In the 1990s, the world watched in horror as a terrible disease swept the English cattle industry. An illness that turned victims’ brains to mush, “mad cow disease,” or bovine spongiform encephalopathy, was a nightmare and one that was a disaster for Britain in more ways than one.
The Very Beginning, and the First Mishandling in 1985
In 1985, one cow in Southern England started showing some strange symptoms. The cow had tremors and seemed uncoordinated. A country veterinarian was called and decided that the cow seemed to be suffering from scrapie, a well-known condition that had been seen for more than 100 years.
Now scrapie is a fatal, degenerative condition in sheep that is quite serious. It is categorized as a transmissible spongiform encephalopathy, which means that it can spread in a flock quite quickly, affecting the brains of a great many animals. At the time, however, there was no evidence that it could be transmitted from animals to humans.
So at this point in 1985, the British government chose to downplay any risk. The British agriculture minister went so far as to make a public announcement on television that British beef was safe. He had his four-year-old daughter eat a hamburger as part of the broadcast on national television to make his point.
Ten Years Later
If that had been all, well, you wouldn’t be reading about it now, would you?
That wasn’t all. By 1995, nearly 100,000 cows were infected with the spongiform encephalopathy. The disease in cows, then, called bovine (meaning related to cattle) spongiform (causing holes in tissue like a sponge) encephalopathy (an infection of the brain), shortened to BSE, was then believed to be causing humans to fall ill.
Victims were initially diagnosed with depression, but then developed symptoms similar to Parkinson’s disease: twitching and loss of coordination.
Unlike with Parkinson’s patients, however, humans who had contracted the encephalopathy died within 14 months, though they had all been young and otherwise healthy adults.
The illness in humans was named vCJD, or variant Creutzfeldt-Jakob disease. Researchers posited that when these victims ate the meat of cattle infected with BSE, they would contract vCJD, which inevitably manifests symptoms of dementia and then causes death. (The symptoms of dementia are what give the disease the nickname “mad cow”).
What Causes “Mad Cow”
Scientists researching the newly discovered condition saw similarities with another illness known as Kuru, a disease of the people of a specific tribe of the Highlands of Paupau New Guinea. People of this tribe had the custom of eating the brains of dead relatives who were infected with the disease, thereby spreading the illness, which carried similar symptoms.
Kuru, along with BSE and vCJD, all belong to the same family of diseases caused by prions. Unlike other diseases caused by bacteria, viruses or fungi, prions represent a new class of infectious agents.
Prions are free-floating, replicating proteins that attack cells. Researchers have found that, terrifyingly, they have a special appetite for brain and nerve cells, so the diseases they cause result in neurological declines.
Scientists believe that when infected sheep were ground up into feed and fed to beef cattle, cattle became infected. Then, when humans ate the infected beef, they became infected. This was an entirely new disease vector and way of thinking about how diseases could be passed from species to species that was unique to the prion.
The “Mad Cow” Epidemic: BSE and vCJD Combined
In the years from 1995 to 2000, 177,500 cases of BSE were reported in British beef cattle across the United Kingdom. Hundreds of thousands of cattle had to be slaughtered in order to stop the spread of the highly infectious disease.
In humans, 88 cases of vCJD were confirmed, and all 88 people with the disease died.
British beef was banned across the world for years, and the entire British meat industry went through drastic reform. Cattle are no longer fed animal remains, and veterinarians are constantly vigilant for new disease symptoms.
Ultimately, it was the terrifying nature of the newly discovered disease agent, the terrible effects of the disease and the whole set of unknowns surrounding the nature of the illness, where it was coming from, how it was transmitted and how it could be stopped that made the panic so intense. We hope, with the benefit of hindsight, that we have learned lessons on how to confront similar new challenges in the future.