The United Kingdom BSE outbreak was a major epidemic of bovine spongiform encephalopathy (BSE; commonly known as "mad cow disease"), an invariably fatal neurodegenerative disease in cattle, and its human form, variant Creutzfeldt–Jakob disease (vCJD). As of April 2023, 183,325 BSE cases in cattle and 178 human cases of vCJD have been reported in the United Kingdom.
The outbreak saw the agricultural industry cull over 4.4 million cattle in an effort to contain the disease, and British beef exports were banned by a number of countries including the European Union, with some bans remaining in place until 2020. It also caused a public health crisis and a political scandal, when vCJD was linked to the consumption of beef contaminated with prions—the infectious agent associated with BSE and other transmissible spongiform encephalopathies (TSEs).
The practice of supplementing cattle feed with meat-and-bone meal, which was made from the remains of animals including other cattle, exacerbated the initial spread of BSE. The zoonotic variant of the disease, vCJD, is believed to have been transmitted to humans through mechanically recovered meat, which allowed infected brain, spinal cord, and offal tissues to enter the human food chain.
Background British agriculture in the twentieth century Agriculture was the leading sector of the British economy until the mid-nineteenth century, when the repeal of the Corn Laws led to an influx of imported food. This reliance on imports, compounded by an increasing population, left it strategically vulnerable during both world wars; after World War II, the government adopted protectionism to reduce this vulnerability and sustain rural areas. This was strengthened in some respects following the United Kingdom's accession to the European Communities in 1973, which provided subsidies to farms through the Common Agricultural Policy.
By the 1980s, cattle farming was the largest sector of British agriculture, comprising up to 38 per cent of the United Kingdom's entire agricultural production, and providing the vast majority of domestic demand for beef and dairy, as well as significant exports of beef and cheese. Cattle feeds derived from animal sources had been used since the early twentieth century, compounded by the inadequate production of vegetable protein feeds, and tariffs on grains, which made animal proteins more competitively priced.
Epidemiology of BSE
Bovine spongiform encephalopathy (BSE) belongs to a group of transmissible spongiform encephalopathies (TSEs), neurodegenerative diseases caused by the structural modification of a proteinaceous agent mainly found in nervous tissue, the prion (PrPC) protein. The form of protein (PrPSc) which is associated with TSEs is also resistant to denaturation, and there is debate as to its exact role in causing prion diseases.
Clinical symptoms of BSE include abnormal behaviour, poor co-ordination, weight loss, and eventual paralysis. The incubation period for classical BSE is 4–6 years, and after the onset of symptoms the animal deteriorates until death, which is usually within 3 months.
Whilst the origin of the disease remains uncertain, some earlier theories suggested that it came from the infection of cattle with scrapie, a TSE found in sheep. However, scrapie is distinguishable from BSE in the molecular profile and deposition patterns of PrPSc prions.
The spread of BSE was only amplified by the supplementation of dairy cattle feeds with meat-and-bone meal (MBM), made using waste products from animal carcasses, including the remains sheep and cattle. In the late 1970s, tallow became less expensive, and hydrocarbons were largely removed from the rendering process, resulting in a MBM product in which infectious material may have remained active. That beef herds were given such feeds less than dairy herds ultimately proved immaterial; as most British beef came from dairy cattle.
Outbreak
Emergence
The first suspected case of BSE was reported by a veterinarian who visited a farm near Midhurst, West Sussex, on 22 December 1984. Following the death of six cattle, the remains of another cow on the farm underwent a post-mortem examination by the Central Veterinary Laboratory in September 1985, which identified spongiform change.
The disease was first identified as a subacute spongiform encephalopathy in November 1986, following additional tests, however the Ministry of Agriculture, Fisheries and Food (MAFF) was not informed until June 1987. By November 1987, there were 92 suspected cases in 53 herds, and 21 cases had been confirmed.
Government response In June 1988, the Southwood Committee, officially the Working Party on Bovine Spongiform Encephalopathy, chaired by zoologist Richard Southwood, recommended a number of control measures that could mitigate the risk of BSE entering the food chain. In the summer of 1988, the MAFF announced a ban on MBM, and introduced a slaughter policy, initially with 50 per cent compensation, for all livestock showing symptoms of BSE.
In November 1989, high risk material, specified bovine offals (SBO), was banned for human consumption. The following year, there was an increase in reported BSE cases after the government announced it would pay full compensation for slaughtered animals, leading to concerns that large numbers of BSE infected cattle had entered the human food chain.
The Southwood Report, published in February 1989, stated that it was "most unlikely that BSE will have any implications for human health", whilst its recommendations led to the foundation of the National CJD Surveillance Unit in 1990, which monitored changes in the nature of Creutzfeldt–Jakob disease (CJD) which could be related to BSE.
Spread to other animals Pet food manufacturers also stopped using high-risk materials, however, on 10 May 1990, it was reported that a Siamese cat had been diagnosed with a BSE-like disease, challenging the assumption that BSE could not cross the species barrier through consuming infected material. TSEs were also later found in exotic zoo animals including nyala, greater kudu, and Arabian oryx.
Later that month, Donald Acheson, the government's Chief Medical Officer (CMO), issued a statement claiming that beef was safe to eat, and John Gummer, the Environment Secretary, appeared in front of cameras encouraging his daughter to eat a beef burger, in an attempt to reassure the public.
The epizootic peaked in 1992–1993 when the total number of cases reached 100,000; there were 37,280 confirmed cases (affecting three in every thousand cattle) in 1992, and more than 300 cases were identified each week in 1993. A reinforced feed ban was later introduced on 31 July 1996, which prohibited the feeding of any animal-derived feed to all types of livestock.
The human variant (vCJD)
In March 1993, the government's assurances were further undermined when The Lancet reported that a dairy farmer had died from CJD, a rare and fatal spongiform encephalopathy which occurs sporadically, and typically in older people.
By late 1995, another three farmers had been diagnosed with CJD, which was dismissed as having been the result of sporadic CJD, although the disease was also being observed in ten younger patients. The first recognised death from variant Creutzfeldt–Jakob disease (vCJD) was that of Stephen Churchill, a 19-year-old from Devizes, who died on 21 May 1995, although the government said there was 'insufficient evidence' to link BSE and CJD.
In November 1995, MAFF banned mechanically recovered meat (MRM), which contained the spinal column from cattle, and was used in pies and hamburgers.
It was not until 8 March 1996 that the Spongiform Encephalopathy Advisory Committee (SEAC) was contacted by the National CJD Surveillance Unit, who identified the novel form of the disease and linked it to the consumption of BSE-infected meat. On 20 March, Stephen Dorrell, the health secretary, announced to the House of Commons that SEAC had found this new variant, and concluded that the disease was most likely related to eating infected meat.
Between 1997 and 1999, the sale of beef on the bone was banned by the government, after evidence arose that nerve endings on beef bones and bone marrow could be infected. By August 2000, 63 deaths had been attributed to vCJD, and there were 12 current cases. As of January 2024, the National CJD Surveillance Unit has identified 178 people (with the most recent case in 2016) who have died from the disease.
Recent cases By April 2023, there were a total of 183,325 confirmed cases of classical and atypical BSE recorded in the United Kingdom, including 184 cases in BARB (born after the reinforced feed ban) cattle. The atypical form has not been found to infect humans. The most recent case was found in August 2026 on a farm in Dumfries and Galloway. Effects
Economic cost The agricultural sector faced an economic crisis after the zoonotic nature of BSE was revealed in March 1996, causing domestic beef consumption to fall by 40% and resulting in the closure of 148 abattoirs. In an effort to control the epizootic, over 4.4 million cattle were slaughtered, with the total public expenditure on control measures valued at £4.2 billion. The crisis also damaged public trust in the government, leading to the creation of the independent Food Standards Agency (FSA) in 2000 to safeguard public health.
International restrictions Following the emergence of BSE, the United States banned the importation of cattle from the United Kingdom in 1989, and 499 cows that had been imported were killed, with a further 116 cows slaughtered in 1996. The European Union (EU) imposed a worldwide ban on exports of British beef in March 1996, causing export numbers to collapse from 242,000 tonnes in 1995 to 60,000 tonnes in 1996. The ban lasted for 10 years before being lifted on 1 May 2006, although restrictions remained on beef containing vertebral material or beef on the bone.
Similar restrictions remained across other markets for decades, including the United States until September 2020. China originally removed its import ban in 2018, a move the UK government estimated would be worth £250 million over five years, but reimposed the restriction in 2021 following an isolated case of BSE case in the UK.
BSE public inquiry On 22 December 1997, Agriculture Minister Jack Cunningham announced a BSE public inquiry (also known as the Phillips Inquiry) to investigate the history of the outbreak and the government's handling of the crisis up until 20 March 1996. The inquiry was chaired by Lord Phillips of Worth Matravers, alongside two other committee members, June Bridgeman and Malcolm Ferguson-Smith.
Over the course of nearly three years, the inquiry examined 3,000 documents, received written evidence from over 630 individuals, and heard testimonies from 333 witnesses. The panel also investigated two microbiologists; Richard Lacey and Harash Narang, who claimed their early warnings linking BSE and CJD had been dismissed by the government. The inquiry cost approximately £27 million, and submitted its final report in October 2000, which was published in full by then-Agriculture Minister Nick Brown.
The inquiry found interdepartmental rivalries between MAFF and the Department of Health (DoH), and was heavily critical of the government's reliance on scientific committees for policy-making. It also found violations of control measures including farmers using stockpiled MBM after the ban was in place, and evidence of cross-contamination in abattoirs; in 1991 environmental inspectors had found that 60 per cent of slaughterhouses they had visited failed to meet European hygiene standards.