Просмотр кода страницы Английская Википедия:Bovine spongiform encephalopathy

{{Английская Википедия/Панель перехода}}
{{cs1 config|name-list-style=vanc}}
{{Short description|Fatal neurodegenerative disease of cattle}}
{{Redirect|Mad cow}}
{{For|the disease in humans|Variant Creutzfeldt–Jakob disease}}
{{Use dmy dates|date=February 2024}}
{{Infobox medical condition (new)
| name = Bovine spongiform encephalopathy
| synonym = Mad cow disease
| image = Aphis.usda.gov BSE 3.jpg
| alt = A cow with BSE
| caption = A cow with BSE
| pronounce =
| field = [[Neurology]], [[Veterinary medicine]]
| symptoms = Abnormal behavior, trouble walking, weight loss, inability to move<ref name=Cas2018/>
| complications = [[Variant Creutzfeldt-Jakob disease]] (if BSE-infected beef is eaten by humans)
| onset = 4–5 years after exposure<ref name=WHO2002/>
| duration =
| types = Classic, atypical<ref name=Cas2018/>
| causes = A type of [[prion]]<ref name=CDC2018Ab/>
| risks = Feeding contaminated [[meat and bone meal]] to cattle
| diagnosis = Suspected based on symptoms, confirmed by examination of the brain<ref name=Cas2018/>
| differential =
| prevention = Not allowing sick or older animals to enter the food supply, disallowing certain products in animal food<ref name=CDC2018Con/>
| treatment = None
| medication =
| prognosis = Death within weeks to months<ref name=WHO2002/>
| frequency = 4 reported cases (2017)<ref name=Cas2018/>
| deaths =
}}
<!-- Definition and symptoms -->

'''Bovine spongiform encephalopathy''' ('''BSE'''), commonly known as '''[[Mad cow crisis|mad cow disease]]''', is an incurable and invariably fatal [[neurodegenerative disease]] of [[cattle]].<ref name=WHO2002/> Symptoms include abnormal behavior, trouble walking, and weight loss.<ref name=Cas2018/> Later in the course of the disease the cow becomes unable to function normally.<ref name=Cas2018/> There is conflicting information about the [[incubation period|time between infection and onset of symptoms]]. In 2002, the [[World Health Organization]] (WHO) suggested it to be approximately four to five years.<ref name=WHO2002>{{cite web |title=Bovine spongiform encephalopathy |url=https://www.who.int/mediacentre/factsheets/fs113/en/ |archive-url=https://web.archive.org/web/20121218132047/http://www.who.int/mediacentre/factsheets/fs113/en/ |url-status=dead |archive-date=2012-12-18 |website=WHO |access-date=27 October 2018 |date=November 2002}}</ref> Time from onset of symptoms to death is generally weeks to months.<ref name=WHO2002/> Spread to humans is believed to result in [[variant Creutzfeldt–Jakob disease]] (vCJD).<ref name=CDC2018Ab/> As of 2018, a total of 231 cases of vCJD had been reported globally.<ref name=CDC2018>{{cite web |title=BSE in North America BSE (Bovine Spongiform Encephalopathy) Prion Diseases |url=https://www.cdc.gov/prions/bse/bse-north-america.html |website=CDC |access-date=26 October 2018 |language=en-us |date=2 October 2018}}</ref>

<!-- Cause -->
BSE is thought to be due to an infection by a misfolded protein, known as a [[prion]].<ref name=CDC2018Ab/><ref name=FDA2018>{{cite web |title=Bovine Spongiform Encephalopathy (BSE) Questions and Answers |url=https://www.fda.gov/vaccines-blood-biologics/safety-availability-biologics/bovine-spongiform-encephalopathy-bse-questions-and-answers |website=FDA |access-date=16 June 2019 |language=en |date=22 May 2019}}</ref> Cattle are believed to have been infected by being fed [[meat-and-bone meal]] (MBM) that contained either the remains of cattle who spontaneously developed the disease or [[scrapie]]-infected [[sheep]] products.<ref name=CDC2018Ab/><ref name=Prusiner2001>{{cite journal | vauthors = Prusiner SB | title = Shattuck lecture--neurodegenerative diseases and prions | journal = The New England Journal of Medicine | volume = 344 | issue = 20 | pages = 1516–26 | date = May 2001 | pmid = 11357156 | doi = 10.1056/NEJM200105173442006 | author-link1 = Stanley B. Prusiner | doi-access = free }}</ref> The outbreak increased throughout the United Kingdom due to the practice of feeding meat-and-bone meal to young calves of [[dairy cows]].<ref name=CDC2018Ab/><ref name=AMJ1997>{{cite journal | vauthors = Nathanson N, Wilesmith J, Griot C | title = Bovine spongiform encephalopathy (BSE): causes and consequences of a common source epidemic | journal = American Journal of Epidemiology | volume = 145 | issue = 11 | pages = 959–69 | date = June 1997 | pmid = 9169904 | doi = 10.1093/oxfordjournals.aje.a009064 | doi-access = free }}</ref> Cases are suspected based on symptoms and confirmed by examination of the brain.<ref name=Cas2018/> Cases are classified as classic or atypical, with the latter divided into H- and L types.<ref name=Cas2018/> It is a type of [[transmissible spongiform encephalopathy]] (TSE).<ref>{{cite web |title=Bovine spongiform encephalopathy (BSE) |url=https://www.who.int/zoonoses/diseases/bse/en/ |archive-url=https://web.archive.org/web/20050309165201/http://www.who.int/zoonoses/diseases/bse/en/ |url-status=dead |archive-date=9 March 2005 |website=WHO |access-date=20 February 2019}}</ref>

<!-- Prevention -->
Efforts to prevent the disease in the UK include not allowing any animal older than 30 months to enter either the human food or [[animal feed supply]].<ref name=CDC2018Con/> In continental Europe, cattle over 30 months must be tested if they are intended for human food.<ref name=CDC2018Con>{{cite web |title=Control Measures BSE (Bovine Spongiform Encephalopathy) Prion Diseases |url=https://www.cdc.gov/prions/bse/control-measures.html |website=CDC |access-date=27 October 2018 |language=en-us |date=2 October 2018}}</ref> In North America, tissue of concern, known as [[specified risk material]], may not be added to animal feed or [[pet food]].<ref>{{cite web |title=Feed Bans BSE (Bovine Spongiform Encephalopathy) {{!}} Prion Diseases |url=https://www.cdc.gov/prions/bse/feed-ban.html |website=CDC |access-date=27 October 2018 |language=en-us |date=2 October 2018}}</ref> About four million cows were killed during the eradication programme in the UK.<ref>{{cite news |title='All steps taken' after BSE diagnosis |url=https://www.bbc.com/news/uk-scotland-north-east-orkney-shetland-45954225 |access-date=27 October 2018 |work=BBC News |date=23 October 2018}}</ref>

<!-- Epidemiology and history -->
Four cases were reported globally in 2017, and the condition is considered to be nearly eradicated.<ref name=Cas2018/> In the [[United Kingdom]], from 1986 to 2015, more than 184,000 cattle were diagnosed with the peak of new cases occurring in 1993.<ref name=CDC2018Ab>{{cite web |title=About BSE BSE (Bovine Spongiform Encephalopathy) Prion Diseases |url=https://www.cdc.gov/prions/bse/about.html |website=CDC |access-date=26 October 2018 |language=en-us |date=2 October 2018}}</ref> A few thousand additional cases have been reported in other regions of the world.<ref name=Cas2018>{{cite book | vauthors = Casalone C, Hope J |title=Human Prion Diseases |chapter=Atypical and classic bovine spongiform encephalopathy |series=Handbook of Clinical Neurology |date=2018 |volume=153 |pages=121–134 |publisher=Elsevier |doi=10.1016/B978-0-444-63945-5.00007-6 |pmid=29887132|isbn=9780444639455 }}</ref> In addition, it is believed that several million cattle with the condition likely entered the food supply during the outbreak.<ref name=Cas2018/>
{{TOC limit}}

==Signs==
[[File:Bse-cattle-250.jpg|thumb|upright=1.3|This cow with BSE displays abnormal posturing and weight loss.]]
Signs are not seen immediately in cattle, due to the disease's extremely long incubation period.<ref>{{Cite web|url=http://www.afrivip.org/sites/default/files/bse_complete.pdf|title=Bovine Spongiform Encephalopathy (BSE)| vauthors = Thomson G |access-date=21 November 2016}}</ref> Some cattle have been observed to have an abnormal gait, changes in behavior, tremors and hyper-responsiveness to certain stimuli.<ref name=":0">{{Cite web|url=http://www.cfsph.iastate.edu/Factsheets/pdfs/bovine_spongiform_encephalopathy.pdf|title=Bovine Spongiform Encephalopathy | date=August 2016|website=The Center for Food Security & Public Health|access-date=30 October 2016}}</ref> Hindlimb ataxia affects the animal's gait and occurs when muscle control is lost. This results in poor balance and coordination.<ref>{{Cite web|url=http://www.ninds.nih.gov/disorders/ataxia/ataxia.htm|title=Ataxias and Cerebellar or Spinocerebellar Degeneration Information Page: National Institute of Neurological Disorders and Stroke (NINDS)|website=www.ninds.nih.gov|access-date=2016-12-01|archive-date=9 February 2015|archive-url=https://web.archive.org/web/20150209002034/http://www.ninds.nih.gov/disorders/ataxia/ataxia.htm|url-status=dead}}</ref> Behavioural changes may include aggression, anxiety relating to certain situations, nervousness, frenzy and an overall change in temperament. Some rare but previously observed signs also include persistent pacing, rubbing and licking. Additionally, nonspecific signs have also been observed which include weight loss, decreased milk production, lameness, ear infections and teeth grinding due to pain. Some animals may show a combination of these signs, while others may only be observed demonstrating one of the many reported. Once clinical signs arise, they typically get worse over the subsequent weeks and months, eventually leading to recumbency, coma and death.<ref name=":0" />

== Cause ==
BSE is an infectious disease believed to be due to a misfolded protein, known as a [[prion]].<ref name=CDC2018Ab/><ref name=FDA2018/> Cattle are believed to have been infected from being fed [[meat and bone meal]] (MBM) that contained the remains of other cattle who spontaneously developed the disease or [[scrapie]]-infected sheep products.<ref name=CDC2018Ab/> The outbreak increased throughout the United Kingdom due to the practice of feeding meat-and-bone meal to young calves of dairy cows.<ref name=CDC2018Ab/><ref name=AMJ1997/>

BSE prions are misfolded forms of the particular brain protein called [[PRNP|prion protein]]. When this protein is misfolded, the normal [[Alpha helix|alpha-helical]] structure is converted into a [[beta sheet]]. The prion induces normally-folded proteins to take on the misfolded phenotype in an exponential cascade. These sheets form small chains which aggregate and cause cell death. Massive cell death forms lesions in the brain which lead to degeneration of physical and mental abilities and ultimately death.<ref>{{cite journal | vauthors = Orge L, Lima C, Machado C, Tavares P, Mendonça P, Carvalho P, Silva J, Pinto ML, Bastos E, Pereira JC, Gonçalves-Anjo N, Gama A, Esteves A, Alves A, Matos AC, Seixas F, Silva F, Pires I, Figueira L, Vieira-Pinto M, Sargo R, Pires MD | display-authors = 6 | title = Neuropathology of Animal Prion Diseases | journal = Biomolecules | volume = 11 | issue = 3 | pages = 466 | date = March 2021 | pmid = 33801117 | pmc = 8004141 | doi = 10.3390/biom11030466 | doi-access = free }}</ref> The prion is not destroyed even if the beef or material containing it is cooked or heat-treated under normal conditions and pressures.<ref name="TSE">{{cite web |title=Bovine Spongiform Encephalopaphy: An Overview |url=http://www.aphis.usda.gov/publications/animal_health/content/printable_version/BSEbrochure12-2006.pdf |access-date=8 April 2008 |date=December 2006 |publisher=[[Animal and Plant Health Inspection Service]], [[United States Department of Agriculture]] |url-status=dead |archive-url=https://web.archive.org/web/20080308030306/http://www.aphis.usda.gov/publications/animal_health/content/printable_version/BSEbrochure12-2006.pdf |archive-date=8 March 2008 |df=dmy }}</ref> Transmission can occur when healthy animals come in contact with tainted tissues from others with the disease, generally when their food source contains tainted meat.<ref name="WHO2002" />

The British Government enquiry took the view that the cause was not scrapie, as had originally been postulated, but was some event in the 1970s that could not be identified.<ref>{{cite web|url=http://www.bseinquiry.gov.uk/report/volume1/execsum4.htm|archive-url=http://webarchive.nationalarchives.gov.uk/20090505194948/http://www.bseinquiry.gov.uk/report/volume1/execsum4.htm|url-status=dead|archive-date=2009-05-05|title=Vol.1 - Executive Summary of the Report of the Inquiry|website=webarchive.nationalarchives.gov.uk}}</ref>

===Spread to humans===
Spread to humans is believed to result in [[variant Creutzfeldt–Jakob disease]] (vCJD).<ref name=CDC2018Ab/> The agent can be transmitted to humans by eating food contaminated with it.<ref name=Budka2015rev/> Though any tissue may be involved, the highest risk to humans is believed to be from eating food contaminated with the brain, spinal cord, or digestive tract.<ref name="FDA/CFSAN">
{{cite web |title=Commonly Asked Questions About BSE in Products Regulated by FDA's Center for Food Safety and Applied Nutrition (CFSAN) |url=http://vm.cfsan.fda.gov/~comm/bsefaq.html |access-date=8 April 2008 |date=14 September 2005 |publisher=[[Center for Food Safety and Applied Nutrition]], [[Food and Drug Administration (United States)|Food and Drug Administration]] |url-status=dead |archive-url=https://web.archive.org/web/20080509164526/http://vm.cfsan.fda.gov/~comm/bsefaq.html |archive-date=9 May 2008 |df=dmy-all }}</ref><ref>{{cite journal | vauthors = Ramasamy I, Law M, Collins S, Brooke F | title = Organ distribution of prion proteins in variant Creutzfeldt-Jakob disease | journal = The Lancet. Infectious Diseases | volume = 3 | issue = 4 | pages = 214–22 | date = April 2003 | pmid = 12679264 | doi = 10.1016/S1473-3099(03)00578-4 }}</ref>

== Pathogenesis ==
The pathogenesis of BSE is not well understood or documented like other diseases of this nature. Even though BSE is a disease that results in neurological defects, its pathogenesis occurs in areas that reside outside of the nervous system.<ref name=":1">{{cite journal | vauthors = Espinosa JC, Morales M, Castilla J, Rogers M, Torres JM | title = Progression of prion infectivity in asymptomatic cattle after oral bovine spongiform encephalopathy challenge | journal = The Journal of General Virology | volume = 88 | issue = Pt 4 | pages = 1379–83 | date = April 2007 | pmid = 17374785 | doi = 10.1099/vir.0.82647-0 | doi-access = free }}</ref> There was a strong deposition of [[Prion|PrP<sup>Sc</sup>]] initially located in the ileal [[Peyer's patch]]es of the small intestine.<ref name=":2">{{cite journal | vauthors = Balkema-Buschmann A, Fast C, Kaatz M, Eiden M, Ziegler U, McIntyre L, Keller M, Hills B, Groschup MH | display-authors = 6 | title = Pathogenesis of classical and atypical BSE in cattle | journal = Preventive Veterinary Medicine | volume = 102 | issue = 2 | pages = 112–7 | date = November 2011 | pmid = 21592603 | doi = 10.1016/j.prevetmed.2011.04.006 | series = Special Issue: Animal Health in the 21st Century – A Global ChallengeAnimal Health in the 21st Century }}</ref> The lymphatic system has been identified in the pathogenesis of scrapie. It has not, however, been determined to be an essential part of the pathogenesis of BSE. The Ileal Peyer's patches have been the only organ from this system that has been found to play a major role in the pathogenesis.<ref name=":1" /> Infectivity of the Ileal Peyer's patches has been observed as early as four months after inoculation.<ref name=":2" /> PrP<sup>Sc</sup> accumulation was found to occur mostly in tangible body macrophages of the Ileal Peyer's patches. Tangible body macrophages involved in PrP<sup>Sc</sup> clearance are thought to play a role in PrP<sup>Sc</sup> accumulation in the Peyer's patches. Accumulation of PrP<sup>Sc</sup> was also found in [[follicular dendritic cells]]; however, it was of a lesser degree.<ref>{{cite journal | vauthors = Hoffmann C, Ziegler U, Buschmann A, Weber A, Kupfer L, Oelschlegel A, Hammerschmidt B, Groschup MH | display-authors = 6 | title = Prions spread via the autonomic nervous system from the gut to the central nervous system in cattle incubating bovine spongiform encephalopathy | journal = The Journal of General Virology | volume = 88 | issue = Pt 3 | pages = 1048–55 | date = March 2007 | pmid = 17325380 | doi = 10.1099/vir.0.82186-0 | doi-access = free }}</ref> Six months after inoculation, there was no infectivity in any tissues, only that of the ileum. This led researchers to believe that the disease agent replicates here. In naturally confirmed cases, there have been no reports of infectivity in the Ileal Peyer's patches. Generally, in clinical experiments, high doses of the disease are administered. In natural cases, it was hypothesized that low doses of the agent were present, and therefore, infectivity could not be observed.<ref>{{cite journal | vauthors = Wells GA, Hawkins SA, Green RB, Austin AR, Dexter I, Spencer YI, Chaplin MJ, Stack MJ, Dawson M | display-authors = 6 | title = Preliminary observations on the pathogenesis of experimental bovine spongiform encephalopathy (BSE): an update | journal = The Veterinary Record | volume = 142 | issue = 5 | pages = 103–6 | date = January 1998 | pmid = 9501384 | doi = 10.1136/vr.142.5.103 | s2cid = 84765420 | url = https://www.researchgate.net/publication/51299099 }}</ref>

== Diagnosis ==
[[File:Histology bse.jpg|thumb|upright=1.3|Brain tissue of a cow with BSE showing the typical microscopic "holes" in the grey matter]]
Diagnosis of BSE continues to be a practical problem. It has an incubation period of months to years, during which no signs are noticed, though the pathway of converting the normal brain prion protein (PrP) into the toxic, disease-related PrP<sup>Sc</sup> form has started. At present, no way is known to detect PrP<sup>Sc</sup> reliably except by examining ''post mortem'' brain tissue using neuropathological and immunohistochemical methods. Accumulation of the abnormally folded PrP<sup>Sc</sup> form of PrP is a characteristic of the disease, but it is present at very low levels in easily accessible body fluids such as blood or urine. Researchers have tried to develop methods to measure PrP<sup>Sc</sup>, but no methods for use in materials such as blood have been accepted fully.{{by whom|date=August 2015}}

The traditional method of diagnosis relies on [[histopathological]] examination of the [[medulla oblongata]] of the brain, and other tissues, ''[[post mortem]]''. [[Immunohistochemistry]] can be used to demonstrate prion protein accumulation.<ref name="WikiVet">{{cite web | url = http://en.wikivet.net/Bovine_Spongiform_Encephalopathy | title = Bovine Spongiform Encephalopathy | archive-url = https://web.archive.org/web/20160503042615/https://en.wikivet.net/Bovine_Spongiform_Encephalopathy | archive-date=3 May 2016 | publisher = [[WikiVet]] | access-date = 11 October 2011 }}</ref>

In 2010, a team from New York described detection of PrP<sup>Sc</sup> even when initially present at only one part in a hundred billion (10<sup>−11</sup>) in brain tissue. The method combines amplification with a novel technology called [[Surround Optical Fiber Immunoassay (SOFIA)|surround optical fiber immunoassay]] and some specific antibodies against PrP<sup>Sc</sup>. After amplifying and then concentrating any PrP<sup>Sc</sup>, the samples are labelled with a fluorescent dye using an [[antibody]] for specificity and then finally loaded into a microcapillary tube. This tube is placed in a specially constructed apparatus so it is totally surrounded by optical fibres to capture all light emitted once the dye is excited using a laser. The technique allowed detection of PrP<sup>Sc</sup> after many fewer cycles of conversion than others have achieved, substantially reducing the possibility of artifacts, as well as speeding up the assay. The researchers also tested their method on blood samples from apparently healthy sheep that went on to develop scrapie. The animals' brains were analysed once any signs became apparent. The researchers could, therefore, compare results from brain tissue and blood taken once the animals exhibited signs of the diseases, with blood obtained earlier in the animals' lives, and from uninfected animals. The results showed very clearly that PrP<sup>Sc</sup> could be detected in the blood of animals long before the signs appeared. After further development and testing, this method could be of great value in surveillance as a blood- or urine-based screening test for BSE.<ref>{{cite journal |title=Detecting Prions in Blood |journal=Microbiology Today. |pages=195 |date=August 2010 |url=https://www.sgm.ac.uk/pubs/micro_today/pdf/081010.pdf |access-date=21 August 2011 |archive-date=31 March 2012 |archive-url=https://web.archive.org/web/20120331021750/https://www.sgm.ac.uk/pubs/micro_today/pdf/081010.pdf |url-status=dead }}</ref><ref>{{cite web | url = http://www.bionosis.com/news/Bionosis%20PrioNet%20Poster.pdf | title = SOFIA: An Assay Platform for Ultrasensitive Detection of PrP<sup>Sc</sup> in Brain and Blood | publisher = SUNY Downstate Medical Center | access-date = 19 August 2011}}</ref>

===Classification===
BSE is a transmissible disease that primarily affects the [[central nervous system]]; it is a form of [[transmissible spongiform encephalopathy]], like [[Creutzfeldt–Jakob disease]] and [[Kuru (disease)|kuru]] in humans, [[scrapie]] in sheep, and [[chronic wasting disease]] in [[cervids|deer]].<ref name=Budka2015rev>{{cite journal | vauthors = Budka H, Will RG | title = The end of the BSE saga: do we still need surveillance for human prion diseases? | journal = Swiss Medical Weekly | volume = 145 | pages = w14212 | date = 12 November 2015 | pmid = 26715203 | doi = 10.4414/smw.2015.14212 | url = https://smw.ch/index.php?id=75&tx_ezmjournal_articledetail[identifier]=smw.2015.14212 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Eraña H, Venegas V, Moreno J, Castilla J | title = Prion-like disorders and Transmissible Spongiform Encephalopathies: An overview of the mechanistic features that are shared by the various disease-related misfolded proteins | journal = Biochemical and Biophysical Research Communications | volume = 483 | issue = 4 | pages = 1125–1136 | date = February 2017 | pmid = 27590581 | doi = 10.1016/j.bbrc.2016.08.166 | url = https://zenodo.org/record/897700 }}</ref><ref>{{cite journal | vauthors = Waddell L, Greig J, Mascarenhas M, Otten A, Corrin T, Hierlihy K | title = Current evidence on the transmissibility of chronic wasting disease prions to humans-A systematic review | journal = Transboundary and Emerging Diseases | volume = 65 | issue = 1 | pages = 37–49 | date = February 2018 | pmid = 28139079 | doi = 10.1111/tbed.12612 | doi-access = free }}</ref>

==Prevention==
A ban on feeding meat and bone meal to cattle has resulted in a strong reduction in cases in countries where the disease has been present. In disease-free countries, control relies on import control, feeding regulations, and surveillance measures.<ref name="WikiVet"/>

In UK and US [[slaughterhouse]]s, the brain, spinal cord, [[Trigeminal ganglion|trigeminal ganglia]], intestines, eyes, and tonsils from cattle are classified as [[specified risk material]]s, and must be disposed of appropriately.<ref name="WikiVet"/>

An enhanced BSE-related feed ban was enacted in both the United States (2009) and Canada (2007) to help improve prevention and elimination of BSE.<ref>{{Cite web|url=https://www.cdc.gov/prions/bse/feed-ban.html|title=Feed Bans BSE (Bovine Spongiform Encephalopathy) {{!}} Prion Diseases {{!}} CDC|website=www.cdc.gov|access-date=2016-09-30}}</ref>

== Epidemiology ==
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 or older), while many cattle are slaughtered younger 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 low levels in blood or urine, and no other signal has been found. Newer tests{{specify|date=July 2016}} are faster, more sensitive, and cheaper, so future figures possibly may be more comprehensive. Even so, currently the only reliable test is examination of tissues during a [[necropsy]].{{citation needed|date=December 2020}}

As for vCJD in humans, autopsy tests are not always done, so those figures, too, are likely to be too low, but probably by a lesser fraction. In the United Kingdom, anyone with possible vCJD symptoms must be reported to the Creutzfeldt–Jakob Disease Surveillance Unit. In the United States, the [[Centers for Disease Control and Prevention|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.

To control potential transmission of vCJD within the United States, the FDA had established strict restrictions on individuals' eligibility to donate blood. Individuals who had spent a cumulative time of three months or more in the United Kingdom between 1980 and 1996, or a cumulative time of five years or more from 1980 to 2020 in any combination of countries in Europe, were prohibited from [[Blood donation|donating blood]].<ref>[http://www.redcrossblood.org/donating-blood/eligibility-requirements/eligibility-criteria-alphabetical-listing#arc5 Eligibility Criteria for Blood Donation], American Red Cross</ref> Due to blood shortages associated with the [[COVID-19 pandemic|2020 COVID-19 outbreak]] these restrictions were temporarily rescinded in 2020.<ref>[https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-provides-updated-guidance-address-urgent-need-blood-during-pandemic FDA Provides Updated Guidance Addressing Urgent Need For Blood During The Pandemic], Food and Drug Administration</ref> This recommendation was removed in 2022.<ref>{{Cite web |last=Research |first=Center for Biologics Evaluation and |date=2022-05-24 |title=Recommendations to Reduce the Possible Risk of Transmission of Creutzfeldt-Jakob Disease and Variant Creutzfeldt-Jakob Disease by Blood and Blood Components |url=https://www.fda.gov/regulatory-information/search-fda-guidance-documents/recommendations-reduce-possible-risk-transmission-creutzfeldt-jakob-disease-and-variant-creutzfeldt |access-date=2023-04-01 |website=U.S. Food and Drug Administration |language=en}}</ref>

Similar rules also apply in Germany<ref name=":4">{{Cite web |date=2017-02-17 |title=Richtlinie zur Gewinnung von Blut und Blutbestandteilen und zur Anwendung von Blutprodukten (Richtlinie Hämotherapie) |url=https://www.bundesaerztekammer.de/fileadmin/user_upload/_old-files/downloads/pdf-Ordner/RL/RiliH_Lese.pdf |archive-url=https://web.archive.org/web/20220628221016/https://www.bundesaerztekammer.de/fileadmin/user_upload/_old-files/downloads/pdf-Ordner/RL/RiliH_Lese.pdf |archive-date=2022-06-28 |access-date=2023-04-01}}</ref> and formerly Australia.<ref>{{Cite web |title=I lived in the UK for six months between 1980-96. Can I donate blood? {{!}} Lifeblood |url=https://www.lifeblood.com.au/faq/eligibility/work-travel-and-living-overseas/united-kingdom |access-date=2023-10-27 |website=www.lifeblood.com.au |language=en}}</ref> Anyone who lived in the UK between 1980 and 1996 for longer than six months is prohibited from giving blood.<ref name=":4" /> There are also prohibitions on donating breast milk and tissue.<ref>{{Cite web | date= 4 April 2018 |title='Mad cow disease' - why you can't donate blood, breast milk and tissues|url=https://www.health.qld.gov.au/news-events/news/mad-cow-disease-why-cant-donate-blood-breast-milk-tissue-UK-Britain|access-date=2021-07-09|website=Queensland Health|language=en-AU}}</ref> However, there are no restrictions on organ donation.<ref name=":3">{{Cite web |title=More information about donating blood if you have lived in the UK {{!}} Australian Red Cross Lifeblood |url=https://www.donateblood.com.au/vcjd-blood-donation |access-date=2021-07-09 |website=www.donateblood.com.au}}</ref> Blood donation organisations first considered relaxing the rules after the COVID-19 pandemic and some natural disasters that depleted the blood supply.<ref>{{cite web | agency =Australian Associated Press |date=2021-04-20|title=Australian blood bank reconsidering ban on UK donations from 'mad cow disease' era|url=http://www.theguardian.com/australia-news/2021/apr/20/australian-blood-bank-reconsidering-ban-on-uk-donations-from-mad-cow-disease-era|access-date=2021-07-09|website=the Guardian|language=en}}</ref>

===North America===
The first reported case in [[North America]] was in December 1993 from [[Alberta]], [[Canada]].<ref>{{cite news|url=http://www.cbc.ca/news2/background/madcow/|access-date=20 January 2015|newspaper=CBC News|date=24 August 2006|title=Mad Cow in Canada: The science and the story}}</ref><ref>{{cite book | vauthors = Forge F, Fréchette JD |title=Mad Cow Disease and Canada's Cattle Industry |date=2005 |publisher=Parliamentary Information and Research Service, Library of Parliament |location=Ottawa |edition=Rev. 12 July 2005 |url=http://www.parl.gc.ca/Content/LOP/researchpublications/prb0301-e.htm |access-date=1 March 2021 |archive-url=https://web.archive.org/web/20120209055143/http://www.parl.gc.ca/Content/LOP/researchpublications/prb0301-e.htm |archive-date=9 February 2012 |oclc=262717605}}</ref> Another Canadian case was reported in May 2003. The first known US occurrence came in December of the same year, it was later confirmed to be a cow of Canadian origin imported to the US.<ref>{{cite news|url=http://www.cattlerange.com/tcr-m.html#3 |title=Investigators Trace Diseased Cow to Canada |archive-url=https://web.archive.org/web/20040211191824/http://www.cattlerange.com/tcr-m.html#3|archive-date=11 February 2004|date=27 December 2003|publisher=The Cattle Range }}</ref> The cow was slaughtered on a farm near Yakima, Washington. The cow was included in the United States Department of Agriculture's surveillance program, specifically targeting cattle with BSE.<ref>{{Cite web|url=https://www1.nyc.gov/site/doh/health/health-topics/mad-cow-disease.page|title=Mad Cow Disease|website=www1.nyc.gov|access-date=2018-08-16|archive-date=2 January 2020|archive-url=https://web.archive.org/web/20200102095612/https://www1.nyc.gov/site/doh/health/health-topics/mad-cow-disease.page|url-status=dead}}</ref> Canada announced two additional cases of BSE from Alberta in early 2005.<ref>{{Cite web | vauthors = Becker GS |url=http://www.nationalaglawcenter.org/assets/crs/RL32627.pdf |title=Bovine Spongiform Encephalopathy and Canadian Beef Imports |publisher=CRS Report for Congress. RL32627 |date=11 March 2005 |access-date=16 February 2011 |archive-url=https://web.archive.org/web/20101219121438/http://nationalaglawcenter.org/assets/crs/RL32627.pdf |archive-date=19 December 2010 |url-status=dead }}</ref>
In June 2005, [[John R. Clifford]], chief veterinary officer for the [[United States Department of Agriculture]] Animal and Plant Health Inspection Service, confirmed a fully domestic case of BSE in [[Texas]].<ref>{{cite news| vauthors = McNeil Jr DG |title=Case of Mad Cow in Texas Is First to Originate in U.S.|url=https://www.nytimes.com/2005/06/30/us/case-of-mad-cow-in-texas-is-first-to-originate-in-us.html|work=The New York Times|date=30 June 2005}}</ref><ref>{{cite web | vauthors = LeBlanc M |title=Chronology of BSE-Related Events and Government Initiatives |url= http://publications.gc.ca/collections/Collection-R/LoPBdP/EB-e/prb0412-1e.pdf |publisher=Parliamentary Information and Research Service, Library of Parliament |access-date=1 March 2021 |date=6 September 2006}}</ref>

==== United States ====
The use of animal by-product feeds was never common, as it was in Europe.{{verify source|date=July 2022}} Soybean meal is cheap and plentiful in the [[United States]], and cottonseed meal (1.5 million tons of which are produced in the US every year, none of which is suitable for humans or any other simple-stomach animals) is even cheaper than soybean meal. Historically, meat and bone meal, blood meal, and meat scraps have almost always commanded a higher price as a feed additive than oilseed meals in the US, so little incentive existed to use animal products to feed ruminants. However, US regulations only partially prohibited the use of animal by-products in feed. In 1997, regulations prohibited the feeding of mammalian by-products to [[ruminant]]s such as cattle and goats. However, the by-products of ruminants can still be legally fed to pets or other livestock, including pigs and [[poultry]]. In addition, it is legal for ruminants to be fed by-products from some of these animals.<ref>{{cite book| vauthors = Rampton S, Stauber J |title=Mad Cow USA|edition=1st|year=2004|publisher=Common Courage Press|location=Monroe, Maine|isbn=978-1-56751-110-9|url-access=registration|url=https://archive.org/details/madcowusa00shel}}</ref> Because of this, some authors have suggested that under certain conditions, it is still possible for BSE incidence to increase in U.S. cattle.<ref>{{cite journal | vauthors = Barnes R, Lehman C | title = Modeling of bovine spongiform encephalopathy in a two-species feedback loop | journal = Epidemics | volume = 5 | issue = 2 | pages = 85–91 | date = June 2013 | pmid = 23746801 | doi = 10.1016/j.epidem.2013.04.001 | arxiv = 1511.04470 | s2cid = 1185101 }}<!--|access-date=12 April 2014--></ref>

The US Department of Agriculture (USDA) announced on 19 May 2023 an atypical case of Bovine Spongiform Encephalopathy (BSE), commonly called mad cow disease, in an older beef cow at a slaughter plant in South Carolina.  USDA said the animal never entered slaughter channels and the agency did not expect any trade impacts as a result. It was the seventh detection of BSE in the United States since 2003 and all but one have been atypical.<ref>{{Cite news |last= |date=2023-05-19 |title=U.S. reports case of atypical mad cow disease |language=en |work=Reuters |url=https://www.reuters.com/world/us/us-reports-case-atypical-mad-cow-disease-2023-05-19/ |access-date=2023-07-11}}
</ref>

US meat producer [[Creekstone Farms Premium Beef|Creekstone Farms]] alleged in a lawsuit that the [[United States Department of Agriculture|USDA]] was preventing the company from testing its slaughtered cattle for BSE.<ref name="Creekstone1">{{cite press release | title = Creekstone Farms response to USDA appeal of summary judgement | publisher = 3buddies | date = 30 May 2007 | url = http://www.3buddies.com/creekstone/news-appeal-response.html | access-date = 20 June 2009 | archive-url = https://web.archive.org/web/20070928064710/http://www.3buddies.com/creekstone/news-appeal-response.html | archive-date = 28 September 2007 |url-status=dead}}
</ref>

The USDA has issued recalls of beef supplies that involved introduction of [[downer (animal)|downer cows]] into the food supply. [[Hallmark/Westland Meat Packing Company]] was found to have used electric shocks to prod downer cows into the slaughtering system in 2007.<ref>{{cite news | title = Meat Recalls to Name Retailers | vauthors = Seltzer M | url = https://www.washingtonpost.com/wp-dyn/content/article/2008/07/11/AR2008071102818.html | agency = Bloomberg News |newspaper=The Washington Post | date = 12 July 2008 | access-date = 20 June 2009 }}
</ref> Possibly due to pressure from large agribusiness, the United States has drastically cut back on the number of cows inspected for BSE.<ref name="USA Today">{{cite news | title = Mad cow watch goes blind | url = https://www.usatoday.com/news/opinion/editorials/2006-08-03-our-view_x.htm |work=USA Today | date = 3 August 2006 | access-date = 20 June 2009 }}
</ref>

====Effect on the US beef industry====
{{Update section|date=November 2016}}{{More citations needed section|date=June 2021}}

Japan was the top importer of US beef, buying $1.7 billion worth in 2003. After the discovery of the first case of BSE in the US on 23 December 2003, Japan halted US beef imports.<ref>{{Cite web |date=26 October 2004 |first=Robert |last=Roos |title=US, Japan agree on BSE precautions for beef trade |url=https://www.cidrap.umn.edu/news-perspective/2004/10/us-japan-agree-bse-precautions-beef-trade |access-date=2022-03-17 |website=CIDRAP |language=en}}</ref> In December 2005, Japan once again allowed imports of US beef,<ref>{{Cite web |date=12 December 2005 |title=Japan ends BSE-related ban on US beef |url=https://www.cidrap.umn.edu/news-perspective/2005/12/japan-ends-bse-related-ban-us-beef |access-date=2022-03-17 |website=CIDRAP |language=en}}</ref> but reinstated its ban in January 2006 after a violation of the US-Japan beef import agreement: a vertebral column, which should have been removed prior to shipment, was included in a shipment of veal.<ref>{{Cite web |last= |date=20 January 2006 |title=Japan reinstates ban on U.S. beef|url=http://edition.cnn.com/2006/BUSINESS/01/20/japan.us.beef/ |access-date=2022-03-18 |website=edition.cnn.com}}</ref>

Tokyo yielded to US pressure to resume imports, ignoring consumer worries about the safety of US beef, said Japanese consumer groups. Michiko Kamiyama from Food Safety Citizen Watch and Yoko Tomiyama from [[Consumers Union of Japan]]<ref>{{cite web|url=http://www.fswatch.org/newsletter/english/issue05.html|title=Food Safety Citizens'Watch English Newsletter|website=www.fswatch.org|access-date=23 December 2009|archive-date=3 October 2018|archive-url=https://web.archive.org/web/20181003131113/http://www.fswatch.org/newsletter/english/issue05.html|url-status=dead}}</ref> said about this: "The government has put priority on the political schedule between the two countries, not on food safety or human health."

Sixty-five nations implemented full or partial restrictions on importing US beef products because of concerns that US testing lacked sufficient rigor. As a result, exports of US beef declined from 1,300,000 [[tonnes]] (t) in 2003 (before the first [[Mad cow crisis|mad cow]] was detected in the US) to 322,000&nbsp;t in 2004. This has increased since then to 771,000&nbsp;t in 2007 and to 1,300,000&nbsp;t by 2017.<ref name="usmef">{{cite web|title=Statistics |url=https://www.usmef.org/TradeLibrary/Statistics.asp |work=Trade Library |publisher=U.S. Meat Export Federation |access-date=20 June 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090514152807/http://www.usmef.org/TradeLibrary/Statistics.asp |archive-date=14 May 2009 }}
</ref><ref>{{cite web |title=Statistics |url=https://www.usmef.org/news-statistics/statistics/?stat_year=2017 |work=Trade Library |publisher=U.S. Meat Export Federation |access-date=30 May 2018 |archive-date=3 August 2020 |archive-url=https://web.archive.org/web/20200803154852/https://www.usmef.org/news-statistics/statistics/?stat_year=2017 |url-status=dead }}</ref>

On 31 December 2006, Hematech Inc, a biotechnology company based in [[Sioux Falls, South Dakota|Sioux Falls]], South Dakota, announced it had used genetic engineering and cloning technology to produce cattle that lacked the PrP<sup>C</sup> form of the [[Major prion protein|major prion protein (PrP)]] necessary gene for prion production&nbsp;– thus theoretically making them immune to BSE.<ref>{{cite news | vauthors = Weiss R | title = Scientists Announce Mad Cow Breakthrough | url = https://www.washingtonpost.com/wp-dyn/content/article/2006/12/31/AR2006123100672.html |newspaper=The Washington Post | date = 1 January 2007 | access-date = 1 January 2007}}</ref><ref>{{Cite journal |last1=Richt |first1=Jürgen A |last2=Kasinathan |first2=Poothappillai |last3=Hamir |first3=Amir N |last4=Castilla |first4=Joaquin |last5=Sathiyaseelan |first5=Thillai |last6=Vargas |first6=Francisco |last7=Sathiyaseelan |first7=Janaki |last8=Wu |first8=Hua |last9=Matsushita |first9=Hiroaki |last10=Koster |first10=Julie |last11=Kato |first11=Shinichiro |last12=Ishida |first12=Isao |last13=Soto |first13=Claudio |last14=Robl |first14=James M |last15=Kuroiwa |first15=Yoshimi |date=31 December 2006 |title=Production of cattle lacking prion protein |journal=Nature Biotechnology |language=en |volume=25 |issue=1 |pages=132–138 |doi=10.1038/nbt1271 |issn=1087-0156 |pmc=2813193 |pmid=17195841}}</ref>

In April 2012, some [[South Korea]]n retailers ceased importing beef from the [[United States]] after a case of BSE was reported.<ref>{{cite news| url=http://in.reuters.com/article/us-korea-beef-idINL3E8FP1J720120425 | work=Reuters | title=S. Korea retailers halt US beef sales, govt may act | date=25 April 2012}}</ref> [[Indonesia]] also suspended imports of beef from the US after a dairy cow with [[Mad cow crisis|mad cow]] disease was discovered in [[California]].<ref>{{Cite news |date=2012-04-26 |title=Indonesia suspends U.S. beef imports over mad cow disease |language=en |work=Reuters |url=https://www.reuters.com/article/us-usa-madcow-indonesia-idUSBRE83P05620120426 |access-date=2022-03-17}}</ref>

===Japan===
With 36 confirmed cases, Japan experienced one of the largest number of cases of BSE outside Europe.<ref>[http://www.mhlw.go.jp/english/topics/foodsafety/bse/dl/5.pdf Ministry of Health, Labour and Welfare: BSE Cases in Japan] (accessed 7 May 2013)</ref> It was the only country outside Europe and the Americas to report non-imported cases.<ref>[http://www.oie.int/animal-health-in-the-world/bse-specific-data/ World Organisation for Animal Health: BSE situation in the world and annual incidence rate] (accessed 7 May 2013)</ref> Reformation of food safety in light of the BSE cases resulted in the establishment of a governmental Food Safety Commission in 2003.<ref>{{cite journal | vauthors = Kamisato T | title = BSE crisis in Japan: A chronological overview | journal = Environmental Health and Preventive Medicine | volume = 10 | issue = 5 | pages = 295–302 | date = September 2005 | pmid = 21432134 | pmc = 2723414 | doi = 10.1007/BF02897705 | bibcode = 2005EHPM...10..295K }}</ref>

=== Europe ===
{{Main|United Kingdom BSE outbreak}}
[[File:ESB UK-1987-2008.svg|lang=en|thumb|upright=1.5|Evolution of the bovine spongiform encephalopathy (BSE) epidemic in the UK]]
Cattle are naturally [[herbivore]]s, eating [[Poaceae|grasses]]. In modern industrial cattle-farming, though, various commercial feeds are used, which may contain ingredients including [[antibiotic]]s, [[hormone]]s, [[pesticide]]s, [[fertilizer]]s, and [[protein]] supplements. The use of meat and [[bone meal]], produced from the ground and cooked leftovers of the slaughtering process, as well as from the carcasses of sick and injured animals, such as cattle or sheep<!-- rendered chicken parts are called poultry meal-->, as a protein supplement in cattle feed was widespread in [[Europe]] prior to about 1987.<ref name="FDA/CFSAN"/> Worldwide, [[soybean]] meal is the primary plant-based protein supplement fed to cattle. However, soybeans do not grow well in Europe, so cattle raisers throughout Europe turned to the cheaper animal by-product feeds as an alternative. The British inquiry dismissed suggestions that changes to processing might have increased the infectious agents in cattle feed, 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"<ref>{{cite web|url=http://www.bseinquiry.gov.uk/index.htm |archive-url=http://webarchive.nationalarchives.gov.uk/20090505194948/http://www.bseinquiry.gov.uk/index.htm |url-status=dead |archive-date=2009-05-05 |title=The BSE Inquiry: Home|work=Open.gov.uk|date =October 2000|access-date=27 August 2014}}</ref> (the prion causing BSE is not destroyed by food heat treatment).

The first confirmed instance in which an animal fell ill with the disease occurred in 1986 in the [[United Kingdom]], and lab tests the following year indicated the presence of BSE; by November 1987, the British [[Ministry of Agriculture, Fisheries and Food (United Kingdom)|Ministry of Agriculture]] accepted it had a new disease on its hands.<ref>{{cite web|url=https://www.newscientist.com/article/dn111-brain-disease-drives-cows-wild/ |title=Brain disease drives cows wild| date=5 November 1987 | work=NewScientist | vauthors = Pain S | access-date=7 December 2018 }}</ref> Subsequently, 177 people (as of June 2014) contracted and died of a disease with similar neurological symptoms subsequently called (new) [[variant Creutzfeldt–Jakob disease]] (vCJD).<ref name="NCJDSU">{{cite web |title=Variant Creutzfeldt–Jakob Disease, Current Data (October 2009) |url=http://www.cjd.ed.ac.uk/vcjdworld.htm |access-date=14 October 2009 |date=October 2009 |publisher=The National Creutzfeldt–Jakob Disease Surveillance Unit (NCJDSU), [[University of Edinburgh]] |url-status=bot: unknown |archive-url=https://web.archive.org/web/20120721234746/http://www.cjd.ed.ac.uk/vcjdworld.htm |archive-date=21 July 2012 |df=dmy }};</ref><ref>{{cite web|url=http://www.cjd.ed.ac.uk/documents/worldfigs.pdf|title=Variant Creutzfeldt-Jakob Disease Current Data|date=June 2014|access-date=11 February 2015|archive-url=https://web.archive.org/web/20150226031911/http://www.cjd.ed.ac.uk/documents/worldfigs.pdf|archive-date=26 February 2015|url-status=dead|df=dmy-all}}</ref> 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 the UK&nbsp;– one each in the [[Republic of Ireland]], [[Canada]], and the US. Also, some concern existed about those who work with (and therefore inhale) cattle [[meat and bone meal]], such as [[horticulture|horticulturists]], who use it as fertilizer. Up-to-date statistics on all types of CJD are published by the National Creutzfeldt–Jakob Disease Surveillance Unit <!-- (NCJDSU) --> in [[Edinburgh]], [[Scotland]].{{citation needed|date=December 2020}}

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.{{Citation needed|date=January 2014}} Disease incidence also appears to correlate with slaughtering practices that led to the mixture of [[nervous system]] tissue with [[ground meat]] (mince) and other beef. An estimated 400,000 cattle infected with BSE entered the human food chain in the 1980s.{{Citation needed|date=November 2008}} 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 five per year). This is attributed to the long incubation period for prion diseases, which is typically measured in years or decades. As a result, the full extent of the human vCJD outbreak is still not known.{{citation needed|date=December 2020}}

The scientific consensus is that infectious BSE prion material is not destroyed through cooking procedures, meaning that even contaminated beef foodstuffs prepared "well done" may remain infectious.<ref>{{cite news|title=Mad cow disease: Still a concern |url=http://premium.edition.cnn.com/HEALTH/library/ID/00012.html |work=MayoClinic.com |publisher=CNN |date=10 February 2006 |access-date=20 June 2009 |url-status=dead |archive-url=https://web.archive.org/web/20050425012159/http://premium.edition.cnn.com/HEALTH/library/ID/00012.html |archive-date=25 April 2005 }}
</ref><ref>{{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 | access-date = 8 April 2008 | date = March 2005 | work = Fact Sheets | publisher = [[Food Safety and Inspection Service]] | archive-url = https://web.archive.org/web/20080413003024/http://www.fsis.usda.gov/fact_sheets/Bovine_Spongiform_Encephalopathy_Mad_Cow_Disease/index.asp | archive-date = 13 April 2008 | url-status = dead }}</ref>

Alan Colchester, a professor of neurology at the [[University of Kent]], and Nancy Colchester, writing in the 3 September 2005 issue of the medical journal ''[[The Lancet]]'', proposed a theory that the most likely initial origin of BSE in the United Kingdom was the importation from the Indian Subcontinent of bone meal which contained CJD-infected human remains.<ref>{{cite journal | vauthors = Colchester AC, Colchester NT | title = The origin of bovine spongiform encephalopathy: the human prion disease hypothesis | journal = Lancet | volume = 366 | issue = 9488 | pages = 856–61 | year = 2005 | pmid = 16139661 | doi = 10.1016/S0140-6736(05)67218-2 | s2cid = 38330299 }}</ref> 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.<ref>{{cite news | title = India dismisses Lancet's mad cow | vauthors = Mago C, Sinha K | url = http://timesofindia.indiatimes.com/articleshow/1218869.cms |work=The Times of India | date = 2 September 2005 | access-date = 20 June 2009 }}</ref><ref>{{cite news | title = New theory traces mad cow disease to animal feed exported from India | vauthors = Thompson G | url = http://www.abc.net.au/worldtoday/content/2005/s1453543.htm | work = The World Today | publisher = ABC | date = 5 September 2005 | access-date = 20 June 2009 }}</ref> The authors responded in the 22 January 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.<ref>{{cite journal | vauthors = Baron T, Biacabe AG | title = Origin of bovine spongiform encephalopathy | journal = Lancet | volume = 367 | issue = 9507 | pages = 297–8; author reply 298–9 | date = January 2006 | pmid = 16443028 | doi = 10.1016/S0140-6736(06)68062-8 | s2cid = 54248829 | doi-access = free }}
</ref>

During the course of the investigation into the BSE epizootic, an enquiry was also made into the activities of the [[Department of Health and Social Care|Department of Health]] [[Medicines and Healthcare products Regulatory Agency|Medicines Control Agency]] (MCA). On 7 May 1999, [[David Osborne Hagger]], a retired civil servant who worked in the Medicines Division of the Department of Health between 1984 and 1994, produced a written statement to the BSE Inquiry in which he gave an account of his professional experience of BSE.<ref name="haggerpdf">{{cite web|url=http://www.bseinquiry.gov.uk/files/ws/s476.pdf|archive-url=http://webarchive.nationalarchives.gov.uk/20080102164404/http://www.bseinquiry.gov.uk/files/ws/s476.pdf|url-status=dead|archive-date=2 January 2008|title=BSE Inquiry, Statement No. 476|date=7 May 1999|publisher=BSE Inquiry|access-date=16 October 2008}} Statement of David Osborne Hagger, Head of Abridged Licensing and Coordinator of the Executive support business of the Medicines Division of the [[British Department of Health|Department of Health]] at Market Towers in London.</ref>

In February 1989, the MCA 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". In July, "[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". In September, the BSE Working Party of the [[Committee on Safety of Medicines|Committee on the Safety of Medicines]] (CSM) 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".{{citation needed|date=December 2020}}

In 1990, the British Diabetic Association became concerned regarding the safety of bovine insulin. The CSM 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, the European Commission "[expressed] concerns about the possible transmission of the BSE/scrapie agent to man through use of certain cosmetic treatments".{{citation needed|date=January 2019}}

In 1992, sources in France reported to the MCA "that BSE had now been reported in France and there were some licensed surgical sutures derived from French bovine material". Concerns were also raised at a CSM meeting "regarding a possible risk of transmission of the BSE agent in gelatin products".<ref name="haggerpdf" />

For this failure, France was heavily criticised internationally. Thillier himself queried why there had never been a ban on French beef or basic safety precautions to stop the food chain becoming contaminated, suggesting "Perhaps because the French government forgot its role in guaranteeing the safety of food products, and this neglect cost the lives of nine people".<ref name="Standard">{{cite news| vauthors = Sparks I |title=Yes, we had mad cow disease too, France confesses|url=https://www.standard.co.uk/news/yes-we-had-mad-cow-disease-too-france-confesses-6927256.html|access-date=23 September 2017|publisher=Evening Standard|date=6 November 2008}}</ref> The ''Sydney Morning Herald'' added, "while blustering French politicians blamed Britain for the emergence of the disease – and tried to quarantine the country by banning imports of British beef – they failed to adopt measures to prevent a hidden epidemic at home".<ref>{{cite web| vauthors = Wilsher K |title=France in denial as BSE-infected beef entered food chain |url= http://www.smh.com.au/articles/2004/07/04/1088879375088.html |website=SMH.com |publisher=Sydney Morning Herald |access-date=23 September 2017 |date=2004-07-05}}</ref>

In 2016 France confirmed a further case of BSE.<ref>{{cite news| vauthors = Rousseau O |title=BSE-infected cow dies in France|url=http://www.globalmeatnews.com/Livestock/BSE-infected-cow-dies-in-France|work=GlobalMeatNews.com|date=24 March 2016}}</ref>

In October 2015 a case of BSE was confirmed at a farm in Carmarthenshire in Wales.<ref>{{Cite web|url=https://www.bbc.co.uk/news/uk-wales-34461158|title=BSE 'mad cow disease' case from Carmarthenshire|website=BBC|date=6 October 2015|language=en-GB}}</ref> In October 2018, a case of BSE was confirmed at a farm in [[Aberdeenshire]], Scotland, the first such case in Scotland in a decade.<ref>{{Cite web|url=https://www.theguardian.com/uk-news/2018/oct/18/bse-case-found-on-aberdeenshire-farm|title=Movement ban imposed on Aberdeenshire farm following BSE case| vauthors = Carrell S |date=2018-10-18|website=the Guardian|language=en|access-date=2018-10-18}}</ref> The case was believed to be an isolated one, but four other animals from the same herd were being culled for precautionary reasons.<ref>{{Cite news|url=https://www.bbc.com/news/uk-scotland-north-east-orkney-shetland-45901043|title='Mad cow disease' at Scottish farm|date=2018-10-18|work=BBC News|access-date=2018-10-18|language=en-GB}}</ref> Scottish officials confirmed that the case had been identified as part of routine testing and that the diseased cow had not entered the human food chain.<ref>{{Cite news|url=https://news.sky.com/story/mad-cow-disease-case-confirmed-on-farm-in-scotland-11528621|title=Farm locked down after mad cow disease found in Scotland|work=Sky News|access-date=2018-10-18|language=en-GB}}</ref>

A number of other countries had isolated outbreaks of BSE confirmed, including Spain, Portugal, Belgium and Germany.<ref name="Economist" />

====The ban on British beef====
The BSE crisis led to the [[European Union]] (EU) banning exports of British beef with effect from March 1996; the ban lasted for 10 years before it was finally lifted on 1 May 2006<ref name="BBC-3-May-2006">{{cite news |url=http://news.bbc.co.uk/1/hi/4967480.stm |work=BBC News |title=End to 10-year British beef ban |date=3 May 2006}}</ref> despite attempts in May through September 1996 by British prime minister [[John Major]] to get the ban lifted. The ban led to trade disputes between the UK and other EU states, dubbed the "beef war" by media.<ref>{{cite news |url=https://money.cnn.com/1999/10/22/europe/beef/ |title=EU beef war escalates |publisher=[[CNNfn]] |date=22 October 1999 |access-date=4 June 2018}}</ref> Restrictions remained for beef containing "vertebral material" and for beef sold on the bone.<ref name="BBC-3-May-2006"/> France continued to impose a ban on British beef illegally long after the European Court of Justice had ordered it to lift its blockade, although it has never paid any fine for doing so.<ref name="Standard" />

[[Russia]] was proceeding to lift the ban sometime after November 2012 after 16 years; the announcement was made during a visit by the UK's chief veterinary officer [[Nigel Gibbens]].<ref>{{cite news |url=https://www.bbc.co.uk/news/business-20454206 |title=Russia to lift 16-year ban on British beef and lamb |date=22 November 2012 |work=BBC News |access-date=4 June 2018}}</ref>

An exception was agreed{{When|date=February 2024}} for beef from Wales bound for the Dutch market, previously an important market for Northern Irish beef. Of two approved export establishments in the United Kingdom in 1999, one was in Scotland&nbsp;– an establishment to which live beef was supplied from Northern Ireland. As the incidence of BSE was very low in Northern Ireland&nbsp;– only six cases of BSE in 1999&nbsp;– partly due to the early adoption of an advanced herd tagging and computerization system in the region, calls were made to remove the EU ban on exports with regard to Northern Irish beef.<ref>[https://publications.parliament.uk/pa/cm199900/cmselect/cmniaf/62/6205.htm UK Parliament website] Select Committee on Northern Ireland Affairs Second Report</ref><ref>{{cite web | title=Northern Ireland (BSE) (Hansard, 10 February 2000) | website=api.parliament.uk | date=2000-02-10 | url=https://api.parliament.uk/historic-hansard/commons/2000/feb/10/northern-ireland-bse#column_393 | quote=My right hon. Friend will be aware that the Ulster Farmers Union has stated: On science and on fact we qualify as a low incidence region. There were, I believe, only six cases of BSE in Northern Ireland in 1999.|access-date=2019-10-12}}</ref>

Wildcat bans from countries known to have BSE were imposed in various European countries, although these were mostly subsequently ruled illegal. ''[[The Economist]]'' noted, "Unfortunately, much of the crisis in Europe can be blamed on politicians and bureaucrats. Even while some European countries were clamouring for bans on British beef, they were ignoring warnings from the European Commission about how to avoid the spread of BSE in their own herds."<ref name="Economist">{{cite news |title=Europe's mad cows |url=http://www.economist.com/node/436033 |access-date=23 September 2017 |newspaper=[[The Economist]] |date=28 November 2000}}</ref>

==History==
Different hypotheses exist for the origin of BSE in cattle. One hypothesis suggests it may have jumped species from the ''[[scrapie]]'' disease in sheep, and another hypothesis suggests that it evolved from a rare spontaneous form of "mad cow disease" that has been seen occasionally in cattle for many centuries.<ref>{{cite journal| vauthors = MacKenzie D |date=17 March 2007| title = New twist in tale of BSE's beginnings| journal = New Scientist| issue = 2595| url = https://www.newscientist.com/article/mg19325954.400-new-twist-in-tale-of-bses-beginnings.html| access-date = 20 June 2009| doi = 10.1016/S0262-4079(07)60642-3| volume = 193| pages = 11}}</ref><ref>{{cite journal | vauthors = Huor A, Espinosa JC, Vidal E, Cassard H, Douet JY, Lugan S, Aron N, Marín-Moreno A, Lorenzo P, Aguilar-Calvo P, Badiola J, Bolea R, Pumarola M, Benestad SL, Orge L, Thackray AM, Bujdoso R, Torres JM, Andreoletti O | display-authors = 6 | title = The emergence of classical BSE from atypical/Nor98 scrapie | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 116 | issue = 52 | pages = 26853–26862 | date = December 2019 | pmid = 31843908 | pmc = 6936354 | doi = 10.1073/pnas.1915737116 | bibcode = 2019PNAS..11626853H | doi-access = free }}</ref> In the fifth century BC, [[Hippocrates]] described a similar illness in cattle and sheep, which he believed also occurred in humans.<ref>{{cite journal | vauthors = McAlister V | title = Sacred disease of our times: failure of the infectious disease model of spongiform encephalopathy | journal = Clinical and Investigative Medicine | volume = 28 | issue = 3 | pages = 101–4 | date = June 2005 | pmid = 16021982 | url = http://works.bepress.com/vivianmcalister/10/ }}</ref> [[Vegetius|Publius Flavius Vegetius Renatus]] recorded cases of a disease with similar characteristics in the fourth and fifth centuries AD.<ref>{{cite book | title = Digesta Artis Mulomedicinae | author = Flavius Vegetius Renatus | work = Centre Traditio Litterarum Occidentalium | publisher = Turnhout Brepols Publishers | date = 2010 | oclc = 720028527 }}</ref>

In more recent UK history, the official BSE inquiry (published 2000) suggested that the outbreak there "probably arose from a single point source in the southwest of England in the 1970s".<ref name=Prusiner2001/>

== See also ==
* [[Mad cow crisis]]
* [[Prion]]

== References ==
{{Reflist}}

== External links ==
{{sisterlinks|d=Q154666|s=no|v=no|voy=no|b=no|q=no|n=Category:Bovine spongiform encephalopathy|c=Category:Bovine spongiform encephalopathy|m=no|mw=no|species=Prions}}
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* {{Curlie|Health/Animal/Conditions_and_Diseases/Transmissible_Spongiform_Encephalopathy/Bovine_Spongiform_Encephalopathy/}}
* World Organisation for Animal Health: [https://www.woah.org/en/disease/bovine-spongiform-encephalopathy/ BSE situation in the world and annual incidence rate]
* [http://webarchive.nationalarchives.gov.uk/20090505194948/http://www.bseinquiry.gov.uk/index.htm UK BSE Inquiry Website, Archived at The National Archives]

{{Beef}}
{{Prion diseases}}
{{Eradication of infectious disease}}
{{Authority control}}

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