Bovine spongiform encephalopathy

with BSE. A notable feature of such disease is the inability of the infected animal to stand.

Source: APHIS]

Bovine Spongiform Encephalopathy (BSE), commonly known as Mad-Cow Disease (MCD), is a fatal, neurodegenerative disease in cattle, that causes a spongy degeneration in the brain and spinal cord and also causes red eyes. BSE has a long incubation period, about 4 years, usually affecting adult cattle at a peak age onset of four to five years, all breeds being equally susceptible.cite web
title = A Focus on Bovine Spongiform Encephalopathy
url = http://fsrio.nal.usda.gov/document_fsheet.php?product_id=169
accessdate = 2008-04-07
year = 2007
month = November
work = Pathogens and Contaminants
publisher = Food Safety Research Information Office] In the United Kingdom, the country worst affected, more than 179,000 cattle have been infected and 4.4 million slaughtered during the eradication programme.cite web
title = The 'recipe for disaster' that killed 80 and left a £5bn bill
url = http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2000/10/27/nbse527.xml
accessdate = 2008-04-07
last = Brown
first = David
date = 2001-06-19
publisher = The Daily Telegraph]

It is believed by most scientists that the disease may be transmitted to human beings who eat the brain or spinal cord of infected carcasses.cite web
title = Commonly Asked Questions About BSE in Products Regulated by FDA's Center for Food Safety and Applied Nutrition (CFSAN)
url = http://www.cfsan.fda.gov/~comm/bsefaq.html
accessdate = 2008-04-08
date = 2005-09-14
publisher = Center for Food Safety and Applied Nutrition, Food and Drug Administration] In humans, it is known as new variant Creutzfeldt-Jakob disease (vCJD or nvCJD), and by April 2008, it had killed 163 people in Britain, and 37 elsewherecite web
title = Variant Creutzfeld-Jakob Disease, Current Data (April 2008)
url = http://www.cjd.ed.ac.uk/vcjdworld.htm
accessdate = 2008-04-08
year = 2008
month = April
publisher = The National Creutzfeldt-Jakob Disease Surveillance Unit (NCJDSU), University of Edinburgh] with the number expected to rise because of the disease's long incubation period. [cite web
title = Creutzfeldt-Jakob Disease Fact Sheet
url = http://www.ninds.nih.gov/disorders/cjd/detail_cjd.htm
accessdate = 2008-04-08
date = 2008-02-13
publisher = National Institute of Neurological Disorders and Stroke] Between 460,000 and 482,000 BSE-infected animals had entered the human food chain before controls on high-risk offal were introduced in 1989. [cite web
title = CJD deaths 'may have peaked'
url = http://news.bbc.co.uk/1/hi/health/1671737.stm
accessdate = 2008-04-08
date = 2001-11-23
publisher = BBC News]

A British inquiry into BSE concluded that the epidemic was caused by cattle, who are normally herbivores, being fed the remains of other cattle in the form of meat and bone meal (MBM), which caused the infectious agent to spread. [http://www.defra.gov.uk/animalh/bse/controls-eradication/causes.html "BSE: Disease control & eradication - Causes of BSE"] , Department for Environment, Food, and Rural Affairs, March 2007.] [ [http://www.bseinquiry.gov.uk/ "The BSE Inquiry"] , led by Lord Phillips of Worth Matravers, report published October 2000.] The origin of the disease itself remains unknown. The infectious agent is distinctive for the high temperatures at which it remains viable; this contributed to the spread of the disease in Britain, which had reduced the temperatures used during its rendering process. Another contributory factor was the feeding of infected protein supplements to very young calves.cite web
title = Supplements used in factory farming can spread disease
url = http://archives.seattletimes.nwsource.com/cgi-bin/texis.cgi/web/vortex/display?slug=madcowdairy28&date=20031228
accessdate = 2008-04-08
last = Harden
first = Blaine
date = 2003-12-28
publisher = The Washington Post]

Infectious agent

The infectious agent in BSE is believed to be a specific type of misfolded protein called a prion. Those prion proteins carry the disease between individuals and cause deterioration of the brain. BSE is a type of transmissible spongiform encephalopathy (TSE).cite web
title = Bovine Spongiform Encephalopaphy: An Overview
url = http://www.aphis.usda.gov/publications/animal_health/content/printable_version/BSEbrochure12-2006.pdf
accessdate = 2008-04-08
year = 2006
month = December
format = PDF
publisher = Animal and Plant Health Inspection Service, United States Department of Agriculture] TSEs can arise in animals that carry an allele which causes previously normal protein molecules to contort by themselves from an alpha helical arrangement to a beta pleated sheet, which is the disease-causing shape for the particular protein. Transmission can occur when healthy animals come in contact with tainted tissues from others with the disease. In the brain these proteins cause native cellular prion protein to deform into the infectious state, which then goes on to deform further prion protein in an exponential cascade. This results in protein aggregates, which then form dense plaque fibers, leading to the microscopic appearance of "holes" in the brain, degeneration of physical and mental abilities, and ultimately death.

Different hypotheses exist for the origin of prion proteins in cattle. Two leading hypotheses suggest that it may have jumped species from the disease scrapie in sheep, or that it evolved from a spontaneous form of "mad cow disease" that has been seen occasionally in cattle for many centuries. [New Scientist, 17 March 2007, p 11] Publius Flavius Vegetius Renatus records cases of a disease with similar characteristics in the 4th and 5th Century AD. [Digesta Artis Mulomedicinae, Publius Flavius Vegetius Renatus] The British Government enquiry took the view the cause was not scrapie as had originally been postulated, and was some event in the 1970s that it was not possible to identify. [ [http://www.bseinquiry.gov.uk/report/volume1/execsum4.htm Vol.1 - Executive Summary of the Report of the Inquiry ] ]

Findings published in PLoS Pathogens (September 12, 2008) suggest that mad cow disease also is caused by a genetic mutation within a gene called Prion Protein Gene. The research shows, for the first time, that a 10-year-old cow from Alabama with an atypical form of bovine spongiform encephalopathy had the same type of prion protein gene mutation as found in human patients with the genetic form of Creutzfeldt-Jakob disease, also called genetic CJD for short. Besides having a genetic origin, other human forms of prion diseases can be sporadic, as in sporadic CJD, as well as foodborne. That is, they are contracted when people eat products contaminated with mad cow disease. This form of Creutzfeldt-Jakob disease is called variant CJD. [cite journal |author=Richt JA, Hall SM|title=BSE Case Associated with Prion Protein Gene Mutation.|journal=PLoS Pathog |year=2008 |date=Sep 12 |pmid=18787697 |PubMed - in process] [ [http://newswise.com/articles/view/544252/ Research Shows Mad Cow Disease Also Caused by Genetic Mutation] Newswise, Retrieved on September 14, 2008.]

Not all scientists agree that the danger of contracting the disease warrants taking extreme measures. They stress that human infection by mad cow disease has been statistically very small.Fact|date=May 2008

The BSE epidemic in British cattle

Cattle are normally herbivores. In nature, cattle eat grass. In modern industrial cattle-farming, various commercial feeds are used, which may contain ingredients including antibiotics, hormones, pesticides, fertilizers, and protein supplements. The use of meat and bone meal, produced from the ground and cooked left-overs of the slaughtering process as well as from the cadavers of sick and injured animals such as cattle, sheep, or chickens, as a protein supplement in cattle feed was widespread in Europe prior to about 1987.Fact|date=February 2007 Worldwide, soya bean meal is the primary plant-based protein supplement fed to cattle. However, soya beans do not grow well in Europe, so cattle raisers throughout Europe turned to the less expensive animal by-product feeds as an alternative. A change to the rendering process in the early 1980s may have resulted in a large increase of the infectious agents in the cattle feed. A contributing factor was suggested to have been a change in British laws that allowed a lower temperature sterilization of the protein meal. While other European countries like Germany required said animal byproducts to undergo a high temperature steam boiling process, this requirement had been eased in Britain as a measure to keep prices competitive. Later the British Inquiry dismissed this theory saying "changes in process could not have been solely responsible for the emergence of BSE, and changes in regulation were not a factor at all." [ [http://www.bseinquiry.gov.uk/report/volume2/chaptea3.htm#820576 Vol.2 - 3. The nature and cause of BSE ] ]

Following an epizootic of BSE in Britain, 165 people (up until 2007) acquired and died of a disease with similar neurological symptoms subsequently called vCJD, or (new) variant Creutzfeldt-Jakob disease. This is a separate disease from 'classical' Creutzfeldt-Jakob disease, which is not related to BSE and has been known about since the early 1900s. Three cases of vCJD occurred in people who had lived in or visited Britain — one each in Ireland, Canada and the United States. There is also some concern about those who work with (and therefore inhale) cattle meat and bone meal, such as horticulturists, who use it as fertilizer. Up to date statistics on all types of CJD are published by the [http://www.cjd.ed.ac.uk UK CJD Surveillance Centre] in Edinburgh.

For many of the vCJD patients, direct evidence exists that they had consumed tainted beef, and this is assumed to be the mechanism by which all affected individuals contracted it. Disease incidence also appears to correlate with slaughtering practices that led to the mixture of nervous system tissue with hamburger and other beef. It is estimated that 400,000 cattle infected with BSE entered the human food chain in the 1980s. Although the BSE epizootic was eventually brought under control by culling all suspect cattle populations, people are still being diagnosed with vCJD each year (though the number of new cases currently has dropped to fewer than 5 per year). This is attributed to the long incubation period for prion diseases, which are typically measured in years or decades. As a result the extent of the human vCJD outbreak is still not fully known.

The scientific consensus is that infectious BSE prion material is not destroyed through normal cooking procedures, meaning that contaminated beef foodstuffs prepared "well done" may remain infectious. [ [http://www.mayoclinic.com/health/mad-cow-disease/ID00012] dead link|date=June 2008] [cite web
title = Bovine Spongiform Encephalopathy - "Mad Cow Disease"
url = http://www.fsis.usda.gov/Fact_Sheets/Bovine_Spongiform_Encephalopathy_Mad_Cow_Disease/index.asp
accessdate = 2008-04-08
year = 2005
month = March
work = Fact Sheets
publisher = Food Safety and Inspection Service]

In 2004 researchers reported evidence of a second contorted shape of prions in a rare minority of diseased cattle. In other words, this implies a second strain of BSE prion. Very little is known about the shape of disease-causing prions, because their insolubility and tendency to clump thwarts application of the detailed measurement techniques of structural biology. But cruder measures yield a "biochemical signature" by which the newly discovered cattle strain appears different from the familiar one, but similar to the clumped prions in humans with traditional CJD Creutzfeldt-Jakob Disease. The finding of a second strain of BSE prion raises the possibility that transmission of BSE to humans has been underestimated, because some of the individuals diagnosed with spontaneous or "sporadic" CJD may have actually contracted the disease from tainted beef. So far nothing is known about the relative transmissibility of the two disease strains of BSE prion.

Alan Colchester, a professor of neurology at the University of Kent, writing in the September 3, 2005 issue of the medical journal, The Lancet, proposed a theory that the most likely initial origin of BSE in Britain was the importation from the Indian subcontinent of bone meal which contained CJD infected human remains. [http://www.gaudiyadiscussions.com/topic_4034.html] The government of India vehemently responded to the research calling it "misleading, highly mischievous; a figment of imagination; absurd," further adding that India maintained constant surveillance and had not had a single case of either BSE or vCJD. [ [http://timesofindia.indiatimes.com/articleshow/1218869.cms India dismisses Lancet's mad cow-India-The Times of India ] ] [ [http://www.abc.net.au/worldtoday/content/2005/s1453543.htm The World Today - New theory traces mad cow disease to animal feed exported from India ] ] The authors responded in the January 22, 2006 issue of The Lancet that their theory is unprovable only in the same sense as all other BSE origin theories are and that the theory warrants further investigation. [ [http://www.thelancet.com/journals/lancet/article/PIIS0140673606680628/fulltext Elsevier ] ]

UK epizootic and UK licensed medicines

During the course of the investigation into the BSE epizootic, an enquiry was also made into the activities of the Department of Health and its Medicines Control Agency. On May 7, 1999, in his written statement [http://www.bseinquiry.gov.uk/files/ws/s476.pdf#search='David%20Osborne%20Hagger' number 476] to the BSE Inquiry, David Osborne Hagger reported on behalf of the Medicines Control Agency that in a previous enquiry the Agency had been asked to:

"... identify relevant manufacturers and obtain information about the bovine material contained in children’s vaccines, the stocks of these vaccines and how long it would take to switch to other products." It was further reported that the: "... use of bovine insulin in a small group of mainly elderly patients was noted and it was recognised that alternative products for this group were not considered satisfactory." A medicines licensing committee report that same year recommended that: "... no licensing action is required at present in regard to products produced from bovine material or using prepared bovine brain in nutrient media and sourced from outside the United Kingdom, the Channel Isles and the Republic of Ireland provided that the country of origin is known to be free of BSE, has competent veterinary advisers and is known to practise good animal husbandry." In 1990 the British Diabetic Association became concerned regarding the safety of bovine insulin and the government licensing agency assured them that: "... there was no insulin sourced from cattle in the UK or Ireland and that the situation in other countries was being monitored." In 1991 a European Community Commission: "... expressed concerns about the possible transmission of the BSE/scrapie agent to man through use of certain cosmetic treatments." Sources in France reported to the British Medicines Control Agency: "... that there were some licensed surgical sutures derived from French bovine material." Concerns were also raised: "... regarding a possible risk of transmission of the BSE agent in gelatin products."

Husbandry practices in the United States relating to BSE

Soybean meal is cheap and plentiful in the United States. As a result, the use of animal byproduct feeds was never common, as it was in Europe. However, U.S. regulations only partially prohibit the use of animal byproducts in feed. In 1997, regulations prohibited the feeding of mammalian byproducts to ruminants such as cows and goats. However, the byproducts of ruminants can still be legally fed to pets or other livestock such as pigs and poultry such as chickens. In addition, it is legal for ruminants to be fed byproducts from some of these animals. [http://www.prwatch.org/books/madcow.html] A proposal to end the use of cow blood, restaurant scraps, and poultry litter (fecal matter, feathers) [The term "chicken litter" also includes spilled chicken feed as well as fecal matter and feathers. It is still legal in the United States to use ruminant protein to feed chickens. Thus, ruminant protein can get into the food chain of cattle in this round about way.] in January 2004 has yet to be implemented [cite web|url = http://www.organicconsumers.org/madcow/cow110504.cfm |title = Reader Questions Poultry Litter And "Downer" Bans |accessdate = 2008-06-14] , despite the efforts of some advocateswho of such a policy, who cite the fact that cows are herbivores, and that blood and fecal matter could potentially carry BSE.

Regulatory Failures

In February 2001, the USGAO reported that the FDA, which is responsible for regulating feed, had not adequately policed the various bans. [cite web|url = http://www.organicconsumers.org/madcow/cnn22602.cfm |title = FDA Not Doing Enough to Prevent Mad Cow Disease? |accessdate = 2008-06-14] Compliance with the regulations was shown to be extremely poor before the discovery of the Washington cow, but industry representatives report that compliance is now 100%. Even so, critics call the partial prohibitions insufficient. Indeed, US meat producer Creekstone Farms alleges that the USDA is preventing BSE testing from being conducted [ [http://www.3buddies.com/creekstone/news-appeal-response.html] dead link|date=June 2008] .

The USDA has issued recalls of beef supplies that involved introduction of "downer cows" into the food supply. Westland/Hallmark was found to have used electric shocks to prod downer cows into the slaughtering system in 2007 [http://www.washingtonpost.com/wp-dyn/content/article/2008/07/11/AR2008071102818.html] Possibly due to pressure from large agribusiness, the United States has drastically cut back on the number of cows inspected for BSE.USA Today, August 3, 2006, archived at [http://www.usatoday.com/news/opinion/editorials/2006-08-03-our-view_x.htm] ]

Effect on the Beef Industry

Japan was the top importer of U.S. beef, buying 240,000 tons valued at $1.4 billion in 2003. After the discovery of the first case of BSE in the U.S. on December 23, 2003, Japan stopped U.S. beef imports in December 2003. In December 2005, Japan once again allowed imports of U.S. beef, but reinstated its ban in mid-January 2006 after a technical violation of the U.S.-Japan beef import agreement: a vertebral column, which should have been removed prior to shipment, was included in a shipment of veal.

Tokyo yielded to U.S. pressure to resume imports, ignoring consumer worries about the safety of U.S. beef, said Japanese consumer groups. Michiko Kamiyama from Food Safety Citizen Watch said about this: "The government has put priority on the political schedule between the two countries, not on food safety or human health."

65 nations implemented full or partial restrictions on importing U.S. beef products because of concerns that U.S. testing lacked sufficient rigor. As a result, exports of U.S. beef declined from 1.3 million metric tons in 2003, before the first mad cow was detected in the US, to 322 thousand metric tons in 2004. This has increased since then to 771 thousand metric tons in 2007. Statistics provided by U.S. government & compiled by US Meat Export Federation, archived at [http://www.usmef.org/TradeLibrary/Statistics.asp] ]

On December 31, 2006, [http://www.hematech.com/ Hematech] , a biotechnology company based in Sioux Falls, South Dakota, announced that it had used genetic engineering and cloning technology to produce cattle that lacked a necessary gene for prion production - thus theoretically making them immune to BSE. [cite news
first = Rick
last = Weiss
title = Scientists Announce Mad Cow Breakthrough
url = http://www.washingtonpost.com/wp-dyn/content/article/2006/12/31/AR2006123100672.html
publisher = The Washington Post
date = 2007-01-01
accessdate = 2007-01-01]

BSE statistics by country

The tableFact|date=June 2008 to the right summarizes reported cases of BSE and of vCJD by country. BSE is the disease in "cattle", while vCJD is the disease in "people".

The tests used for detecting BSE vary considerably as do the regulations in various jurisdictions for when, and which cattle, must be tested. For instance, in the EU the cattle tested are older (30 months+), while many cattle are slaughtered earlier than that. At the opposite end of the scale, Japan tests all cattle at the time of slaughter. Tests are also difficult as the altered prion protein has very small levels in blood or urine, and no other signal has been found. Newer tests are faster, more sensitive, and cheaper, so it is possible that future figures may be more comprehensive. Even so, currently the only reliable test is examination of tissues during an autopsy.

It is notable that there are no cases reported in Australia, Brazil, New Zealand and Vanuatu where cattle are mainly fed outside on grass pasture and, mainly in Australia, non-grass feeding is done only as a final finishing process before the animals are processed for meat.

As for vCJD in humans, autopsy tests are not always done and so those figures too are likely to be too low, but probably by a lesser fraction. In the UK anyone with possible vCJD symptoms must be reported to the UK Creutzfeldt-Jakob Disease Surveillance Unit. In the U.S., the CDC has refused to impose a national requirement that physicians and hospitals report cases of the disease. Instead, the agency relies on other methods, including death certificates and urging physicians to send suspicious cases to the National Prion Disease Pathology Surveillance Center (NPDPSC) at Case Western Reserve University in Cleveland, which is funded by the CDC.

References

External links

Government
* [http://www.aphis.usda.gov/newsroom/hot_issues/bse/index.shtml APHIS - BSE Information] - U.S. Department of Agriculture
* [http://www.inspection.gc.ca/english/anima/heasan/disemala/bseesb/bseesbfse.shtml Canadian BSE FAQs] - Canadian Food Inspection Agency
* [http://www.defra.gov.uk/animalh/bse/index.html BSE Homepage] - Department for Environment, Food and Rural Affairs (UK)
* [http://www.bseinquiry.gov.uk UK government inquiry into BSE from discovery to 1996]
* [http://www.cjd.ed.ac.uk/ UK Creutzfeldt-Jakob Disease Surveillance Unit]
* [http://www.bseinquiry.gov.uk/files/ws/s476.pdf#search='David%20Osborne%20Hagger' British Medicines Control Agency statement] PDF - (Excerpts cited above.)
* [http://www.foodsafety.gov/%7Efsg/bse.html BSE Resources] - Food Safety.gov
* [http://www.ers.usda.gov/features/bse/index.htm Impact of BSE on U.S. Economy] - Economic Research Service
* [http://www.state.ma.us/dph/cdc/factsheets/madcow.htm Mad Cow FAQs] - Massachusetts Public Health
* [http://www.hc-sc.gc.ca/fn-an/securit/animal/bse-esb/index_e.html BSE (Mad Cow Disease)] - Health Canada
* [http://a257.g.akamaitech.net/7/257/2422/10apr20061500/edocket.access.gpo.gov/cfr_2006/aprqtr/21cfr589.2000.htm List of prohibited substances in ruminant feed] - U.S. Code of Federal Regulations
* [http://www.didgood.com/health/BSE/northamerica.html Bovine Spongiform Encephalopathy in North America] - enumeration of reported cattle incidentsConsumer/health groups
* [http://science.howstuffworks.com/mad-cow-disease.htm HowStuffWorks] Craig C. Freudenrich, Ph.D.
* [http://www.organicconsumers.org/madcow.htm Mad Cow Disease news and information] - Organic Consumers Association
* [http://pediatrics.about.com/cs/inthenews/a/madcow.htm Pediatrician's evaluation of BSE risk] - About.com
* [http://www.bna.com/webwatch/madcow.htm Mad Cow information] - Bureau for National Affairs
* [http://www.ific.org/publications/qa/bseqa.cfm BSE FAQs] - International Food Information Council
* [http://www.prwatch.org/books/madcow.html Mad Cow USA] - Center for Media and Democracy
* [http://www.cspinet.org/foodsafety/saferbeef.html Choosing Safer Beef to Eat] - Center for Science in the Public Interest

Science/research
* [http://www.thelancet.com/search/results?search_searchuri=%2Fsearch%2Fadvanced&search_resulturi=%2Fsearch%2Fresults&search_preview=no&search_reqfirst=1&search_reqcount=20&search_submode=citation&update_search=no&search_mode=journal&search_cluster=thelancet&search_discipline=cluster&journal_picker=lancet&restrictterm_lancet=lancet&restrictname_lancet=lancet&restricttype_lancet=journal&restrictdesc_lancet=The+Lancet&restrictterm_laneur=&restrictname_laneur=laneur&restricttype_laneur=journal&restrictdesc_laneur=The+Lancet+Neurology&restrictterm_laninf=&restrictname_laninf=laninf&restricttype_laninf=journal&restrictdesc_laninf=The+Lancet+Infectious+Diseases&restrictterm_lanonc=&restrictname_lanonc=lanonc&restricttype_lanonc=journal&restrictdesc_lanonc=The+Lancet+Oncology&search_volume=368&search_issue=9552&search_startpage=2061&Submit=Search BSE and blood transfusion] (The Lancet - Vol. 368, Issue 9552, 09 December 2006, Pages 2061-2067)
* [http://www.cmpharm.ucsf.edu/cohen/media/images/Scientifc_American.pdf Scientific American] - Article from 2004
* [http://www.ext.nodak.edu/extpubs/ansci/beef/as1206w.htm Mad Cow Information] - North Dakota State University
* [http://www.iowabeefcenter.org/content/bsemain.htm BSE Information Center] - Iowa State University
* [http://www.markpurdey.com/science_the_origins_of_bse.htm The Origins of BSE] - Mark Purdey

Beef/cattle industry
* [http://www.aamp.com/foodsafety/BSEnews.asp BSE News & Information] - American Association of Meat Processors
* [http://www.afia.org Livestock Feed Industry News] - American Feed Industry Association
* [http://www.oznet.ksu.edu/library/agec2/mf2678.pdf Economic Impact of BSE on the U.S. Beef Industry]