Posts falsely claiming that the areas of the country that voted for Brexit are the same areas affected by mad cow disease outbreaks in 1992 have been shared thousands of times on social media.
While the posts have been circulating online since 2016, with many versions shared several years ago, the claim has recently picked up traction again after being reposted to X (formerly known as Twitter) and Facebook.
Some of the posts simply show a graphic of two maps, while others use the same graphic apparently projected onto a large screen during a lecture.
Both show two maps side-by-side, one with blue and yellow colouring and the other in different shades of grey. The grey map is labelled “1992 - mad cow disease outbreak areas”, while the other is labelled “2016 - Brexit referendum results”.
The two maps appear to show a perfect overlap between the areas that voted to leave the European Union in 2016 and those that suffered mad cow disease outbreaks in 1992—implying that leave voters were suffering from a condition that affects the brain.
But, as other fact checkers have written, the reason these two maps align so exactly is that they are the same map. The blue and yellow version is a screenshot of the BBC’s EU referendum results map from 2016, while the other is exactly the same image just edited into greyscale.
The graphic shared online would suggest there were no cases of mad cow disease in Scotland (which voted to remain in the EU) in 1992. As records from the time show, this is not true, though case numbers were relatively low in Scotland.
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What is mad cow disease?
Mad cow disease is the common name for a brain disease called Bovine spongiform encephalopathy (BSE), that can infect cattle, sheep and goats. It was first discovered in cattle in 1986.
If humans eat infected meat it can result in serious illness and death from a human variant of the disease. This is called variant Creutzfeldt-Jakob Disease (vCJD), with the link between the two diseases discovered in 1996.
Strict controls have since been put in place to prevent meat from infected cattle entering the food chain. However, the average time it takes for symptoms of vCJD to occur after infection is still unclear—it could be very long (more than a decade) in some people, meaning those exposed to infected food before the controls were put in place could still develop the disease.
Symptoms of CJD include loss of intellect and memory, changes in personality, loss of balance and coordination, slurred speech, vision problems, abnormal jerking movements and progressive loss of brain function and mobility. Most people with CJD die within a year of the symptoms starting.
Since 1995, 178 people are known to have died of definite or probable vCJD in the UK.