BSE/Mad Cow Disease FAQ

  1. What is BSE or Mad Cow Disease?

    Bovine Spongiform Encephalopathy (BSE) or Mad Cow Disease is a degenerative neurological disease caused by an aberrant protein called a prion. It is in a family of diseases caused by prions and referred to as transmissible spongiform encephalopathies, or TSEs. TSEs include scrapie in sheep and goats, chronic wasting disease (CWD) in deer and elk, and Creutzfeldt-Jakob disease, or CJD, in humans. It is important to note that TSEs are not communicable; they do not spread easily like viruses.

  2. What causes BSE?

    The basis of BSE/Mad Cow Disease and other TSEs is still controversial. However, growing evidence strongly suggests that these diseases are not caused by typical infectious agents such as bacteria or viruses, but rather by something called a prion. Several species other than cows have diseases associated with prions, including humans. Creutzfeld-Jakob disease is the most common TSE of humans, and spontaneously occurs at an annual rate of 1-2 cases per million people.

  3. What is a prion?

    A prion (pronounced pree' on) arises from a normal protein in the body that becomes a deadly agent when it undergoes a shape change that prevents it from being broken down by normal degradative activities of the body. These misshapen or abnormal proteins collect in nerve cells and eventually crowd out the normal functions of individual brain cells and neurons. Apparently, prions are able to recruit and convert normal proteins into the pathogenic form. This process is poorly understood, but is slow, and likely explains the long incubation periods associated with these diseases. The footprint left behind from these abnormal protein aggregates consists of holes in the nervous tissue that gives rise to its characteristic sponge-like appearance.

  4. How is BSE spread in cattle?

    There is no scientific evidence that shows BSE can be spread by contact between unrelated adult cattle or from cattle to other species. There is some evidence suggesting maternal transmission may occur at extremely low levels. Cattle can become infected with BSE by eating feed contaminated with the infectious BSE agent. This is why in 1997 the U.S. Food and Drug Administration prohibited the use of most mammalian protein in the manufacture of animal feed intended for cows and other ruminants. For more information on the feed ban, please visit the U.S. Food and Drug Administration's website at

  5. Do we have Mad Cow Disease in the United States?

    The recent case of BSE confirmed in Washington State was the first such case in the United States. Because this animal originated in Canada, there have as yet been no infected animals originating in the United States.

  6. Can people get Mad Cow Disease?

    No. Mad Cow Disease is an illness of cattle. However, a new form of human TSE has appeared in England called the new variant of Creutzfeld-Jakob disease (vCJD). In recent years, over 100 cases of vCJD have been confirmed in England. Mounting evidence suggests that the cluster of vCJD is due to the same agent that caused BSE in cattle.

  7. Are Americans at risk of getting vCJD?

    Definitive statements about poorly understood emerging diseases such as vCJD are difficult to make. However, one can have confidence in the following facts
    • The United States Department of Agriculture (USDA) mandates the removal of a variety of at-risk tissues (specified risk materials) in slaughter plants.
    • There is a ban on importation of live animals and animal products from countries with BSE.
    • There is also a ban on the feeding of mammalian-derived protein to animals.
    • The USDA continues to test possible BSE-suspect animals.

  8. What is the situation regarding the cow in Washington state that was diagnosed with bovine spongiform encephalopathy (BSE)?

    On December 23, 2003, a preliminary diagnosis of BSE was made in a single non-ambulatory dairy cow that had been slaughtered on December 9 at Vern's Moses Lake Meats in Washington State. The BSE World Reference Laboratory in Weybridge, England confirmed this on December 25, 2003. Since this cow originally came from Canada, USDA and Canadian officials worked together to confirm the identification of this cow through DNA testing.

    On January 6, 2003, USDA announced that DNA evidence verified, with a high degree of certainty that the BSE positive cow found in the state of Washington did in fact originate from a dairy farm in Alberta, Canada.

    The USDA's Animal and Plant Heath Inspection Service (APHIS) and Canadian officials have determined that the infected animal was approximately 6-1/2 years old at the time of slaughter. The age of the animal is significant because she would have been born before feeding bans were implemented in North America in August 1997. The feed bans prohibit the inclusion of mammalian protein in feed intended for other ruminants to eat. This practice has been identified time and time again as the primary means by which BSE is spread.

    This cow had three calves while in the United States. The first was stillborn. The second, a yearling heifer, is among 129 animals being depopulated from the affected farm. The third, a bull calf, was among a group of calves depopulated January 6 from a nearby bull calf farm. The herd the affected animal came from is under quarantine in Washington State. Any cattle that die on the farm will be tested for BSE. All depopulated animals were euthanized according to American Veterinary Medical Association animal euthanasia guidelines. No products from any of the slaughtered animals will enter the human food chain, nor will products be rendered.

    The infected animal was part of a Canadian herd dispersal and entered the United States with 81 other animals that crossed into the United States in September 2001. The USDA is currently tracing these other animals. To learn the latest number and locations of animal traced, please check the daily BSE update at

  9. What steps is USDA taking in response to the detection?

    The USDA Food Safety Inspection Service (FSIS) has taken the following actions:
    • USDA has banned all non-ambulatory disabled (downer) cattle from the human food chain effective immediately.
    • FSIS inspectors will no longer mark cattle targeted for testing under the BSE surveillance program as "inspected and passed" until confirmation is received that the animals have, in fact, tested negative for BSE. This new policy is in the form of an interpretive rule that was published January 8, 2004 in the Federal Register. It is important to note that FSIS inspection program personnel have always and will continue to perform ante- and post-mortem inspection of cattle that are slaughtered in the United States. As part of the ante-mortem inspection, FSIS personnel look for signs of disease, including signs of central nervous system impairment. Animals showing signs of systemic disease, including those exhibiting signs of neurological impairment, are condemned and do not enter the food chain. Meat from all condemned animals has never been permitted for use as human food.
    • Effective January 8, 2004, USDA enhanced its regulations by declaring as specified risk materials skull, brain, trigeminal ganglia, eyes, vertebral column, spinal cord and dorsal root ganglia of cattle over 30 months of age and the distal ileum of the small intestine of cattle of all ages, thus prohibiting their use in the human food supply. Tonsils from all cattle were already considered inedible and therefore do not enter the food supply. These enhancements are consistent with the actions taken by Canada after the discovery of BSE in May 2003.
    • In March 2003, FSIS began a routine regulatory sampling program for beef produced from AMR systems to ensure that spinal cord tissue is not present in beef. In a new interim rule announced December 31, 2003, meat-processing establishments have to ensure process control through verification and testing to guarantee that neither spinal cord nor dorsal root ganglia is present in the product.
    • In order to ensure that portions of the brain are not dislocated into tissues of the carcass as a consequence of humanely stunning cattle during the slaughter process, FSIS has issued a regulation to ban the practice of air-injection stunning.
    • USDA will prohibit use of mechanically separated meat in human food.
    • USDA has begun immediate implementation of a verifiable system of national animal identification. The development of such a system has been underway for more than a year-and-a-half to achieve uniformity, consistency and efficiency across this national system.
  10. What steps is FDA taking in response to the detection?

    On January 26, 2004, the United State Food and Drug Administration (FDA) announced two interim rules to further protect FDA-regulated human food and cosmetics.
    • The first rule will ban the following material from use in FDA-regulated human food and cosmetics: any material from "downer" or non-ambulatory cattle, any material from "dead" cattle (having died on the farm), and "specified risk materials" (SRMs) that are known to harbor the highest concentrations of the infectious agent for BSE, such as the brain, skull, eyes, and spinal cord of cattle 30 months or older, and any mechanically separated beef which may contain SRMs. This makes the FDA policy consistent with previous USDA actions.
    • The second rule is designed to further lower the risk that cattle will be purposefully or inadvertently fed prohibited protein and will implement four specific changes in FDA's present animal feed rule. It will:
      1. Eliminate the present exemption in the feed rule that allows mammalian blood and blood products to be fed to other ruminants as a protein source. Recent scientific evidence suggests that blood can carry some infectivity for BSE.
      2. Ban the use of "poultry litter" as a feed ingredient for ruminant animals. Poultry litter consists of bedding, spilled feed, feathers, and fecal matter that are collected from living quarters where poultry is raised. This material is often used in cattle feed when cattle and poultry operations are located near each other. Poultry feed may legally contain protein that is prohibited in ruminant feed, such as bovine meat and bone meal. The concern is that spillage of poultry feed in the chicken house occurs and that poultry feed (which may contain protein prohibited in ruminant feed) is then collected as part of the "poultry litter" and added to ruminant feed.
      3. Ban the use of "plate waste" as a feed ingredient for ruminants. Plate waste consists of uneaten meat and other meat scraps that are currently collected from some large restaurant operations and rendered into meat and bone meal for animal feed. The use of "plate waste" confounds FDA's ability to analyze ruminant feeds for the presence of prohibited proteins, compromising the ability to fully enforce the animal feed rule.
      4. Require all feed mills and feed mixing facilities to designate equipment, facilities or production lines as dedicated to non-ruminant animal feeds if they use protein that is prohibited in ruminant feed. This will further minimize the possibility of cross-contamination of ruminant and non-ruminant animal feeds. This might require some feed mills to operate separate production lines if they produce both ruminant and non-ruminant feed in order to prevent cross-contamination.
  11. What is Advanced Meat Recovery?

    AMR is an industrial technology that removes muscle tissue from the bone of beef carcasses under high pressure without incorporating bone material when operated properly. AMR products can be labeled as "meat." FSIS has previously had regulations in place that prohibit spinal cord from being included in products labeled as "meat." An FSIS regulation published January 8, 2004, expands that prohibition to include dorsal root ganglia, and clusters of nerve cells connected to the spinal cord along the vertebrae column, in addition to spinal cord tissue. Like the spinal cord, the dorsal root ganglia may also contain BSE infectivity if the animal is infected. In addition, because the vertebral column and skull in cattle 30 months and older will be considered inedible, it cannot be used for AMR.

  12. What is Specified Risk Material?

    Specified Risk Materials (SRMs) include skull, brain, trigeminal ganglia, eyes, vertebral column, spinal cord and dorsal root ganglia of cattle over 30 months of age and the distal ileum of the small intestine of cattle of all ages, thus prohibiting their use in the human food supply. These so-called "specified risk materials" present the greatest risk of carrying the BSE agent and have not entered U.S. food supply channels. The scientific community believes that there is no evidence to demonstrate that muscle cuts or whole muscle meats that come from animals infected with BSE are at risk of harboring the causative agent of the disease.

  13. What is the Mammalian Protein Feeding Ban?

    The Food and Drug Administration has banned the feeding of certain proteins derived from mammals to ruminants since 1997. Ruminants are animals that chew their cud, such as cattle, sheep, goats, deer, elk, and bison. Bovine Spongiform Encephalopathy in Great Britain may have been caused by feeding cattle rendered proteins produced from the carcasses of scrapie-infected sheep or cattle with a previously unidentified transmissible spongiform encephalopathy (TSE). The practice of using products such as meat-and-bone meal as a source of protein in cattle rations had been common for several decades. Restrictions on including ruminant protein in feed for ruminant animals were first imposed in England in 1988. On August 4, 1997, the U.S. Food and Drug Administration (FDA) established regulations that prohibit the feeding of most mammalian proteins to ruminants.

  14. What is a non-ambulatory cow?

    A non-ambulatory cow is unable to walk. The new USDA regulations ban all non-ambulatory disabled (downer) cattle from the human food chain. Animals unable to stand or unable to walk (although standing) are both categorized as non-ambulatory.

  15. What is a downer cow?

    Same as a non-ambulatory cow. See above.

  16. What does the detection of BSE in the United States mean for the country's beef exports?

    In accordance with international trade agreements, USDA has notified the international animal health governing body, the Office of International Epizootic's (OIE), of the positive BSE detection and is working to provide U.S. trading partners and international animal health officials with information regarding the steps being taken in response to the detection. For a current list of countries that have placed BSE restrictions on the United States visit the following website:

  17. What are the risks to the U.S. food supply as a result of the detection of the infected cow in Washington State?

    USDA remains confident in the safety of the U.S. food supply. The risk to human health from BSE is extremely low. The following lists some precautions previously taken to protect the United States meat supply:
    • There are no risky tissues in the US meat supply. The BSE agent is not found in cuts of meat like steaks and roasts. It is found in central nervous system tissues such as brain and spinal cord. This is the reason for the efforts by USDA and FDA to eliminate the presence of brain and spinal cord in meats for human consumption.
    • The discovery of the BSE-infected animal in Washington State led to a meat recall as a precautionary measure.
    • An aggressive surveillance program conducted by the USDA at slaughterhouses and on farms to detect the disease. The present surveillance system is designed to find 1 case in one million with a 95% confidence rate of finding the disease. 12,500 cattle would need to be tested to meet this 1 case in one million standard. Approximately 20,000 cattle were tested each year in 2002 and 2003. There are plans to test 38,000 animals in 2004.
    • All US cattle are inspected by a USDA Inspector or veterinarian before slaughter. Animals with signs of neurological disorder are tested for BSE.
    • Imports of cattle meat and bovine products from countries with BSE was banned beginning in 1989.
    • It appears that the only way BSE spreads is through contaminated feed. The US Food & Drug Administration in 1997 instituted a ban on feeding ruminant-derived meat and bone meal supplements to cattle. This should effectively eliminate infections from contaminated feed.
    • There has been no instance nor is there any evidence that the BSE agent in passed into milk.

  18. Is there a phone number consumers can call with questions about meat products?

    Consumers with other food safety questions can phone the toll-free USDA Meat and Poultry Hotline at 1-888-MPHotline. The hotline is available in English and Spanish and can be reached from 10 a.m. to 4 p.m. (Eastern Standard Time), Monday through Friday. Recorded food safety messages are available 24 hours a day.

This fact sheet was put together using the following sources:

AAFCO. 2001. American Association of Feed Control Officials. Mammalian Protein Feeding Ban. July 2001.

FDA. 2004. United States Food and Drug Administration. Expanded "Mad Cow" Safeguards Announced To Strengthen Existing Firewalls Against BSE Transmission. January 26, 2004.

Parsons, Thomas. 2001. University of Pennsylvania. Bovine Spoingiform Encephalopathy Q&A Fact Sheet.

USDA-APHIS. 2004. United States Department of Agriculture - Animal and Plant Health Inspection Service. BSE Trade Ban Status as of 1-28-04. January 28, 2004.

USDA-APHIS. 2004. United States Department of Agriculture - Animal and Plant Health Inspection Service. Bovine Spongiform Encephalopathy (BSE) Q & A's. January 21, 2004.

USDA-APHIS. 2004. United States Department of Agriculture - Animal and Plant Health Inspection Service. Case of BSE in the United States: Chronology of Events. January 20, 2004.

USDA-APHIS. 2004. United States Department of Agriculture - Animal and Plant Health Inspection Service. Bovine Spongiform Encephalopathy (BSE). January 29, 2004.

  1. Rutgers
  2. Executive Dean of Agriculture and Natural Resources
  3. School of Environmental and Biological Sciences