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March 30, 2001


FROM: Robert A. Hahn

RE: “BSE Briefing” Sponsored By American Meat Institute Foundation


On March 23, 2001, the American Meat Institute Foundation sponsored a “BSE Briefing” on bovine spongiform encephalopathy (BSE). This memorandum summarizes the presentations made at the conference.

1. The European Situation

Dagmar Heim, DVM, Head of TSE Project, Swiss Federal Veterinary Office, offered an overview of the BSE situation in Europe. She noted that the countries that have recently reported their first cases of BSE (e.g., Germany, Spain, Italy) do not represent a “second wave” of BSE. The European Union’s (EU) Geographical BSE Risk Assessment had previously identified these countries as having a high probability of BSE. However, these countries did not report actual cases of BSE in native cattle until they began conducting active surveillance in 2000.

Dr. Heim stressed the importance of both passive and active surveillance for BSE. First, she stated that the clinical symptoms of BSE (i.e., fearful or aggressive behavior; tremors; stiffness; ataxia; hypermetria; hypersensitivity to light, touch and noise; weight loss and reduced milk yield) are often subtle, may not all be present simultaneously, and are symptoms common to many other animal diseases. Therefore, passive surveillance (i.e., looking for cattle with clinical symptoms) alone is not very effective. Active surveillance (i.e., testing brain tissue samples for BSE) is also necessary. In 1999, Switzerland began conducting active surveillance for BSE. This includes testing brain tissue samples from cattle not killed at slaughter (e.g., cattle that die on the farm), emergency slaughter cattle (i.e., cattle that cannot go through normal slaughter because they are ill or have a broken leg), and a random sample of slaughter cattle. In Switzerland’s active surveillance program, of the cattle found to have BSE, one-third had demonstrated typical symptoms, one-third had demonstrated “weak” typical symptoms, and one-third had demonstrated symptoms not generally associated with BSE (e.g., mastitis, recumbency, claw problems). Thus, active surveillance finds cases that passive surveillance misses. In addition, active surveillance improves passive surveillance. When there is an active surveillance program in place, farmers are more likely to report suspect cases, because they know that such cattle are likely to be noticed and tested for BSE anyway (i.e., there is no way out).

Dr. Heim questioned whether a ban on animal protein in ruminant feed, like that in United States, can be completely effective at stopping the spread of disease. She noted that after the United Kingdom (UK) banned animal protein in ruminant feed in 1988, the number of new BSE cases declined but did not disappear. This was probably due to cross contamination and imperfect compliance with the feed ban. However, since the UK banned animal protein in feed for all farm animals in 1996, there have only been one or two new cases of BSE.

Dr. Heim also reviewed the principal measures taken by the EU to stop the spread of BSE and protect public health:

o A ban on animal protein in ruminant feed (1994)

o Mandating time/temperature/pressure minimums of 20 minutes/133 degrees C./3 bars for rendering process used to produce meat and bone meal (MBM) (1996)

o A ban on specified risk material in human food (2000)

o A ban on animal protein in all feed for farm animals (2001)

2. The U.S. Situation

Will Hueston, DVM, Ph.D., Professor and Associate Dean, University of Maryland, summarized the U.S. situation with regard to BSE. According to Dr. Hueston, there is little risk of a de novo or “home-grown” BSE epidemic in the United States as occurred in the UK. This is because of significant differences between the U.S. and UK livestock industries. The UK has four times as many sheep as the United States and a much higher sheep to cattle ratio. The UK sheep population also increased sharply in the 1980’s as a result of the EU’s Common Agricultural Policy. The UK also has much more scrapie in its sheep population. As a result, it was possible in the UK for a high dose of scrapie-infected tissue to enter rendered animal proteins that were fed to cattle. In the 1980’s, cattle rations in the UK included more rendered animal protein than in the United States, and animal proteins were fed to calves as young as 2-3 days old. In addition, UK sheep and dairy cows live longer than their U.S. counterparts, allowing more time for a transmissible spongiform encephalopathy (TSE) to develop.

Dr. Hueston also felt there is little risk that BSE has been introduced, or will be introduced, into the United States from the UK or other affected countries. In the years 1981-89, 496 cattle from the UK were imported into the United States. All of these cattle were subsequently quarantined (of which only four are still alive) except for 35 head which could not be traced. Smaller numbers of cattle were imported from other countries that subsequently discovered BSE in their native herds, but these cattle are also currently quarantined. The United States also imported relatively little meat and bone meal, about 12 tons, from the UK during the 1980’s.

According to Dr. Hueston, BSE has not been found in the United States because of U.S. import restrictions, good risk communication to key players, and the ban on most mammalian protein in ruminant feed. While he emphasized that the risk of BSE in the United States is low, Dr. Hueston said that zero risk is a fallacy. He predicted that BSE would appear in additional countries, other than those that have already reported it, and that the U.S. risk analysis would need to be updated regularly based on future developments. Therefore, the United States should not be complacent.

Dr. Hueston said that a BSE risk analysis should look at inputs, processing, and end product use. Inputs refer to the source of the cattle (i.e., the BSE status of their country of origin) and the particular cattle tissues being used. Tissues that have been found to be infective for BSE are brain, spinal cord, dorsal root ganglia, trigeminal ganglia, distal ileum, retina, and, possibly, bone marrow. T-bone steaks and rib roasts may contain dorsal root ganglia; mechanically separated meat may contain spinal cord and dorsal root ganglia; bone-in meat may contain marrow; and some sausage casings are made from distal ileum. Bovine-derived products are ubiquitous in pharmaceutical products. These include tallow (i.e., the fat resulting from the rendering of offal), gelatin, as well as blood, serum and tissue infusions used as bacterial and viral culture media. Processing has to do with methods of slaughter and processing. Stunning and pithing during slaughter may spread infective tissue to other parts of the carcass. On the other hand, manufacturing processes may reduce infectivity through partitioning, inactivation, and dilution of the infectious agent. Lastly, end product use may also affect risk. If a product is implanted in the brain, the risk of infection is far greater than if the product is consumed orally. Other end product use factors include the size of the dose, number of doses, and the age of the person exposed.

3. BSE and Human Health

Paul Brown, MD, Ph.D., Senior Research Scientist at the National Institutes of Health and Chairman of FDA’s TSE Advisory Committee, stated that BSE and new variant Creutzfeld-Jakob disease (vCJD) are, without doubt, the same disease. He noted that, unlike traditional or sporadic CJD, vCJD is primarily a disease of young people. The victims of vCJD, with one exception, have ranged in age from 12 to about 50. It is impossible to distinguish sporadic CJD from vCJD without performing an autopsy to look for the identifying feature of vCJD, amyloid plaques surrounded by vacuoles in the shape of a daisy. The infectious dose in humans is not yet known. However, experiments are being done in which different doses are being fed to primates. When these experiments are completed in a few years, they will provide a good sense of the infectious dose in humans.

Dr. Brown noted that BSE infectivity is concentrated in the brain and spinal cord of infected cattle. Some of the experiments testing various tissues for infectivity are still ongoing. The study that found infectivity in bone marrow has not yet been replicated. There is no evidence that muscle tissue or milk are infective. With regard to meat, there is a “remote possibility,” he said, that brain emboli from stunning might be present in meat or other tissues.

Dr. Brown identified what he called “points of vulnerability” in the United States’ preventive program for BSE. These include:

· Possible weaknesses in the feed ban: Dr. Brown expressed concern about the exception for “plate waste” in FDA’s ban on most mammalian protein in ruminant feed. Plate waste could potentially include bones and tissues capable of transmitting BSE (e.g., a T-bone steak). He also noted that non-ruminants (e.g., swine, poultry) are still being fed meat and bone meal made from ruminants. Dr. Brown also expressed concern about the enforceability of the feed ban, especially with regard to feed mills that handle both ruminant and non-ruminant feed and farmers that raise both ruminants and non-ruminants (and might feed non-ruminant feed containing mammalian protein to ruminants).

· Mechanically separated meat: The product known as “mechanically separated (species)” (MS(S)) includes spinal cord tissue (unless the spinal cord was completely removed before bones are processed) and dorsal root ganglia. Dr. Brown also noted that brain, spinal cord, and other “specified risk materials” are not required to be removed at slaughter.

· Dietary supplements that contain “glandulars”: Some dietary supplements contain cow’s brains and other potentially infective tissues.

4. U.S. Import Controls

Lisa Ferguson, DVM, Senior Staff Veterinarian at USDA’s Animal and Plant Health Inspection Service (APHIS), reviewed USDA and FDA import restrictions. The United States banned import of live ruminants from the UK in July 1989 and banned ruminant products (including meat and bone meal) from the UK in November 1989. These import bans were adopted as formal regulations in 1991. Because of concerns of unreported BSE on the European continent, APHIS banned import of all live ruminants and most ruminant products from all of Europe west of the former Soviet Union in December 1997, issuing an interim final rule to this effect in January 1998.

In December 2000, the U.S. import restrictions were extended to all rendered animal proteins, regardless of species.

Under U.S. import restrictions, the following products are subject to restricted entry: blood, heparin, hormones, lipids, tissue extracts, gelatin, microbiological media with ruminant derived proteins, and collagen derivatives. The decision whether to allow import of these products is made on a case-by-case basis. Some products (e.g., chondroitin sulfate) are made from tissues of U.S. cattle but are processed in Europe and then shipped back to the United States. The following products are allowed unrestricted entry: milk and milk products, semen, hides and skins, tallow, and tallow derivatives.

The United States is part of a tripartite agreement with Canada and Mexico to harmonize North American policies on TSE’s, including import policies. Although the EU’s Geographical BSE Risk Assessment rated the United States as Level II (unlikely but not excluded), APHIS does not completely agree with this ranking. [1]

5. U.S. Feed Ban

George Mitchell, DVM, Associate Director for Policy & Regulations at FDA’s Center for Veterinary Medicine (CVM), described the ban on most mammalian protein in ruminant feed. The purpose of the ban is to prevent amplification of BSE in U.S. livestock in the event that BSE enters the United States. The ban, which became effective August 4, 1997, applies to renderers, feed mills, blenders, feed distributors, and ruminant feeders (e.g., dairy farms, feedlots). It prohibits most mammalian protein in feed for ruminants. Non-mammalian protein and non-protein materials are exempt from the ban. Other exemptions include: pure porcine protein, pure equine protein, blood, milk, and “plate waste” (i.e., products that have already been cooked and offered for human food). Feed containing prohibited materials is required to be labeled with the cautionary statement “Do not feed to cattle or other ruminants.”

CVM’s goal is 100 percent compliance with the feed ban. CVM intends to complete inspections of all uninspected firms during this fiscal year. Noncompliant firms will be re-inspected to ensure they are in compliance. For firms that are out of compliance, CVM will first issue a Warning Letter. If the violation remains uncorrected, CVM would then consider possible enforcement action, depending upon the nature of the violation.

6. U.S. Surveillance for BSE

Lisa Ferguson, filling in for Dr. Linda Detwiler (who was detained in Vermont in connection with an APHIS seizure of sheep), spoke about U.S. surveillance for BSE. Dr. Ferguson said that as of January 31, 2001, brain samples for 12,103 cattle had been tested for BSE; all results have been negative. Although this number represents a very small percentage of the total U.S. cattle herd, within the target population of adult cattle with central nervous system (CNS) symptoms, APHIS testing is capable of finding the disease if present at the level of one in a million, with a 95 percent confidence interval.

Brain tissue samples come from cattle displaying CNS disorders in the field or at ante-mortem inspection, “downer” cattle (i.e., cattle that cannot walk), as well as rabies-negative cattle whose tissue samples are submitted to veterinary diagnostic laboratories and teaching hospitals. The carcasses of tested cattle are either incinerated or held pending a negative test result. Some brain tissue samples are examined histopathologically, while others are tested using an immunohistochemistry (IHC) technique, and USDA is increasing the number of tests that use the IHC testing method. The IHC test is capable of detecting the infectious prions themselves, rather than merely identifying the effects of the disease on brain tissue, and is therefore considered a more sensitive test.

APHIS now plans to improve its surveillance by setting regional surveillance goals. APHIS has divided the country into eight regions and will treat each region as if it were a separate country under the Office International des Epizooties (OIE) guidelines, except that APHIS will double the number of tests recommended by the OIE.

APHIS surveillance also includes monitoring of cattle and other livestock imported from the UK and Europe. Of the 496 cattle imported from the UK during the 1980’s, only four cows in Vermont are still alive; they are quarantined and under surveillance. During a brief window in 1996-1997 before the ban on ruminants from all of Europe was put in place, the United States imported a number of cattle and sheep from European countries that subsequently reported BSE. These animals are quarantined and are being monitored.

APHIS and state agencies are also conducting surveillance of deer and elk with chronic wasting disease (CWD), another TSE. While CWD has appeared in some elk on elk farms, the only free-ranging animals that have the disease are cervids in northeastern Colorado and southeastern Wyoming. Dr. Ferguson emphasized that CWD is not BSE, and there is no evidence that humans can be infected by eating deer meat. To date, all cases of CJD in deer hunters have turned out to be sporadic CJD, not vCJD.

USDA has also developed a BSE Response Plan to be used in the event that BSE is detected in U.S. cattle. Dr. Ferguson noted that it would take about 13-17 days after collection of a brain tissue sample to confirm a suspected case of BSE. The BSE Response Plan sets out actions to be taken at each point in this timeline. For example, upon reporting of a presumptive positive case, APHIS will quarantine the herd in question, trace the herdmates and progeny of the affected animal, and begin an epidemiologic investigation. Upon confirmation of a BSE case, APHIS will depopulate the herd in question and the progeny of the affected animal.

Finally, Dr. Ferguson listed some potential vulnerabilities in the U.S. BSE prevention plan. If BSE were to enter the United States, it might spread through cross contamination of feed, cross feeding (i.e., feeding ruminants feed intended for non-ruminants), or use of blood meal (which is currently exempt from the feed ban). Possible pathways to humans include Advanced Meat Recovery (AMR) product, intentional consumption of high-risk tissues (e.g., brains), and slaughter practices that may spread CNS tissue to other tissues (e.g., pneumatic stunning, missplitting of carcasses).

7. U.S. Industry Response

Tom Cook, President of the National Renderers Association, stated that there are 260 rendering plants in the United States that together render 50 billion pounds of raw material and produce 18 billion pounds of rendered product each year. He noted that, when a brain tissue sample is taken from a carcass, the carcass is not rendered until the sample tests negative for BSE. To ensure compliance with the feed ban, the Animal Protein Producers Industry, which includes 243 rendering plants, has established a certification program that will begin operations April 1, 2001. APPI hopes to certify all member plants by May 15, 2001.

David Bossman, President of the American Feed Industry Association, said that AFIA has created a third-party certification program for feed mills operated by the Facility Certification Institute. The program will begin operations this month, and the names of certified facilities will be posted on AFIA’s website (www.afia.org). In addition, AFIA has recommended that its members who produce ruminant feed should remove all prohibited mammalian meat and bone meal from their facilities, to prevent any risk of cross contamination.

Gary Weber, Ph.D., Executive Director for Regulatory Affairs of the National Cattlemen’s Beef Association, stated that NCBA has established a Beef Quality Assurance program to ensure that cattle producers comply with the feed ban. He predicted that, with more and more branded beef products on the market, beef processors in the future would only purchase cattle from producers that comply with all regulatory requirements, including the feed ban.

8. Customer and Media Response to BSE

Jill Hollingsworth, DVM, Vice President of the Food Safety Program at the Food Marketing Institute, discussed consumers’ concerns regarding BSE. Dr. Hollingsworth said that a Supermarket News poll in February 2001 found that virtually all consumers are aware of BSE and that most tended to believe that it could happen in the United States. The poll found that most consumers rely on the government to protect them from BSE but are not convinced that existing protections are sufficient.

Dr. Hollingsworth listed possible avenues through which BSE in cattle could infect consumers:

· Stunning of cattle during slaughter: Given evidence that some forms of stunning may cause brain emboli to enter other tissues, USDA’s Food Safety and Inspection Service (FSIS) inspectors should verify that this is not occurring. This could be done as part of FSIS verification that a plant is complying with the Humane Slaughter Act and should be easy to do. FSIS should be able to tell the public with 100 percent confidence that brain emboli are not present in meat or other edible tissues.

· Spinal cord: The current regulations provide that spinal cord that remains in the carcass is edible tissue. If it is removed from the carcass, it is no longer considered edible tissue and thereafter may not enter human food. Legally, spinal cord may not be present in “meat,” but it may be included in “meat food products.” Dr. Hollingsworth said that spinal cord tissue may be present in both mechanically separated (species) and in AMR product. MS(S) is rarely used in the beef industry, but AMR is used in products including ground beef. Dr. Hollingsworth suggested that all spinal cords be removed from beef carcasses at slaughter to ensure that no spinal tissue enters human food. Removal at slaughter would also ensure that spinal cord does not enter the rendering process and, therefore, does not find its way into animal feed. Dr. Hollingsworth recommended that the 1998 proposed rule on AMR be re-proposed with an added provision requiring removal of spinal cord at slaughter.

Steven Grover, R.E.H.S., Vice President for Health and Safety Regulatory Affairs with the National Restaurant Association, also stated that consumers do not want CNS tissue in their food and would not be pleased if they knew this was the case. He also identified AMR product as possibly containing spinal tissue. Mr. Grover warned that consumption patterns could change very quickly if consumers feel a product poses a health risk. A Roper-Starch Worldwide poll found that 20 percent of respondents may have reduced beef consumption because of BSE fears, 3 percent may have stopped eating beef entirely because of BSE concerns, and 76 percent would avoid beef if BSE were found in the United States. He noted that restaurants have been getting questions by their customers about BSE. Mr. Grover urged the industry to address consumer fears honestly and openly.

Scott Sindelar from the Dairy, Livestock and Poultry Division of USDA’s Foreign Agricultural Service spoke about the impact of BSE on U.S. trading partners. He stated that BSE and the recent outbreak of foot-and-mouth disease in Europe will result in a large beef surplus in the EU. The drop in EU beef consumption and the loss of major markets for EU beef (e.g., Russia, Egypt) will also contribute to the EU beef surplus. It is not clear how the EU will dispose of this surplus. If the EU donates beef as aid to Russia, this could adversely affect U.S. poultry exports to Russia. Mr. Sindelar also stated there would be limited opportunities for U.S. beef to expand into former EU markets, because the United States sells a different product. Mr. Sindelar said that the United States needs to reassure the major importers of U.S. beef (i.e., Japan, Korea, Mexico) that U.S. beef is safe.

Janet Riley, Vice President for Public Affairs at the American Meat Institute, discussed media coverage of BSE. She stated that most reporters have very limited knowledge of BSE and that food and restaurant reporters are sometimes called upon to cover BSE. She said that coverage of BSE is likely to improve as reporters learn more.

I hope this information is helpful. If you have any questions about this memorandum, or if you would like to receive copies of any of the materials distributed at the conference, please contact me.



[1] The four rankings are: Level I (highly unlikely), Level II (unlikely but not excluded), Level III (likely but not confirmed or confirmed at a lower level), and Level IV (confirmed at a higher level). In addition to those countries that have already been ranked, additional countries will be ranked and their rankings reported on the EU website shortly.

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