Variant Creutzfeldt–Jakob disease (vCJD), formerly known as new variant Creutzfeldt–Jakob disease (nvCJD) and referred to colloquially as "Creutzfeldt–Jakob Disease", "mad cow disease" or "human mad cow disease" (to distinguish it from its BSE counterpart), is a fatal type of brain disease within the transmissible spongiform encephalopathy family. Initial symptoms include psychiatric problems, behavioral changes, and painful sensations. In the later stages of the illness, patients may exhibit poor coordination, dementia and involuntary movements. The length of time between exposure and the development of symptoms is unclear, but is believed to be years to decades. Average life expectancy following the onset of symptoms is 13 months.
It is caused by prions, which are misfolded proteins. Spread is believed to be primarily due to eating beef infected with BSE. Infection is also believed to require a specific genetic susceptibility. Spread may potentially also occur via blood products or contaminated surgical equipment. Diagnosis is by brain biopsy but can be suspected based on certain other criteria. It is different from typical Creutzfeldt–Jakob disease, though both are due to prions.
Treatment for vCJD involves supportive care. As of 2020, 178 cases of vCJD have been recorded in the United Kingdom, due to a 1990s outbreak, and 50 cases in the rest of the world. The disease has become less common since 2000. The typical age of onset is less than 30 years old. It was first identified in 1996 by the National CJD Surveillance Unit in Edinburgh, Scotland. Controversial research by Harash Narang, who worked as a virologist at the Public Health Laboratory Service (PHLS) suggested a link between BSE and CJD as early as 1989.
Signs and symptoms Initial symptoms include psychiatric problems, behavioral changes, and painful sensations. In the later stages of the illness, patients may exhibit poor coordination, dementia and involuntary movements. The length of time between exposure and the development of symptoms is unclear, but is believed to be years. Average life expectancy following the onset of symptoms is 13 months.
Cause Tainted beef In Britain, the primary cause of vCJD has been eating beef tainted with bovine spongiform encephalopathy. A 2012 study by the Health Protection Agency found that around 1 in 2000 had abnormal prions present in appendix cells.
Jonathan Quick, instructor of medicine at the Department of Global Health and Social Medicine at Harvard Medical School, stated that bovine spongiform encephalopathy (BSE) is the first man-made epidemic, or "Frankenstein" disease, because a human decision to feed meat and bone meal to previously herbivorous cattle (as a source of protein) caused what was previously an animal pathogen to enter into the human food chain, and from there to begin causing humans to contract vCJD.
The risk of contracting vCJD from ingestion of cattle products has led to many countries banning the import of beef from countries where BSE has been known to occur, such as the ban on beef from the United States imposed by Japan, South Korea, Mexico, Canada, and other countries in 2003 immediately following the first reported case of BSE in American cattle. Stringent preventative and surveillance practices implemented since then to prevent the disease from entering the human and cattle food chains have caused some to conclude that such bans are unnecessary.
Blood products As of 2018, evidence suggests that there may be prions in the blood of individuals with vCJD, but this is not the case in individuals with sporadic CJD.
In 2004, a report showed that vCJD can be transmitted by blood transfusions. The finding alarmed healthcare officials because a large epidemic of the disease could result in the near future. A blood test for vCJD infection is possible but is not yet available for screening blood donations. Significant restrictions exist to protect the blood supply. The UK government banned anyone who had received a blood transfusion since January 1980 from donating blood. Since 1999 there has been a ban in the UK for using UK blood to manufacture fractional products such as albumin. Whilst these restrictions may go some way to preventing a self-sustaining epidemic of secondary infections, the number of infected blood donations is unknown and could be considerable. In June 2013 the government was warned that deaths, then at 176, could rise five-fold through blood transfusions.
On 28 May 2002, the United States Food and Drug Administration instituted a policy that excludes from blood donation anyone having spent at least six months in certain European countries (or three months in the United Kingdom) from 1980 to 1996. Given the large number of U.S. military personnel and their dependents residing in Europe, it was expected that over 7% of donors would be deferred due to the policy. Later changes to this policy first relaxed the restriction to a cumulative total of five years or more of civilian travel in European countries (six months or more if military) then, in 2022, removed it entirely.
In New Zealand, the New Zealand Blood Service (NZBS) in 2000 introduced measures to preclude permanently donors having resided in the United Kingdom (including the Isle of Man and the Channel Islands) for a total of six months or more between January 1980 and December 1996. The measure resulted in ten percent of New Zealand's active blood donors at the time becoming ineligible to donate blood. In 2003, the NZBS further extended restrictions to permanently preclude donors having received a blood transfusion in the United Kingdom since January 1980, and in April 2006, restrictions were further extended to include the Republic of Ireland and France. The restriction was rescinded in late February 2024.
In Canada, individuals were formerly ineligible to donate blood or plasma if they had spent a cumulative total of three months or more in the mainland UK or its Crown Dependencies or six months or more in Saudi Arabia from January 1, 1980, through December 31, 1996. They were also ineligible if they had spent a cumulative total of five years or more in France or the Republic of Ireland from January 1, 1980, through 31 December 2001. These restrictions were removed by December 2023.
In Poland, anyone having spent cumulatively six months or longer between 1 January 1980 and 31 December 1996 in the UK, Ireland, or France is permanently barred from donating.
In France, anyone having lived or stayed in the United Kingdom a total of over one year between 1 January 1980 and 31 December 1996 is permanently barred from donating.
In the Czech Republic, anyone having spent more than twelve months in the UK or France between 1980 and 1996 or received transfusion in the UK after the year 1980 is not allowed to donate blood.
In Finland, anyone having lived or stayed in the mainland United Kingdom or its Crown Dependencies for a total of over six months between 1 January 1980 and 31 December 1996 was formerly barred from donating; the restriction was removed in March 2026.
Sperm donation In the U.S., the FDA has banned import of any donor sperm, motivated by a risk of variant Creutzfeldt–Jakob disease, inhibiting the once popular import of Scandinavian sperm. Despite this, the scientific consensus is that the risk is negligible, as there is no evidence Creutzfeldt–Jakob is sexually transmitted.
Occupational contamination In France, the last two victims of variant Creutzfeldt–Jakob disease, who died in 2019 and 2021, were research technicians at the National Research Institute for Agriculture, Food and the Environment (INRAE). Émilie Jaumain, who died in 2019, at the age of 33, had been the victim of a work accident in 2010, during which she had pricked herself with a tool contaminated with infected brain. The efficacy of this route of contamination was subsequently demonstrated in primates. Pierrette C., who died in 2021, had been victim of the same type of work accident; after her diagnosis, a moratorium was initiated in all French laboratories on research activities on infectious prions. In March 2022, INRAE recognized the occupational cause of these two deaths, raising serious questions about the safety of personnel in these laboratories. Inspections noted failures in the protection of agents in the face of this deadly risk, and the long incubation period of this disease led to fears of new cases in the future.
False link to consumption of squirrel brains A 1997 article in The Lancet postulated that a connection existed between the consumption of squirrel brains and CJD. Media reporting on this myth was reignited in 2018 when an article by Live Science reported on a Rochester man who was alleged to have contracted vCJD from his consumption of squirrel brains.
Creutzfeldt-Jakob Disease and eating squirrel brains, the 1997 article by the Lancet has been almost entirely discredited due its lack of scientific evidence and false statistical assumptions. An article published by the New Yorker in the year 2000, shortly following the release of the 1997 Lancet article was one of the first to report on the lack of scientific footing for the Lancet's study. It reported that many issues revolved around the researchers conflating statistical correlation with epidemiological causation. This is especially important with a slow moving, and hard to trace disease like vCJD, a point emphasized in their statement that "the Lancet study blundered blithely into such statistical pitfalls".
One of the most direct and robust dismissals of the connection between consumption of squirrel brains and vCJD was a statement made in 2018 by the Creutzfeldt–Jakob Disease Foundation, addressing both the 1997 Lancet article and Live Science article. This statement was part of a press release, reading that “The previous ProMed commentary mentioned a 1997 Lancet report that hypothesized about a potential link between consumption of squirrel brains and CJD; there was no mention of vCJD in that report. Since that brief report, there has been no convincing evidence found suggesting that the consumption of squirrel meat, brain or otherwise, is a risk factor for any prion disease. While prion diseases have been identified in several other types of mammals, they have never been identified in squirrels. Without additional experimental or epidemiological evidence, a link between consumption of squirrel brain and human prion disease is unjustifiably speculative.”
An article by Democrat and Chronicle provided another primary source debunking this myth. This report included interviews with the epidemiologist overseeing the 2018 case reported on by Live Science. In a statement, Dr. Emil Lesho stated that “We never thought squirrel brains”.
Despite the fact that there is no scientific basis for this connection, much reporting surrounds both the 1997 Lancet article, and the 2018 Live Science article, most echoing their statements. Although eating the nervous tissue of any mammal is not recommended due to the risk of disease transmission, fundamentally, there is no robust scientific evidence that the consumption of squirrel brains presents a risk factor for vCJD at any level, or has ever caused a case of vCJD in humans.
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