Mad Cow Facts

Causes of Mad Cow Disease FAQ

There are many online resources attempting to answer commonly asked questions about topics that include the causes of Mad Cow Disease or Bovine Spongiform Encephalopathy (BSE), Mad Cow Disease symptoms and other forms of prion diseases. We encourage you to consider the source and as such suggest the U.S. Food and Drug Administration, U.S. Department of Agriculture, and the Center for Disease control as reliable sources for such information.

Here are their mad cow/BSE-related FAQs:
US Food and Drug Administration
http://www.fda.gov/oc/opacom/hottopics/bse.html

Issued January 2004

Commonly Asked Questions About BSE in Products Regulated by FDA’s Center for Food Safety and Applied Nutrition (CFSAN)

In light of the December 23, 2003, diagnosis of BSE in a single cow that had been imported into the United States, CFSAN has reviewed the products it regulates to ensure their safety.

What is “Mad Cow Disease” (Bovine Spongiform Encephalopathy/BSE)?

Mad Cow Disease is the commonly used name for Bovine Spongiform Encephalopathy (BSE), a slowly progressive, degenerative, fatal disease affecting the central nervous system of adult cattle. Since 1990, the U.S. Department of Agriculture (USDA) has conducted aggressive surveillance of the highest risk cattle going to slaughter in the United States, in which 10,000- 20,000 animals per year have been tested. To date, the only cow that has been found to be affected with BSE was the one diagnosed with BSE in December 2003.

What are the causes of Mad Cow Disease, or BSE?

The exact cause of BSE is not known but it is generally accepted by the scientific community that infectious forms of a type of protein, prions, normally found in animals cause prion diseases such as BSE. In cattle with BSE, these abnormal prions initially occur in the small intestines and tonsils, and are found in central nervous tissues, such as the brain and spinal cord, and other tissues of infected animals experiencing later stages of the disease.

Was a case of BSE identified in the U.S. in December 2003?

Yes, the USDA surveillance program identified the first BSE case in the U.S. in a dairy cow in Washington State. The cow was bought from a farm in Canada.

Did meat and meat products from the BSE cow enter the food supply?

As soon as the BSE case was identified, both USDA and FDA activated their BSE Emergency Response Plans and USDA immediately recalled the meat. Meat that did enter the food supply was quickly traced and was removed from the marketplace. Moreover, all the organs in which infectious prions occur were removed at slaughter and did not enter the food supply. Scientific research indicates that muscle meat is not a source of infectious prions. As a result of the agencies’ quick actions and the removal of organs that contain infectious prions, there is no significant risk from products of this animal.

FDA and state inspectors located all other parts of the animal, and rendering plants that processed this material from the BSE cow voluntarily held the material. None of this material left the control of the companies and entered commercial distribution.

Will there be additional cases?

Regulatory measures to prevent introduction of BSE into U.S. cattle herds and contamination of U.S. foods and food products are being reviewed and updated. Since 1989, the USDA has banned imports of live ruminants, such as cattle, sheep and goats, and most products from these animals from countries known to have BSE. This ban was extended to all Europe in 1997. The FDA prohibited the use of ruminant protein in the manufacture of animal feed intended for cows and other ruminants in 1997 and extended the prohibition in 2001 to forbid use of all mammalian protein in ruminant feed. See the FDA/CVM website at www.fda.gov/cvm for further information on the “ruminant feed ban”.

Under an Import Alert, FDA also prevents U.S. entry of cosmetic and dietary supplement ingredients containing high risk bovine materials from animals originating in BSE countries.

In 1998, the USDA commissioned the Harvard Center for Risk Analysis to conduct an analysis and evaluation of the U.S. regulatory measures to prevent the spread of BSE in the U.S. and to reduce the potential exposure of U.S. consumers to BSE. The Harvard study concluded that if introduced, due to the preventive measures currently in place in the U.S., BSE is extremely unlikely to become established in the United States. Should BSE enter the United States, the Harvard study concluded that only a small amount of potentially infective tissues would likely reach the human food supply.

Furthermore, on Jan. 8, 2004, the USDA’s Food Safety and Inspection Service issued four new rules to enhance safeguards against BSE. Details on these rules may be found at the USDA website, www.usda.gov.

Does BSE affect people?

There is a disease similar to BSE called Creutzfeldt-Jacob Disease (CJD) that is found in people. A variant form of CJD (vCJD) is believed to be caused by eating contaminated beef products from BSE-affected cattle. To date, there have been 155 confirmed and probable cases of vCJD worldwide among the hundreds of thousands of people that may have consumed BSE-contaminated beef products. The one reported case of vCJD in the United States is in a young woman who contracted the disease while residing in the UK and developed symptoms after moving to the U.S.

What additional measures are being taken to ensure food safety in the U.S. from BSE?

Since 1989, the FDA and other federal agencies have had ongoing regulatory measures in place to prevent BSE contamination of U.S. food and food products since 1989. Following the identification in a Washington state dairy herd of the BSE-positive cow imported from Canada, the USDA has issued four new regulations containing additional safeguards to further minimize risk for introduction of the BSE agent into the U.S. food supply. These safeguards include:

a. A ban on use of live, but non-ambulatory cattle from entering
the human food supply
b. A ban on use of organs, from cattle older than 30 months, in
which infectious prions occur and the tonsils and small intestine of cattle of all ages for human food
c. Restrictions on techniques to mechanically remove meat from
bones, and
d. Meat from tested animals will not be certified as USDA-inspected
until test results are final.

See the USDA website www.usda.gov for further information.

FDA fully supports the safety policies announced by the USDA, which build on the principles and procedures that FDA and USDA have developed since 1989. These protective measures will add an additional layer of protection for the American public.

FDA will fulfill its increased responsibilities for protecting the safety of the food and animal feed supply.

Is the food in the U.S. likely to be a BSE risk to consumers?

FDA and other federal agencies have had preventive measures in place to reduce the U.S. consumer’s risk of exposure to any BSE-contaminated meat and food products. Since 1989, the USDA had prohibited the importation of live animals and animal products from BSE-positive countries. Since 1997 the FDA has prohibited the use of most mammalian protein in the manufacture of ruminant feed. FDA continues to implement policies to keep safe all FDA-regulated products, including food, food ingredients, dietary supplements, drugs, vaccines, and cosmetics from risk of any BSE-contaminated bovine material.

Is cow’s milk a source of BSE?

Scientific research indicates that BSE cannot be transmitted in cow’s milk, even if the milk comes from a cow with BSE.

In the process of locating herd mates of the BSE-positive cow in Washington state, at least one dairy herd was quarantined. Is there any known risk to consumers that milk from this herd contains the BSE infectious agent or may transmit BSE?

No, because BSE is not transmitted through milk. It is FDA’s opinion, based on the totality of scientific data available to the agency, that milk from healthy cows from the same herd in which the BSE-positive cow was found does not present a BSE risk to consumers. Likewise, milk from healthy cows in other herds quarantined because one of the cows is identified as a previous herd mate of the BSE-positive cow does not present a BSE risk to consumers. If the cows in a herd are healthy and not clinically affected by BSE, there is no scientific basis for restricting that milk.

Can milk be infected with BSE from a BSE-positive cow?

No detectable infectivity in cow’s milk has been reported from any BSE-infected cows. Infectious prions have not been detected by bioassay of milk from cattle with BSE.

Are milk and milk products BSE-safe?

Yes. The World Health Organization (WHO) has stated that tests on milk from BSE-infected animals have not shown any BSE infectivity, and there is evidence from other animal and human transmissible spongiform encephalopathy studies to suggest that milk does not transmit these diseases. Milk and milk products, even in countries with a high incidence of BSE are, therefore, considered safe.

Should milk from a BSE-positive cow be discarded?

Even though milk does not transmit BSE, the milk from a cow with BSE should be discarded. The Food, Drug, and Cosmetic Act and state milk safety regulations require that products from animals with any disease not be used for human use. This is consistent with actions taken in the U.K, and with WHO recommendations on human use of products from BSE cows.

Does the use of bovine-derived ingredients in dietary supplements mean that they are not safe?

No. The risk to human health from BSE in the United States food supply, which includes dietary supplements, is extremely low. Since 1992, FDA has advised dietary supplement manufacturers and distributors that they should take steps to ensure that no dietary supplement ingredients come from cattle born, raised or slaughtered in any country known to have BSE or that has inadequate methods to detect and control it. We have also had import procedures in place since then to prevent the importation of bulk ingredients and finished dietary supplements that contain bovine-derived ingredients from so-called BSE-countries. Also, the vast majority of cattle-derived ingredients are obtained from U.S. sources or from countries not known to have BSE.

Since the BSE-positive cow was discovered in the U.S., does that mean that dietary supplements made with domestic ingredients might be unsafe?

No. Like all foods that are made using bovine-derived ingredients, the procedures that FDA and USDA have had in place to ensure the safety of the food supply should give consumers confidence that their food, including dietary supplements, is safe. Even though an imported BSE-positive cow was identified in the U.S., the risk to human health from dietary supplements and other foods containing bovine-derived ingredients remains extremely low.

What steps is FDA currently taking to ensure the safety of dietary supplements that contain bovine ingredients?

FDA continues to monitor dietary supplements and their ingredients when they enter the country. Those containing bovine-derived ingredients from cattle originating in prohibited countries are prohibited entry into the US. In addition, the restrictions on the use of certain cattle and cattle tissues in human food that were recently announced by USDA will also reduce the risks that potentially infective tissue is used in dietary supplements. FDA is exploring what further safeguards may be needed to provide greater assurance to consumers that dietary supplements and other foods remain safe. Most ingredients used to produce dietary supplements and most other food ingredients come from cattle that are slaughtered when they are less than 30-months of age and, because of their age, present little risk of being BSE-positive.

Given the recent BSE case in Washington State, should consumers be concerned about cosmetics made using tallow from the rendering process?

No. The World Health Organization considers tallow to be a low risk for transmission of BSE. Specifically, the rendering process separates fats from proteins. Because the disease is transmitted by prions, which are a type of protein, they would be separated by the rendering process from the tallow or fat, which is the portion that goes into cosmetics. Additionally, the tallow is processed with excessive heat and pressure which may further minimize any risk of infectivity prior to use in cosmetics. Nevertheless, the agency has encouraged cosmetic manufacturers to acquire tallow from sources that do not include cattle with BSE.

What about the use of gelatin, another bovine-related material, in cosmetics and dietary supplements and other foods?

Gelatin may be derived from cattle bones and hides, which are considered low risk tissues for BSE transmission, although most food-grade gelatin in the U.S. is of porcine origin. In 1997, FDA published guidance for gelatin manufacturing that recommends that bones and hides from cattle with any neurologic disease not be used to manufacture gelatin. The guidance also recommends that the heads, spines, and spinal cords of cattle from BSE countries not be used in gelatin production. The manufacturing process for gelatin further reduces any BSE risk for humans to negligible levels. The agency is currently revising the 1997 guidance.

When and how did BSE in cattle occur?

BSE in cattle was first reported in 1986 in the United Kingdom (UK). The exact origins of BSE remain uncertain but it is thought that cattle initially may have become infected when fed feed contaminated with scrapie-infected sheep meat-and-bone meal (MBM). Scrapie is a prion disease in sheep similar to BSE in cattle. The scientific evidence suggests that the U.K. BSE outbreak in cattle then was expanded by feeding BSE-contaminated cattle protein (MBM) to calves. The definitive nature of the BSE agent is not completely known. The agent is thought to be a modified form of a protein, called a prion, which becomes infectious and accumulates in neural tissues causing a fatal, degenerative, neurological disease. These abnormal prions are resistant to common food disinfection treatments, such as heat, to reduce or eliminate their infectivity or presence. Research is ongoing to better understand TSE diseases and the nature of prion transmission.

Is BSE in cattle the same disease as CWD in deer and elk in the U.S.?

BSE is a Transmissible Spongiform Encephalopathy (TSE), a family of similar diseases that may infect certain species of animals and people such as scrapie in sheep and goats, bovine spongiform encephalopathy (BSE) in cattle, chronic wasting disease (CWD) in deer and elk, and Creutzfeldt-Jacob disease (CJD) in people.

To date, there is no scientific evidence that BSE in cattle is related to CWD in deer and elk. Research is continuing but there is no evidence that either BSE or CWD can be transmitted between cattle, deer, or elk. FDA is working closely with other government agencies and the public health community to address CWD in wild and domesticated deer and elk herds. Wildlife and public health officials advise people not to harvest, handle, or consume any wild deer or elk that appear to be sick, regardless of the cause, especially in those states where CWD has been detected.

What countries have reported cases of BSE or are considered to have a substantial risk associated with BSE?

These countries are: Albania, Austria, Belgium, Bosnia-Herzegovina, Bulgaria, Croatia, Czech Republic, Denmark, Federal Republic of Yugoslavia, Finland, France, Germany, Greece, Hungary, Ireland, Israel, Italy, Liechtenstein, Luxembourg, former Yugoslavia Republic of Macedonia, The Netherlands, Norway, Oman, Poland, Portugal, Romania, Slovak Republic, Slovenia, Spain, Sweden, Switzerland, Japan, and United Kingdom (Great Britain including Northern Ireland and the Falkland Islands).

Canada (May 2003) and the U.S. (December 2003) each have recently reported one BSE-positive cow but remain countries considered to have a low risk. The U.S. BSE-positive cow reported in December 2003 was confirmed to have been imported from Canada in 2001.

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This document was issued in January 2004.

For more recent information on Bovine Spongiform Encephalopathy (BSE) See http://www.fda.gov/oc/opacom/hottopics/bse.html
U.S. Department of Agriculture

Updated January 21, 2004
http://www.aphis.usda.gov/lpa/issues/bse/bse_q&a.html
Bovine Spongiform Encephalopathy (BSE) Q & A’s

Q: What is the current situation regarding the bovine spongiform encephalopathy (BSE) detection?

A: On the morning of December 25, 2003, the BSE World Reference Laboratory in Weybridge, England, confirmed USDA’s December 23 preliminary diagnosis of BSE in a single non-ambulatory dairy cow that had been slaughtered on December 9 at Vern’s Moses Lake Meats in Washington State. USDA and Canada worked together to confirm the identification of this cow through DNA testing.

On December 30, 2003, Agriculture Secretary Ann Veneman announced additional safeguards to bolster the U.S. protection systems against BSE and further protect public health. The policies will further strengthen protections against BSE by removing certain animals and specified risk material and tissues from the human food chain; requiring additional process controls for establishments using advanced meat recovery (AMR); holding meat from cattle that have been targeted for BSE surveillance testing until the test has confirmed negative; and prohibiting the air injection stunning of cattle.

The Secretary also announced that USDA will begin 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.

Q: What are the results of USDA’s investigation so far?

A: 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 index 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 feed 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.

The index cow had three calves while in the United States. The first was stillborn. The second, a yearling heifer, is among 129 animals from the index farm being depopulated. The third, a bull calf, was among the group of calves depopulated January 6. The herd the affected animal came from is under a State quarantine in Washington State. Any cattle that die on the farm will be tested for BSE.

Through its traceback investigation, the USDA’s Animal and Plant Health Inspection Service (APHIS) has determined the following additional
information:

* The Canadian health certificate, dated August 28, 2001, lists 82 ear tag numbers from cattle that were part of herd dispersal in Alberta, Canada. USDA has confirmed that 81 of those 82 animals crossed into the United States in September, 2001. It is believed that one of the 82 remained in Canada. To learn the latest number and locations of animal traced, please check the daily BSE update at http://www.aphis.usda.gov/lpa/issues/bse/bse.html
* USDA depopulated the bull calf operation that included the calf born to the cow infected with BSE on January 6. The depopulated herd contained approximately 450 head of cattle. The depopulation effort took place at a slaughter facility that currently is not in use. Animal care veterinarians were on hand at both the farm where the calves were loaded and at the slaughter facility to ensure that the animals were treated in a humane manner. The 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.

Bovine Spongiform Encephalopathy (BSE)

Q: What is BSE?

A: BSE is a degenerative neurological disease caused by an aberrant protein called a prion. It is in the family of diseases-all caused by prions-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’s important to note that TSEs are not communicable diseases-they do not spread easily like viruses.

Q: How is BSE spread in cattle?

A: 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 www.fda.gov.

Q: What steps is USDA taking in response to the detection?

A: USDA’s 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 Mad Cow Disease, or 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 Mad Cow Disease symptoms, including signs of central nervous system impairment. Animals showing Mad Cow Disease symptoms, 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 ilium 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 ensue process control through verification testing to ensure that neither spinal cord nor dorsal root ganglia is present in the product. (For a more detailed description of AMR see below).

* 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. Consumers with other food safety questions can call the toll-free USDA Meat and Poultry Hotline at 1-888-MPHotline (674-6854). The hotline is available in English and Spanish and can be reached from 10 a.m. to 4 p.m. (Eastern Time), Monday through Friday. Recorded food safety messages are available 24 hours a day.

Q: What is Advanced Meat Recovery?

A: 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.

Testing and Surveillance

Q: Given the Secretary’s announcement to prohibit downer cattle from slaughter establishments, what does that mean in terms of USDA’s BSE surveillance program?

A: USDA has tested 20,000 animals annually for each of the last 2 years, and approximately 75 percent of these were downers at slaughter. USDA is working with industry to reposition its efforts to collect samples on-farm, at rendering facilities, and at facilities where meat products are harvested for non-edible purposes. USDA is committed-and the industry shares this commitment-to ensuring that a robust surveillance program for BSE continues in this country. USDA will be working very closely with the rendering and animal disposal industry and other government agencies in the days and weeks to come to ensure that USDA continues to have access to the population of animals considered to be at highest risk for BSE.

Q: Will USDA be issuing licenses for rapid diagnostic tests for BSE?

A: USDA’s Center for Veterinary Biologics, in Ames, Iowa will accept license and permit applications for rapid test kits. Accepting license and permit applications at this time will allow CVB to respond to submissions, test master seeds and serials and inspect facilities should a decision to license need to be made to further protect animal agriculture.

BSE and its effect on U.S. trade

Q: What does the detection of BSE in the United States mean for the country’s beef exports?

A: 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.

USDA officials will be 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 place BSE restrictions on the United States visit the following website:
http://www.aphis.usda.gov/lpa/issues/bse/bse_trade_ban_status.html

BSE and the U.S. Food Supply

Q: What are the risks to the U.S. food supply as a result of this detection?

A: USDA remains confident in the safety of the U.S. food supply. The risk to human health from BSE is extremely low. As is standard practice for downer animals identified prior to slaughter, the animal’s brain, spinal cord, and other related products were removed and sent to a rendering facility. 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.

Q: Is there a meat recall associated with the detection?

A: Yes. On December 23, 2003, FSIS issued a Class II recall of approximately 10,410 pounds of raw beef that may have been exposed to tissues containing the infectious agent that causes BSE. FSIS’ designation of the recall as Class II was due to the extremely low likelihood that the beef contained the infectious agent that causes BSE. According to scientific evidence, the tissues of highest infectivity are the brain, spinal cord, and distal ileum portion of the small intestine. All were removed from the rest of the carcass at slaughter. Therefore, the meat produced were cuts that would not be expected to be infected or have an adverse public health impact. The recall is being conducted out of an abundance of caution.

* FSIS has conducted an investigation and determined the points of distribution for the entire recalled product.

* All of the primary, secondary and tertiary establishments that may have received product subject to this recall have been contacted by FSIS compliance officers. All have acknowledged being contacted about the recall by their suppliers. All have confirmed securing whatever product they had upon notification of the recall and making their customers aware of the recall as well.

* FSIS will now focus its efforts toward verifying the return and destruction of the recalled products.

* Recall effectiveness checks have determined that product was sent to six states. Those states are Washington, Oregon, California, Nevada, Idaho and Montana. Alaska, Hawaii and Guam did not receive any of the products subject to recall.

Q: What is the significance of a “Class II” designated recall?

A: FSIS’ designation of this recall as Class II is due to the extremely low likelihood that the beef being recalled contains the infectious agent that causes BSE.

According to scientific evidence, the tissues of highest infectivity are the brain, spinal cord, and distal ileum, which were removed from the rest of the animal’s carcass at slaughter. Therefore, the meat produced would not be expected to be infected or have an adverse public health impact, but are being recalled out of an abundance of caution.

Q: Will the recalled beef be tested to determine if it contains any central nervous system tissue and if it is positive, will it be tested for BSE?

A: No. There is no BSE test for muscle tissue. Tests can only be conducted on brain tissue.

Q: Is there a phone number consumers can call with questions about meat products?

A: 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.
Center for Disease Control
http://www.cdc.gov/ncidod/diseases/cjd/bse_cjd_qa.htm

Last reviewed December 29, 2003

What is bovine spongiform encephalopathy?

Bovine spongiform encephalopathy (BSE) is a progressive neurological disorder of cattle that results from infection by an unconventional transmissible agent.

Through the end of November 2003, more than 183,000 cases of BSE were confirmed in the United Kingdom alone in more than 35,000 herds. Regularly updated numbers of reported BSE cases, by country, are available on the website of the Office International Des Epizooties at: http://www.oie.int/eng/info/en_esb.htm
The BSE epidemic in the United Kingdom peaked in January 1993 at almost 1,000 new cases per week. The outbreak may have resulted from the feeding of scrapie-containing sheep meat-and-bone meal to cattle. There is strong evidence and general agreement that the outbreak was amplified by feeding rendered bovine meat-and-bone meal to young calves.

The nature of the transmissible agent is unknown. Currently, the most accepted theory is that the agent is a modified form of a normal cell surface component known as prion protein. The pathogenic form of the protein is both less soluble and more resistant to enzyme degradation than the normal form.

Is BSE occurring in the United States?

On December 23, 2003, the U.S. Department of Agriculture (USDA) announced a presumptive diagnosis of bovine spongiform encephalopathy (BSE, or “mad cow” disease) in an adult Holstein cow from Washington State. Samples were taken from the cow on December 9 as part of USDA’s BSE surveillance program. The BSE diagnosis was made on December 22 and 23 by histopathology and immunohistochemical testing at the National Veterinary Services Laboratory, Ames, Iowa. The diagnosis was confirmed by an international reference laboratory in Weybridge, England, on December 25. Preliminary trace-back based on an ear-tag identification number suggests that the BSE-infected cow was imported into the United States from Canada in August 2001.

Is BSE a foodborne hazard in the United States?

Strong evidence indicates that BSE has been transmitted to humans primarily in the United Kingdom, causing a variant form of Creutzfeldt-Jakob disease (vCJD). In the United Kingdom, where over 1 million cattle may have been infected with BSE, a substantial species barrier appears to protect humans from widespread illness. As of December 1, 2003, a total of 153 vCJD cases had been reported worldwide; of these, 143 cases had occurred in the United Kingdom. The risk to human health from BSE in the United States is extremely low.

Is there any monitoring of the incidence of Creutzfeldt-Jakob disease in the United States?

Yes. The possibility that BSE can spread to humans has focused increased attention on the desirability of enhancing national surveillance for Creutzfeldt-Jakob disease (CJD) in the United States.

The Centers for Disease Control and Prevention (CDC) monitors the trends and current incidence of CJD in the United States by analyzing death certificate information from U.S. multiple cause-of-death data, compiled by the National Center for Health Statistics, CDC. A summary of these data was published in the Journal of the American Medical Association on November 8, 2000 (Volume 284, No. 18, pp. 2322-3). and in Clinics of Laboratory Medicine in December 2002 (Volume 22, pp. 849-62).

The average annual CJD death rate in the United States has remained relatively stable at about one case per million population per year. In addition, CJD deaths in persons aged <30 years in the United States remain extremely rare (<1 case per 100 million per year). In contrast, in the United Kingdom, over half of the patients who died with variant CJD were in this young age group.

What is the variant form of CJD that the experts in the United Kingdom believe might be related to the BSE outbreak in cattle?

In contrast to the classic form of CJD, the variant form in the United Kingdom predominantly affects younger persons (median age at death around 29 years) and has atypical clinical features. These atypical features include prominent psychiatric or sensory symptoms at the time of clinical presentation or early in the course of the illness, delayed onset of neurologic abnormalities, duration of illness of at least 6 months, and a diffusely abnormal non-diagnostic electroencephalogram.

The characteristic neuropathologic profile of variant CJD includes, in both the cerebellum and cerebrum, numerous kuru-type amyloid plaques surrounded by vacuoles and prion protein (PrP) accumulation at high concentration indicated by immunohistochemical analysis.

Recently published data indicate that the epidemic of variant CJD in the United Kingdom may have already reached a peak. A listing of monthly updated numbers of variant CJD cases in the United Kingdom is available at: http://www.doh.gov.uk/cjd/cjd_stat.htm.

Is there evidence directly linking this newly recognized variant of CJD to BSE exposure?

There is strong epidemiologic and laboratory evidence for a causal association between variant CJD and BSE. The absence of confirmed cases of variant CJD in other geographic areas free of BSE supports a causal association.

In addition, the interval between the most likely period for the initial extended exposure of the population to potentially BSE-contaminated food (1984-1986) and onset of initial variant CJD cases (1994-1996) is consistent with known incubation periods for CJD.

An experimental study reported in June 1996 showed that three cynomologus macaque monkeys inoculated with brain tissue obtained from cattle with BSE had clinical and neuropathological features strikingly similar to those of variant CJD (Nature 1996;381:743-4).

A study published in 1996 indicated that a Western blot analysis of infecting prions obtained from 10 variant CJD patients and BSE-infected animals had similar molecular characteristics that were distinct from prions obtained from patients with other types of CJD (Nature 1996;383:685-90).

An experimental study involving inoculation of a panel of inbred mice with the agents causing BSE and variant CJD substantially increased the strength of the scientific evidence for a causal association between variant CJD and BSE (Nature 1997;389:498-501). In this study, groups of inbred mice and a group of cross-bred mice inoculated with brain homogenates from variant CJD cases were reported to have had latency periods and lesion profiles consistent with the BSE pattern.

The latency period, neuropathology, and disease-causing PrP isoforms in transgenic mice expressing bovine PrP that were inoculated with variant CJD, BSE, and scrapie brain extracts provided additional evidence supporting the link between BSE and variant CJD (Proc Natl Acad Sci 1999;96:15137-42).

Has CDC initiated increased surveillance efforts to determine whether the newly recognized variant of CJD occurs in the United States?

Yes. In addition to the ongoing review of national CJD mortality data, CDC has conducted active CJD surveillance in its four established Emerging Infections Program areas (Minnesota, Oregon, Connecticut, and the San Francisco Bay area, California) and in a metropolitan Atlanta site.

Additionally, with the support of the Council of State and Territorial Epidemiologists, CDC conducts follow-up review of clinical and neuropathology records of CJD decedents aged <55 years who are identified through the national mortality data analysis.

CDC, in collaboration with the American Association of Neuropathologists, established the National Prion Disease Pathology Surveillance Center at Case Western Reserve University, Cleveland, Ohio in 1996-1997. This pathology center provides free, state-of-the-art diagnostic services to U.S. physicians. It also helps to monitor the possible occurrence of emerging forms of prion diseases, such as variant CJD, in the United States. For more information about the center visit its website at: http://www.cjdsurveillance.com .

In 2002, CDC reported the occurrence of variant CJD in a 22-year-old Florida resident who was born in and grew up in the United Kingdom. Information about this patient is available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5141a3.htm.

Is BSE a foodborne hazard for travelers to Europe?

The current risk for infection with the BSE agent among travelers to Europe is extremely small, if it exists at all. Information describing this risk is available in the document titled “Bovine Spongiform Encephalopathy and Variant Creutzfeldt-Jakob Disease” available on the CDC website at http://www.cdc.gov/ncidod/diseases/cjd/bse_cjd.htm.