Bse

USMEF Backgrounder
November 2007
Cause and Impact
Bovine spongiform encephalopathy (BSE) is a degenerative neurological disease that affects the central nervous system (CNS) of cattle. It belongs to the family of transmissible spongiform encephalopathies (TSE), which includes scrapie in sheep and chronic wasting disease in deer and elk. BSE was first discovered in England in 1986 when several older cows displayed physical symptoms associated with forms of TSE. Because many countries had used rendered meat and bone meal (MBM) for animal feed in the beef, poultry and pork industries, the theory was that the new problem was associated with the feeding of ruminant MBM back to ruminants. Two years later the British government banned MBM and imposed an accelerated slaughter priority for infected cattle. Studies eventually determined that rendering of infected offals, including brains and spinal cords, was the primary transfer mechanism. BSE reached its peak in England in January of 1993 when 1,000 new cases per week were being reported. Although there was no evidence that the disease spread from animal to animal, delays in instituting feed bans and other controls slowed the pace of disease eradication or reduction in the U.K. By 1994 three in every 1,000 British cattle had developed BSE. At that time the European Union banned British beef imports except from farms without BSE cases in the previous six years. In 1995, nine years after the first reported beef cattle case of BSE, the first human died from BSE-type symptoms. Because it was suspected (although never proven) that the death resulted from eating BSE-infected products, the human disease was named vCJD to indicate its status as a new variant of Creutzfeldt-Jacob Disease (CJD). While BSE, vCJD and CJD are all TSEs, only vCJD and sporadic CJD affect humans. They all, however, are associated with the accumulation of abnormal prion proteins in the brain. Sporadic CJD and vCJD differ in that each has its own unique clinical features. Sporadic CJD was first identified in the 1920s and has a worldwide incidence of about one case per million people each year. There is no evidence that sporadic CJD is caused by what a person eats. Scientific evidence suggested that the vCJD was caused by the transmission of the BSE agent to humans through consumption of CNS tissue from infected animals. In total, 157 cases of definitive or probable cases of vCJD had been reported worldwide as of July 5, 2004, with 147 of those having occurred in the U.K. On May 20, 2003 a case of BSE was discovered in Canada. After an initial ban, in August 2003 the USDA allowed resumption of imports of Canadian boneless boxed beef from cattle under 30 months of age so long as exporters receive permits. Beef trimmings derived from skeletal muscle with associated tissues are also allowed into the U.S. Copyright 2007 U.S. Meat Export Federation Page 1 of 4 For additional USMEF resources, go to www.usmef.org USMEF Backgrounder
November 2007

History In The U.S.
In May, 2007, the World Organization for Animal Health (OIE) classified the United States as a controlled risk country for BSE. This confirms that U.S. regulatory controls are effective and U.S. fresh beef and beef products from cattle of all ages can be safely traded due to interlocking safeguards. From the very beginning the U.S. launched efforts to protect its cow herd from BSE. • In 1989, the United States instituted an import ban on live animals, beef and beef products, such as meat and bone meal, from any country known to have BSE; • In 1990, the U.S. government launched an aggressive surveillance program – the first of its kind by a country without BSE within its borders. By 2003, this level of surveillance was 47 times higher than international standards; • Since 1990 cattle showing signs of neurological disorder have not been • In 1997, the U.S. Food and Drug Administration mandated a feed ban prohibiting the use of feed supplements in cattle containing byproducts such as meat and bone meal from cattle and other animals The U.S. was the first country to institute such a ban; • This “triple firewall” is reinforced by the common practice in the U.S. of harvesting the vast majority of cattle before the age of 24 months; BSE is more likely to occur in animals older than 30 months. (In fact, even in Europe, where BSE has reached epidemic proportions, of 1.6 million animals less than 30 months of age tested in 2002 there was not one positive case.) Despite these safeguards, a Holstein dairy cow became the first confirmed case of BSE in the U. S. on Dec. 23, 2003. The investigation revealed that the single case occurred in a Canadian-born cow in Washington State. A second U.S. BSE case was announced on June 24, 2005. The animal was identified November 18, 2004, by the surveillance program implemented by the USDA and the beef industry to maintain an extraordinary safe beef supply, but initial tests found no evidence of BSE. Subsequent, more aggressive testing ordered during an internal audit of the program noted an unusual pattern of conflicting test results. Using an additional test procedure, commonly referred to as Western Blot, on an enriched sample from this animal found this sample to be a “weak positive” and deemed worthy of further testing by both U.S. and international laboratories. These additional tests confirmed the presence of BSE in the animal. It is important to remember that by U.S. law this animal was immediately isolated from the food and feed supply and was destroyed. Indeed, the animal was about 12 years old and had been intended for pet food. Still, the entire carcass was incinerated. A third case was announced March 13, 2006, and a battery of tests, including both immunohistochemistry (IHC) and Western Blot, confirmed that the cow had BSE. Based on dentition, the animal was determined to be more than 10 years of age and thus born before the 1997 ban on feeding ruminant protein to ruminants. Copyright 2007 U.S. Meat Export Federation Page 2 of 4 For additional USMEF resources, go to www.usmef.org USMEF Backgrounder
November 2007
This non-ambulatory cow was euthanized by the examining veterinarian, who collected a sample to submit for BSE testing, and buried on the farm. The discovery of these cases of BSE was not unexpected by the USDA or the beef industry. Neither the current surveillance program, nor the intensive program involving 542,697 tests completed in March 2006, discovered additional cases. Because the U.S. for many years had its protections in place against the spread of BSE, and because all CNS tissue is removed and doesn’t enter the food supply, little danger was presented by the discovery of these three isolated cases of BSE. Nevertheless, the government reviewed its policies and strengthened its already robust system to include additional rules and regulations. See USMEF BSE Fact Sheet. In fact, with the discovery of the single BSE-infected cow in the United States, the government and industry established a rigid safety mechanism to protect consumer safety. The procedures 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 is confirmed as negative; and prohibiting the air-injection stunning of cattle. In addition, the U.S. defines the skull, brain, trigeminal ganglia, eyes, vertebral column, spinal cord and dorsal root ganglia of cattle 30 months of age or older, and the distal ileum and tonsils of all cattle to be specified risk materials (SRM) and prohibits their use in the human food supply. Non-ambulatory cattle are banned from the human food chain, while no animal tested for BSE is allowed into the human food supply until negative results are returned. In 1998 the USDA asked Harvard University’s Center for Risk Analysis to conduct a risk assessment of the U.S. animal agriculture industry to determine the potential for BSE discovery and spread. This research suggested that whatever the cause of BSE, spread most likely was through oral exposure to infectious material rendered from diseased animals. It also found that even if hypothetical cross-species transmissions or spontaneous cases existed, these would give rise to at most only one to two BSE cases per year. In short, the assessment concluded that: • IF BSE were to be introduced into the United States, measures already in place when the review was done should prevent any substantial spread of the disease to animals or the human food supply; and • Further USDA modifications to existing food safety regulations could reduce the Other government and independent researchers agree that the U.S. has put significant and sufficient safeguards in place to protect against the spread of BSE in this country. Dr. Ron DeHaven, APHIS Administrator, has declared that consumers have “every reason to remain confident in the safety of U.S. beef.” Copyright 2007 U.S. Meat Export Federation Page 3 of 4 For additional USMEF resources, go to www.usmef.org USMEF Backgrounder
November 2007
David Ropeik of the Harvard Center for Risk Analysis says that the risk is “as close to zero as you can get.” Dr. Ken Petersen of the USDA Food Safety Inspection Service says “Clinical studies tell us there’s virtually zero risk.” In 2006 OIE estimated the annual incidence rate of BSE in U.S. bovine animals that were more than 24 months of age at 0.024 cases per million animals. According to the U.S. Centers for Disease Control and Prevention, the risk of contracting the disease from eating beef and beef products, even when infected cows are in the food supply, “appears to be extremely small, perhaps about one case per 10 billion servings.” In fact, nearly every reputable expert on the subject agrees that there’s no added risk from eating steaks, hamburgers or any other beef product. For more information on BSE visit the USMEF BSE Resources page at: Copyright 2007 U.S. Meat Export Federation Page 4 of 4 For additional USMEF resources, go to www.usmef.org

Source: http://www.usmef.info/TradeLibrary/assets/15129/bsebackgrounderfile/07_1003_BSEBackgrounder.pdf