneinker Syndrome (GSS)
- Fatal Familial Insomnia (FFI)
- Alpers Syndrome (a prion disease in infants)
All of the animal diseases, and at least both Kuru and nv-CJD, are classified as "transmissible spongiform
encephalopathies" (TSEs): They can be transmitted from one individual to another by the infectious prion.
BSE currently appears to have the widest range of species susceptibility. BSE prions have transmitted TSEs to
humans, monkeys, sheep, pigs, mice, domestic cats, large cats, and a number of hoofed mammals. Scrapie may be
transmissible to at least a limited number of other species.
"Classical" CJD has two forms: Spordic, which appears to arise from a random mutation of a gene for the prion-like
protein, and familial, which runs in families and is an inherited, mutated gene condition. FFI also appears to be an
Much of what we now know about spongiform encephalopathies is the result of observations made on the Fore people of
Papua, New Guinea. These people were essentially isolated from contact with the outside world until early in the 20th
Century, and traditionally ate parts of their deceased relatives as part of a mourning ritual.
In the 1940s, an epidemic of a strange brain wasting disease, characterized by the onset of tremors and uncontrollable
laughter in afflicted individuals, was noted in the Fore people. The disease was named "Kuru". Studies finally linked the
occurrence of the disease with ingestion of human brains. Once cannibalism was banned in the late 1950s and early
1960s, the occurrence of the disease quickly began to decline. However, scientists studying Kuru observed that people
were still getting the disease long after their last ingestion of human organs. Latent periods of 10 years, to well over 20
years, were commonly being seen. In a recently diagnosed case, Kuru symptoms developed in a man some 40 years
after his last participation in a cannibalistic death ritual.
Studies of brain tissue from people who have died from Kuru has established that the disease is in fact a prion-based
spongiform encephalopathy that is closely related, if not identical to, CJD. It is now thought that one or more members
of the Fore people somehow contracted CJD in the early 20th Century, and that the epidemic was created when other
tribe members ritually ate the brains of these infected individuals after they died.
Recent scientific study of prions has suggested that there may be genetic factors in the disease process.
Some people appear to develop CJD spontaneously: There is the so-called sporadic-CJD which may develop as the
result of a random mutation in a gene that codes for a normall (harmless) prion-like protein and causes the production of
mis-folded, disease-causing prions. Then there is familial-CJD, which appears to be caused by an inherited gene
defect. These forms of the disease ("classical CJD") are extremely rare, occurring only 1 - 5 times per one million
The third form of CJD (and CJD-like diseases) is likely to be the result of exposure to prions. And genetics may again
play a role in the disease. We all have many different types of normal prion-like proteins in us, and we have two copies
(a pair) of the gene for each protein type.
Individuals with gene pairs that contain two slightly different versions of the gene appear to be either resistant to CJD, or
to have significantly longer incubation periods before the disease is first expressed (20 years or more after exposure to
infectious prions). By contrast, people with identical genes in their prion-like protein gene pairs may be especially
What this suggests, in terms of the BSE issue, is that some people who are or have been exposed to prion-containing
beef may be genetically predisposed to contract v-CJD relatively quickly (i.e., within 5 - 12 years after exposure). On the
other hand, there may be another population of people who have at least partial genetic protection from the disease, and
who may not express symptoms for 20, 30, maybe even 40 years after exposure to infectious prions.
There has only been one cow in the United States with Mad Cow Disease.
Only one cow in the United States has ever been confirmed to have the disease.
If in fact this one 6 year old cow was infected in Canada as a result of eating beef by-product-supplemented feed, before
that practice was banned in 1997, then it is likely that there have been thousands, possibly millions, of other similarly-
fed animals that found their way into the U.S. food supply between at least 1995 and 2003. No one knows how many of
those animals were infected with prions or had undiagnosed Mad Cow Disease.
All offspring and herd cohorts of the one infected U.S. animal have been identified and destroyed, eliminating any
residual risk of BSE in U.S. cattle herds.
Not enough is known about how prions are transmitted between individuals to know if that statement is true. In sheep
and goats, it has long been thought that the Scrapie prion was passed through a herd as a result of animals grazing on
grass contaminated with placenta tissues, or maybe even eating abandoned placentas. It has also not been ruled out
that prions can be transmitted via insects and possibly ticks.
This raises the possibility that any animal that had contact with an infected individual, or at some time passed through
the same facilities as an infected animal, might now also be infected with BSE prions.
No one in the United States has ever died from Mad Cow Disease.
No one knows if that statement is true or not. We do know that animals from Canadian herds in which Mad Cow
Disease was later detected were imported into the U.S. and entered the food supply. The number of people in the
United States that have been exposed to the BSE prion since at least the early 1990s remains entirely unknown.
It is also important to remember that CJD, and related diseases, are not required to be reported to the Centers for
Disease Control (CDC). So, there really are no good figures for how many CJD and CJD-like cases there have been in
the U.S. Further complicating the issue is the fact that CJD symptoms often mimic many other neurological diseases,
such as Alzheimer's Disease, and that CJD can only be definitively diagnosed by evaluating thin-sections of brain
tissue during an autopsy.
A study completed at Yale University in 1989 found that 13% of the people who presumably had died from Alzheimer's
Disease actually had CJD (1). This suggests that almost 1/2 million of the 4 million people in the United States
estimated to have Alzheimer's Disease (2) might currently have CJD. That number is more than 300 times what is
expected in the U.S. population due to "classical" CJD.
There have also been some suspicious clusters of CJD. In one case, seven unrelated individuals, whose only link was
that they all had frequented and eaten at the Garden State Race Track in Cherry Hill, New Jersey, died of what was
attributed to sporadic-CJD over an eight year period. But none of the affected individuals was ever autopsied to
determine if their CJD was in fact the sporadic version, or the new variant CJD (nv-CJD) connected with Mad Cow
Research conducted in Italy has recently identified a new strain of TSE in beef: One that shows neurological changes
that are strikingly-different from typical mad cow disease, but very similar to the changes seen in humans with sporadic
CJD (6). This newly-discovered strain again raises the possibility that many, possibly even most or all, sporadic CJD
cases are actually the result of consumption of prion-infected meat.
Contracting nv-CJD from infected beef is an extremely low risk: Only 153 people (out of a potentially exposed population
of 60 million) died in Britain as a result of the Mad Cow Disease outbreak there.
Again, no one really knows the level of risk. It is true that as of December 2003, only 153 people have been confirmed
to have died of nv-CJD in the United Kingdom since 1995 (the year when nv-CJD was recognized and linked to BSE).
But as discussed above, CJD has a wide range of incubation periods before symptoms first appear. Some people may
be genetically programmed to express symptoms in as little as 4 - 5 years after exposure to prions, while other people
may silently harbor the infection for 10, 20, 30, maybe even 40 or more years before symptoms first occur.
The estimates of the total number of people in Britain who eventually will develop nv-CJD as a result of the 1985 Mad
Cow Disease epidemic has ranged from a few hundred, to tens of thousands, to hundreds of thousands, and maybe
even more than a million. The fact is, no one knows how many people were exposed to the BSE prions, or what the
public health consequences of exposure will be over the next few decades.
The first detection of Mad Cow Disease in North America in 1996 (Canada) was the wake-up call that something had to
be done to protect the safety of beef in the United States. It is unfortunate that given how little was really known about
the disease, minimal and scientifically unvalidated precautions were implemented at that time.
The beef and rendering industries chose to gamble that BSE would never enter the U.S. herd. They fought universal
testing and a variety of other restrictions, trading public safety for continued growth of profits. The "science" that they
cited to support this stance was a combination of bad science and non-science. And too many people in government,
those that were supposed to be looking after the public's welfare, were either unable or unwilling to comprehend the real
scientific information that was available.
What is particularly disturbing is the fact that the U.S. government is spending hundreds of millions (possibly billions) of
dollars to protect the public against the possible threat of biological agents being used by foreign terrorists. Emergency
personnel are being trained and equipped, people are being inoculated, and vaccines are being stockpiled. At the same
time, we have an actual biological threat at our back-door: A disease agent that almost always results in death.
However, because this disease involves potential impacts to the profits of a very well connected and powerful industry ,
the government appears to be bowing to pressures to give financial considerations precedence over public safety
issues. The rational response to the BSE threat is to institute maximum levels of protection until such time as it is
conclusively shown that particular restrictions are not actually necessary.
The beef and rendering industries gambled, and they lost. What they claimed would never, and could never happen,
did. It will probably be many years before we know how widespread BSE-impacted beef has been in our food supply
over the last six or seven years. But at least we now once again have an opportunity to take steps assure, going
forward, that public safety is fully protected.
These are the measures that have been implemented since 1997:
1997: Brains and spinal cords, and a limited number of other body parts, from ruminants (e.g., cows; cattle; sheep;
goats) are banned from being used as protein supplements in feed for some, but not all, food animals.
[The loopholes in the ban mean there is continued risk of prion-contaminated feed being either inadvertently, or in some
cases intentionally, fed to susceptible food animals. A complete ban on the use of potential prion-containing animal by-
product material in livestock feeds and animal foods is needed.]
2003: All beef-producing animals older than 30 months of age must now have their brain and spinal cord separated
from the carcass at the time they are slaughtered.
[Good, but not enough. As previously discussed, the 30 month age limit has been shown to not be scientifically valid.
The brain and spinal cord should be removed from all slaughtered ruminants, irrespective of their age.]
2003: "Downer" animals are banned from being used for human consumption.
2003: Mechanical strippers are banned. These are machines that "thrash" bits of meat off carcass bones. The
problem with this process is that it often also tears off neural tissues.
These represent a good start at tackling the problem, but fall well short of the comprehensive program that is needed to
fully assure public safety.
Given all that we currently do not know about transmissible spongiform encephalopathies (TSEs), it is our opinion that it
is essential in that the following steps be implemented:
1. All ruminants (e.g., cows; cattle; sheep; goats) must be tracked from the day they are born until the day they are
slaughtered or otherwise die. Technologies such as implantable microchips are available and would be difficult to cheat
or defeat. As part of the tracking process, complete records about each animal must be maintained: Where it was
born, every place it has ever been located, and any pertinent health information. No ruminant should be allowed to be
imported into the United States without a complete documentation of its history.
2. All ruminants must be tested for TSEs, irrespective of their age, at the time that they are slaughtered. Universal
testing is the only way to fully assure that prion-contaminated materials are not entering the food supply or being
incorporated into by-products. There are now relatively-fast test procedures available, and it is estimated that universal
testing of cows and cattle would only add between $ 0.20 and $ 0.50 per pound to the price of beef.
3. The brains and spinal cords of all mammals destined for human consumption need to be removed at the time that
the animal is slaughtered.
4. Brains, spinal cords and other neural tissues, small intestines, and lymphoid tissues from mammalian species need
to be banned from use as constituents of:
(a) any food or feed product, or pharmaceutical or supplement, to be used by any other mammalian animal species
(b) any health, hygiene, or beauty product to be used by humans or any other mammalian species
(c) any product designed to be used by individuals less 18 years of age
5. The mechanical splitting of ruminant carcasses by sawing through the spinal column must be prohibited.
6. Any product which contains rendered mammalian materials must be labeled as such, with appropriate warnings to
avoid ingestion and/or inhalation of dusts.
7. Meat products derived from ruminants should be allowed to be imported into the United States only from those
countries of origin that meet or exceed these same levels of food safety.
You could adopt a vegetarian lifestyle, but that probably would be an over-reaction, especially since it is possible that
many of us have already been exposed to prions.
What does need to be done however, is to convince public officials that stringent and comprehensive precautions must
now be implemented to assure the future safety of our food supply.
If you agree, please feel free to either e-mail a link to this Web page (The URL from your browser "address" window) to
your elected federal representatives and/or other federal officials, or mail them a hardcopy of this monograph (NOTE:
The best way to print this monograph is to copy and paste it to a word-processing program
[edit > select all > copy >> paste]).
U.S. Department of Agriculture (USDA)
E-mail the Secretary of Agriculture:
for other contact information:
Food and Drug Administration (FDA)
Form-mail and postal contact information:
(for form-mail, use "food" topic)
U.S. House of Representatives
Find and contact your Representative:
(note: you'll need your Zip+4 code; a lookup is available from this site)
Find and contact your Senator:
1 Alzheimer Disease and Associated Disorders, 1989, vol 3, nos. 1-2, pgs 100-109
2 Alzheimer's Association
3 The New York Times, Health Section, February 3, 2004
4 New England Journal of Medicine, vol 349, pgs 1812-1820
5 The Seattle Post-Intelligencer, February 16, 2004
6 The New York Times, April 18, 2004
7 The Associated Press, July 27, 2004
Frederick W. Scalise holds degrees in microbiology, biology (neuroendocrinology), and molecular biology and
biochemistry. He is a certified hazardous materials manager and a registered professional industrial hygienist. Dr.
Scalise is a senior consultant for both OMNICON Environmental Management (since 1987), and OMNICON Research &
Information Systems (since 1983). His background includes risk assessment, and analysis and development of public
safety policy and programs.
Copyright (c) 2003 - 2004, OMNICON Research & Information Systems. All Rights Reserved
No part of this monograph may be duplicated, re-printed, or disseminated in any format or by any means, except as stipulated below, without
written permission from the author.
Copyright exception: Private individuals may copy and print this monograph for the purpose of sending said copies to elected representatives
and/or governmental officials.
Testing representative samples of herds is protective of human health.
At present (August 2004), approximately 220,000 animals out of about 35 million animals slaughtered are tested each
year for BSE in the United States (up from about 40,000 per year, 1997 - 2003). This is a testing rate of 0.63% (10.5
out of every 1,750 animals slaughtered is tested). The majority of the animals that are tested are "suspect": Displaying
an inability to stand or walk properly ("downer" animals). This means that not only is the sample size statistically
extremely small, but also that the sampling is not randomly distributed throughout all animals destined for the human
The beef industry and the Agriculture Department claim that the testing protocol used can detect the presence of Mad
Cow Disease even if it is present in only 1 animal in a million. What they don't say is that by biasing the sampling
towards "downer" animals, they are assuming that BSE is not present in animals that are not displaying symptoms.
But there is no evidence to support that asymptomatic animals are not capable of transmitting the BSE prion. In fact,
the one cow in which BSE has been detected in the United States was not a "downer", according to the man who
actually killed it (David Louthan), and was not displaying any Mad Cow symptoms (3).
According to Louthan, the testing of this cow was itself a fluke. The animal probably would not have been tested except
that it was brought outside to keep it from trampling other animals. Company protocol called for any animal killed
outside the slaughterhouse to be tested for BSE.
The current U.S. testing program is more like a game of Russian Roulette, and relies heavily on luck to detect diseased
animals. It is a program that in no way can assure public safety.
Testing programs in other countries are fully protective of human health.
Only Japan currently tests each and every animal destined for human consumption for BSE at the time of slaughter.
The Japanese program is protective of public safety.
Testing programs in European countries, while vastly superior to the U.S. program, may still not be adequate. Most
European countries test any animal slaughtered that is 30 months or older. Germany tests all animals older than 24
months. This testing by age comes from early data that suggested that the BSE prion was not present in the brains
and spinal cords of animals younger than 2 - 3 years. But the Japanese claim that they have found diseased animals
as young as 21 months of age (these results reportedly have been recently confirmed by researchers in Europe).
The flaw in the European testing program is that no one knows what happens to prions after they are ingested by an
animal. Current evidence suggests they first accumulate in lymphoid (immunologically active) tissue called Peyers
Patches in the wall of the small intestines after ingestion. From there they may eventually migrate to other lymphoid
sites in the body, such as tonsils and the spleen, and replicate to increase their number. At some point the prions
manage to access the central nervous system (CNS), where they begin the visible disease process that is
characterized by spongiform lesioning in the brain. Clearly there are prions present in infected animals from the
moment they first ingest prion-contaminated material. The fact that it may take 2 - 8 years for those prions to migrate
to the CNS and manifest themselves as visible disease symptoms does not mean that the animal is not infectious at
early ages when prions are not yet detectable in the brain and spinal cord. The prions are still in the animal
somewhere, and a person who ingests those prions, irrespective of their location in the animal's body, is likely to be at
risk for contracting nv-CJD.
In the final analysis, the European testing program is capable of detecting the beginnings of a new BSE epidemic, but
is not fully effective at detecting individual asymptomatic animals that might be carrying infectious prions. The European
testing program is better than the U.S, program, but not by much.
I'm safe if I don't eat beef containing brain or spinal cord materials.
This is what was originally believed. Then BSE prions were found in accumulated in areas of small intestines. Now it is
believed that prions may migrate to, and spend time in, a variety of lymphoid sites including the tonsils, the spleen, and
possibly the thymus gland before entering the CNS. There is also disturbing research from different laboratories around
the world which claim to have detected prions in muscle tissues.
An examination of tissues from sporadic-CJD patients found prions in 36% of the spleens examined, and 25% of the
skeletal muscle samples examined (4). There have also been reports of BSE / nv-CJD prions detected in muscle
tissues of mice and hamsters artificially infected with these prions.
Another problem is the way killed animals are prepared for butchering. A large band-saw is used to cut the carcass in
half, from neck to tail, slicing right through the spinal column and exposing the spinal cord. Hot water is sprayed onto
the saw blade as it cuts, and a slurry of water, fat, bone dust, meat, and spinal cord material is splattered all over the
The final answer is........ no one really knows at this time whether non-neural / non-intestinal tissue from prion-infected
animals is completely safe or not.
Feeding beef by-products, including intestines and CNS tissue, to other animals is safe.
Completely false! BSE is thought to have originated as a result of feeding cattle high-protein feed supplements
containing prion-infected neural tissues and bone meal prepared from sheep and goats. And it is almost universally
accepted that the BSE prion causes a variant form of CJD in humans. Clearly the BSE prion can be transmitted, and
remain infectious, across species lines.
A number of animal species have been now shown to be susceptible to transmissible spongiform encephalopathies
caused by a prion that is very similar to the BSE prion, including monkeys, cats, and a variety of ungulates (hoofed
mammals) including sheep and pigs.
The beef industry and the animal rendering industry have fought hard to prevent additional restrictions on the use of
animal by-products. But in reality, the feeding of beef by-product material that is potentially infected with BSE prions to
mammals (such as pigs) that will enter the human food supply is another public crisis waiting to happen. And isn't it
comforting to know that you may be contributing to Fluffy's or Rover's early demise with every meal you give your pet?
Beef by-products represent no risk to humans.
No knows for sure if there is a risk or not. What is known is that prions are very stable and hardy. They are not
destroyed or inactivated by chemical disinfectants and are resistant to heating. There is nothing to suggest that they
don't remain intact and potentially still infectious after the rendering (melting down) process.
Some of the types of products derived from or which contain rendered animal by-product materials (including beef brains
and spinal cords which could potentially contain prions) include: soaps; toothpaste; nail polish and other cosmetics;
mouthwash; glues; crayons; pharmaceuticals; dietary supplements; pet foods; fertilizers
Whether there is potential for human infection as a result of exposure to prions in these products is not currently
known. There has however already been some concern expressed about the possibility of gardeners and farm workers
being exposed to prion-containing dusts generated during the use of bone meal and fertilizer products.
April 18, 2004:
A small Kansas beef processor, Creekstone Farms, took steps to re-enter the Japanese beef market. They built a special
laboratory, obtained training for staff, and purchased machinery that provides test results for BSE within 7 hours. Their
goal was to test every beef carcass that they processed, as is required by the Japanese government.
But USDA objected, and has told Creekstone Farms that they are prohibited from testing every slaughtered animal.
Voicing the chorus of the corporate beef industry, USDA has stated that such testing, to certify some beef products as
BSE-free for the Japanese market, is not necessary ("no scientific justification") and might confuse American consumers
into thinking that untested beef was not safe (6).
Say WHAT ?? The role of the USDA is to set and enforce minimum food safety standards. If someone wants to go above
and beyond to demonstrate the purity and/or safety of their product, that's their business, not USDA's. Using the same
logic, maybe USDA should also ban the use of kosher standards. The simple fact is, the corporate beef industry is afraid
that if one company starts universal testing, then all will be required to do the same in order to respond to consumer
demands and stay competitive. And the corporate beef industry long ago decided that it did not want to face the the cost
of implementing a significant BSE testing program. Makes you wonder whose interests the current USDA is really
January 2004: US Department of Agriculture (USDA) proposes development of a system to track the origin and
movement of cattle.
The USDA revealed that it allowed Canadian beef products to be imported in the United States, under special
permit, from September 2003 through April 2004, despite the known continued presence of BSE in Canadian herds.
July 26, 2004: The Food & Drug Administration (FDA) bans bovine brain, spinal cord, other neural tissues, and blood
from cosmetics and dietary supplements, and stipulates that beef tallow can not be contaminated with neural tissue. This
ban evolved from January 2004 recomendations of an international panel. In addition, the FDA implemented measures to
assure that processed foods (e.g., canned soups; frozen pizza; cold cuts) are not made with material from "downer" cows
or mechanically-separated ("thrashed") meat (7). The FDA also proposed to study a possible ban on neural and other
high-risk bovine tissues from all animal feeds, including pet foods.
July 2004: Two cases of nv-CJD (the variant from ingestion of BSE prion-contaminated food) are detected in individuals
who received blood transfusions. This raises the possibility of blood being a reservoir for prions, and a potentially
unrecognized source (ingestion of blood; blood transfusions; use of medical products derived from blood) for transmission
of prion-based infections.
February 16, 2004: Italian researchers reported finding (5) a new strain of TSE in beef, that shows neurological changes
similar to those seen associated with sporadic CJD (the human form of CJD that has been thought to arise by random
mutation). The "new" disease is differnet from BSE, and current tests for BSE do not detect the newly identified TSE. This
raises the possibility that sporadic CJD in humans is actually a slow-acting prion infection acquired by ingestion of infected
beef, and one that is currently not being tested for.
September 2004: Some disturbing recent findings about Chronic Wasting Disease (CWD) in deer and elk:
The disease is spreading throughout the Rocky Mountain states (Colorado to Montana, and well into western Canada).
There is recent research that suggests that the prions that cause the disease may be present in muscle tissues (i.e., in the
There is now evidence that the disease might be transmitted to animals just by their passing through areas where infected
animals have been.
These findings open the possibility that there is an as of yet unidentified disease vector (e.g. ,fleas; ticks; mosquitoes), and
also the possibility that CWD prions might be transmitted to livestock co-existing in disease-affected areas.