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Bovine Spongiform Encephalopathy Information

July 15, 2003
Bovine Spongiform Encephalopathy Information from the U.S. Department of Agriculture and Food and Drug Administration
(Updated June 6, 2003)

Overview
  • BSE has never been found in the United States, despite an aggressive surveillance program -- 19,990 cattle were tested in fiscal year 2002 using a targeted surveillance program.
  • Since 1989, the U.S. government has implemented a series of safeguards to protect the United States from BSE. Ruminant animals (such as cattle, sheep, and goats), ruminant meat and meat products, and animal feed containing processed animal proteins can not be imported from countries declared by the United States to be at-risk for BSE.
  • The United States Department of Agriculture (USDA) and the Food and Drug Administration (FDA) have developed emergency response plans to prevent the spread of the disease in the unlikely event that a BSE-infected animal is ever found in the United States.


Current Situation
  • On May 20, Canada received confirmation from a laboratory that a single cow tested positive for BSE. The cow came from a commercial farm in northern Alberta, Canada.
  • The BSE test was done as a part of Canada?s active, targeted, on-going surveillance program, which is similar to USDA?s on-going targeted surveillance program that tested 19,990 cattle in 2002.
  • The animal was condemned at slaughter, and the meat did not enter the food chain.
  • The remains of the infected cow were sent to a rendering plant in Canada. Rendering is the process of discarding parts of animal carcasses to produce two products ?meat and bone meal? and ?tallow.? The Canadian Food Inspection Agency (CFIA) is tracing rendered products from the affected cow.
  • The case farm, the potential source farms, and other farms at risk have been placed under quarantine.
  • The entire affected herd has been slaughtered and has tested negative for BSE.
  • On Tuesday, June 3, 2003, Canada reported to USDA?s Animal and Plant Health Inspection Service (APHIS) its their investigation indicates that five bulls from one of the possible birth herds of the BSE index animal in Saskatchewan were sold to a ranch in Montana.
  • Through an initial review of brand inspection records and interviews with the Montana rancher, investigators have determined that 24 bulls were moved off of this farm from 1997 to 2002. Twenty-three were moved from this farm to one stockyard in Montana and two in South Dakota. One was slaughtered for personal consumption. Presumably the five bulls in question were included in these 24 animals.
  • Following up on information obtained from Montana veterinary officials on June 5, USDA, the U.S. Food and Drug Administration, and state veterinary officials in Montana, Nebraska, Minnesota, South Dakota, Texas and Wyoming are conducting traceout investigations on 24 animals that moved off the Montana ranch. The agencies are working to determine the final disposition of these animals. This investigation is consistent with the investigation ongoing in Canada and will contribute to that overall investigation.
  • Records indicate that the animals were born in Saskatchewan in 1996 and left Canada for Montana on April 28, 1997.
  • As of June 6, preliminary tracebacks on the 24 animals have been made available by the state of Montana. Initial results of the investigation show that between 1997 and 2002 three bulls were purchased by slaughter facilities in Nebraska, five bulls in Minnesota, two bulls in Texas and 12 bulls in South Dakota. One bull went to Wyoming and the traceouts on this animal are still underway.
  • For several reasons, USDA believes it is unlikely that any of the bulls were infected with BSE:
    - The Canadian herd that the bulls came from was depopulated and those cattle have tested negative for BSE, including cattle born in the same year as the positive cow.
    - Research indicates that a low dose of infection results in a longer incubation period. As the infected animal in Canada was seven to eight years old, that suggests that the infected animal received a low dose of BSE. Any exposure of BSE to other animals in that herd would be even lower.
    - In Europe, where animal exposure to BSE was greatest, herds affected by BSE typically have a very low prevalence of disease and usually do not have additional positive cows in infected herds.
    - If investigation reveals that the bulls were slaughtered, it was after implementation of the FDA feed ban, thus ensuring that these animals did not enter the animal food chain.
    - Consistent with the science and international standards, we know that bovine semen is not a means of transmitting the disease. So, the fact that these were breeding bulls is not a concern.
  • Canada is no longer issuing health certificates on animals or animal products that state Canada is free of BSE.


U.S. Response
  • While the incidence in Canada is a single isolated case, the U.S. Government took certain actions determined to minimize risks to the United States.
  • The United States has placed Canada under its BSE restriction guidelines and will not accept any ruminants or ruminant products from Canada pending further investigation. This temporary ban is consistent with the U.S. response to other countries that have detected BSE.
  • USDA has dispatched technical teams to Canada to assist in the investigation and will continue to provide more detailed information as it becomes available.
  • The United States is in constant communications with Canadian officials to determine if additional actions are necessary to protect the public.


Trade with Canada
  • Canada and the U.S. share one of the world?s largest bilateral trade relationships. The United States imported 1.7 million head of live cattle from Canada in 2002, most for the purpose of slaughter.
  • The U.S. is the primary destination for Canadian beef exports. Of the 1.2 million metric tons of beef exported by Canada in 2002, 83 percent of the product was destined for U.S. markets. During 1999 to 2002, the United States imported more than 180 thousand tons per year of cattle feed from Canada.
  • Since both Canada and the United States established regulations in 1997 prohibiting feeding of most mammalian proteins to ruminants, this feed should not have contained ruminant material.
  • The impact a finding of BSE in Canadian cattle will have on U.S. exports has not yet been determined. The epidemiological information related to the Canadian BSE case currently being collected by Canadian and U.S. animal health officials should better define whether the United States is facing any additional BSE risk. This information is necessary in order for U.S. trading partners to make informed and science-based decisions regarding importation of U.S. animals or products. It is also necessary in order for USDA to determine if any animals form the affected herd or any of the quarantined herds have entered the United States. USDA also will work with Harvard to assess the U.S. risk based upon the current situation.
  • On May 20,2003, APHIS instituted emergency measures to minimize BSE risk to U.S. livestock, livestock producers, and other industries by suspending the following animals and animal products from Canada: Live ruminants (cattle, sheep, goats, cervids, and camellids), ruminant meat and meat products, processed animal proteins, animal feed (unless demonstrated to be of only milk or plant origin), pet food, milk replacers containing animal fat or non-milk animal protein, ruminant blood and blood products, animal vaccines that contain ruminant derived products, ruminant offal, ruminant casings, ruminant glands, ruminant gland extracts/derivatives, unprocessed ruminant fat, processed fats and oils, bulk shipments of nutritional supplements containing specified risk materials, ruminant bones, tankage, tallow (except for tallow derivatives), ruminant bone derived gelatin for animal use, bulk shipments of ruminant-derived cartilage and/or chondroitin sulfate, non-hide derived collagen, and ruminant urine and urine derivatives. As USDA obtains more information about the case of BSE in Canada, the restrictions placed on Canadian imports will be re-evaluated. For more specific information, visit the APHIS Web site at: http://www.aphis.usda.gov
  • Non-ruminant livestock -- horses, pigs, or poultry, for example -- are still eligible for entry into the United States, as are products from these animals. In addition, certain ruminant products that aren?t known to transmit BSE are still eligible for entry. These products are milk, milk products, ruminant hides, and ruminant hide-derived products, and ruminant semen and embryos (under certain conditions).
  • While Canada and the United States are quite similar in terms of the timing and types of preventative measures taken to keep BSE from entering their countries, USDA still believes that the United States is at low risk for having BSE.


Firewall Prevention Efforts
  • The United States remains diligent in its BSE surveillance and prevention efforts.
  • Since 1989, the U.S. Government has taken a series of preventive actions to protect against this animal disease. This includes USDA prohibitions on the import of live ruminants, such as cattle, sheep, goats and most ruminant products from countries that have been or are considered to be at risk for having BSE.
  • For the last 14 years, USDA?s Animal and Plant Health Inspection Service (APHIS) has also had an active a surveillance program in place in the United States to ensure detection and swift response in the event that an introduction of BSE were to occur.
  • To date, no evidence of BSE had been found in the United States through this surveillance program.
  • In August 1997, FDA promulgated regulations, known as the ?animal feed rule,? to prohibit the recycling of the high risk material. The animal feed rule also prohibits feeding most material from mammals to cattle or other ruminant animals to further enhance BSE prevention efforts. The feed rule was implemented to prevent the introduction or spread of BSE to the United States.
  • In addition, FDA and the state regulatory agencies have increased the number of inspections of renderers, animal feed manufacturers, feed mills, and other firms responsible for keeping prohibited mammalian protein out of cattle and other ruminant feed. FDA has dedicated more resources to these animal feed inspections and has upgraded its tracking system and database to ensure effective and timely follow-up.
  • Since the animal feed rule became effective in August 1997, FDA has conducted more than 19,000 inspections of firms in the feed industry, and it continues to annually inspect 100 percent of the firms that actually handle prohibited material.
  • By industry sector, this represents:
    - 68 percent (154) of the 228 renderers;
    - 25 percent (286) of the 1,126 FDA-licensed feed mills;
    - 11 percent (549) of the 5,059 non-FDA-licensed feed mills; and
    - 13 percent (574) of the 4,335 other firms (includes protein blenders, distributors, retailers, ruminant feeders, and on-farm mixers)
  • In 2001, a risk assessment done by Harvard University showed the risk of BSE occurring in the United States as extremely low. The report also determined that early protection systems put into place by the USDA and Department of Health and Human Services (HHS) have been largely responsible for keeping BSE out of the United States and would prevent it from spreading if it ever did enter the country. USDA is working with Harvard to update the U.S. risk assessment based upon the current situation.
  • In fiscal year 2002, USDA established a goal to test 12,500 cattle for BSE and USDA surpassed its goal and tested 19,990 cattle for BSE using a targeted surveillance approach designed to test the highest risk animals, including downer animals (animals that are non-ambulatory at slaughter), animals that die on the farm, older animals and animals exhibiting signs of neurological distress. This is significantly higher than the standards set by the Office International des Epizooties (OIE), the standard-setting organization for animal health for 162 member nations. Under the international standard, a BSE-free country like the United States would be required to test only 433 head of cattle per year. The USDA is now testing 41 times that amount.
  • To date in FY 2003, USDA has tested 11,500 cattle. Since 1990, USDA has tested more than 48,000 cattle.
  • USDA?s Food Safety and Inspection Service (FSIS) inspects all cattle presented for slaughter in the United States for signs of central nervous system impairment. All animals exhibiting neurological signs during this inspection are condemned, and the meat is not permitted for use as human food. The brains from these animals are submitted to USDA's National Veterinary Services Laboratories (NVSL) for analysis. All BSE testing is conducted at NVSL. The average turnaround time for these samples is eight days from receipt of the samples at the laboratory.
  • FSIS also actively conducts tests of U.S. ground beef to ensure no high-risk products are present.
  • Animal identification is a crucial part of USDA disease-control programs. USDA?s established animal identification systems have served the United States well as a part of past disease control efforts. However, USDA continues to investigate new identification methods and technologies and to work with livestock industries to improve animal identification programs to address current and future needs.


Background
  • BSE, widely known as "mad cow disease," is a chronic, degenerative neurological disease affecting the central nervous system of cattle. Worldwide, more than 185,000 cattle have tested positive for BSE since the disease was first diagnosed in 1986 in Great Britain.
  • BSE has never been found in the United States.
  • BSE belongs to a family of diseases known as transmissible spongiform encephalopathies (TSE's). In animals, TSE?s include chronic wasting disease (CWD) of deer and elk, scrapie of sheep and goats, transmissible mink encephalopathy, and feline spongiform encephalopathy. In humans, TSE?s include kuru, both classical and variant Cruetzfeldt-Jakob disease (vCJD), Gertsmann-Straussler-Scheinker syndrome, and fatal familial insomnia.
  • BSE is not a contagious disease that spreads naturally from cow to cow. Rather, the infectious agent is introduced when BSE-infected tissue or tissue products are added to animal feed and fed to cattle.
  • The human form of BSE is variant or vCreutzfeldt-Jakob Disease (vCJD). Approximately 135 people worldwide have been infected with variant CJD. It is believed they became infected by eating products from BSE-infected animals.
  • BSE-affected animals may display changes in temperament, such as nervousness or aggression; abnormal posture; incoordination and difficulty in rising; decreased milk production; or loss of body condition despite continued appetite. There is no treatment, and infected cattle die.
  • The incubation period ranges from 2 to 8 years. Following the onset of clinical signs, the animal's condition deteriorates until it dies or is destroyed. This usually takes from 2 weeks to 6 months. Most cases in Great Britain have occurred in dairy cows between 3 and 6 years of age.
  • There is no test to detect the disease in a live animal, although this is a high research priority. Diagnosis can only be confirmed by microscopic examination of, or detection of the abnormal prion protein in, the animal?s brain after its death.
  • The primary means of transmission of BSE to cattle is by eating feed contaminated with rendered material from BSE-infected cattle. There is also a possibility that in rare cases, mother to offspring transmission may occur, but this is unconfirmed. There is no evidence that BSE is transmitted directly from animal to animal and all of the information gathered in the outbreak in Great Britain continues to support this.


What Americans Should Do. . .
  • FDA and USDA are recommending no changes in what Americans eat. Both agencies continue to recommend a balanced and varied diet.
  • Information about BSE, variant CJD and CJD is available on multiple Web sites including USDA, the Department of Health and Human Services, FDA, Center for Disease Control and Prevention, and the National Institutes of Health.


BSE vs. CWD
  • While BSE and chronic wasting disease (CWD) are both TSE?s, they are different agents with a different natural host range.
  • There is currently no evidence that cattle of other non-cervid ruminant species can be naturally infected with CWD. Completed and on-going collaborative studies continue to support this. These studies include:
  • A survey of about 250 cull cattle in Colorado that shared a range with infected deer and elk in the endemic area conducted by Colorado State University. No evidence of TSE was found in any of these cattle.
  • Natural exposure studies being conducted concurrently in Colorado and Wyoming by the Colorado Division of Wildlife and the University of Wyoming. These studies involve direct pasture contact of cattle with infected mule deer in a research facility and feeding cattle the brain material from affected mule deer. After more than five years, there has been no evidence of natural transmission. These studies are scheduled to last 10 years.
  • The brains of 13 cattle were directly inoculated with brain material from the same source (affected mule deer) used for the natural exposure study above. CWD was transmitted via this unnatural route to five of these animals. While inoculation directly into the brain is not a good indicator of whether or not a TSE will transmit naturally to a species, it does give us confidence that our current diagnostic tools could detect such a transmission.


Contacts for More Information About BSE

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