In scientific terms Bovine Spongiform Encephalopathy (BSE) and variant Creutzfeldt-Jakob Disease (vCJD) are Transmissible Spongiform Encephalopathies (TSEs). Put simply this means that the diseases can be passed on to animals or humans through eating contaminated tissue. Once it takes hold, the disease produces innumerable microscopic holes in the brain by the production of an abnormal protein (misfolded prions). This gives it a spongy appearance when analyzed at autopsy.
In 1985 vets and farmers across Britain began to notice that a large number of cows were displaying erratic behavior – losing coordination, rolling around as if drunk and eventually dying. Autopsies on the dead animals showed alarming similarity in brain damage to the sheep disease scrapie. A disease, it seemed, had crossed species. This discovery had a devastating effect on the British beef industry. The public were treated to the spectacle of the Agriculture Secretary, John Selwyn Gummer, feeding a beef burger to his daughter and declaring British beef safe to eat. The rest of the world was not so sure and most countries banned imports, costing the UK economy billions of pounds. All herds where the disease was present were slaughtered.
Just over a decade later, the worst fears were realized when it was found that BSE could affect humans in the form of vCJD and that the disease had once again jumped a species barrier. In that time more than five million cattle had been destroyed across Europe and cattle over 30 months old had been removed from the food chain. Though these measures will probably prevent future cases of vCJD, its long Incubation period may mean we are looking at the tip of an iceberg. Diagnosis can only be made after death, and research from America shows that many deaths that were previously thought to be from Alzheimer’s may in fact have been caused by vCJD.
When: BSE: 1985 to present; vCJD: 1996 to present
Where: Britain has been worst affected, but there have been cases of both diseases across Europe, North America and Japan, in countries where cattle were fed hay and soya the diseases are non-existent.
Death toll: 180,000 cattle died from BSE in the UK. The annual death toll from vCJD has stabilized at around 20, but it is highly likely that this figure is an underestimate.
You should know: in Papua New Guinea in the mid 20th century there was an outbreak of laughing disease, known locally as Kuru. It is believed that the disease was spread via cannibalistic practices where it was traditional to eat the brains of the dead to preserve their spirit. The practice is now taboo and the fatal disease has been eradicated. Studies of its pathology have given us vital clues in the understanding of all Transmissible Spongiform Encephalopathies.